Carbide Saw Manual By Lowell C. Freeborn

Carbide Saw Manual
By
Lowell C. Freeborn
Copyright 1977 by Lowell C. Freeborn
Freeborn Tool Company
P.O. Box 6246
Spokane, WA 99217
800-523-8988 Toll Free
509 484-3033 Local
509-484-9932 Fax
2
FORWARD
This manual was prepared for the purpose of helping anyone interested in the servicing of
carbide-tipped circular saw blades. If it helps in any small way, it will be most gratifying
to the author.
Lowell c. Freeborn
Editor’s Comments
As I write this it is 2005 and this book is twenty-eight years old. It is still an extremely
good book and is much better, in many ways than anything else available.
The copy I had to work with is a copy of a copy and so on. I have used as much original
material as possible. I think the saw blade pictures are sufficient especially since the
accompanying drawings are excellent.
I have never had the pleasure of meeting Lowell Freeborn but several things have become
clear in this project. He has a true gift for explaining very complicated matters in a very
simple and clear manner. He is also extremely thorough and exacting. I reconstructed
his chart on decimal, fraction and metric conversion. I originally used the common
conversion figure of 25.4 to convert inches to millimeters and the numbers didn’t match
Mr. Freeborn’s. It was only when I used the more correct number of 25.4000508001016
that my numbers matched his. The comment has been made that this is an unnecessary
level of accuracy. However it seems that one way to build exceptionally good tools, as
Freeborn did and still does, is to take great pains at every part of the manufacturing
process.
Sincerely,
Mr. Thomas J. Walz
President
Northwest Research Institute, Inc. / Carbide Processors, Inc.
3847 S. Union Ave.
Tacoma, WA. USA 98409
800 346-8274
Ph (253) 476 1338
Fax (253) 476 1321
[email protected]
www.carbideprocessors.com
3
TABLE OF CONTENTS
Saw Terms And Ordering Information ……. 4
Saw Gauge Equivalents……………………. 4
Decimal And Millimeter Equivalent Chart… 6
Carbide Grade Charts………………………. 7
Saw Tooth Load……………………………. 9
Edger Saw Design Calculations……………. 10
Triple Chip Grinding Chart…………………11
Grinding Shop Order Flow………………… 12
Saw Steel……………………………………13
Carbide………………………………………14
Diamond Grinding…………………………..17
Brazing………………………………………19
Gumming……………………………………22
Hammering………………………………….24
Grinding Carbide Saws…………………….. 29
Face Grinding……………………………….29
Side Grinding……………………………….32
Top Grinding………………………………..35
Carbide Saw Sharpening Guidelines………..36
Trim And Cutoff Saws……………………...36
Rip Saws And Edger Saws………………….37
Aluminum And Metal Saw………………….38
Saw Styles………………………………….. 38
Flat Top Rip Style………………………….. 39
Safety Rip Style……………………………. 40
Contractor's Combination Style……………. 41
Planer Combination Style………………….. 42
Plymaster Style…………………………….. 43
Alternate Top Bevel……………………….. 44
Triple Chip Style…………………………… 45
Three And One Combination………………. 46
Locked In Tooth…………………………… 47
Thin Rim…………………………………… 48
Controlled Chip Metal…………………….. 49
Face Bevel………………………………….. 50
V Tooth…………………………………….. 51
Chip Breaker……………………………….. 52
Dado Set……………………………………. 53
Problems And Answers……………………..54
Rip Saws…………………………………… 54
Crosscut Saws ………………………………54
Aluminum Rip Saws……………………….. 55
Saw Noise………………………………….. 55
4
SAW TERMS AND ORDERING INFORMATION
TO ORDER
TO ORDER A STANDARD SAW
Specify 1) Diameter, 2) Eye Size, 3) Number of teeth,
4) Catalogue style and number if available.
State side clearance, dish angle, and back angle.
EXAMPLE: Sides .035" x 2o X 3o
TO ORDER A SPECIAL SAW:
Specify 1) Diameter, 2) Number of Teeth, 3) Eye Size, 4) Plate Gauge, 5) Kerf Width, 6)
Hook Angle, 7} Side Angles, 8) Number of Expansion Slots, 9) Pin Holes or Bolt
Holes, with the size of hole and the bolt circle they are to be drilled on, and 10) The side
of the saw countersunk holes are on. (Furnish a rubbing of holes and tooth style if
possible.)
5
SAW GAUGE EQUIVALENTS
Carbide Saw Plates
are generally made to a decimal thickness
and the thickness may fall
in between the gauge sizes.
DECIMAL EQUIVALENT CHART
Fractions, Decimals and Millimeters
convert inches to millimeters
25.4000508001016
Inches
Inches
MM
Fractions Decimals Millimeters
--0.0004
0.010
--0.004
0.102
--0.01
0.254
1/64
0.0156
0.396
--0.0197
0.500
--0.0295
0.749
1/32
0.03125
0.794
--0.0394
1.001
3/64
0.0469
1.191
--0.059
1.499
1/16
0.062
1.575
5/64
0.0781
1.984
--0.0787
1.999
3/32
0.094
2.388
--0.0984
2.499
7/64
0.109
2.769
--0.1181
3.000
1/8
0.125
3.175
--0.1378
3.500
9/64
0.141
3.581
5/32
0.156
3.962
0.1575
4.001
11/64
0.172
4.369
--0.177
4.496
3/16
0.1875
4.763
--0.1969
5.001
13/64
0.203
5.156
--0.2165
5.499
7/32
0.219
5.563
15/64
0.234
5.944
--0.2362
5.999
1/4
0.25
6.350
--0.2559
6.500
17/64
0.2656
6.746
--0.2756
7.000
9/32
0.281
7.137
--0.2953
7.501
19/64
0.297
7.544
5/16
0.312
7.925
--0.315
8.001
21/64
0.328
8.331
--0.335
8.509
11/32
0.344
8.738
--0.3453
8.771
23/64
0.359
9.119
--0.374
9.500
3/8
0.375
9.525
25/64
0.391
9.931
--0.3937
10.000
13/32
0.406
10.312
0.413
--10.490
27/64
0.422
10.719
--0.4231
10.747
7/16
0.438
11.125
29/64
0.453
11.506
15/32
0.469
11.913
--0.4724
11.999
Inches
Inches
MM
Fractions Decimals Millimeters
25/32
0.7810
19.837
--0.7874
20.000
51/64
0.7970
20.244
13/16
0.8125
20.638
--0.8268
21.001
53/64
0.8280
21.031
27/32
0.8440
21.438
55/64
0.8590
21.819
--0.8661
21.999
7/8
0.8750
22.225
57/64
0.8906
22.621
--0.9055
23.000
29/32
0.9062
23.018
59/64
0.9220
23.419
15/16
0.9375
23.813
--0.9449
24.001
61/64
0.9530
24.206
31/32
0.9690
24.613
--0.9843
25.001
63/64
0.9844
25.004
--1.0000
25.400
--1.0236
25.999
1-1/32
1.0312
26.193
1-1/16
1.0620
26.975
--1.0630
27.000
1-3/32
1.0940
27.788
--1.1024
28.001
1-1/8
1.1250
28.575
--1.1417
28.999
1-5/32
1.1560
29.362
--1.1811
30.000
1-3/16
1.1875
30.163
1-7/32
1.2190
30.963
--1.2205
31.001
1-1/4
1.2500
31.750
--1.2598
31.999
1-9/32
1.2810
32.537
--1.2992
33.000
1-5/16
1.3120
33.325
--1.3386
34.001
1-11/32
1.3440
34.138
1-3/8
1.3750
34.925
--1.3779
34.999
1-13/32
1.4060
35.712
--1.4173
35.999
1-7/16
1.4380
36.525
--1.4567
37.000
1-15/32
1.4690
37.313
--1.4961
38.001
1-1/2
1.5000
38.100
1-17/32
1.5310
38.887
--1.5354
38.999
1-9/16
1.5620
39.675
--1.5748
40.000
1-19/32
1.5940
40.488
--1.6142
41.001
1-5/8
1.6250
41.275
6
Inches
Inches
MM
Fractions Decimals Millimeters
--2.1650
54.991
2-3/16
2.1875
55.563
--2.2047
55.999
2-7/32
2.2190
56.363
--2.2440
56.998
2-1/4
2.2500
57.150
2-9/32
2.2810
57.938
--2.2835
58.001
2-5/16
2.3120
58.725
--2.3228
58.999
2-11/32
2.3440
59.538
--2.3622
60.000
2-3/8
2.3750
60.325
--2.4016
61.001
2-13/32
2.4060
61.113
2-7/16
2.4380
61.925
--2.4409
61.999
2-15/32
2.4690
62.713
--2.4803
63.000
2-1/2
2.5000
63.500
--2.5197
64.001
2-17/32
2.5310
64.288
--2.5590
64.999
2-9/16
2.5620
65.075
2-19/32
2.5940
65.888
--2.5964
65.949
2-5/8
2.6250
66.675
--2.6380
67.005
2-21/32
2.6560
67.463
--2.6772
68.001
2-11/16
2.6875
68.263
--2.7165
68.999
2-23/32
2.7190
69.063
2-3/4
2.7500
69.850
--2.7559
70.000
2-25/32
2.7810
70.638
--2.7953
71.001
2-13/16
2.8125
71.438
--2.8346
71.999
2-27/32
2.8440
72.238
--2.8740
73.000
2-7/8
2.8750
73.025
2-29/32
2.9062
73.818
--2.9134
74.001
2-15/16
2.9375
74.613
--2.9527
74.999
2-31/32
2.9690
75.413
--2.9921
75.999
3
3.0000
76.200
3-1/32
3.0312
76.993
--3.0315
77.000
3-1/16
3.0620
77.775
--3.0709
78.001
3-3/32
3.0940
78.588
--3.1102
78.999
3-1/8
3.1250
79.375
--3.1496
80.000
Inches
Inches
MM
Fractions Decimals Millimeters
3-1/16
3.6875
93.663
--3.7008
94.001
3-23/32
3.7190
94.463
--3.7401
94.999
3-3/4
3.7500
95.250
--3.7795
95.999
3-25/32
3.7810
96.038
3-13/16
3.8125
96.838
--3.8189
97.000
3-27/32
3.8440
97.638
--3.8583
98.001
3-7/8
3.8750
98.425
--3.8976
98.999
3-29/32
3.9062
99.218
--3.9370
100.000
3-15/16
3.9375
100.013
3-31/32
3.9690
100.813
--3.9764
101.001
4
4.0000
101.600
4-1/16
4.0620
103.175
4-1/8
4.1250
104.775
--4.1338
104.999
4-3/16
4.1875
106.363
4-1/4
4.2500
107.950
4-5/16
4.3120
109.525
--4.3307
110.000
4-3/8
4.3750
111.125
4-7/16
4.4380
112.725
4-1/2
4.5000
114.300
--4.5275
114.999
4-9/16
4.5620
115.875
4-5/8
4.6250
117.475
4-11/16
4.6875
119.063
--4.7244
120.000
4-3/4
4.7500
120.650
4-13/16
4.8125
122.238
4-7/8
4.8750
123.825
--4.9212
124.999
4-15/16
4.9375
125.413
5
5.0000
127.000
--5.1181
130.000
5-1/4
5.2500
133.350
5-1/2
5.5000
139.700
--5.5118
140.000
5-3/4
5.7500
146.050
--5.9055
150.000
6
6.0000
152.400
6-1/4
6.2500
158.750
--6.2992
160.000
6-1/2
6.5000
165.100
--6.6929
170.000
6-3/4
6.7500
171.450
7
7.0000
177.800
--7.0866
180.000
--7.4803
190.000
7-1/2
7.5000
190.500
--7.8740
200.000
CARBIDE GRADE CHART
C-1 TO C-8 Machining Applications
Carbide
Manufacturers
Adamas
C-1
B
AMCARB
C-2
A
AM
PWX
D15
D13
B106
B168
7
C-3
PWX
AA
C-4
AAA
C-5
DD
5X
434
C-6
6X
D
C-7
7X
C
548
Titan 80*
C-8
CC
Titan 80*
B108
B211
B109
B221
B102
B207
B365*
370
78B
78
350
CA-606
CA-720
S2
B103
B104
B205
B245
350
78
320
CA-711
CA-704
S1P
FO2*
FT-5
FT-62
FT-6
FT-62
FT-7
FT-72*
TXH
T22
DMC32
T22
TXL
DMC35
T31
WF*
K2S
K3H
K4H
K45
K45
K5H
K7H
K7H
K165*
N60
N70
NM-93
N80
NM-93*
NM-95*
TE
TE
S-92
S-900
8T
5S
S-94
U70
U73
U73
U80
U88
VC-8
VC-83*
VC-85*
HV
VR-73
VR-65*
BESLEY-WELLES
B101
CARBOLOY
44A
883
860
883
905
895
999
895
320
370
78B
CARMET
CA-3
CA-7
CA-8
COROMANT
H20
H1P
K05
CA-610
CA-740
S6
S4
FIRTH-LOACH
FA-5
CA-4
CA-443
H1P
H13
H20
FA-6
FA-7
FA-8
H
HA
H-23
DMC21
HE
HF
K1
K6
C8735
K68
K68
K8
K11
MULTI METALS
NEWCOMER
OM1
N10
OM2
N20
OM3
N30
OM4
N40
4M5
N50
SINTERCAST
SPEEDICUT MITIA
FerroTic J
A
FerroTic J
B
C
C
FerroTic J
TTA
TALIDE
C-89
C-91
C-93
C-95
FerroTic J
TA10
TA5
S-880
9
9H
9C
9B
UNIMET
U10
U20
U30
U40
11T
9S
10T
U53
9S
10T
5S
U53
U60
VALENITE
VC-1
VC-3
VC-4
VC-125
VC-55
VC-125
VC-6
VC-7
VR WESSON
2A-68
VR-54
VC-2
VC-22
VC-28
2A-5
VR-54
2A-7
VR-52
2A-7
VR-65*
VR-75
WM
WA-141
WA-141
WA-159
CQ12
WA-2
WA-63
WA-149
CQ2
WA-35
WA-35
WA-4
WS
VR-77
VR-89
VR-75
WA-66
WA-5
VR-73
WH
HV
VR-65*
WA-147
WA-7
CQ3
CQ4
CY12
CY16
CY16
CY5
WICKALOY
N
H
HH
HHH
G8
WILLEY'S
E8
E6
E5
E3
X7A
X7A
945
8A
10A
FIRTH STERLING
FUTURMILL
KENNAMETAL
TUNGSTEN ALLOY
WALMET
WENDT-SONIS
FT-3
FT-4
FT-5
TO4
NTA
DMC30
DMC32
KM
K21
K2S
S-901
WA-5
WA-6
8A
CY14
CY2
T18*
GX
606
6A
320
5S
WA-8
CY31
T18*
FX
6AX
509
Cast Iron, Non-Ferrous and Non-Metallic Materials
Steel and steel alloys
C-1
Roughing
C-5
Roughing
C-2
General Purpose
C-6
General Purpose
C-3
Finishing
C-7
Finishing
C-4
Precision Finishing
C-8
Precision Finishing
Listings do not necessarily imply equivalency of various manufacturers’ grades
This chart is not to be considered an endorsement of or an approved list of any manufacturers’ products
* grades containing more than 50% Titanium Carbide
CARBIDE GRADE CHART
C-9 to C-19 Wear & Impact Applications
8
Carbide Grade Chart
C-9 to C-19 Machining Applications
Carbide
Manufacturers
Adamas
C-9
A
C-10
B
C-11
BB
C-12
BB
C-13
HD15
C-14
HD25
C-15
434
474
C-15A
474
GG
D13
D10
D5
D30
D20
D13
D50
D40
D50
D41A
D40
D65
D50
D41A
D80
D75
D41A
D43
D55
44A
883
895
CA-4
44A
779
55A
55B
55B
55A
190
77B
90
241
115
CA-12
CA-10
55A
779
115
CA-214
CA-11
CA-225
H05
H20
FA-6
H20
H25
FA-5
H35
H45
FA-3
G4
G5
S2
S6
FB-5
FB-4
FB-3
FT-8
FT-9
FM-3
FM-5
HA
H
HC
DC2
DC1
DCX
DC3
DC4
T89
T75
MPD2
K6
K96
K68
K95
K6
K96
3109
K92
K94
3109
K94
K96
3109
K92
K94
K90
K91
3109
KM
K162B
3365
3411
3047
MULTI METALS
NEWCOMER
SINTERCAST
OM3
N20
FerroTic C
OM2
N10
FerroTic C
1M2
1M12
OM1
1M13
FerroTic C
FerroTic C
FerroTic C
FerroTic C
SPEEDICUT MITIA
TALIDE
B
C-99
A
C-88
RD-7
C-80
H
C-85
M
C-80
XT
C-75
TA5
CT-28
TA10
S-880
TUNGSTEN ALLOY
9
9H
9M
9
9A
9A15
15C
9A15
9A20
15C
9A30
9A25
16G
16G
U10
VC-10
2A-68
2A-6
WA-10
U130
VC-13
VR-14
U140
VC-14
VR-15
VC-125
VR-89
VC-55
VR-87
WA-12
WA-13
WA-140
WA-14
WA-5
WA-64
WENDT-SONIS
CQ2
CQ12
CQ15
CQ13
CQ16
CX3
CX3
CQ13
WICKALOY
N
HW
D8
D13
U110
VC-11
2A-1
2A-3
WA-11
WA-138
WA-134
CQ14
CY4
D15
D20
U110
VC-12
VR-13
WALMET
U20
VC-9
2A-68
2A-5
WA-2
D13
D20
D25
X7
X7
WILLEY'S
E6
E8
E9
E16
W12C
E8
E16
E25
FBS
FBT
FBY
E9
AMCARB
BESLEY-WELLES
CARBOLOY
CARMET
COROMANT
FIRTH-LOACH
FIRTH STERLING
FUTURMILL
KENNAMETAL
UNIMET
VALENITE
VR WESSON
Wear Surface
C-9
No shock
C-10
Light shock
C-11
Heavy shock
C-16
569
783
502
DA210
C-17
HD25
HD257
C-18
190
608
4237
CA-815
CA-210
CA-225
CA-220
CA-815
C-19
D60
D70
D80
G5
FH-2
FH-3
FH-4
ND25
FIRTH
HEAVY
METAL
K90A
K90A
K91
K701
K801
K151A
K162B
K601
FerroTic C
FerroTic C
S45 &
S55
W10
W2
1M13
PSM
C-88-X
C-90-X
11C
RD7
C75
VC-11
VR-13
VR-14
WA-11
WA-12
VC-14
CR83
CT50
W
ALLOY
WA-200
WALTUNG
25H
30H
20H
WA-140
WA-14
D25
E25
Miscellanseous
C-15
Light cut hot flash weld removal
C-15A heavy cut flash weld removal
C-16
Rock bits
C-17
Cold header dies
Impact
C-18
Wear at elevated temperatures and / or
C-12
Light
resistance to chemical reactions
C-13
Medium
C-19
Radioactive shielding, counter balances
C-14
Heavy
and kinetic applications
Listings do not necessarily imply equivalency of various manufacturers’ grades
This chart is not to be considered an endorsement of or an approved list of any manufacturers’ products
9
SAW TOOTH LOAD
To arrive at the tooth load for a saw, you must first know how fast the board is feeding
into the saw in feet per minute, the revolutions per minute of the saw, and the number of
teeth in the saw.
Using the above information, "the formula to find the tooth load is: FEED IN: FEET PER
MINUTE TIMES 12 DIVIDED BY THE REVOLUTIONS PER MINUTE TIMES THE
NUMBER OF TEETH
Tooth Load = Feed in per minute x 12
RPM. x No. of Teeth
EXAMPLE:
50 F.P.M. x 12 = 600 / 3600 R.P.M. x 80 teeth = 288000.
600 / 288000 = .002 tooth Load
You will note that it is necessary to know the feed rate to arrive at the tooth load. This of
course means that you cannot figure the tooth load on saws fed by hand.
The tooth load you figure for a saw is only true if the saw is true. If the bore of the saw is
bad the saw will not run round. If the shaft is small the saw will not run round. And of
course the teeth must all dial indicate the same height and width for the tooth load to be
uniform.
If a saw has alternate top bevel teeth, you will have to double your tooth load figure.
Triple chip style saws also cut on every other tooth. In the case of combination saws, the
tooth load will also vary depending on the individual saw geometry.
•
•
•
•
•
Generally speaking, saws cross-cutting wood should not exceed .005 tooth load.
Saws ripping wood should not exceed .020 tooth load.
Saws cutting aluminum and other non-ferrous metal should not exceed .002 tooth
load.
When finer finish cuts are required, use less chip load.
Tooth load gives you a good place to begin when recommending a saw or trying
to solve a sawing problem.
10
EDGER SAW DESIGN CALCULATIONS
I. CALCULATING EDGER SAW TOOTH BITES
Formula:
Tooth Bite = Feed Speed (feet/min.) x 12
RPM x Number of Teeth
EXAMPLE:
Tooth bite =
150 x 12
1750 x 26
=
1800
45,500
=
.039”
II. CALCULATING REQUIRED GULLET CAPACITY
Formula:
Required Gullet = Tooth Bite x Depth of Cut x 1.30
Example:
Required Gullet = .039" x 6" x 1.30 = .304 sq. in.
III. DETERMINING GULLET CAPACITY ON EXISTING SAWS
Steps
1. Take- a rubbing of gullet shape
2. Place rubbing over 1/4" square engineering paper
3. Count the number of squares in the gullet area
4. Divide that number by 16 (16 is the no. of 1/4" squares per cubic inch)
5. Multiply this number by .70
6. This is your usuable gullet capacity
7. Compare this with the required area figured in #2 above.
Example:
Calculations:
Gullet Area (usable) = 10 = .625 x .70 = .437 Sq. In.
16
Note: This gullet has sufficient capacity for requirements in above examples.
11
TRIPLE CHIP GRINDING CHART
12
GRINDING SHOP ORDER FLOW
1. Receiving
Saws are marked with customer's name with electric etch or
engraving tool. Order is written giving any special instructions.
2. Cleaning
Saws are soaked in a solution of Oakite rust-stripper to loosen
pitch, gum, and aluminum.
3. Wash & Dry
Saws are washed with fresh water, then dipped in a water soluble
oil solution and dried.
4. Brazing
Saws are inspected and bad tips replaced as required, i'iote on
order.
5. Hammering
Saws are checked on a test runout arbor and hammered as required.
Note on order.
6. Face Grind
Saws are face sharpened. Note on order.
7. Side Grind
Saws are side ground as required. Note on order.
8 Top Grind
Saws are top ground as required. Note on order.
9. Clean
Saws are sand blasted lightly, polished with grit paper or a brush or
otherwise cleaned.
10. Inspect & Dip
Saws are inspected and dipped in hot plastic to protect them.
11 Shipping
Order is completed and saws prepared for shipping.
13
SAW STEEL
The steel in a saw blank must be high quality, machined, heat-treated and handled
properly.
There are two grades of steel most generally used in plates. These are plain carbon steel
and nickel alloy steel.
Plain carbon steel is difficult to heat-treat properly and consistently. Nickel steel is easier
to handle and gives good results.
Steel is generally known as Iron or Ferrite, and iron carbide compound known as
Cementite. The two mixed make Pearlite. In annealed, or soft steel, these elements are
separated in layers. When the steel is heated above its critical point, the elements merge
with each other and form Austenite. If cooled slowly it will return to its original state.
When the steel is cooled rapidly another transformation takes place changing the
Austenite to Martensite and making the material hard and brittle, depending on its carbon
content.
These changes are critical and affect the steel adversely if not done properly.
After rapidly cooling the steel, it is then necessary to temper it to reduce the brittleness
and make it more uniform in structure and softer, but tougher.
Carbide saw blanks are tempered to approximately 40 to 42 Rockwell C. The Rockwell C
scale is a standard test to determine the relative hardness of various steels.
The reason for discussing saw steel is to impress upon you the necessity of handling it
with care. Many saws are ruined by faulty gumming and brazing techniques. If the steel
turns blue when grinding, it changes its structure and causes a stress area. Steel begins its
first transformation around 1400 F which is the first real critical temperature.
Silver solder melts at around 1300 F and thus it is very difficult to control the brazing
temperature below the critical change in the steel structure.
If the brazing is performed too rapidly, the steel will change its structure directly behind
the tooth or below it. This will create a very hard chill line because the cold plate cools
the steel rapidly right where the steel change is taking place.
When the brazing is done more slowly the heat has a chance to run further into the plate
and to draw the chill line out.
A simple test using a file behind the teeth will tell you if you have a hard chill line. The
steel will resist the file if it is too hard.
Treat your saw steel with respect and handle it carefully.
14
CARBIDE
There are numerous large books written on carbide, but we intend to discuss those things
that should be the most important to you.
The carbide industry manufactures several hundred grades of sintered carbide. There are
between 15 and 20 used in any volume in industry. Each manufacturer insists upon using
his own grade identification system, but industry has established standards starting with
C-l, C-2, C-3 etc..
Tungsten carbide is a chemical compound of tungsten and carbon sintered with a binder
of cobalt. The means of properly uniting these materials was discovered in Germany
over forty years ago. (1931 - Editor) Today there are several other additives that affect
the product in different ways. The most prominent additives are tantalum and titanium.
This discussion of carbide will be limited to four grades. These four grades are used on
nearly all carbide saws in use today.
The abrasion resisting grades are the straight tungsten carbide grades, and the steel
cutting grades are the alloy grades with titanium and tantalum.
It would be safe to say that 80% of all carbide saws are made with grade C-2, which is
the most generally accepted grade for general purpose use. Its uses include plywood,
particle board, plastics, non-ferrous metals, cast iron, and hard rubber. Grade C-l is used
where heavy shock is present, such as in edger saws, rip saws, and interrupted cuts on
other abrasive materials.
Grade C-3 is a very hard and abrasive resistant grade and is very brittle. This grade is
used on formica, particle board, and other very abrasive materials where little shock is
present. Grade C-6 is an alloy grade and most generally used for cutting steel. There are
several other grades that may have some uses in carbide saws, but very infrequently.
It should be noted that the more cobalt, the tougher and softer the carbide is.
The following chart should give you a better idea of these four grades properties and
relationships.
15
It should be noted that an increase in one chemical property results in a loss in another.
This makes it very difficult to flatly state that one grade must perform better than another
on any given job. You must prove it on the job. In some cases a marked difference can be
gained by just changing from one manufacturer's carbide to another using the same
industry grade. But you would be wise to not experiment too much because it is costly
and most often does not result in enough improvement to justify the time spent.
More About Carbide
Abrasive wear is the type caused by cutting materials like graphite, transite, textolite,
hard rubber, and non-ferrous metals like aluminum, bronze, brass, etc.. To combat
straight abrasive wear use the straight tungsten grades of carbide.
Cratering wear is the type of wear encountered by seizing, galling, and pull-out generally
ocurring when sawing ferrous metals like steel. To combat cratering wear use carbide
grades with tantalum and/or titanium.
Problems related to carbide can usually be traced to something other than the grade of
carbide. These problems can be poor geometry, sudden overheating from grinding
causing thermal cracks, and rough handling.
NO Picture Available
These pieces of carbide are broken from surface thermal cracks from grinding too hot and
fast. This type of crack is characterized by a smooth moon-like break that is discolored.
These breaks can be distinguished from force breaks by the appearance of the break. A
forced break will be clean and not discolored and the surface will be rough. Break a piece
of carbide and you will see the difference. You would be wise to purchase tips that have
been treated for brazing.
16
Unheated carbide
Burnt carbide
These pieces of carbide were heated in an oven to 1500 decrees and held for five minutes.
The surfaces are badly oxidized and are soft enough to cut with a knife. This oxidation
growth will continue until you remove the heat. If these pieces had been well fluxed, the
flux would have formed a crystal over the surface and the oxidizing would not have
occurred. You cannot braze on an oxidized surface. This is why flux is so necessary.
17
DIAMOND GRINDING
The first question you should ask yourself is: What do I expect from a diamond wheel?
Your answer should be a wheel that removes carbide fast and cool. Think this over very
carefully and do not get talked into purchasing a wheel simply because it will last longer
than any other. This is a very false economy and you will pay in lost time as well as in
cracked and poorly ground carbide.
One way of arriving at diamond wheel cost is to add the cost of the wheel and the cost of
the labor required to produce a certain dollar volume of work. There can be a point of no
return when too much wheel is used or too much labor. Bear in mind that if you grind
one saw for $10.00 in 15 minutes and use $2.00 worth of diamond, you are far better off
than to grind the same saw in 30 minutes and use $1.00 worth of diamond. This lesson in
economics is only meant to impress you with the need for a practical approach to the use
of diamond wheels and the fact that labor is a far more costly part of the grinding job.
There is one fact that you must be aware of; you have to use up diamonds to grind
carbide. It is up to you to figure a successful proportion of diamond and labor costs that
will give you the return you are looking for.
Some l8 years ago, manufactured diamonds were introduced to industry, and since that
time its use has expanded tremendously. Today these diamonds are more uniform in size
and resist shock better than natural diamonds. Of course the metal coating of diamonds
with nickel and copper has also added greatly to their life. It is generally accepted that
copper coated diamonds are best suited for dry grinding, and nickel coated diamonds are
best suited for wet grinding. Even though coated diamonds last longer, they do create
more grinding heat and do not grind as cool as plain diamonds do.
There are two major bond types; resinoid and metal. Metal bonds work well on nonmetallic materials such as glass, ceramic, stone, etc. but do not grind carbide efficiently.
Due to the fact that metal bonds are too hard and severe for carbide grinding, we shall
limit our discussion to resin bonds.
Diamond wheel manufacturers make resin bonds in numerous grades and hardnesses.
Diamonds also come in different grades and in different coarsenesses. You must
carefully select the wheels that work best for your operation. Generally, wheels with 150
grit, 75 concentration, and R hardness are used for regular grinding.
Finer grit wheels will give better finishes on the carbide and improve the cut quality,
lengthen life between sharpening, and require less power than saws with rough grinds.
These wheels, however, grind slower and require more time to finish a saw. Again you
will have to be the judge of your customer's requirements.
If a saw pushes hard and tends to wobble in the cut, the problem can often be traced to
rough grinding. By using a fine wheel and putting a good finish on the saw teeth, it is
often possible to solve this saw problem.
18
There is a definite difference in the "grindability" of various grades of carbide. Some are
harder on diamond wheels than others. The greater the cobalt content in the carbide, the
greater the diamond wheel wear will be. In other words, the softer grades of carbide
cause greater diamond wheel wear.
One very important consideration is the concentration of diamond in the wheel. There is
no doubt that an increase of diamond up to 125% greatly improves the grinding
performance. The extended life of these diamond wheels outweighs the cost. Wheels
with 50% or lower concentration of diamond are very poor performers and should be
avoided.
The most important operating variables are wheel speed and traverse rate. Also
important are wheel rim width and diamond concentration. These variables can affect
your costs considerably and should be watched carefully and a controlled evaluation
study should be made for each variable.
It should be emphatically stated that two thirds of "On The Job Testing" is evaluated by
operator opinion, and that this is the most common method of testing used today.
Operator opinion is certainly important but it should not be used exclusively in place of
some good old fashioned records with facts and figures.
The rapid wear of diamond wheels can be attributed to many things»
1. Heat causes breakdown of the bond and rapid wheel breakdown. The heat is
caused by too fast a feed and too much wheel contact. Wet grinding helps this
problem, but the main thing is to let the wheel cut without forcing it too much.
2. Dry grinding causes more wear than wet grinding, so if you are dry grinding
you must grind slower in order to keep your wear down.
3. The grit size of the diamond makes a big difference in wear and stock removal.
The coarser grits yield rougher finishes but stay in the bond better and remove
stock faster and cooler.
4. Diamond wheels sometimes load due to improper use and can act dull and
grind very hot. Wheel dressing will remove this build up but it is wasteful and
should not be necessary if the correct wheel is used on the job. If wheels must be
dressed, the dressing should be done carefully so as to avoid excessive diamond
loss.
For the sake of economy it is often necessary to rough grind a saw and then finish it with
fine grit wheels in the 400 or 500 grit size. This is particularly true if making a new saw
or retipping an old one.
19
A good rule of thumb to use for arriving at end cost is to have your labor cost equal your
diamond wheel cost. This is an easy way of determining the efficiency of your operation.
Diamonds are a man's best friend when grinding a carbide saw, but you cannot do a good
job in a minimum amount of time without using some diamond to do it. Just be sure that
you do a first class job and can make a profit using labor and diamonds in relation to the
price of the job.
BRAZING
This operation actually consists of silver soldering and requires practice to become
efficient at it. There are two generally accepted methods. One is to pre-tin the carbide
tip by applying flux to it and laying it on a graphite block or fire brick. Heat it slowly
until the silver solder can be applied and tinned to the surface. Then install it in the saw.
The other method is to install the tip in the saw with flux and then heat and apply silver
solder. Either method is satisfactory if done properly.
The best silver solder will contain 50% silver and will melt at approximately 1270° F.
Solders with higher melting points are generally not satisfactory because they set up
stresses in the carbide even in small sections like saw tips.
Flux is very important to a good braze joint, and should be of good quality and not mixed
with water to the point that it has lost its effectiveness. Black fluxes are generally the
best because they will withstand higher temperatures and they contain flouride to help
clean the work. The presence of flux also helps to surround the joint and prevent
oxidation.
The first requirement of a good braze is a good clean recess to put the tip in. Remove all
burrs and sand blast, if necessary. The second is to apply flux thoroughly to the recess
and the tip. The third is to apply heat at the base of the recess with the torch pointing
outward away from the center of the plate. Do not heat too rapidly, and use a torch tip of
the size you are capable of handling.
If the carbide tip is not pretinned, add a small amount of silver solder by carefully
melting the very end of the silver rod. Now use a small 3-corner file or other small steel
rod and push the tip into the recess when the solder melts. Do not overheat. You can
seat the tip better by pulling it out and pushing it back into the recess. This allows excess
silver solder to escape and also removes any excess flux from the joint. Be sure that the
tip and recess are well wetted with braze material.
One major thing, too often overlooked, is the safety factor that should be used when
brazing. There are two very dangerous elements involved; flouride and cadmium. Both
of these can injure your lungs or kill you if you do not take precautions to vent their
fumes. Do not use silver solder without a fan or other means of ventilation to keep you
from inhaling these very toxic fumes.
20
Another thing to recognize is that the steel plate you are working on has been heat treated
to make it capable of doing the job it is intended to do. When you heat the steel behind
the tip you draw the temper out of it. Sometimes if you heat too rapidly you create a chill
line between the steel you heat and the body of the plate. This causes the whole tooth to
break off. Go a little slower and allow the heat to dissipate more gradually and you
should not cause these chill line conditions.
A difference in expansion and contraction in the metals involved is of great importance
and deserves consideration and understanding. Steel has an expansion rate of .004
thousandths to the inch. Silver solder has an expansion rate of .012 thousandths to the
inch. It is very apparent from these two values that expansion has a great deal to do with
a good braze joint. With each metal working against the other it is very necessary to do
the best job possible and establish a good sound procedure to stick to.
Following is a good sound procedure that works.
1. Set your oxygen and acetylene gauges to a value of 5 pounds. No more than
this is required and the flame will be smoother with less blow.
2. Light the torch by opening the acetylene torch valve. Open this valve until the
flame separates from the tip. Now back off the valve until a small amount of
black smoke appears at the end of the flame. Now turn on the oxygen valve and
adjust the flame until there is no feather appearing on the cone of the flame. You
now have a neutral flame and the hottest flame that should be used with this size
tip. Only two sizes of tips are necessary for brazing saws; number 0 and number
1. Use the # O tip on saws thinner than .095, and the #1 on thicker saws. Never
try to use a tip too big for you to handle and don't rush the brazing job. Practice
will allow you to speed up the operation.
3. Be sure your tips are clean and not oxidized. Tips treated for brazing are the
best. Next, the recess should be clean and free from burrs.
4. Flux all surfaces liberally with a good grade of flux, preferably black flux.
5. Position the tip in the recess and be sure it is located at the desired distance
from the sides of the plate to clean up to the dimension required.
6. Apply the heat and silver solder, and wipe the tip into place with a positioning
rod.
7. Allow to cool and inspect to be sure that the silver solder is uniformly applied.
If you follow good procedure and are careful you should get good results. Again, be sure
that you silver solder in a well ventilated area. Why take chances?
21
Not enough flux
good
Bad
Surface
Preparation
Good
untinned
PRE-TINNING CARBIDE
The lower piece of carbide has not been tinned. The two top pieces have been fluxed and
heated without spreading out the flux. The lower right-hand piece has been tinned, but
had not been properly fluxed first, so you will note that the silver will not flow a11 over
the surface. The left hand piece has been properly fluxed and tinned. The flux was
puddled to form a complete crystal over the surface and the silver solder was applied and
it flowed all over the tip under the protective crystal coating of flux.
Editor’ Note:
These are not the original pictures as the originals were unusable.
22
GUMMING SAWS
Saw gumming is an operation that must be performed on all saws to be retipped. It must
be done accurately so the saw does not run out of balance and the tip recesses are all the
same depth. The job can best be accomplished by using a gear index fixture where the
gears can be changed for different tooth quantities. Using this method, the indexing is
done by finger indexing into the gear teeth, which leaves the tooth area open on the saw
and allows all the freedom you need in gumming.
The first thing to do is to draw your hook line on the saw with a pencil. This can be easily
done by the use of a standard drawing instrument used on drawing boards. First
draw a center line to the tip of the tooth you start with, then draw a line from the same
point at the desired hook angle. Now line up the hook line with the side of the wheel and
you are ready to-gum the saw.
Layout of Hook Line
23
Do not grind so fast that the saw gets hot and turns color. This will cause a surface
hardening of the steel and could be a cause of cracking. In order to keep the wheel
from burning it is sometimes advisable to bounce it several times as you grind. This will
help rough it and keep the wheel from glazing as well as allow the stock to cool a little.
Several sizes of wheels are necessary to get the job done quickly and to gum the various
shapes of teeth required.
Following are some recommendations of wheels that perform well and the most popular
sizes you will require.
These wheels can be dressed by using a dressing stick or a rotary wheel dresser. The
latter is best.
Gumming also includes recessing for carbide tips. This operation must be done with
precision. To accomplish this it is best to use a spring type locating finger that
will index in the opening just below the tip recess. The best procedure is to use a 1/8"
cutoff wheel and rough in the recesses before finishing them to the proper depth. Then
dress the wheel square and proceed to gun the recesses to their finished depth. After
going around once, it may be necessary to dress the wheel square and go around again.
The corner of the wheel will break down and you must have a seat for the tip that it will
fit in properly and not hang up on a large corner radius caused by excessive corner break
down of the wheel.
Do not install a broken wheel. Be sure that you ring it to check for possible
cracks.
Be sure to wear eye protection.
All gumming machines should be equipped with a wraparound shield to protect
the eyes of people in the vicinity of the machine.
Gumming is one of the most important operations performed on a saw, so do it
right.
24
HAMMERING
There are no mysteries involved in the act of hammering a saw. However, you must
know the basic principles and apply them conscientiously. Saw hammering requires
complete concentration on what you're doing. The only way to learn how to hammer is
to start with a knowledge of the basics and then proceed by trial and error until you
understand what happens when you hammer the saw, in all areas of the saw. The first
rule to observe in hammering is very simple: do not hit a saw with a hammer unless you
know exactly why you are hitting it. The second rule is to know exactly what happened
where you hit it. If you concentrate on what you are doing, and observe these two rules
carefully, hammering will gradually begin to make sense to you. It takes a lot of patience
and a lot of time to learn the art of hammering.
You must also be aware that when you hit a saw with a hammer, you expand and stretch
the metal. It is impossible to shrink metal with a hammer. The harder you hit, the more
the metal expands. The larger the hammer, the more effect it will have. Also, the shape
of the hammer face influences the metal expansion. You have to start out realizing these
factors, and then carefully observe all the results you obtain.
This discussion will be centered around small diameter saws of 14" diameter or less.
These small saws comprise 90% of all carbide saws in use today. Small saws do not
require much tension if any. However, as a saw gets larger, the centrifugal force and the
temperature on the saw's rim affect the body of the saw more, and create the necessity for
proper tensioning.
You must have the proper tools to do a proper job. The first requirement is a test arbor
equipped with a dial indicator. The next tool needed is a straightedge. With these tools,
you can now determine if a saw needs to be hammered. First put the saw on the arbor
and dial indicate it for wobble. Note the reading on the indicator, then turn the saw over
and dial the opposite side. This will tell you if the saw is bent, or has tension areas, and
how much and where. It will also tell you if the saw is dished over and not running on
the center line. Now use your straightedge to check for lumps and bumps.
Now that you have determined that the saw does, or does not, need corrective
hammering, you will need the other tools of the trade.
You will need an 8" round anvil slightly crowned, a three pound dog face hammer, a two
pound cross peen hammer, and two or three various length straightedges. It is also
advisable to have oil to wipe on the saw plate to help prevent rough hammer marks, and a
piece of chalk to mark with.
At this point a few common saw terms, and what they mean may help.
25
1. LUMP - This word is used to describe an area that is raised up on one side. In
other words, a bump that is caused by a burned spot on the saw. Most generally it can be
visually detected before you straightedge it by being blue in color.
2. RIDGE -This is a sharper bump area normally caused by an actual bending of
the saw, and is long and narrow. A ridge runs from the rim to the eye of the saw.
3. TWIST -This area is the same as a ridge except it twists the saw. It is also
caused by opposite areas without tension.
4. DISHED -This is self-explanatory and means that the saw is no longer on a
center line, but has taken the shape of a dish.
5. LOOSE - A spot that shows light under the straightedge is said to be loose
when referring to a larger area of the saw than a lump or a ridge.
6. FAST - Just the opposite of loose, or a large lumped up area under the
straightedge.
7. TIGHT OR STIFF - These terms are used to describe an area that is straight or
flat under the straightedge when the saw is being broke or bent over to check tension
uniformity.
8. TENSION - This seems to be the mystery word used in saw hammering. It is
actually a very simple function in most carbide saws. Tension is very important in large
diameter saws, but in small saws the amount required is so little that in most cases it is
checked merely to judge the uniformity of the saw to correct for loose or tight areas.
Tension in a saw has to do with the equalizing of strain on the saw caused from the
centrifugal force stretching the rim. When the rim stretches it pulls on the body of the
saw. This is why the body must be stretched slightly so the rim has this stretch to
compensate for. Thermal expansion of the rim or hub and cutting strain need to be
compensated for by tension. If the saw does not bend with a uniform curve when broken
at the center line, the tension is not uniform and the saw will have a high speed wobble.
The amount of tension needed in small saws is not too great; thin saws do require slightly
more tension than heavy ones.
Now that you understand the terms used you are ready to go to work on the saw.
The first step is to apply a thin film of oil on both sides of the saw. Then locate and mark
with chalk the lumps and ridges by using a straightedge. This can be done easily by
holding the straightedge against the saw and looking under the straightedge at a light
source such as daylight or a neon tube.
In order to level a saw, the lumps and ridges must first be hammered down with as few
blows as possible. When doing this you will stretch the metal over a larger area and
cause a loose spot. In the process of leveling down the bumps you also remove any
tension that existed before hammering. Practice and observation are the main essentials
in doing this job properly.
26
If you have removed the lumps and ridges and now find you have a loose area, you must
mark the area of the loose spot and then direct your blows between it and the rim in
order to stretch out the extra tension that exists in the loose area.
If a tight spot is witnessed under the straight edge, you must increase the tension in the
tight spot by hammering that spot on both surfaces of the saw to prevent dishing the plate
and to put tension in the saw.
The removal of these loose and tight areas must be checked frequently and can be readily
observed by bending the saw, with the center of the saw as the fulcrum or point of break
or bend. (See the illustration below.) As you pull the rim of the saw down to bend it
slightly you use a straightedge in your other hand and note the loose and tight spots. If a
saw is properly fit up, the bend will be a uniform curve and will not show a curve on one
side of the eye and a flat spot on the other. Check it in six or eight places across the
center of the saw. A11 checks should show a uniform curve. If not, the tight or loose
areas will again have to be worked on. Be sure to work both sides uniformly to keep the
saw flat.
27
This indicates a tight eye
and it must be stretched.
This indicates a loose eye
and the rim must be stretched.
When you break a saw you can discover a loose
or tight eye. Always hammer both sides or you
will create a dish in the saw.
When the saw is flat to the straightedge and breaks over with uniform curves it is then
ready to dial indicate for wobble. If your work was done properly, the saw will require
very little additional work to get it to dial on the test arbor within three thousandths of an
inch total dial indicator reading.
The biggest problem a saw has is heat. Heat in a saw is the result of friction. When the
rim of a saw is working in a cut, heat is developed by the cutting action and by the
sawdust rubbing past the teeth. This heat can cause the rim of the saw to expand and
create a wobble. The heat also melts the resins and pitch in the chips and causes them to
deposit on the saw. If there is not enough clearance between the plate and the tip, the
gum will build up on the sides of the plate. As this gum deposit enlarges, the gum will
also rub the sides of the cut. Now more heat is generated and all of a sudden the steel in
one spot will get so hot it will actually turn red or blue. This causes that one spot to swell
up and the gum be burned off of it. When the gum is burned off, the blue spot will cool
off and shrink back away from the cut. After this point the saw is going to give trouble
and must be hammered to run properly. If people would keep their saws clean a lot of
these problems would not happen.
Let’s start by relating hammering to a band saw instead of a circle saw.
This area will have to be hammered to stretch it. In other words, the bump is "loose" and
the flat area is "tight". By hammering the tight area, you tension it the same as the loose
area and the bump goes down.
28
This piece has the bump in the middle. First hammer the bump down, then hammer areas
on both sides of bump until flat and uniform. Again, hammer both sides of piece so the
expansion will be uniform.
Serious conditions in a saw body.
A twisted saw with the ridge down the middle will
have two tight areas that must be tensioned to
remove the twist. Work both sides.
Work this area first.
Work this area next.
If a saw is loose at the eye in this area it
must be removed by gradually working
toward the rim. Both sides are a must. If you
work the rim only, you will destroy the
tension or pull it out of the central area
where it belongs.
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Every saw is an individual and the hammer man is confronted with the problem of
analyzing; where a particular saw needs work on it. This is why it is most essential that
he know what he is doing. Every man cannot hammer. If you get frustrated you will
never make it and had better give up. In other words, use your head and keep your cool.
GRINDING CARBIDE SAWS
This operation is accomplished in three stages. The first stage is Facing. The second
stage is Side Grinding . And the third is Top Grinding. These grinding stages must be
followed in this one, two, three stage method because of the following reasons.
The number one stage, Facing, is done first in order to true up the face and prepare it for
an index finger to squarely fit against it. Facing is generally a hand operation and does
not require exact indexing.
The number two stage is Side Grinding to establish the correct distance from each side of
the plate in order to finish with the Top Grinding and to be able to dial tooth height the
same on the O.D..
Grinding a carbide saw properly is where the so-called men are separated from the boys,
or the good mechanics separated from the poor ones.
Following are the three stages outlined in more detail.
FACE GRINDING
More saws are literally butchered by facing improperly than by any other grinding
operation. In the first place, when a saw is first manufactured it has cutting geometry
that is designed to perform a certain way. When a customer buys a saw for a specific
purpose and it performs to his satisfaction, it now becomes the responsibility of the
sharpener to see to it that it does as good a job after servicing as it did before. This
means that there can be no changes made in the original geometry of the saw.
Now getting back to the facing operation. Most saws are ruined by facing when the
person doing it is not careful and does not grind the face of the tooth parallel with the
back and changes the geometry by dubbing the top part of the face back, thus changing
the hook angle of the tooth. See the illustration below.
30
The next thing that is too often done wrong is not grinding the same amount off of each
tooth face. This causes the saw to lose its joint by making some teeth higher than
others and some teeth wider than others. Study the illustrations below.
Note how tops of teeth become out of
joint when improperly faced.
Note how sides also vary when saws are
improperly faced.
You may say that these drawings are misleading because they are exaggerated to prove a
point. The first thing to be aware of is that chip load per tooth on cutoff saws is down in
the area of .002 to .004 thousandths of an inch. Now you have but to dial indicate the
tops and sides to see what variation any given saw has.
If a saw varies on the top even as much as .002 thousandths the tooth directly behind the
low tooth will be loaded that much more than it should be or than the saw was designed
for. These variations do not have to be very large before you begin to wonder why an 80
tooth saw is necessary for a job when only 40 teeth are working.
31
The sides of the saw are also affected in the same way and the performance will fall off
rapidly when the saw is merely improperly faced. Be assured that there is no substitute
for a job done accurately and consistently right. Most face grinding is performed on a
gumming type machine that is a hand operation and completely at the mercy of the
operator. This requires the operator to have a good feel for the job and a thorough
understanding of its basics. Proper set up to face the saw is very important and should
not be done in a slipshod manner. See the illustration below.
After a diamond facing wheel has been used for a while, it becomes rounded over from
extending down beyond the carbide and grinding into the steel below. The steel tends to
pull the diamond out of the bond causing this rounded condition. When the wheel gets
into this condition it is necessary to
32
compensate or dress the wheel face flat again. Most people do not want to dress away
their diamond so they go right on butchering their saws and sending out disgraceful work
to their customers. This really opens the door for their competition. Refer to the drawing
below.
If you must relieve the backing behind the diamond in order to do a saw with narrow
gullets, you must be very careful. It is far better to buy a narrower diamond wheel with
1/32 inch diamond thickness for doing saws with narrow gullets. A well maintained
facing wheel will save a lot of time and do a better job.
Treat the facing of a carbide saw like a highly precision grinding job and try to do i t
better each time you do it.
SIDE GRINDING
The side grinding of carbide saws is the most critical grinding operation as it relates to
the saw's performance. The angles ground in the side are not as important as the
uniformity of the grinding job. The most common angles on the sides are 2° dish and 3°
back for general purpose use on nearly all wood-cutting saws, 2 ° dish and 1 ° back on
metal and plastic-cutting saws, and no dish and 4° back for smooth cutting rip saw
applications. Most carbide saw grinders do not pay enough attention and are not aware
that this operation must be done properly. Following is a sequence grinding operation
that may help explain the major problems.
33
34
The condition described in the preceeding drawing is what causes most of the saw
grinding problems. Without the point extending the farthest out on the sides, the saw has
to cut without a point on the sides. This causes it to cut rough and lead off and require
more power to operate. It can also cause burning and make the saw wobble. It cannot be
stressed enough to guard against this condition. Machines that are weak and tired will
exaggerate this problem and are very hard to live with if you need any production off of
them.
The next thing to watch is the plate springing away from the wheel. This is caused when
the plate support is too far away from the tip. It will affect thin saws far more than heavy
ones. On very thin plates it is sometimes necessary to provide support directly behind the
carbide tip to prevent it from pushing away from the wheel.
Diamond wheels are also culprits that cause bad side grinding. The wheels should be soft
enough to cut freely and should be not less than 75 concentration. The diamond section
should be no more than 1/16" wide so that it does not exert as much pressure as a wider
section would.
Reducing the amount of stock removal and allowing the wheel to cut clean and spark out
will also help.
A simple inspection can be accomplished by holding a rule on the side of the tip and
looking toward a bright light. See if the rule will rock on the tooth or if you can see light
at both ends of the tooth under the rule.
The sides must be ground accurately and the correct angle ground so the saw can perform
satisfactorily. If you are not sure of the angles on the side of a tooth, you can find them
by a simple method of using a black felt ink pen and very lightly touching the wheel to
the tip. Then adjust angles carefully until you wipe off the whole side of the inked tooth.
Saws that have been in service and exposed to abrasion and wear should be examined on
the sides carefully and if wear is present it is frequently necessary to lightly dress the
sides to bring them up to a sharp corner and restore their original cutting ability.
It should be noted here that if a saw is returned to your shop dull, it should be sharpened
well enough to go back into service and give the same cut quality and service life as it did
when it was new. Anything less than this is a poor sharpening job. Sometimes as saws
are returned for sharpening frequently and in very dull condition, a good thorough
sharpening job each time will shorten their life expectancy because of the necessity of
removing carbide all over each time they are serviced. Remember, however, that it is
better to have to apologize for a new saw wearing out too soon than to apologize for one
that does not cut properly and does not go back on the job in first class condition.
Keep your eyes on the sides.
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TOP GRINDING TO KEEP DIAMETER WITHIN TOLERANCE
This operation must be done with a good solid index finger that does not spring when the
tooth is forced against it. If the finger springs or moves differently each time a tooth is
ground, the teeth will vary in height and create a variation in tooth load. If the tooth
height varies, you again will have to ask yourself why you have so many teeth in the saw.
Assuring uniform tooth load is the major function of the tops of the teeth, therefore they
must be accurately ground for correct geometry and height, and the grinding finish must
be of good quality.
Several things affect good top grinding. The most important is the finger. Next most
important is the wheel. Third most important would be the operator doing the grinding.
A good rigid grinding machine is absolutely necessary and should be equipped with an
accurate ball bearing saw holder.
In order to get good results on the outside of the saw, you must have an accurate hole or
eye in the saw to start with. No saw bore should be over .002 thousandths of an inch over
the nominal size of the bore. Even with close tolerance bores you must have the shaft the
saw rotates on accurate and on size. The biggest problem, as it relates to bores and the
eye of the saw, is bushings that are used to reduce a bore to fit the grinder arbor. It is
impossible to grind a saw properly if the saw is turned on the bushing. You may start out
new and do fairly well, but the bushings will begin to wear and your tolerance will
disappear fast.
The better way is to bush the saw down with a bushing that has a bore which closely fits
the shaft, and an outside which tapers very slightly, about .006 thousandths of an inch
in 3/16" of bushing length. This will assure a good seat on the bushing O.D. which
locates well down into the bore.
Now you must turn this saw and bushing combination on a ball bearing spindle so you do
not create wear on the bushing. The very best way to prove you have a good set-up and
an accurate one is to grind the saw and then dial the O.D. carefully. Mark any slight
variations on the saw in the location they occur. Now remove the saw and bushing from
the arbor. Again install the saw the way you did the first time and dial the O.D. again. If
you do not repeat exactly, you have your answer, and also know how much your error is.
Runout on the O.D. of a rip saw is not nearly as critical as on a cut-off saw because of the
large tooth load. Some service shops are aware of this and get sloppy in their work. It
still takes no longer to do a good job than a poor one, and service people should get
oriented into this routine.
The biggest assets you can have in top grinding are 1) a good accurate rugged machine to
grind on, 2) a good solid index finger that absolutely does not yield when pressure is
applied to it, 3) an accurate bushing system to center the saw properly, 4) a ball bearing
spindle for the saw to revolve on, and 5) the desire to do a good job and improve your
work at all times.
36
When top grinding, all tooth styles should
be dial indicated on top to assure proper
tooth height and proper joint.
CARBIDE SAW SHARPENING GUIDELINES
TRIM AND CUTOFF SAWS
These saws have light tooth loads and the extreme outside corner of the tooth must cut
through the grain fiber without disturbing it any more than necessary. This means that
the uniformity of the chip load is very important. If you refer to the section in this
manual on facing, you will note that it plays a key role in trim saw performance.
The hook or rake angle must be maintained and a uniform amount of carbide removed
from the face of each tooth.
A good rule of thumb is to try and maintain at least 95% efficiency of the saw. If a saw
has 100 teeth, no more than 5 teeth can be out of the cut due to broken teeth or irregular
grinding. These must be staggered around the saw. If the corner teeth have very small
corner breaks, these teeth will probably come back into the cut after the saw has been
sharpened once or twice. If you don't want these small nicked teeth to show, they can be
ground down on the top until the nick is gone. They will still come back into the cut after
additional sharpenings.
Of course, the very best way to service is to shoot for 100%. No trim saw should be faced
more than twice without
37
going over the sides and tops. Sometimes it is necessary to do the complete job every
time the saw is serviced. This is where good judgement and experience comes into play.
Top grinding a trim saw is also very important to the saw's overall performance. In the
case of the Alternate Bevel saws, the teeth must be dialed the same height and ground to
the same angle. If they are not, the saw will lead off track and cut erratically.
Concentricity is a must. Side grinding is the most important grinding done on a trim saw.
It is the side of the tooth that has to sheer the cross grain fiber. The sides should be
finished with a very fine diamond wheel. The better the surface finish on the sides, the
better the saw will cut. The sides must also be straight and not dubbed over on the
corners.
RIP SAWS AND EDGER SAWS
These saws have less teeth than trim saws and also heavier chip loads. The tops of the
teeth cut across the grain fiber just like a hand chisel cuts across the grain fiber.
It takes very little additional power for a rip saw to have a .020 chip load than a .040 chip
load. The tooth still has to sheer all the way across the top of the tooth, regardless of the
tooth load. The sides of rip saw teeth get very little action. They wear themselves dull
by rubbing the sides of the cut.
The more hook or rake a rip tooth has, the easier it penetrates the cross grain fiber. The
more back clearance on the tooth, the easier the tooth also penetrates.
In the case of carbide; it is necessary to limit the included angle on the tops of the teeth to
prevent carbide breakage. Tougher grades of carbide are required on most rip operations,
due to shock from heavy chip loads and knots. Face grinding properly is very important
and the hook or rake angle must be maintained and the faces not dubbed over on the outer
portion of the face. It is also very important that an equal amount of carbide is removed
from each face in order to keep the saw in joint and the chip load uniform.
Top grinding is the most important grinding job done on a rip saw. The keener the
cutting edge, the easier the saw will penetrate the grain fiber and the less power is
required. The finer the surface finish on the tops, the better the overall performance
including time between sharpenings.
Side grinding is important as it relates to the finish on the sides of the cut. All teeth must
be kept in joint so that deep scratches and revolution marks do not adversely effect the
cut quality.
38
All the teeth in a rip saw must cut uniformly and it is not wise to take any teeth out of the
cut. The tooth loads are heavy and the removal of one tooth loads the following tooth far
too much for comfort.
ALUMINUM AND METAL SAWS
The tooth load on metal saws is light to medium and in the range of .001" to .005".
Facing-Topping and Side grinding are all of equal importance since they all play a vital
role in the saw's performance.
Facing should be straight and true and a very fine finish is important. The face of the
tooth is forming the chip and if it is not smooth, the chip will seize or freeze on the face.
Chips that are deposited on the face of the tooth must go around again and attempt to
form a chip with the deposited metal instead of the tooth face. Good lubrication helps
prevent this chip galling, but a smooth face is also essential.
Top grinding must be done accurately, so the chip load is uniform. The surface finish on
the tops should be very smooth so that a very sharp corner enters the cut and not a ragged
edge caused by rough grinding.
Side grinding is of equal importance in order to obtain a smooth cut on the sides of the
cut. Here again, the smoother the surface finish, the better the cut.
The two most important operations in servicing a carbide saw are: #1 - accuracy, and
# 2 - the surface finish on the carbide. You just can't compromise and expect consistent
results.
SAW STYLES
The following pages show photographs of several styles of carbide saws and their general
specifications.
39
FLAT TOP RIP STYLE
SERVICE SPECIFICATIONS
Hook 25°
Sides 2° & 3°
USE:
This is the traditional flat top rip style tooth and is characterized by the addition of hook
so the chisel type tooth will cut the grain fiber easily.
40
SAFETY RIP STYLE
SERVICE SPECIFICATIONS:
25° Hook
Flat Top and race
2° and 3° Sides
Top clearance from top of tip to body of plate
should be .020 for hand feed and .040 for power feed.
USE:
The main purpose of this style saw is safety and next its free cutting ability. By limiting
the top clearance from tip to plate, the saw chip is controlled and the saw cannot grab or
overfeed. This saw should be used for ripping only.
41
CONTRACTOR'S COMBINATION STYLE
SERVICE SPECIFICATIONS:
Standard 20° Hook
2 Scoring Teeth and 1 Raker
25° A.T.B. Scoring Teeth
Raker .015 Below Scoring Teeth
Sides 2° and 3°
USE:
This saw has enough hook to make it cut very freely. It is an excellent rip saw and a fair
cutoff saw. The free cutting action makes it ideal for hand-fed radial arm and table saws.
42
PLANER COMBINATION STYLE
4 TOOTH AND RAKER COMBINATION
SERVICE SPECIFICATIONS:
Hook 15°
4 Teeth 25° A. T. B.
1 Tooth Raker .015 Lower
Sides 2° and 3°
USE:
This is one of the oldest style carbide saws in the combination style. Its uses include
crosscut and rip on wood, plywood, particleboard, hardboard, and other general purpose
uses in cabinet shops and furniture plants. Not meant for power feed use. This saw cuts
freely for general cutting use and works well on any machine.
43
PLYMASTER STYLE
10 TOOTH AND RAKER COMBINATION
SERVICE SPECIFICATIONS:
10° Hook
Top Angles 25°
Sides 2° and 3°
USE:
This combination saw has more scoring teeth and less rakers. It will crosscut better than
other combination styles, but will not rip as fast and freely. A very good saw for
plywood cutting and general shop use.
44
ALTERNATE TOP BEVEL STYLE (A.T.B.)
SERVICE SPECIFICATIONS:
Standard Hook 15°
25° A.T.B.
Sides 2° and 3°
USE:
These saws are designed to crosscut solid wood, plywood, Particle board, and hardboard.
The sharp points penetrate the fiber easily, thus minimizing breakout.
45
TRIPLE CHIP STYLE (T.C.G.)
SERVICE SPECIFICATIONS:
Hook varies from 0° for metal & plastic to 25° for rip saws.
Top Geometry (See Triple Chip Chart)
Sides 2° & 3° for most saws,
And 1/2° for glue joint rip saws.
USE:
This tooth style is rugged and is used where shock is present or where a real stable cut is
desired. Its uses include non-ferrous metals, plastics, hardboard, formica, and materials
without grain. Some woodcutting operations also apply.
46
3 & 1 COMBINATION STYLE
SERVICE SPECIFICATIONS:
Hook 10°
20°
F. B.
20°
T. B.
Sides 2° & 3°
USE:
These styles of saws are used where one side of the cut is scrap. They are made in right
and left hand for use on both sides of plywood and for tenoners. They present more teeth
on the good side of the cut than on the scrap side. There are several versions of this style
saw. Some have four teeth and a scrap tooth, others have five teeth and a scrap tooth.
They are also made with straight faces and varying degrees of hook and top bevels.
47
LOCKED IN TOOTH STYLE
SERVICE SPECIFICATIONS:
Hook 0° for metal & plastics to 15° for wood styles.
Made in T. C.G. , A. T. B. ,and Chip Breaker Styles.
Sides Generally 1° & 2°.
USE:
Locking in the teeth is necessary when the tooth spacing gets close together or when a
rugged tooth is needed to withstand shock. These saws must have a light tooth load
because of limited gullet capacity. They are used for very fine wood crosscutting. Also
for non-ferrous metal cutting, well lubricated.
48
THIN RIM STYLE SAWS
USES:
The specification for this design can vary to include all the popular tooth geometries. Its
purpose is to cut a thinner kerf. Its limitations are depth of cut, and it is not intended for
hard use applications. The thin rim concept can be used on both rip saws and crosscut
saws. By holding the width of cut down, it will be necessary to use less side clearance.
These saws will gum up easily and tend to get hot quickly. They must be kept clean.
49
CONTROLLED CHIP METAL STYLE
SERVICE SPECIFICATIONS:
Hook 10°
Top of Carbide is .008" Above Steel
Sides 1° & 2°
USE:
This is a very rugged design for non-ferrous metal cutting. The teeth protrude slightly
above the body of the saw. This will keep the saw from grabbing and overfeeding. Works
well for hand fed operations on radial arm and chop saws.
50
FACE BEVEL STYLES
SERVICE SPECIFICATIONS:
The specs for these saws can vary over a wide range. A common
specification would be 10° Hook, 15° A.F.B., and 20° A.T.B..
USE:
These saws are used mainly on green lumber or very soft woods. They tend to become
unstable on hard or very dry woods. The face bevels allow them to sheer the grain fiber
easier and with less tear and breakout.
51
"V" TOOTH STYLE
SERVICE SPECIFICATIONS:
Hook 10°
Top Angles 25°
Sides 2° & 3°
USE:
This is a cutoff saw used for high speed operation cross-cutting on wood. It has the
advantage of every tooth cutting on both sides. This means the tooth load is only one half
as much as an Alternate Top Bevel saw. Very smooth and stable in the cut.
52
CHIP BREAKER STYLE
SERVICE SPECIFICATIONS:
Standard 10° Hook
All Teeth Same Diameter
All Corner Chamfers 30°
Sides 1° & 2°
USE:
These tooth styles are used mainly for cutting metals such as aluminum, brass, and
copper. Other materials such as particleboard, hardboard, and high pressure laminates are
also cut. The chips are smaller and of uniform width. This is a quiet and stable saw both
in and out of the cut.
53
DADO SET
SERVICE SPECIFICATIONS
15° Hook on Top Bevel Teeth
30° Hook on Chipper Teeth
30° Angles on Top Bevel Teeth
Sides 2° & 3°
Raker teeth are chamfered on opposite corners to decrease the chip size. This makes the
chips smaller and thus the Dado runs quiet and with little chip out.
USE:
The uses are plowing, dadoing, and rabeting. This style Dado cuts very fast and clean.
54
PROBLEMS AND ANSWERS
All saws have one common enemy. This is the person who installs and uses them.
To install a saw by using a piece of wood or other object against the teeth to hold it from
turning when the nut is tightened is inexcusable. The more the nut is tightened, the more
the teeth are bent.
When a new saw or a serviced saw is returned because it cuts rough, look first for a bent
tooth, especially if it cuts rough on only one side.
There are several things that can create poor saw performance. Don't put all the blame on
the saw blade. Check the machine. Check the bearings. Check the arbor. Check alignment
and power or other factors as well as the saw.
RIP SAWS
The top of a rip saw tooth cuts across the grain of the wood and the tooth cuts with the
grain on the sides. This makes the tooth act like a chisel cutting cross grain. This is also
why hook is so necessary in a rip saw. The more hook you have the easier you cut
through the cross grain.
Because carbide is hard and brittle, the hook should be limited to a maximum of 30° on
green woods and 25° on dry wood. The included angle on the carbide should never
exceed 45°.
Tough grades of carbide are sometimes necessary to keep from having too much tip
breakage especially on hard knots.
As the tip is forming a chip, it is compressing the wood fiber and creating friction and
heat. This action forces the resins and pitch out of the chip in a hot liquid form. This
liquid deposits itself on the saw plate behind the teeth and on the sides of the plate. When
it builds up too much, it rubs on the sides of the board and will get so hot it will swell a
spot on the plate and burn up, causing a blue spot on the plate.
To help prevent this, the saw needs more side clearance. Rip saws should have a
minimum of .020 side clearance.
CROSS CUT SAWS
The top of a cross cut tooth cuts with the grain and the sides cut or shear across the grain.
Top beveled teeth cut the grain diagonally, but still cut mostly with the grain.
The sharper and more needle-like the tips are, the easier they penetrate and shear the
grain fiber on the sides of the cut. Here again carbide angles are limited because of its
hardness. The advantage carbide saws have is the accuracy to which they are ground.
Each tooth has uniform loading that cannot be obtained on a steel saw by grinding or
filing.
You must do a good job to maintain and build the reputation carbide has gained.
55
ALUMINUM RIP SAWS
The two major problems are galling or sticking of the aluminum to the blade, and sawing
pieces of aluminum with improper clamping.
If a saw is galling with aluminum, there is only one reason, inadequate and improper
lubrication. Do not use water soluble oils mixed 50 parts water to 1 part oil. This mixture
may prevent rust and work as a coolant, but it does not lubricate. Mix not more than 5
parts water to 1 part oil. If galling still occurs, mix 2 or 3 to 1. There are a lot of
applications that require better lubrication than water soluble products provide. A good
grade cutting oil or sulphur base oil may be needed. The method of applying the
lubricant is also very important. Don't try to lubricate into the rim of the saw. The fan
action of the teeth blow it away. Put the lubricant on both sides of the saw. This will
allow it to oil the side of the saw and feed out to the teeth by centrifugal force.
The cutting problem can be dangerous if not handled properly. The biggest problem is
holding the material being cut. Some people will fix a solid stop on the machine,
particularly radial arm and chop saws, and then proceed to cut the piece that is against the
stop without clamping it. The saw will cut through the part o.k., but when it is returned
through the cut is where the danger lies. The part is wedged between the stop and the
saw. If it moves slightly, the teeth will grab it and turn it until it either breaks the saw or
it flies through the air like a bullet. If you see someone cutting like this, clear the area
and run like mad:
SAW NOISE
This is a very elusive subject and the cure has baffled many people for a long, long time.
The first thing that should be recognized is where the sound comes from. There are three
main sources of sound. Number 1 is Air Noise created by the fan action of the teeth.
Number 2 is Plate Noise created by plate vibration induced into the body of the plate by
both the air turbulence and the material being cut. Number 3 is Cutting Noise.
Air noise can be down to a soft purr or up to a high ear piercing siren type sound. The air
noise generally is progressive with the rim speed of the saw. At low R.P.M. the saw noise
may be bearable, but as the R.P.M. is increased so is the noise. If saws could a11 be run
at a fixed rim speed, it would be a lot easier to design teeth in such a way that you could
predict the air noise level. Of course, saws run at all different rim speeds so we have to
compromise and attempt to design saw tooth geometry so the saw will do a satisfactory
job and disturb the air as little as possible.
Plate noise is started by the action of the teeth fan in the air and creating a vibration in the
plate. Each plate seems to have its own sound. The plates that vibrate at an annoying
frequency are the trouble makers. Plates that are manufactured to the very same
specifications will not necessarily produce the same sound. Plate noise can be altered by
numerous methods. The most common is to install expansion slots in the rim of the saw.
The next effort would be to plug the expansion slot holes with a soft metal or plastic plug.
56
Going further with plate sound, it is possible to cement sound deadening material to the
sides of the plate. Plates are also laminated with different metals. These approaches only
tend to make hammering and servicing more difficult.
Cutting noise is a tough problem and it occurs from the teeth producing chips and then
throwing them at a high velocity, thus creating a noise by the chips accelerating through
the air and also contacting each other. The problem here is the size of the chips. Large
chips have greater velocity than small ones and make more noise on impact with other
chips or other objects. In considering cutting noise it is necessary to reduce the chip size
and shape. This can be done in many ways. One way is to put more teeth in the saw.
Decreasing the feed speed will also reduce chip size. Altering tooth geometry can be
effective. In any event a change in chip shape and size must be accomplished.
In summarizing saw noise, it should be noted that a lot of things can be done to generally
improve noise. There are, however, a lot of noise problems that must be dealt with
individually and in some cases the actual noise must be stopped by deadening the object
being cut. We also must recognize that there are so many different operating conditions
and materials to saw that it is impossible to curb saw noise by approaching the problem
from just one aspect. About the time you feel you have solved the problem, you'll find
that another one exists. Time, study, and patience are what it is going to take.