Sniral Stemmed Candlestick - Max Carey Woodturning Trust

Arfisan Item
13
26May
20ll
Sniral Stemmed Candlestick
Robin Goodman explains
how to create a spiral stem
lntroduction:
1.
7o drirrn
Spirals have beenpopular for
hundreds ofyears, as can be
seen in old furniture, and come
in many forms and sizes. The
bead around the perimeter is
called a bine and spirals
normally have between one and
four intertwined bines. A
frequently used form is the
Barley twisl named by the
Victorians after the Barley
45 diu^
Sprral
sugar sweets, where the bead is
rounded. A small spiral will
I and 4 separate
intertwined bines. A rope
have between
twist is as the name suggests
and there is a convex bines has
no coves between
them. A
double open twist has a gap
where the cove would be and a
?o d^0.*
hollow centre.
Double Barley Twist ln beech and Padauk
1
The double Barley twist with 2 starts has been chosen for this candlestick (photo 1). The gtgh
in this context is taken as the length of stem over which a single bine completes one 360o turn.
Visually a double twist will therefore appear to have a pitch of half this amount. Stuart
Mortimer in his book "Techniques of Spiral Work" goes into great detail about the different types
of spirals and should be consulted if you are interested.
J.
To create a spiral, the amount ofturning is limited, but it is easiest to carve a spiral on the lathe.
The last time I made some spirals was over 40 years agoo when there was no lathe around and it
was more diffrcult having to hold the spiral in a vice. Without an ornamental lathe or sophisticated
routingjig as used by some commercial woodworkers, most of the spiral has to be formed by hand
methods.
open twist
4.
50 x 50 sq x 300 long spindle blank in straight grained wood with no knots.
Best not to have too hard a wood or carving and sanding will take that much longer. Suggest
Blanks
-
Stem:
sycamore, ash, beech, mahogany etc.
Base and top : from a single 100 dia x 75mm bowl blank in the same wood as the stem or else in
wood of contrasting colour.
5.
Tools - Having the right tools will make the carving much easier.
AdditioJral tools required: tenon or hack saw; various rasps & files, both convex and flat - the
microplane cutter rasps are probably the best and quickest for removing wood along the spiral.
Traditionally a woodworking gouge was used to remove wood for the coves and a flat chisel for the
bines. If you do not have rasps suitable for removing significant amounts of wood, then you can
use these woodworking tools. Drilling as an option is only suitable for open twists. A spokeshave
or mini plane is quite effective at rounding off the top half of the bines. Note that these should be
used only in one direction on the spiral to avoid going against the grain, so the blank has to be
reversed between centres to work on the other side of the bines. The more accurate the shape that
can be formed with these tools, the less sandpapering
Double Barlev Twist
will
Stem
be required afterwards.
.
6.
Turn the blank to round between centres to give a diameter of approx 45mm. This diameter
together with a pitch of 100mm gives a form that is relatively large easy to carve, especially if you
are new to carving spirals. Bring to a smooth shaight finish, using sandpaper if necessary, to make
marking out easier. The pitch angle created will be approx 45o '
7.
Marking out. Mark out 2 circumferential pencil rings 250mm apart and approximately 25mm in
from each end; this will leave room for an end bead and tenon. Divide the remainder into 10
segments 25mm long and mark each with another circumferential line. Pencil on 4 equally spaced
lengthwise lines around the circumference - an indexing system on the lathe makes it easier, but is
not essential. Now draw out spirals for the top of each bine and the bottom of each cove.
Masking tape can be wound along each of the 4 spirals ( 2 bines & 2 troughs) to give a good line
for marking up. Start at one intersection on the end circumference line and join to intersection of
the next longitudinal and circumferential lines.
8.
Note that the spiral can be either right or left handed; you need to decide which. A right hand
spiral is easier to form for a right hander - for filing etc. the tool naturally faces diagonally to the
left as is the line of the bines and coves; it is also easier when rotating the lathe to and fro by hand.
Similarly a left hand spiral is easier for lefthanders like me. A pair of candlesticks will often have
one right and one left handed spiral.
9.
Continue to mark out the spiral over the
full length, then
repeat for the other 3 sets of intersections
(photo 3). It is suggested you use pencil for the 2 alternate lines indicating centre of bines and
colour pen or pencil for the centre ofthe troughs between.
marked out spiral
10. Make a saw cut approx 10mm deep along the cbloured centre line of each cove.
standard hacksaw with a l2nm deep blade, saw until only 2mm of
If using
a
blade is showing; if using a tenon saw ( photo 4) add masking
tape as a depth gauge 10mm above tips of the teeth. Saw a slot
along the
full length of each coloured line indicating the centre of
each cove, but stop just short of the 2 end circumference lines. You
are now ready to start forming the spiral.
4
11.
Forming the coves
:
Use a suitable rasp, such as a microplane (photo 8), to file away along each saw
cut until the bottom of the saw cut has just disappeared. To get the
if additional markings are
pencil
line and the saw cut to
made half way between the bine
indicate the width of the cove at mid-depth i.e. for initial shaping
assume the cove is semi-circular(photo..). Your final shape may
20mm cove width correct, it is easier
be slightly more of a sine curve than2 semi-circles.
A simple depth gauge can easily be made for checking depth of
coves ( photo 6).
12. Refine the cove width and shape as far as possible with the rasp, before using coarse sandpaper, 80
or I20 grit, wrapped around a dowel or finger to improve the cove section to approx a semi-circle
(photo 7).
For initial rasping it may be easier to fix the piece against
rotation; an indexing lock is ideal for this. If not available,
the tool rest can be jammed against the piece as a brake, but
some padding such as router mat may be needed. When
refining the shape, it is often helpful to slowly rotate the
piece using the other hand.
Initial shaping of coves completed
13. Shaping the bines: Use a flat rasp such as a microplane, a spokeshave (photo 9 ), a mini-plane
or a flat chisel to round off one side of the bines, working with the grain. Reverse the blank
between centres to do the other side. Keep the shaping just clear of the pencil lines along the top of
the bines that act as guides. When shaped as near to final shape as
possible, change to sandpaper to smooth out and blend in the
curves. If your lathe can run extremely slowly, then some sanding
may be done wfth it turning. Finish with sanding along the grain
where possible. Care needs to be taken at the ends to blend in the
ends of the spiral.
T*
9
14. Completing the stem: A cove and bead can now be formed at each end to finish it off. Whilst
these can be formed before carving the spiral, they may get damaged while shaping the spirals, so
better to leave until the end. Form a small tenon on each end to facilitate fixing to base and top.
Consider what size drill bits you have available, before sizing the tenon diameter to match. Make
sure the shoulder adjacent to the tenon slopes inwards slightly, otherwise the joint between stem
and top or bottom may be slightly open when assembled ( photo 10 ).
10
completed stem
15. Apply sanding sealer and finishes as required. [f necessary, trim ends to give a suitable tenon
length e.g. 10mm. A shorter spiral could have been formed initially and the top candle holder
formed integral on the stem. Candles come in different sizes and often do not fit a candlestick, here
I have adopted a spike to hold the candle in place; most diameters of candle can then be
accommodated.
Base
16. Form a spigot to fit your chuck on one end of the bowl blank and
true up to round. Mount on scroll chuck and drill hole to suit the
tenon on the bottom of your stem. Decide on depth, say 30-
40mm, and shape of the base, before shaping, sanding and
applying finishes (photo 11). Part off. If you wish to improve
the underside, then reverse chuck onto a shapedjam chuck and
hold in place with tailstock.
11
17. Top
Decide on shape and
size. With the remainder of the blank still in the
scroll chuck, turn to your chosen shape, turn the underside inwards until the
diameter is less than that of the top of the stem.
Sand, seal and apply finishes (photo 12).
t2
13
Drill appropriate small diameter hole for spike e.g. 2mm nail ( a spike of greater diarneter is more
likely to split the bottom of a candle ), with drill bit in a Jacobs chuck. Part off. Select drill bit to
suit your tenon and drill a hole in the underside to the required depth on a pillar drill - the small
spike hole will enable you to make the hole central ( photo 13 ).
18. Assemblv
Check fit of both tenons. Remove the head from a non rusting nail and hammer, head end first,
into top of stem to give required length of spike, allowing for the wood thickness of the top. Then
glue the 3 parts together to finish the piece.
19.
Alternative - Open twist
.g'dt
:-: l
Robin's 3 twist open spiral stem
ci
iii
table lamps made 45 yrs ago.
li.
(Note that if made today, 3 core
i)
5l
:1
n
r.
5
i!
,'
flex would need to be used.)
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-le
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14.
lens shaped bines
I5.
round bines
the look of an open twist ( photos 14 &15 ). A hole has to be drilled
down the entire length of the stem before forming the spiral. A long hole boring kit can be used on
some lathes, but is normally only available in one diameter. Otherwise use a long drill bit to drill
from both ends using a Jacobs chuck. Forstner bit extension pieces have a diameter that will be
Some people visually prefer
too large for the hole, unless the spiral is to have a very large diameter.
An open twist is inheritently weaker, so a longer pitch is preferahle. It is desirable to hold one end
in a scroll chuck, so that tailstock pressure can be reduced to a minimum.
With care, the saw cuts can be carried right down to the central hole and the long unwanted infill
pieces between the bines removed in one go, although you will need to split them into short lengths
by drilling holes in order to remove them. Alternatively the stem can be supported horizontally on
a 'V' shaped block and the waste drilled out carefully with a pillar drill. Shaping the inside of the
bines can be time consuming, since access for files or rasps is limited. Sandpaper wound around
the bines is effbctive, but slow to do the shaping.