Feed Bed 1 - Mereen

Mereen-Johnson LLC
Service Bulletin #GRS-2-04/06
Machine Type - Gang Rip Saw
Subject - Feed Bed
Keeping your feed bed in proper operating condition can assure your machine’s capability
to provide a glue line finish and proper accuracy tolerances. The purpose of this service
bulletin is to inform Mereen-Johnson Gang Rip Saw users of common service issues
associated with the feed bed system.
For further information, contact contact your Mereen-Johnson Customer Service representative at 1-888-4MJ-SAWS (465-7297). Additional information is available in your
operations manual. If you do not have an operations manual for your machine, contact
your Customer Service representative to order a replacement.
Mereen-Johnson LLC
575 Ninth Street SE, Suite 200
Minneapolis, Minnesota 55414
USA
Phone (612) 529-7791 Fax (612) 529-0120
Mereen-Johnson LLC
Service Bulletin #GRS-2-04/06
Machine Type - Gang Rip Saw
Subject - Feed Bed
Mereen-Johnson Gang Rip Saw feed beds consist of steel backed rubber inserts, aluminum feed slats,
and hardened steel dip cams. All three components of the feed bed are common wear items.
FEED SLAT INSERTS
Typical life expectancy of a set of inserts is approximately 2 to 3 years, based on single, 8 hour, shift
production running surfaced material Processing rough stock material will shorten component life.
The most common cause of premature insert failure
is saw blade contact. This factor is directly correlated
to the operator’s ability to properly set the arbor down
stop each time a new or re-sharpened set of tooling is
installed on the machine, limiting saw blade contact
with the feed bed.
(Note: Down stop will be located on top of
arbor on machines built prior to year 2000)
Arbor down stop
Proper training and procedures can reduce the number
of occurrences in which saw blades contact the feed bed.
A recommended procedure is to place a notice on each
Power arbor hoist limit
tooling set or have the operator sign out new or resharpened tooling sets, notifying the operator that they
are responsible for re-setting the arbor down stop when the tooling is installed.
For machines equipped with power arbor hoist, resetting of the limit switch stops is also required.
Always sharpen and store matched tooling sets together. Splitting or combining tooling sets can lead to
installing blades of different diameter on the same arbor arrangement, increasing the likelihood of blade
/ feed bed contact.
Note that in fixed fence applications, feed slat inserts are symmetrical in design allowing removal and
reverse installation. This can allow additional run time on these components for applications in which
materials are predominantly feed in one location.
Feed speed can also effect feed slat longevity, especially in applications where conveyor systems are
used to feed the gang rip saw. In this case it is important to assure that the conveyor pinch roll speed is
within 10% of the gang rip saw feed speed.
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Mereen-Johnson LLC
Service Bulletin #GRS-2-04/06
Machine Type - Gang Rip Saw
Subject - Feed Bed
Timing of the pinch drive roll vertical jump actuation on conveyor fed systems is also important. The pinch
drive roll should jump down to engage each board only until each board is contained by the saw feed system.
The roll should jump up shortly after the board is under the first hold down roll of the gang rip saw. The
longer the force of the pinch drive roll and containment of the gang rip saw’s feed system overlap, the faster
the feed bed will wear.
Whether manually or automatically feeding the gang rip saw, it is a good practice to slow the feed bed to
match the capacity of the operators or feeding device. Running the feed bed at a higher rate than the feeding
capacity of the operator or feed system will shorten feed bed component life and have little or no effect on
production capacity.
Feed slat inserts are normal stock items and can usually ship within 24 hours of order placement. Be aware
that our competitor’s offering (non-Mereen-Johnson) feed slat inserts are typically bonded rubber to steel in
lieu of Mereen-Johnson’s moulded rubber to steel design. Our experience has proven that the bonded (glued)
feed slat design is an inferior product and much more likely to delaminate, causing premature failure.
ALUMINUM FEED SLATS
From the Model year 1963 to 1995 an “H” style feed slat design was utilized. With the introduction of wider
capacity machines such as the 31” and 40” capacity saws, higher strength components were required, which
brought about the new “I” type design on all 400 Series machines. The “I” style feed slat is capable of bearing
significantly greater vertical loads then the previous H style design. The “I” style design is a direct fit
replacement on any machine equipped with the H style design and is now available for all 312-DC Series
machine as well.
Saw blade contact is also the most common reason for feed slat failure and it’s detection is visibly obvious.
Other reasons for failure include, machine jams, improper conveyor system elevations and improper pressure
head settings. In these cases, the damage is less obvious because these failures typically cause bending of the
slats. A simple means for checking feed slats is to lay a straight edge on (parallel with) each slat to check for
straightness.
“H” Style Feed Slat
“I” Style Feed Slat
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Mereen-Johnson LLC
Service Bulletin #GRS-2-04/06
Machine Type - Gang Rip Saw
Subject - Feed Bed
HARDENED STEEL DIP CAMS
Dip cams create the clearance or dip in the feed bed at the saw blade centerline by contacting the
extended pins mounted on each feed chain. The chamfered style dip cam was replaced with a
radius style design offering smoother and quieter feed bed operation. The radius dip cam is a direct
fit replacement to older machines equipped with the chamfer style design.
Dip cams are also symmetrical in design, meaning that once they have worn beyond the case
hardening (approximately .030”) they can be removed and re-mounted on the opposite chain’s
mounting location, doubling their operational life expectancy. Operating the rip saw with worn dip
cams can reduce the amount of dip clearance of the feed bed, greatly increasing the chances for saw
blade / feed bed contact.
The other factor regarding dip bed clearance is wear to the extended pins mounted on the feed
chains. In most cases, the maximum allowable wear area or flat created on the pin from the
contact surface of the dip cam is 3/16”. This topic to be covered in greater detail in a future
service bulletin regarding gang rip saw feed drive systems.
Contact the Mereen-Johnson Customer Service department to order quality OEM replacement
components at 1-888-4MJ-SAWS (465-7297) or visit our web site at www.mereen-johnson.com
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