Changing the
Grinding Wheels
Disassemble and check your car-
borundum grinding wheels every 6
months. If the wheels are clogged
or worn, they can be flipped to
the other side for additional wear.
Once the wheel is noticeably worn,
or warped from absorbing water,
it is not recommended that the wheel is flipped. Checking your
wheels every six months also allows for routine maintenance of
the drainage area, and for removal of chunks of plaster that inter-
fere with efficient drainage.
1. Unplug your machine, turn off the water supply, and disconnect
the plumbing at the machine by unscrewing the pipe union #3154.
2. Remove the work table and all tools. Remove the work light and
safety shield (if installed).
3. Undo the seven (7) housing screws and wing nuts and take off
the front housing/cover.
4. Remove the fine wheel first, using the spanner wrench #3208.
Make sure that threads on each hub are clean of plaster before try-
ing to turn off the wheel nut. Use a wire brush if needed. Place the
pins of the spanner in the holes of the wheel nut, hold the wrench in
place with one hand over the wheel nut, and give the handle of the
wrench a sharp blow with a hammer (counterclockwise to remove).
Also remove the plastic spacer between the nut and the wheel.
5. Remove the fine wheel back-up plate. Both back-up plates are
secured in place with three (3) machine screws size 8-32 x 1/4”.
Once these screws are removed , the back-up plate should pull off
easily. If it does not, apply some penetrating oil around the center
hole, and at the union between the plate and the hub. Pull outward
from the top edge of the plate, rotating 1/8 - 1/4 turn per each pull.
Repeat until plate is free. DO NOT strike the back-up plate with a
hammer, as it may become damaged and not spin smoothly when
the machine is re-assembled.
6. Repeat steps 4 and 5 for the coarse wheel, removing both the
wheel and the back-up plate.
7. Clean both back-up plates on both sides, scraping off any plaster
build-up which could interfere with the balance of the wheel. Also
clean the mating surfaces on the wheel mounting hub.
8. Replace the coarse wheel back-up plate and install the new
coarse wheel.
9. Replace the fine wheel back-up plate and install the new fine
wheel.
10. Check the front/rear housing gasket. If it is not soft and pliable,
or has flattened out, it should be replaced (part #3440). Make sure
the gasket is free from plaster residue, and that the mating surface
of the front housing is also clean. Any bits of dried plaster could
cause leakage after the machine is reassembled.
11. Re-install the front housing and secure with housing screws.
12. Connect water supply connections, plug in your trimmer, and
allow to run for 5 minutes. Check for smooth operation of wheels,
and for any water leaks.
When installing a new fine wheel, it may be necessary to “dress”
the surface of the wheel to remove loose abrasive particles that
can transfer a gray grit to finished plaster models. A silicon carbide
dressing stone #3344 can be purchased if required.
When replacing wheels, consider diamond wheels
from Wehmer available in coarse and fine grit.
Preventive Maintenance
Here’s a few basic guidelines that will keep your trimmer in top
shape. Follow them and you’ll significantly extend the life of your
investment.
1. Let your trimmer run after trimming! - After trimming your last
model, allow the unit to run with the water flow turned on for at least
two minutes. This will flush out plaster residue and keep the inside
of the housings clean.
2. Clean your tools! - When your trimming day is done, remove
and clean your trimming table and tools. Plaster that dries will
cause wear on the threads of the angulation tool and knobs as well
as cause chemical deterioration of the table. Remember to clean
off the sill on which the trimming table rests, as plaster in this area
will effect the squareness of the table to the wheel.
3. Keep the spray tube clean! - Particles in your water supply can
cause clogging of the tiny holes which spray water onto the wheels.
Luckily, the spray tube is removable and can be cleaned. Complete
instructions are on page 9.
4. Don’t trim with dull wheels! - You won’t be able to keep a flat
surface, and the additional pressure needed to trim will put excess
wear and tear on trimmer components (motor, bearings, shaft, etc.).
In an orthodontic office laboratory, silicon carbide wheels should be
flipped at least every 6 months and changed once a year. See
complete instructions on this page. When changing wheels, clean
all drain areas and check for dried plaster on the back of back-up
discs. Plaster residue is the #1 reason wheels run out of balance
and cause vibration.
5. Maintain threads on wheel nuts and hubs! - When changing
wheels on your trimmer, counterclockwise loosens and clockwise
tightens. Use the spanner wrench supplied with your machine to
avoid damage to the wheel nuts. If you’ve lost yours, we sell re-
placements (#3208). Make sure the threads on your hubs are free
of plaster before remounting the wheel nut. Nuts should thread back
on easily, with only finger pressure. Use the wrench and a hammer
for final tightening only.
6. Keep the housing gasket and mating surfaces clean! - When-
ever you disassemble your trimmer, make sure that no bits of plas-
ter stick to the gasket. Also check the mating surface on the front
housing, cleaning with a wire brush when necessary. When the
gasket begins to leak - replace it (#3340). Thoroughly clean out the
gasket groove with a wire brush prior to installing the new rubber
seal.
7. Keep an eye on the water level in the housing! (Wheels slosh-
ing in water) - Excessive water build-up - caused by insufficient
drainage or too much water flow - can cause all sorts of problems
to your trimmer. Drive belts can get wet and stretched, water can
flow by the slingers to the motor and\or bearing assembly, and plas-
ter residue can get on the hubs causing premature wear of the
v-belt grooves. Keep the drain open and flowing. When using a
diamond wheel, the amount of debris generated during grinding is
significantly increased and requires additional water flow to keep
the wheel clean. This extra plaster must be removed from the drain
area to prevent clogging and water backup. A great solution is to
use the Wehmer Drain Tray #1126, and to remove the clean-out
plug, drain hose, and drain hose nipple - allowing free flow directly
into the tray from two openings.
8. Lubricate the Fine Wheel Bearing! - On the back of the ma-
chine, directly behind the fine wheel, is a round tapered section
of the trimmer housing with a hole in it. This is an oil hole, and
you should lubricate the bearing that is beneath this hole every six
months with a few drops of SAE 10 weight , or another light weight
lubricating oil.
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