8
96-0041 Rev U
July 2010
Another common type of work holding on a milling machine is clamps. If you
have an odd shaped work piece or a large one that does not t into a mill vise,
you can clamp it directly to the mill table or xture plate using clamps. Clamps
are usually a bar type with an oval slot cut through the bar for a bolt and a
tapped hole in the bar for a jackscrew. The jackscrew is set to be slightly longer
than your work piece is tall. A small shim made of soft material .05” minimum
thickness should be placed between the jackscrew and the machine table to
prevent the screw from damaging the table when the clamp is tightened.
Set the clamp on top of the work piece and the jackscrew and shim on the
table. Place a bolt through the slot in the clamp and screw it into a tee nut in
the table’s tee slot and tighten the bolt to increase the clamping pressure. A
series of clamps around your part should hold it in place during machining.
If you need to machine completely through the part, you will need to get the
work piece off of the table. In this case, place blocks between your work piece
and the table at the same locations where your clamps are. The blocks need to
be directly under the clamps and all the blocks need to be the same height.
Another method of getting your work piece up off the table is to make a xture
plate. The xture plate can be bolted to the machine table using tee nuts and
bolts. Drill and tap holes where the clamps need to be. Clamp your part to the
xture plate as described above.
A third method of work holding is for round, cylindrical work pieces. A chuck
with movable clamping jaws can be mounted to the machine table. The chuck
works like the small chucks on a drill press or a drill motor. A chuck key is used
to turn a screw in the side of the chuck, which moves all the clamping jaws
simultaneously to clamp on a round work piece.
For information on other types of work holding or more information on the types
discussed here, contact your local distributor of industrial supplies.
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