IS-57

Form Tool Holders for Davenport Screw Machines


Instructions for use of Somma Resharpenable Quick-Change
RQCDAV-S and RQCDVB-S Form Tool Holders for
Davenport Screw Machines

Mount tool holder securely on slide as normal.

Rotate actuator screw (Pt. 17) counterclockwise until opening of clamp wedge (Pt. 4) is wide enough to accept insert.

Install formed insert into pocket, being certain that opening is clean and free of chips. Make sure insert is fully seated and then clamp securely by rotating actuator screw (Pt. 17) clockwise.

With dovetail clamp screws (Pt. 13) snugged up, turn adjusting screw (Pt. 15) until cutting edge of tool is adjusted to centerline of workpiece for best cutting action. Then lock in place by securely tightening dovetail clamp screws.

Tool is now ready for use. If part is tapered, tapers can be corrected by rotating eccentric adjusting stud (Pt. 6). It is necessary to loosen lock screw (Pt. 7) before rotating stud and locking it in position again with lock screw (Pt. 7).

When cutting edge needs resharpening, remove worn insert only (Do not disturb holder settings.) and replace with sharpened insert as per previous instructions. Since clamping pressure is upward on insert, replacement insert will be on same centerline as original insert, thereby eliminating the need to reset tool for center height. Also since inserts are identical in form and have a parallelogram configuration, they will maintain same workpiece lengths and diameters. Machine should be producing perfect parts again in less than a minute.

For best size control and for longest life, insert should be sharpened as soon as cutting edges start to show wear of .005" maximum.

When approximately 1/8" has been resharpened off thickness of insert, insert will no longer be able to be clamped in holder. However, a 1/8" thick matched form backup spacer is available that can be placed under insert for support. This spacer allows for additional resharpenable tool life of 1/16" to 1/8" depending on configuration of insert.

 

To sharpen dull insert, install insert into sharpening fixture and clamp securely. Tap insert down to be sure it is fully seated against bottom face. Mount fixture on magnetic chuck of surface grinder horizontally or vertically depending on the wheel being used. **IMPORTANT: If grinding horizontally, position fixture so that grinding wheel pressure against insert is towards screw head stop in fixture that contacts back end of insert, not towards end of insert with form.

Remove stock evenly from entire top surface of insert so that top and bottom surfaces are parallel within .001" and as smooth as possible. It is essential that the top surface of the insert is flat and free of steps since steps would cause insert to not repeat center setting when remounted in holder and could also result in lack of rigidity and possible breakage of insert and damage to holder.

Grind off only minimum amount necessary to remove wear of cutting edges. Remember, inserts should be resharpened prior to .005" wear.

Always spark out final grinding passes for better finish and longer tool life, honing of top surface will further increase tool life and improve finish.

 

Wheel grade recommendation for carbide inserts: CMD180 R100 B-1/8

Style of wheel: 
If grinding horizontally Use D1A1
If grinding vertically Use D11V9

Take .0001/.0003" deep passes if grinding dry.
Take .0002/.0005" deep passes if grinding wet.

For best results true up wheel as per grinding wheel manufacturer’s instructions as needed.

 

WARNING!! It is always important to be certain that insert is clamped securely in the tool holder. If insert is not clamped securely, machine damage or personal injury can result.

Extra care must be taken when you have resharpened the insert (including the 1/8" spacer when used) down to about 1/4" total thickness since it will no longer be possible to clamp the insert in the holder. This is done intentionally so that insert will not be used when it’s thickness is less than that which is required to support the cutting edge.

Therefore, it is important to be certain that clamp is actually clamping on insert, holding it securely in the holder and not merely bottoming out.