9/17/2015 | 1 MINUTE READ

Craftsman's Cribsheet: 30 Potential Causes of Part Length Variation on Screw Machine Parts

Facebook Share Icon LinkedIn Share Icon Twitter Share Icon Share by EMail icon Print Icon

There are many different ways that part length can vary when using a cut-off tool on multiple-spindle automatic screw machines.

Here are some of the major reasons grouped into a rough classification by where the cause exists.

The Cut-Off Tool Itself

• Tool is dull

• Tool is improperly ground (point angle too large)

• Tool is loose/improperly inserted into holder

• Tool blade is too thin

• Cut-off tool is hitting while in high speed

• Cut-off tool is being hit by die head or chasers


The Cut-Off Toolholder

• Toolholder itself is loose

• Toolholder is hitting work spindle

• Toolholder is hitting tool post

• Toolholder is warped or bent

• Toolholder is worn


The Work Spindle

• Spindle has end play

• Spindle has worn bearings

• Spindle carrier has end play

• Index lock pin spring is broken

• Finger holder is not adjusted properly

• Broken pins or fi ngers are in the fi nger holder

• Feed tubes are bent or beat up

• Wrong stock feed cam. Overfeeding stock will cause bounceback from stock stop resulting in short part

• Incorrect collet tension


The Cross Slide

• Cross slide has play

• Cross slide is loose

• Cam is loose

• Cut-off cam is too large and causes too much feed

• Cam drum is loose


Other Tools

• Stock pushed back into collet by drill (dull drill pushing stock rather than cutting chip)

• Stock pushed back into collet by reamer

• Face-off tool is loose

• Face-off tool is dull

• Face-off toolholder is loose

• Die head is pulling stock out of collet, making the part long