A Dedicated Chuck for Shortening Screws
© Frank Ford 2008; Photos by FF

At this point, I have literally thousands of cap screws in various sizes for assembling the endless variety  of projects I get myself into.  Despite the number of different lengths, I still find myself needing to cut small batches of them for particular uses.   While attempting to organize a corner of my shop, I bumped into this 5C collet mounted chuck.  I got it for use on my old lathe because it was a great time saver when switching from collets to a small chuck.  My new lathe doesn't need that kind of help, so the chuck has remained unused for the last four years.

Rather than grinding steps in the jaws, I thought it would be nicer to have replaceable soft jaw caps that I could use for gripping screws while cutting or shaping their threaded sections.


I took a four inch long piece of cold rolled steel rod and drilled a 5/8" hole through its length.  Then, I milled two flats along its length, sliced the piece into 3/8" thick sections, drilled and tapped for set screws.  Here's a set of collars for my chuck jaws:


The pointy set screws go into the grooves in the outer portion of  the jaw, and the two regular cup point set screws on the flats control the angle of the jaw caps. 

To true up the jaw caps, I simply grip a washer back in the original jaws, and run a small boring bar in.


Now I can grip pretty much any size screw I want, from #10 up to a half inch or more.  I don't t hink I'd want to try to cut a much bigger screw, because even taking light cuts, it would be quite a strain on these little jaw caps.

Here, I've cut the screw shorter, and I'm turning a small section on the end:


Makes a nice neat job of it:


Once I was satisfied this rig would work for my purposes, I took advantage of the internal threads on the 5C collet section by making up a collet stop:



It screws in place, and makes a perfect stop for repetitive jobs.


Here  you can see the collet stop in action:



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