What Is The Proper Way To Shorten A Bolt?

For larger bolts, I thread on a nut and mount the bolt in the lathe chuck, using the head and the nut as bearing surfaces. The bolt can be shortened with a parting tool or other lathe tool or with a hack saw. If using a hack saw, leave the lathe off and place a piece of sheet metal, plywood, etc. to protect the ways. After shortening the bolt, I will face the cut surface and use a file to chamfer the end. If you don't mind the sawn surface, the chamfering process will remove any burrs.

For smaller bolts, I use the screw shear function on the wire stripper, as stated by Mark above. One trick that I had used on my wire stripper was to run a tap through it while applying a slight pressure. This cut partial threads into the shearing jaw which tends to prevent the jaw from splaying out and has less chance of deforming the freshly cut thread. After shearing, I will advance the screw about 1/4 turn and shear again. This removes the burr on the far end, giving clean thread.

Edit: The first paragraph should say for larger hex head bolts. If I am cutting a socket head cap screw, I would use three nuts with the third nut being a lock nut to prevent the bolt from rotating while cutting or dressing. If cutting something like a carriage bolt with a head larger than the distance across the flats, I would use a split bushing, as suggested above, to hold the bolt securely.
 
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Use 2 nuts (jam nut) and you should be able to chuck it up on a lathe. After you part off the bolt, use a file to chamfer the end.
 
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cut on band saw..finish edge on belt sander
 
I made this:

26477563210_7432d4bccd_h.jpg

26657021882_cc62ba4884_h.jpg
Set the fence for exactly 2". Screw the screw in to the length you want and cut. I have threaded holes in the plate for common sizes. I use it a lot. The screws can rotate so usually I lock them in with a nut snugged against the plate.
R
 
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rwm said:
I made this:

26477563210_7432d4bccd_h.jpg

26657021882_cc62ba4884_h.jpg
Set the fence for exactly 2". Screw the screw in to the length you want and cut. I have threaded holes in the plate for common sizes. I use it a lot. The screws can rotate so usually I lock them in with a nut snugged against the plate.
R
Click to expand...
Nice simple tool! Thanks for sharing and posting the photos.

Mark, the take away I get is the tool provides a platform for the screw (allen in this case) for the blade to cut square. If you look closely, there are 4 different threaded holes to choose from. It will not bevel the end, but it will be square. I suspect the threads are chased as you screw the bolts out. I can see making more holes for larger bolts or another plate to screw on with other holes.
 
originally, I could not view the second photo. Once I finally got that second photo, I understand now. It is a nice way to do it. It works similar to the way I do it on the horizontal band saw. The difference is I clamp the fixture in the saw vise and screw a bolt in the proper hole and cut it. That is a great variation for those using a vertical saw. Brilliantly done. Sometimes I find it amazing the ways we find to do something.
 
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