# What Is The Proper Way To Shorten A Bolt?



## Epictetus (Jul 29, 2016)

You can just pop a nut on the threads and then hacksaw off excess from the bolt then unscrew the nut to clean up the threads.  It will usually do the job but doesn't look nice.  I'm thinking there must be a better way, especially now I have a 7x12 lathe.
Problem is - I don't think the chuck can adequately grip, say. a machine screw and, add to that, the fact that parting off would put it a lot of pressure - ie it would probably come flying out of the chuck?
Maybe the chuck could grip an allen head screw?

Cheers!


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## Franko (Jul 29, 2016)

I use a belt grinder to chamfer the sawn end back about the depth of one or two threads. It cleans off the burr left by sawing and the bolt will feed into a nut or threaded hole very well.

One way of chucking a bolt in a 3-jaw lathe chuck is thread a nut on it to give more purchase for the chuck jaws to grip. The nut doesn't have to be turned all the way to the bolt head, just close enough that the lathe chuck jaws can clamp down on both it, and the bolt head.

Once chucked, you can spin the bolt and smooth and bevel the end with a file.


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## Mark_f (Jul 29, 2016)

Cutting a bolt in a lathe is , I consider, kind of like over engineering and borderline dangerous. You already know in your mind what probably will happen. You already have most of it figured out. The quickest way, is hacksaw it off then dress the end flat on the belt sander or grinder, then hold at a 45 degree angle to the belt and lightly dress the end thread. It will look just like before you cut it.i have a piece of angle iron with all sizes of tapped holes in one side. I clamp it in my band saw , screw the bolt through to where I want to cut and saw it off. Then clean the end up on the belt sander.

Anything under a 1/4" I cut with a screw cutting tool ( a wire stripper cutter) that has the holes you screw the screw in , squeeze and cut the screw to length . The threads straighten when you screw it out of the tool.


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## chips&more (Jul 29, 2016)

In a lathe the standard lathe chuck has a hard time holding fasteners because of the head of the fastener. It gets in the way. If you want to use the lathe you can safely hold fasteners in a collet, like a 5c collet. You can also make a split bushing to hold fasteners in a standard lathe chuck with excellent success. A lathe can be used without any problems…Dave.


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## Ulma Doctor (Jul 29, 2016)

i'll keep small sections of nylon, copper and aluminum tubing and split the tubing longitudinally to make split bushings. i'll use the split bushing to protect the bolt


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## Billh50 (Jul 29, 2016)

I put a nut on the bolt or screw up toward the head and then cut the bolt with my angle grinder while holding the bolt in a vise. I then take the bolt and using either a bench grinder or belt sander chamfer the end slightly. Then remove the nut to push off any remaining burrs. I will also hit the end on a wire wheel to make sure all burrs are gone and nut starts easily.


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## Epictetus (Jul 29, 2016)

OK, many thanks to all who replied!  Best of all, it all makes sense.
Mark, you are talking about a horizontal band saw, right?


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## Tony Wells (Jul 29, 2016)

Bolt cutters anyone? So named for a reason. Just kidding!


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## karim (Jul 29, 2016)

I do almost exactly the same thing. In my piece of angle (aluminum because I typically work with very small screws), I have tapped holes down one side of the angle and clearance holes down the other (opposite the matching tap). I use the tapped holes to hold the screw while cutting, then I put the screw into the clearance hole and press against the angle bar with the appropriate driver for the screw. This lets me hold the screw against the belt sander/grinder by holding the angle, while rotatating it to get a smooth, even bevel all around the cut face.


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## Mark_f (Jul 29, 2016)

Epictetus said:


> OK, many thanks to all who replied!  Best of all, it all makes sense.
> Mark, you are talking about a horizontal band saw, right?


Yes. and for larger bolts such as 1/2" or larger, I saw in the band saw and then put in the lathe and face the end.


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## RJSakowski (Jul 29, 2016)

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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## MSD0 (Jul 29, 2016)

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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## TOOLMASTER (Jul 29, 2016)

cut on band saw..finish edge on belt sander


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## rwm (Jul 29, 2016)

I made this:






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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## Mark_f (Jul 29, 2016)

What is it and how does it work?


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## CraigB1960 (Jul 30, 2016)

rwm said:


> I made this:
> 
> 
> 
> ...


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.


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## Mark_f (Jul 30, 2016)

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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## bill stupak (Jul 30, 2016)

I use a HF cutoff saw,     http://www.hobby-machinist.com/posts/313484/             Bill


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## jpfabricator (Jul 30, 2016)

Deepen the hole 

Sent from somwhere in east Texas by Jake!


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## rwm (Jul 30, 2016)

bill stupak said:


> I use a HF cutoff saw,     http://www.hobby-machinist.com/posts/313484/             Bill


That HF cutoff wheel probably is faster and cleaner than my version. Perhaps I should modify my  holder to fit that.
R


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## lens42 (Jul 30, 2016)

Here's another method that works nicely if you have many to cut. Mill a pocket to match the bolt in in some scrap. Clamp that in the bandsaw and drop in the bolt to cut. It goes fast because there's no threading. Works best for hex heads because the head pocket keeps the bolt from turning.




Sent from my iPhone using Tapatalk


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## Wreck™Wreck (Jul 30, 2016)

The "Proper Way" is to buy them at the correct length.

However there is really no proper way in machining, aside from the way that works for you and your equipment, one may spend a lifetime following the guidelines in MH and advice on the "Internet".

If you have a small lathe what conventional wisdom says would likely not work well as the literature available is geared toward production machines, Machinery's Handbook  is not aimed at Hobbyists.

Do what the equipment that you have allows as there is no "Proper Way:


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## TOOLMASTER (Jul 30, 2016)

thinking of making something like this...


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## Epictetus (Aug 3, 2016)

I like Wrecks answer but I took Bill's advice and ordered up that cheapo chop saw from HF.
Cheers and thanks again for all the replies!


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