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Cutting threads on stainless bolts

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Aquachiefofficer

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I use stainless cap bolts to secure power tools like my mitre saw, scroll saw and grinder to the bench and sometimes find that the bolts have a few mm of unthreaded shank projecting below the worktop which means I have to use several washers to fit the nut tightly. I have a cheap set of taps and dies which perform reasonably on mild steel, aluminium and brass but will not cut a thread on stainless. Any recommendations on makes or grades of dies which will do the job would be greatly appreciated.
Regards, Paul
 

Aquachiefofficer

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I perhaps should add that I only need to extend the threads 5 or 6 mm along the shanks of the bolts. I have a good set of A002 drills which work well on stainless plate, I just need to know what to buy in dies: 6 , 8 and 10mm are all I really need.
Paul
 

Rorschach

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You would need a HSS die but even then I would not be all that hopeful you will be able to do it. Bolts are usually roll threaded while hot and stainless especially work hardens easily so you might fit too tough to thread any further.

To be honest for the cost of the die, potential for breakage etc I think you would be better just buying new bolts.
 

Rorschach

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Set screw is not the best terminology here, I think bolt is better.
 

novocaine

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I'll just leave this pendant here. :D (sorry and to be honest, unless you're in an engineering environment, it really really doesn't matter what you call it)


and to make up for doing that, I prefer this one. :)



edit: to actually add something to the thread instead of being silly.

SS is as said, hot roll threaded normally and depending on the grade (304 etc.) can be very hard to cut threads, if you really want to throw money at it instead of new chunks then a split die for someone like presto (hay presto) so you open it up and cut the thread in increments is a good idea. otherwise, a quick trip out is in order. or you could add wooden load spreader on the underside of the bench which would have 2 benefits, one it let you use your incorrect screws and 2 it would spread the load a bit and help prolong the life of your bench. :D

I gt all my stainless in chineasium grade, that way you can cut new threads with a spoon and they still rust so you feel a bit more like the good old days when stuff like this cost more than a few beans.

edit to my edit
have you thought about buying a length of threaded bar and cutting it to size instead?
 

Rorschach

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I love those special bolts! :lol:

I know set screw is technically correct but I think what most people imagine (me certainly) when you say set screw is really a grub screw type with no head.
Anyway, lets get down to the nitty gritty here, what kind of diamond hone should I use to sharpen my set screws? :twisted:
 

novocaine

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Honestly you don't need all that modern diamond rubbish, a chunk of slate was good enough for my great great great great grandfather and it's all you'll ever need, next you'll be asking what jig is best.
 

Phil Pascoe

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Rorschach":p63l2mtv said:
I love those special bolts! :lol:
I know set screw is technically correct but I think what most people imagine (me certainly) when you say set screw is really a grub screw type with no head.
Until I looked it up I had never heard a grub screw called anything other than a grub screw. :D
 

Phil Pascoe

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novocaine":1nnk5ci5 said:
Honestly you don't need all that modern diamond rubbish, a chunk of slate was good enough for my great great great great grandfather and it's all you'll ever need, next you'll be asking what jig is best.
Ah ............ but was it dished? :D
 

woodfarmer

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Wouldn't it be easier to cut down the unthreaded portion in a lathe ? so the shank fits inside the tapped thread hole.
 
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