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Shortening screws

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John MC13/03/2018 12:36:10
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320 forum posts
38 photos

Many years ago I acquired a large quantity of 8BA screws, cheese and hex. head and varying lengths, probably a life times supply. As might be expected, they are never the right length! So I take the next longest, screw on a nut, cut it to length, then touch it on a fine grinding wheel to tidy up. This is fine when only a few need shortening but tedious for the 50+ I need for my next project.

Any ideas to make the job easier?

Thanks, John.

Ian Parkin13/03/2018 12:55:01
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870 forum posts
212 photos

I have a set of pliers side cutters and they have screw cutting holes for m3.5 and m4 near the joint they work great if your screw fits in the holes

Shortest length is perhaps 8mm

Mike Clarke13/03/2018 13:19:35
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93 forum posts
7 photos
Hi.

I shorten screws/bolts with a "nut plate". Just a random bit of MS plate, drilled and tapped to suit screw. You can set required length with washers or spacers under head of screw. Cut off the excess with a hacksaw and then file flush with nut plate.

Mike
Brian H13/03/2018 13:38:01
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1867 forum posts
106 photos

Plus 1 for Mike Clarkes' method. When you've finished just store them away for future reuse.

Brian

Matt Harrington13/03/2018 13:41:18
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130 forum posts
6 photos

I use simple jig.

This one is a little better and easy to make on the lathe:

http://www.clickspringprojects.com/screwhead-holding-tool.html

Matt

Martin Kyte13/03/2018 13:48:06
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2132 forum posts
37 photos

If you use a piercing saw the grinding op is not needed so that speeds things up a little.

regards Martin

Vic13/03/2018 14:07:54
2645 forum posts
20 photos

I’ve made up some little threaded (M3, M4, M5, M6) jigs to trim down screws on the lathe. They screw in from the back and I then run the lathe in reverse to trim the screws.

FMES13/03/2018 14:50:58
605 forum posts
2 photos

One of these will crop them off square, **LINK** just a burr to clean off.

Sorry I couldn't find a UK pic

Regards

Lofty

Speedy Builder513/03/2018 15:01:48
2151 forum posts
152 photos

Same question - different answers.

**LINK**

Michael Cox 113/03/2018 16:23:15
535 forum posts
27 photos

Here are a couple of good methods from Rick Sparber:

http://rick.sparber.org/aubc.pdf

http://rick.sparber.org/BCF.pdf

He also has a simple jig for bevelling the ends of cut bolts:

http://rick.sparber.org/ubb.pdf

Mike

Russell Eberhardt13/03/2018 16:42:39
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2600 forum posts
85 photos

I use a lantern chuck and a fine parting tool.

Russell

Tractor man13/03/2018 17:47:53
426 forum posts
1 photos
I saw a design for a lantern chuck in M.E. I think.
Trying to think of a way to do batches of five or ten at a time but it involves making jigs etc.
John MC14/03/2018 08:37:57
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320 forum posts
38 photos

Many thanks for the replies. The root of the problem is not cutting the screw to length but tiding up the cut end so it will screw in to the mating thread. I like the ides of the of a "nut plate" as that will hold the screw while being cut and the end tidied up, unscrewing it through the plate will restore the thread.

Off to the workshop to make a nut plate.

John

Alan Wood 414/03/2018 09:41:35
155 forum posts
6 photos

Further ideas

**LINK**

Matt Harrington14/03/2018 09:55:33
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130 forum posts
6 photos

Thanks for posting Alan, I like simple approaches and the brass collars are just that.

Matt

mechman4814/03/2018 10:59:07
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2797 forum posts
431 photos

I have a couple of nut plates made from scrap aluminium to cover metric & imperial.... ugly as sin ... but do the job.

screw cutting plates..jpg

George.

Fowlers Fury14/03/2018 12:02:16
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355 forum posts
80 photos

Re: " The root of the problem is not cutting the screw to length but tiding up the cut end so it will screw in to the mating thread"
Have searched for a current source of these without success.
I use the concave, diamond-impregnated surface of this "cutter" in a hi-speed mini drill then onto the end of a cut-off BA bolt. It produces a nice rounded end without damaging the leading threads in a few seconds. It's lasted for years - only wish I could find a new spare.
concave diamond.jpg

Addendum: Presumably the similar concave-shaped, but aluminium oxide stones which are freely available for mini-drills would be as effective although not as long lasting.

Edited By Fowlers Fury on 14/03/2018 12:27:24

Grindstone Cowboy14/03/2018 15:07:17
374 forum posts
32 photos

I like the idea of that diamond grinding cup, so a quick search found **LINK**

Not found anything in the UK yet, but they seem to be a fairly common jeweller's tool so will keep looking.

Rob

Fowlers Fury14/03/2018 15:28:48
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355 forum posts
80 photos

".......so a quick search found......"

Rob., well found !
However at 6mm D it's unlikely to fit the chuck of a hi-speed mini drill but mounted in a drill press it might do the job. Over the years, I've learned the best way to round the cut edge is to hold the mini drill in one hand and move the bolt with the other hand in a sort of 'conical way' inside the rotating concave (harder to describe than to do !).
If the bolt is held in the vice and the rotating cutter applied, the mini drill tends to jump about quite a bit.
Yet.....with drill press and vice it should be OK.

Prompted by your reference to a "jeweller's tool" - I'll also start searching.

Steve Crow15/03/2018 13:40:08
246 forum posts
122 photos

I made a primitive lantern chuck for small screws. The collets are for 12BA and M1.6.

lantern1.jpg

lantern2.jpg

lantern3.jpg

lantern4.jpg

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