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Shear Tool

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martyn nutland25/10/2020 11:16:47
115 forum posts
7 photos
Not long ago (26/8/20) I asked for some advice on obtaining a high quality finish on some Austin Seven track rod pins I was machining. The consensus was that I should be making the last pass(es) with a 'shear tool'. In my ignorance I had never encountered a 'shear tool' and I don't think you can buy them.
 
Anyhow, I sent for a blank and watched Tubal Cain (American not old British) on the internet who happens to deal with making one. I thus ground up something that approximated to Tubal's although not nearly as neat. Tried it on a piece of scrap aluminium and worked like a dream on the finish and even produced swarf like maiden's hair! Picture attached (hopefully)
 
Thought you'd like to know and receive renewed thanks.
 

1.jpg

Martin Connelly25/10/2020 11:34:06
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1516 forum posts
170 photos

I made one some years ago for the sole purpose of making a steel between centres test bar (dumbbell type with two raised bands) for setting the tailstock on centre as I didn't have access to suitable grinding equipment. The finish on the bands still looks polished. I haven't used the tool again.

Martin C

Bo'sun25/10/2020 13:28:19
234 forum posts

Looks like it could be useful tool in the armoury. For a relative newcomer, could someone post a picture of one please. Googling "shear tool" was hopeless.

Phil P25/10/2020 13:45:45
668 forum posts
168 photos

The shear tool works really well on a shaping machine for finishing cuts.

You can see the shape of the tool and how it works here.

https://www.youtube.com/watch?v=-CWGScRNXfw

Phil

Edited By Phil P on 25/10/2020 13:48:16

John Baron25/10/2020 14:52:41
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339 forum posts
142 photos

Hi Guys,

For those of you that saw my fly cutter, I've used "Shear tool" bits in that and you can easily get glass like finishes with it. The idea came about in the early 1900's for use with shapers to get a smooth finish. Bear in mind that in those days they only had carbon steel tools, so getting a fine finish wasn't easy.

new_flycutter-1.jpg

Edited to add fly cutter picture.

 

Edited By John Baron on 25/10/2020 14:55:10

Martin Connelly25/10/2020 15:37:15
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1516 forum posts
170 photos

Here is the setting tool I made some time back and the shear bit I made to make it. In use somewhere along the cutting edge is used, not a corner. The top picture shows how the tool is presented to the workpiece, very slow power feed is used.

p1150526.jpg

p1150527.jpg

Martin C

Nicholas Farr25/10/2020 18:05:56
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2479 forum posts
1198 photos
Posted by Bo'sun on 25/10/2020 13:28:19:

Looks like it could be useful tool in the armoury. For a relative newcomer, could someone post a picture of one please. Googling "shear tool" was hopeless.

Hi Bo'sun, try searching for "shear tool for lathe"

Regards Nick.

Neil Wyatt26/10/2020 10:27:00
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Moderator
18320 forum posts
718 photos
77 articles

The simplest way to make one is similar to a flat-ended d-bit. Grind a step on a length of round HSS to half diameter, grind relief behind the cutting edge.

Fitted in a simple round holder (e.g. a boring bar holder) with the mid point approximately at centre height, you just rotate the tool for the most effective result. Ideally you are taking cuts of a thou or less.

Neil

Bo'sun26/10/2020 13:23:54
234 forum posts

Thank you, it's quite obvious once you've seen one in action.

Howard Lewis27/10/2020 15:34:15
3766 forum posts
3 photos

Sounds like using a square toolbit, with the end ground at an angle, and mounted so that it is below centre height would do the job?

Must give it a try!

Howard

Neil Wyatt27/10/2020 20:37:34
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Moderator
18320 forum posts
718 photos
77 articles
Posted by Howard Lewis on 27/10/2020 15:34:15:

Sounds like using a square toolbit, with the end ground at an angle, and mounted so that it is below centre height would do the job?

Must give it a try!

Howard

The edge needs to cross the work at a fairly steep angle. If it's vertical the contact point is automatically at centre height.

Neil

mechman4828/10/2020 11:26:06
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2792 forum posts
431 photos

Have a look here..

**LINK**

I made one last year based on the above; works nice giving a fine finish in trials. I'll take a pic of mine later & post.

George.

mechman4828/10/2020 16:33:52
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2792 forum posts
431 photos

Re. my previous post ...My shear tool...

shear tool (2).jpg

Only used on trial DoC .001-2" haven't got pic of 'angel hair' cuttings, will arrange something later although there are plenty on YouTube.No need for centre height setting as cutting edge tangential to work & can be adjusted up/down to suit as edge wears.

George.

edited by george... typo's.

Edited By mechman48 on 28/10/2020 16:35:51

Howard Lewis02/11/2020 21:56:29
3766 forum posts
3 photos

Have tried making one, although not quite in the form shown.

Based on the first couple of cuts, it looks to be an interesting tool.

Thanks for bringing it to our attention!

Howard

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