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How would this lathe tool be used?

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Robin Graham18/10/2018 22:23:48
597 forum posts
130 photos

Found this in a box of miscellaneous tools given to me:

ThreadingTool1.jpg

ThreadingTool2.jpg

Obviously a threading tool, but how and in what circumstances might it it be used I wonder?

Robin.

mechman4818/10/2018 22:41:27
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2503 forum posts
371 photos

Tapered thread chaser ? my Zeus book states 22 tpi as 5/16 BSF, must be a home made special.

George.

David Standing 118/10/2018 22:54:14
1280 forum posts
46 photos

BSF is sometimes referred to as Whitworth Fine

Bob Stevenson18/10/2018 23:27:13
308 forum posts
6 photos

Not home made,...it's a product of Thomas Chatwin makers of fine threading equipement mainly for industry, and it's for 'chasing' or repairing/polishing threads. Its used in the top slide which is set to the right angle for the particular thread and then can be fed into the thread until the required finish is atained.

duncan webster18/10/2018 23:37:55
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2255 forum posts
32 photos

Many years ago I worked with a chap who had served his time in Birkenhead shipyard at around the time of WW1. Underneath the bench was a bag of thread chasers with wooden handles, a bit like wood turning tools. I think they were used for finishing a thread started by screwcutting rather than starting from scratch, no doubt someone will correct me. They definitely were not intended to be clamped in the topslide

charadam18/10/2018 23:39:47
180 forum posts
6 photos

Thread burnishing?

Mark Rand19/10/2018 00:38:27
785 forum posts

Yup, a thread chaser. Useful for cleaning up a single pointed thread. Particularly when full profile threading tools were called dies.

Brian G19/10/2018 06:47:40
603 forum posts
25 photos

Hope not to appear too stupid here (well, not much more than normal), but wouldn't a chaser or die be needed to round off a Whitworth thread that had been screwcut?

Brian

Hopper19/10/2018 07:42:12
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3741 forum posts
76 photos
Not really
The radius is more theory than practice.
Michael Gilligan19/10/2018 09:48:11
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14134 forum posts
615 photos

Posted by Brian G on 19/10/2018 06:47:40:

Hope not to appear too stupid here (well, not much more than normal), but wouldn't a chaser or die be needed to round off a Whitworth thread that had been screwcut?

Brian

.

Not stupid at all, Brian

Three answers:

  1. Hopper, speaking as a practical man, says "Not really"
  2. If you use a 'full form' cutting tool [*], No
  3. If you use a conventional single point cutting tool; and you [or QA] care about accuracy of thread form,  then Yes.

MichaelG.

.

[*] See the excellent illustration by Andrew Johnston, here: 

https://www.model-engineer.co.uk/forums/postings.asp?th=137131

... noting, of course, that he shows ISO Metric thread form, not Whitworth.

.

Edit: Here's an 'external' insert of Whitworth form:

https://www.rileyshutt.co.uk/ProductGrp/00160003001f0002

Edited By Michael Gilligan on 19/10/2018 10:00:30

Edited By Michael Gilligan on 19/10/2018 10:08:10

Michael Gilligan19/10/2018 11:04:04
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14134 forum posts
615 photos
Posted by duncan webster on 18/10/2018 23:37:55:

... Underneath the bench was a bag of thread chasers with wooden handles, a bit like wood turning tools. I think they were used for finishing a thread started by screwcutting rather than starting from scratch, no doubt someone will correct me. ...

.

Not a correction, Duncan; merely an observation ...

That style of chaser was commonly used, on a plain lathe, for putting threads on brass tubes and fittings for 'scientific instruments'.

MichaelG.

Neil Wyatt19/10/2018 11:36:41
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Moderator
16655 forum posts
687 photos
75 articles

Has anyone here besides me tried hand chasing a thread?

It is very definitely a skill' and worth a try just to see what's involved!

Neil

Michael Gilligan19/10/2018 11:40:57
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14134 forum posts
615 photos
Posted by Neil Wyatt on 19/10/2018 11:36:41:

Has anyone here besides me tried hand chasing a thread?

It is very definitely a skill' and worth a try just to see what's involved!

Neil

.

To my shame ... No

But I did [many years ago] watch my Dad do it

I was probably only about ten years old, but I remember being very impressed.

MichaelG.

Mick B119/10/2018 11:52:33
1214 forum posts
70 photos

I've seen straight chasers with a tapered tang that looked as if they were made for a file handle, but not one with that angle before.

I'd guess it was designed to work in an angled toolpost close to a chuck or other workholder, avoiding collisions with projections.

Edited By Mick B1 on 19/10/2018 11:53:07

Michael Gilligan19/10/2018 11:55:39
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14134 forum posts
615 photos
Posted by Mick B1 on 19/10/2018 11:52:33:

I'd guess it was designed to work in an angled toolpost close to a chuck or other workholder, avoiding collisions with projections.

.

yes

ega19/10/2018 12:06:59
1290 forum posts
109 photos

For anyone interested in seeing hand chasing, here is a link to a fascinating video about Japanese fountain pen making:

Edited By ega on 19/10/2018 12:07:47

Edited By Neil Wyatt on 19/10/2018 19:29:05

Michael Gilligan19/10/2018 18:43:57
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14134 forum posts
615 photos

Thanks for the link, ega

Very interesting to see the different approach to turning

... as with Japanese saws, there is much sense in it.

MichaelG.

Phil Stevenson19/10/2018 20:55:25
73 forum posts
13 photos

The tool looks just like a hand chaser as would be used by a woodturner. Very commonly done in some forms of wood and exotic material turning. I once watched the now deceased Bill Jones make up a chess king out of about 6 pieces of ivory (or more likely imitation ivory), all individually turned and hand threaded to fit together to form the finished piece in order to maximise the use of the material. Hand threading lidded boxes is pretty commonly done nowadays, usually in boxwood, African blackwood and other very dense timbers to take and hold a fine thread. There is definitely a knack to doing it but if you are shown the technique by someone who knows, you will have a fair chance of making a functional male and a female thread within an hour. Lots of stuff on Youtube as usual eg **LINK**. Hand chaser sets are available for wood turning. I know nothing about hand chasing metal, you may not be surprised to hear ....

Robert Atkinson 219/10/2018 21:42:10
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385 forum posts
21 photos
Posted by Hopper on 19/10/2018 07:42:12:
Not really
The radius is more theory than practice.

Maybe for model engineers, but there have been cases of wings folding on aircraft (e.g. Tiger Moth) due to threads on replacement tie bars not being formed correctly.This causes stress concentrations and fatigue cracking.

Robert.

Sam Stones20/10/2018 00:14:37
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652 forum posts
255 photos

A lack of fillet radii - cannot be over stressed.

Okay, I am playing with words here but in the light of the above remark …

The radius is more theory than practice …

and with due respect to Hopper (assuming we are referring to thread root and not thread crest), in the many years while I was ‘doing’ technical service, the vast number of moulded products that failed in service, failed through lack of adequate fillet radiusing. This included a wide variety of threaded components, e.g. caps, closures, water filter canisters, and on through a wide assortment of moulded parts, big and small.

The source of the problem was often tool design or mould-making oversight, i.e. sharp edges left on the external corners of mould cores and profiles.

For further reading - Google ‘Fillet radii’ and a myriad of examples will appear.

My apologies if I’ve covered this somewhere else.

Regards,

Sam smile d

BTW – when I bought my (now long gone) ML7, it came with a box of thread chasers, mostly with tangs for hand chasing.

That's a fascinating video of pen making, especially the method of closing the lathe collet.   

Edited By Sam Stones on 20/10/2018 00:19:38

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