How would this lathe tool be used?

[Neil WyattModerator @neilwyatt]

Posted by ega on 20/10/2018 11:01:15:

Neil Wyatt:

Thank you for taking the trouble to upgrade my link (Japanese fountain pen making); would you please remind me how this is done?

Good to know that it has been of interest, and not just on the chasing point.

On youtube click share and then embed.

You can ignore the various settings and use the defaults.

Copy the code and then in your posting click the 'YouTube' icon.

Paste the code in the box and then click OK, an 'iframe' box will appear in your post.

Once you have made your posting the video will be embedded.

The blue icon with <> on it to the right of the YouTube one can be used to embed other things like tweets etc. taht give you html 'embed' code when you click share.

I'm not entirely convinced that the two buttons do different things…

Neil

[egaParticipant @ega]

Neil Wyatt:

Thank you.

I think I have noticed in the past that after viewing an embedded video other, unwanted, videos are offered; is there a way to avoid this?

[JohnFParticipant @johnf59703]

Posted by Robert Atkinson 2 on 19/10/2018 21:42:10:

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.

Hi a bit more info here on an older post relating to threads and truncating, mainly used on Whit form when cut by single point where the crest is truncated in place of the radius when a full form tool isn't available.

**LINK**

In particular look at the link by Jon Gibbs on his second post and page 34 in the BS84 standards relating to thread truncation.

Truncated threads were the norm in the aircraft industry in the 60's when many threads on difficult parts were all screwcut rather than with a die box etc. done many hundred's of them.

However as Robert says if the part is subject to high stress its best not to compromise on the root profile !

John

[Mick B1Participant @mickb1]

Posted by JohnF on 20/10/2018 18:41:10:

….

However as Robert says if the part is subject to high stress its best not to compromise on the root profile !

John

True, but better still to roll the thread rather than cut it at all, if that's the case.

One of my first engineering jobs was in a Nottingham factory that made jacking screw legs for articulated lorry trailers. The ones I was doing were inch-and-three-eighths 2-start Acme left hand. The thread rollers were fed 10 foot lengths of bar-turned steel, so quite large threads could be handled in this way.

[Sam StonesParticipant @samstones42903]

I was quite surprised to note, when I added a Myford (Norton) gear box and new leadscrew to my ML7, that the leadscrew was thread rolled. That was in about '65.

Sam

[Sam StonesParticipant @samstones42903]

Simple knurling is a less obvious use for thread chasers.

Allowing for the helix angle, grip the chaser sideways in the tool post. As here.

Rotate the work in 60° steps, each time shaving grooves across/along the workpiece.

If you don’t have a chaser, you can make one up using half of a screw thread as here.

The piece (half of a screw) could be glued in place or brazed. In this instance, a steel screw suitable hardened would last longer, but brazing would interfere with the degree of hardening.

In this photograph is one I prepared earlier – about twenty five years earlier.

Knurling the brass knob by the above method took only a couple of minutes. The red and the black knobs were commercial mouldings intended to be pressed onto Alan screw heads.

Regards,

Sam

[Robin GrahamParticipant @robingraham42208]

Thanks replies and interesting digressions. I had assumed this was a hand made tool because of the engraving – but following up Bob Stevenson's suggestion I found a reference to Thomas Chatwin in Grace's Guide **LINK**. Is that the firm you were thinking of Bob? I couldn't find the distinctive Chatwin sig.

Anyhow, I now have a better idea of what the tool is meant for, and shall bung it back in the box, pending the need to cut a full form 22 TPI Whit thread. Which will happen in the next week or so if I see it as a useful lump of HSS and regrind it, but probably never if I leave it alone.

Robin

[Neil WyattModerator @neilwyatt]

I thought the point of a chaser was to create a full profile thread?

One thing most of us can manage is running a hand chaser gently over a cut thread to tidy it up.

Neil

[Michael GilliganParticipant @michaelgilligan61133]

This might put the 'Chatwin' tool in conext: **LINK**

http://www.lathes.co.uk/chasescrewcutting/

MichaelG.

.

P.S. This, from Grace's Guide, looks promising:

https://www.gracesguide.co.uk/images/1/19/Im192001AE-Chat.jpg

… except, of course, that its inclusion of a 'pitch error compensating device' would presume the use of a single-point tool. 

Edited By Michael Gilligan on 21/10/2018 08:33:51

[Mick B1Participant @mickb1]

Posted by Sam Stones on 20/10/2018 19:26:05:

I was quite surprised to note, when I added a Myford (Norton) gear box and new leadscrew to my ML7, that the leadscrew was thread rolled. That was in about '65.

Sam

Well, I'd've thought that was the right way to do it – accurate, strong and wear-resistant.

[BazyleParticipant @bazyle]

Posted by Robin Graham on 20/10/2018 22:11:49:

pending the need to cut a full form 22 TPI Whit thread.

Could be useful if you get an early Drummond as the cross-slide screw is 22 tpi. The awkward number not being considered a problem by the manufacturer as they didn't provide a dial, nor list 22tpi in the screwcutting chart although achievable with the gears provided.

[Dinosaur EngineerParticipant @dinosaurengineer]

A chaser is very useful for rounding BSW crests . If measuring the O.D. or "try to fit" BSW threads with sharp crests at nominal O.D. the result will be very loose fitting threads. Better to have the recommended alternative flat crest than sharp crests.

[Neil WyattModerator @neilwyatt]

Posted by ega on 20/10/2018 17:47:21:

Neil Wyatt:

Thank you.

I think I have noticed in the past that after viewing an embedded video other, unwanted, videos are offered; is there a way to avoid this?

I think it's in the settings when you generate the embed code.

You will generally be offered things relevant to what you have seen before … if you have cookies enabled.

Neil

[Sam StonesParticipant @samstones42903]

… Posted By Mick B1

… Well, I'd've thought that was the right way to do it – accurate, strong and wear-resistant.

Yes Mick!

Another plus for Myford.

‘You'll See It When You Believe It’ – Wayne W. Dyer.

Regards,

Sam

 

Edited By Sam Stones on 21/10/2018 19:33:46

[Mick B1Participant @mickb1]

Posted by Sam Stones on 21/10/2018 19:32:49:

… Posted By Mick B1

… Well, I'd've thought that was the right way to do it – accurate, strong and wear-resistant.

Yes Mick!

Another plus for Myford.

‘You'll See It When You Believe It’ – Wayne W. Dyer.

Regards,

Sam

Edited By Sam Stones on 21/10/2018 19:33:46

Really? Doesn't everyone do 'em that way? Quicker and cheaper as well as better, if you can justify the capital cost.

[Neil WyattModerator @neilwyatt]

I have to smile at you fellows in the Myford Squad

There was a recent thread about a cracked Myford gear cover and owners were queuing up to say how they had repaired theirs. No one suggested the gear covers might not be 'fit for purpose'

Neil

[Sam StonesParticipant @samstones42903]

I have to admit Mick, I’ve only ever taken the time to examine the Myford I owned.

Even the machines in the toolroom (except for the ball screws on the Cincinnati) missed out.

Apologies to Robin for my digression.

Neil,

As I recall, those gear covers were die-cast.

Swinging on the hinges when the cover was open invited problems.

Regards to all,

Sam

Expected top in Melbourne, a comfortable 26 degrees.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 21/10/2018 21:34:50:

I have to smile at you fellows in the Myford Squad

There was a recent thread about a cracked Myford gear cover and owners were queuing up to say how they had repaired theirs. No one suggested the gear covers might not be 'fit for purpose'

Neil

.

Martin Cleeve's 'Hot Rod' approach is a stylish alternative:

MichaelG.

[Robin GrahamParticipant @robingraham42208]

Posted by Sam Stones on 21/10/2018 21:48:23:

I have to admit Mick, I’ve only ever taken the time to examine the Myford I owned.

Even the machines in the toolroom (except for the ball screws on the Cincinnati) missed out.

Apologies to Robin for my digression.

No apology needed Sam, I know some folk get hot get hot under the collar if they start a thread and it veers away from the initial question, but not me. My question was answered and I got some bonus info. Digress away!

MichaelG – thanks for the link to to Tony Griffith's thread chasing page, interesting reading.

Robin.

[David Standing 1Participant @davidstanding1]

Posted by Neil Wyatt on 21/10/2018 21:34:50:

I have to smile at you fellows in the Myford Squad

There was a recent thread about a cracked Myford gear cover and owners were queuing up to say how they had repaired theirs. No one suggested the gear covers might not be 'fit for purpose'

Neil

I saw that thread, and my first thought was 'repair it? – just get another one off eBay'!

[Neil WyattModerator @neilwyatt]

Posted by David Standing 1 on 22/10/2018 09:34:05:

Posted by Neil Wyatt on 21/10/2018 21:34:50:

I have to smile at you fellows in the Myford Squad

There was a recent thread about a cracked Myford gear cover and owners were queuing up to say how they had repaired theirs. No one suggested the gear covers might not be 'fit for purpose'

Neil

I saw that thread, and my first thought was 'repair it? – just get another one off eBay'!

Or use a biscuit tin

[David Standing 1Participant @davidstanding1]

Posted by Neil Wyatt on 22/10/2018 10:50:20:

Posted by David Standing 1 on 22/10/2018 09:34:05:

Posted by Neil Wyatt on 21/10/2018 21:34:50:

I have to smile at you fellows in the Myford Squad

There was a recent thread about a cracked Myford gear cover and owners were queuing up to say how they had repaired theirs. No one suggested the gear covers might not be 'fit for purpose'

Neil

I saw that thread, and my first thought was 'repair it? – just get another one off eBay'!

Or use a biscuit tin

Bonus, also increase it's value in one fell swoop

[mickParticipant @mick65121]

Very useful for cutting fine multi start threads. Grind back the teeth until you have the number of starts required, set in the tool post then set the lead screw to pitch multiplied by the number starts and cut the multi start thread in one operation.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by mick on 23/10/2018 10:03:13:

Very useful for cutting fine multi start threads. Grind back the teeth until you have the number of starts required, set in the tool post then set the lead screw to pitch multiplied by the number starts and cut the multi start thread in one operation.

.

That's ingenious

MichaelG.

[Mick B1Participant @mickb1]

Posted by Michael Gilligan on 23/10/2018 10:08:05:

Posted by mick on 23/10/2018 10:03:13:

Very useful for cutting fine multi start threads. Grind back the teeth until you have the number of starts required, set in the tool post then set the lead screw to pitch multiplied by the number starts and cut the multi start thread in one operation.

.

That's ingenious

MichaelG.

Certainly is .

Just make sure the skew of the teeth and/or the front clearance is enough to allow for the increased helix angle without interference.

[Author]

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