It’s a thread Jim, but…

[Robin GrahamParticipant @robingraham42208]

Thanks for clearing up my measurement confusion Jason – all is now clear.

I tried using the Kkmoon (cheapo) inserts with the angled topside feed method – marginal, if any, improvement. I then had a rummage and found a Glanze tool which I thought I'd lost. This has a smaller insert which probably wouldn't cut deep enough for a 2mm thread, so I did a direct comparison between the Glanze and the Kkmoon at 1.5mm pitch. The Kkmoon thread looked much as in my original pic but this is what the Glanze produced:

This was at 65rpm. Not perfect perhaps, but acceptable for my purpose. So there is certainly a problem with the cheap insert, at least in the way I'm using it. I'll buy a better 16mm insert and see how it goes.

Robin.

[Pete RimmerParticipant @peterimmer30576]

I can't see any reason why you would be unhappy with that Robin. Looks perfectly good to me.

[Neil WyattModerator @neilwyatt]

Posted by Michael Gilligan on 24/11/2018 08:25:02:

Posted by JasonB on 24/11/2018 07:07:54:

Its the length you would get if you carried the edges on until they meet at a point.

.

Rather like Apple's way of describing the screen-size on the latest iPad Pro …

[quote] The 12.9-inch iPad Pro display has rounded corners that follow a beautiful curved design, and these corners are within a standard rectangle. When measured as a standard rectangular shape, the screen is 12.9 inches diagonally (actual viewable area is less). [/quote]

… but, of course, related to a triangle !!

MichaelG.

Try understanding the sizes of imaging chips. They are given as the diameter of a tube containing an old fashioned TV camera sensor, So a 2/3" sensor is only 8.6 by 6.6mm.

Neil

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 24/11/2018 21:20:32:

Try understanding the sizes of imaging chips. They are given as the diameter of a tube containing an old fashioned TV camera sensor, So a 2/3" sensor is only 8.6 by 6.6mm.

.

Yes, I've been doing that for years.

Apple's nonsense, however, reminded me of Sir Walter Scott's:

"'What a tangled web we weave …"

MichaelG.

[Will NobleParticipant @willnoble66529]

I know this thread has gone cold for a few days, but:

Have we all fallen out with using thread chasers – either manually, of in the toolpost?

Will

[Robin GrahamParticipant @robingraham42208]

Will, having never never used a thread chaser I can't comment on that, but…..

I ordered a 16ERAG60 insert from JB tools, as suggested by JasonB. It arrived today:

On the left is a 1.5mm thread cut with the JB, on the right with the Kkmoon. Same stock, speed (180rpm) &c. The JB thread isn't perfect by any means, but it's OK for my purpose. As someone said earlier on I can always finish with a die. I just got curious as to what was going on with my first attempts on the lathe – I've learned some stuff by making these experiments.

It took almost a week for the insert to arrive from JB – an enquiry as to when I might expect it elicited no response, but when it came there was a note from Jenny saying she'd put an internal insert in the bag as well. I thought that was pretty dashed sporting of her so a from me. I don't think I've bought from the firm before and I was beginning to get disgruntled by the delay, but now I am – well, regruntled I suppose.

Anyhow, I think I'm sorted now, thanks for all the advice/comments.

Robin

 

 

 

 

Edited By Robin Graham on 01/12/2018 20:28:33

[Alan Wilkinson 1Participant @alanwilkinson1]

Using carbide then you must use the right speed 600 rev at least ,preferably 1000+ then you will have a nice shiny finish. look up the recomended speeds and be shocked at work we would cut that size at 2000RPM no problem.

[Will NobleParticipant @willnoble66529]

Posted by Robin Graham on 01/12/2018 20:15:31:

Will, having never never used a thread chaser I can't comment on that, but…..

One of this sort of thing.

https://www.cromwell.co.uk/shop/cutting-tools/chasers-hand-and-machine/high-speed-steel-ground-thread-chasers-metric-form-hand-internal/f/12141?query=external%20thread%20chasers

Old fashioned approach and going back a long time since I was taught how but I've often used them to finish threads, internal and external. I was lucky and picked up a load of oldies-but-goodies at a boot fair, then bought the ones to fill the gaps. I roughed the thread with HSS, sometimes carbide, then finished with one of them.

I know it doesn't address your problem regarding tearing but if the tearing isn't too bad and you have enough metal left, you can still use one to finish and rescue the job.

Apologies if the last bit of the above was an egg-sucking offering.

Will

[Robin GrahamParticipant @robingraham42208]

Posted by Alan Wilkinson 1 on 10/12/2018 15:11:47:

Using carbide then you must use the right speed 600 rev at least ,preferably 1000+ then you will have a nice shiny finish. look up the recomended speeds and be shocked at work we would cut that size at 2000RPM no problem.

Thanks Alan, just for the hell of it I'll give it a go at 1000rpm – with a suitably generous relief of course! For the actual application I had a 4mm relief, so for 2mm pitch that's two turns of the work, which at 1000rpm gives me 120ms to snap the half nuts open. Hmm. Maybe a good glute workout technique though. Presumably the 2000rpm you'd use at work is with CNC machinery?

Will – thanks for the pointer to the Cromwell chasers. I'm sorted for this job, but something to bear in mind for the future.

Robin.

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