I am not a Myford man but a search on here should come up with spread sheets giving you what you need. It has been discussed several times.

Well done Rod, that’s a comprehensive answer!

Guy

I found that the chart in the gear cover was hard to read with the lighting in my shop so I printed it out 8 1/2 x 11, laminated it, and it hangs on the wall behind the lathe were I can read it while standing it front of the lathe.

I have it as a PDF file and can send it to you if you pm me your e-mail address. You can then print it out and laminate it.

John

You could buy Brian's book and rip the pages out, but he would probably come around and confiscate your lathe as punishment

Neil

Only the last line? I reckon the last 15 lines are likely never used for threading! Anyone on here cutting threads of more than 60tpi?

Question might be: Is 1.8 thou per rev a small enough increment for all power feed uses? I would have though it would be – at least for most jobs.

The last half dozen or so lines on the inch chart are intended as fine feeds. I only added the TPI out of curiosity!  120 TPI is UNF 000 and 160 is 0000 but obviously a thread of 569 TPI is a little over the top and not much practical use, at least for the kind of work we do!

John

Edited By John Purdy on 05/02/2019 18:05:18

My best offer is 508tpi on a micro-adjuster. I found this on the Kozak website:

Our imperial sized matched set micro positioning adjustment screws and unbraked bushings deliver precision smooth movements in the most demanding OEM applications. These matched sets provide the smoothest and most precise movements in the industry with sub micron resolution not commonly found in direct drive hardware offering 127 TPI (.0079" per rev.), 200 TPI (.005" per rev.), 254 TPI (.0039" per rev.), and 508 TPI (.0019" per rev.), taking ultra fine to new industry levels.

Not sure how standard the threads are – they also say 'Note: Kozak Micro cannot guarantee that our screws and bushings will be compatible with screws and bushings sold by other manufacturers. '

Dave

I think you might have to make one, at least the gear train has already been worked out for you

Mike

Sacrilege indeed, but it would be your lathe I would impound for the suggestion !!

Brian

Norm

Yes your tool will have to be very sharp. The theoretical tip radius for a 569 TPI Whitworth thread is only .000247" and the flat on a 60deg. tool for a UN thread is .000225" wide!    Good luck measuring that, at least with our normal measuring kit.   About all you could do is to sharpen it to as fine a point as you can and as the theoretical thread depth for a sharp Whitworth thread is only .00173' and a 60 deg. one is .0016 there wouldn't be much of a tip load!

John

Edited By John Purdy on 06/02/2019 20:38:11