You can look up the single depth of thread for any pitch of a 60 degree thread.

You can find or derive a mathematical expression that says d = x/p where d is the single depth, x is a number based on the thread geometry and p is the tpi of the thread.

An example chart for UN form threads is here:

https://kb.wisc.edu/engr/teamlab/page.php?id=81932

If you take the numbers from that, and divide the 20 tpi single depth by three, you get a number that is double that which you obtain if you take the 12 tpi single depth and divide it by nine.

You can also see from that chart that no integer threads per inch number will work on a feedscrew, because the numerator for the fraction they give for the single depth is not a ‘nice’ number.

You can also also see that if the feedscrew had a pitch of 10tpi and a dial graduated in 100 divisions or 100 ‘clicks’ (i.e. one division is 0.001″), 20 tpi would need 32 clicks, 16 tpi would need 41 clicks, 14 tpi would need 46 clicks and 12 tpi would need 54 clicks.

On that basis, something smells fishy.

However, we do not know if the device is made for UN (flat-crested) threads or sharp 60 degree threads, so reacalculate based on sharp threads (a much easier exercise for your brain than doing so for a flat-crested item), and see what you conclude.

Can you link to the device’s product description.

On 4 August 2024 at 17:24 DC31k Said:

You can look up the single depth of thread for any pitch of a 60 degree thread.

You can find or derive a mathematical expression that says d = x/p where d is the single depth, x is a number based on the thread geometry and p is the tpi of the thread.

…
On that basis, something smells fishy.

However, we do not know if the device is made for UN (flat-crested) threads or sharp 60 degree threads, so reacalculate based on sharp threads (a much easier exercise for your brain than doing so for a flat-crested item), and see what you conclude.

Can you link to the device’s product description.

I attempted similar assuming that Wood Threads were Whitworth, and my answers also smell of fish!

Made me think, is there a standard for Wood Threads?   I couldn’t find one.

I tend to assume unknown threads ‘must’ be based on one of the fastener standards such as BSW, UNC, or Metric,  but that ain’t so. Look at any bottle-top!

Maybe wood threads aren’t standardised, in which case let’s hope a kind person with a wood threading jig will measure how far a click moves it.   Wonderful too if they could identify the thread form.

Dave

On 4 August 2024 at 18:21 SillyOldDuffer Said:

Look at any bottle-top!

Bottle tops are produced to Standards. It may be that because you have never needed them, you are unfamiliar with them.

https://www.paramountglobal.com/uk/knowledge/bottle-neck-thread-finish/

https://www.gewinde-normen.de/en/KS-KT-thread.html

https://www.gewinde-normen.de/en/glass-thread.html

In a similar vein, the threads on 25 litre plastic drums are documented, as are the ones on IBCs (intermediate bulk containers – the large, roughly 1000 litre plasti cubes).

With 3D printing becoming ever more popular, having these sources for this obscure information makes many things possible.

Nothing says how many clicks per rev.
However from the progression given initially the next one is 10tpi with 11 clicks. I’d want my 10tpi to be about 1/10th in deep so roughly 1 click = 1/100in as a nice round figure.
If it weren’t in metric land most toolmakers would use a 10tpi thread and 10 clicks per rev. But woodworkers would have gone for a standard fixing thread and have thought in wood vice size so perhaps chosen the way over strength but familiar size of 3/4 BSW being 10tpi.