Does anyone ever need to thread anything finer than 56 TPI?

qualitymachinetools

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Hey guys, working on some updated models of some small lathes, and every once in a while, I get people who ask me why a lathe does not thread any finer than 56 or 60 TPI.
What would anyone make that would be finer than that, anything common?

I never remember cutting anything in my life finer than that, but I just wanted to see how important it was, if maybe I was missing something.
 
The finiest I have done is 40 tpi to date. Likely model makers are using finer as some kits are using 0, 1, 2 sized machine screws.
Pierre
 
The lathes probably will already cut much finer threads, even using the feed setup instead of the threading setup. There is not much room on the charts mounted to the lathes for TMI (too much information.) Until you need it. Only the most common and useful threads are shown on the charts, MANY more are usually possible using the stock gearing. A comprehensive chart of them sent with the new lathe, and a downloadable file online would solve the issue for those willing to look it up.
 
After reading this thread I opened the manual for my Grizzly G9249 thread. This illustrates Bob K's point.
The inch thread chart goes up to 112 tpi. I never paid attention, only for the thread I needed at the time, which may have been up to 24 tpi.

Grizzly_G9249_inch_thread_chart.jpg


The other chart in the manual is for metric and additional inch thread which is also greater than 44 tpi

Grizzly_G9249_metric_additional_inch_thread_chart.jpg
 
Optical stuff also has very fine threads. I haven't taken a thread gage to my old Unihex, but I'm guessing it's around 80 TPI and 1.25" major diameter.

One of my backburner projects is to make an adapter so I can use it on my Meade LX50.

Sent from my Pixel XL using Tapatalk
 
i used to make taps and thread gages, i threaded 140 pitch 1 time, 00 80 was very common
 
Toolroom lathes also have a wide range, mine has:

C13 thread chart.jpg


It does need a couple of gears swapped for Metric, though, and some I don't have for DP and Module pitches (the same ones), a hatful for BA threads which don't adhere to anything in the QCGB...

Dave H. (the other one)
 
I have done up to 80 tpi, but typically don't use anything finer than 60 tpi. Mostly for telescopes and small stuff requiring precision movement like that.

For most of my stuff I don't get beyond 40 tpi.
 
I did some 72 tpi for a microscope eye piece on the little EMCO Compact 5 I started with.
 
Not even a tease of what you're working on? :)
 
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