Question about threading on a lathe

If the thread to be cut is a factor of the lead screw, you can open the half nuts and restart the thread at any point where the half nuts will close; as an example, if you had a 4 TPI lead screw, you can cut 4,8,16, & 32 TPI without having a thread dial, otherwise you can simply back up the tool by engaging reverse back to the starting point, OR you can stop at the end of the thread, disengage the half nuts and measure back in full 1" distances and reengage the half nuts before starting the lathe spindle, that is what the thread dial does.
 
Bob Korves said:
I completely understood that the lathe was US made when I posted, and understood the approximate vintage of the lathe. That SUGGESTS that the lathe is imperial, but does not make it so. Don't guess, prove!

PHPaul's measurement appears to show 9 TPI. Which could also be 2.82mm pitch, or maybe even 3.0 mm. Definitely not 10 TPI per the photo.
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Apparently, Seneca Falls did use a 9 tpi lead screw. https://www.hobby-machinist.com/threads/change-gear-chart-for-9-tpi-lead-screw.52432/
 
middle.road said:
(8) I get, (10) I understand, but who in the heck would have thought that (9) was a good idea?
Facilitate the change gears? I'm trying to wrap my head around that one, and failing.
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My Grizzly 602 has a 12 tpi lead screw. There are 48 teeth on the thread dial gear so it travels 4 inches for one complete rotation of the thread dial. The dial has 12 divisions and any thread where the tpi is divisible by 3 can be engaged on any mark. All other integer tpi are engaged on every third mark. and odd half integers on every sixth mark.
A similar setup should be possible for a 9 tpi lead screw but it's to close to midnight to try to work it out.
 
RJSakowski said:
My Grizzly 602 has a 12 tpi lead screw. There are 48 teeth on the thread dial gear so it travels 4 inches for one complete rotation of the thread dial. The dial has 12 divisions and any thread where the tpi is divisible by 3 can be engaged on any mark. All other integer tpi are engaged on every third mark. and odd half integers on every sixth mark.
A similar setup should be possible for a 9 tpi lead screw but it's to close to midnight to try to work it out.
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Heck, I'm trying to work out the 48/12/3, cause 3 doesn't go into 48... I don't think I have any gray matter to spare if we start discussing 9TPI...
 
middle.road said:
That's a plum fancy screen compared to the old 5" green/orange on black ones...
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A <$100.00 Dell 16" monitor simply plugged in to the output that was used by the original 5" X 5" monochrome display which would cost >$750.00 to replace. Works a charm and is far easier on the old eyeballs.
 
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