5 tpi crossfeed

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1949DC
Posts: 39
Joined: Thu Apr 02, 2020 6:31 pm

5 tpi crossfeed

Post by 1949DC »

How common is a 5 tpi crossfeed found on lathes? I suspect my very old lathe has been repaired using a 5 tpi. Im wondering if I’m better off replacing the screw with a 10 using a 200 graduated dial. My lathe is 15” swing. I’d prefer an 8 tpi but 250 dials are not found. My concern using a 10 tpi would be very slow functionality.
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Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: 5 tpi crossfeed

Post by Harold_V »

Hmmm. I'm not sure I'd have an opinion. My Graziano has the 5 pitch screw, and the dial has 400 marks, but they're difficult to read, although I've done so with success since I purchased the machine, new.

Random thoughts:

I think if I was to make the choice, I'd consider what work I'd do. If you expect to do a lot of fine work, where tolerance was important, I'd lean in favor of the ten pitch thread. Easier to hold tight tolerances with a fine screw, and the marks are separated by a more generous margin, making the dial easier to read.

Dial diameter is important. If you have small dials, lean towards the finer pitch. I always think of how nice the large dials are on those Hardinge chuckers.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
1949DC
Posts: 39
Joined: Thu Apr 02, 2020 6:31 pm

Re: 5 tpi crossfeed

Post by 1949DC »

All opinions welcome. I do more and more tight tolerance work. I recently installed a 100 division dial not previously found on this lathe coumpund. I purchased a Bridgeport 200 div dial for crossfeed. I don’t care to make a 250 dial or any for that matter. I’m most concerned about not liking the slow feed since I’m so use to the fast travel with a 5 tpi. I thought for close work I’d use the coumpund set to 30 deg for 2-1 ratio for that —.0005” cut. Both dials are new and very easy to read. Im trying to think of all pros and cons to decide. I’d really like to have an 8 but have not found any dials. Just curious if 5 or 10 tpi was commonly found. If 10 then it’s apparent I just need to get use to it.
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Harold_V
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Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: 5 tpi crossfeed

Post by Harold_V »

1949DC wrote: Sat Sep 19, 2020 6:46 pm I thought for close work I’d use the coumpund set to 30 deg for 2-1 ratio for that —.0005” cut.
I don't much care for that idea, as if one is working to demanding tolerances, lengths may be important, too. By using the compound as you suggested, you also alter linear dimensions, albeit in a minor way. If that isn't enough of a reason, I also don't like losing registration on other tools in the same setup. I operate with my compound locked unless I have need for the compound (like threading).

Just sayin!

H
Wise people talk because they have something to say. Fools talk because they have to say something.
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