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Gallery, Projects and General => How do I?? => Topic started by: bert4255 on April 10, 2017, 05:19:36 PM

Title: metal lathe thread dial
Post by: bert4255 on April 10, 2017, 05:19:36 PM

I would like to make a thread dial for my lathe. it is a large lathe has a 49" swing, nt that that matters. How do i determine how many teeth the thread dial needs in relation to the lead screw. Is there a ratio? I want to do imperial threads.

Title: Re: metal lathe thread dial
Post by: RussellT on April 11, 2017, 04:58:03 AM

I think we need more information.  Is the lead screw metric or imperial.  What's the thread pitch?

Russell

Title: Re: metal lathe thread dial
Post by: bert4255 on April 11, 2017, 06:58:33 PM

I think the lead screw is imperial. I'm not sure on pitch. I'll try and find out. thanks

Title: Re: metal lathe thread dial
Post by: John Stevenson on April 11, 2017, 07:03:50 PM

The gear has to be a multiple of the threads per inch.
Just guessing from the size but your lathe probably has a 4 tpi thread so the gear needs to be a minimum of 8 or better 16 teeth

Title: Re: metal lathe thread dial
Post by: bert4255 on April 11, 2017, 09:47:27 PM

Thanks John, I will check and see what the thread count is

Title: Re: metal lathe thread dial
Post by: bert4255 on April 25, 2017, 02:07:29 PM

John, I'm getting about 2 1/2 threads per inch, not even 2 1/2. how do i determine if it is metric screw or imperial
thanks

Title: Re: metal lathe thread dial
Post by: shipto on April 25, 2017, 03:05:49 PM

Some pictures of the screw with a ruler lined up might help.

Title: Re: metal lathe thread dial
Post by: bert4255 on May 10, 2017, 11:47:43 PM

ok, it is a metric leadscrew with a 2.5" TPI

Title: Re: metal lathe thread dial
Post by: Pete. on May 11, 2017, 01:41:48 AM

That would be a 10mm pitch screw. It's a big boy alright.

A large lathe like that might well have a single tooth dog clutch which would remove the need for a dial. What make is it?

Title: Re: metal lathe thread dial
Post by: bert4255 on May 11, 2017, 07:24:24 AM

Peter, I figured it out thanks

Title: Re: metal lathe thread dial
Post by: mattinker on May 11, 2017, 09:55:21 AM

Thread dials get more complicated on metric lathes. Inch dial gauges are easier than metric ones because they work using parts of an inch as the base. You can need several thread dial gears to make a metric lead screw work.

I would make a ten tooth gear (four times the aprox  TPI, even though it is metric!) I would then use the technique that Tom Lipton describes here

i am sure the a mathematicians who could work it al out , I suffer from what the Americans call "Matth anxiety" S o I do things to avoid calculating!

Regards, Matthew