Author Topic: metal lathe thread dial  (Read 938 times)

Offline bert4255

  • Jr. Member
  • **
  • Posts: 6
metal lathe thread dial
« 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.

Offline RussellT

  • Sr. Member
  • ****
  • Posts: 391
  • Country: gb
Re: metal lathe thread dial
« Reply #1 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

Offline bert4255

  • Jr. Member
  • **
  • Posts: 6
Re: metal lathe thread dial
« Reply #2 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

Offline John Stevenson

  • Hero Member
  • *****
  • Posts: 1645
  • Nottingham, England.
Re: metal lathe thread dial
« Reply #3 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
John Stevenson

Offline bert4255

  • Jr. Member
  • **
  • Posts: 6
Re: metal lathe thread dial
« Reply #4 on: April 11, 2017, 09:47:27 PM »
Thanks John, I will check and see what the thread count is

Offline bert4255

  • Jr. Member
  • **
  • Posts: 6
Re: metal lathe thread dial
« Reply #5 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

Offline shipto

  • Hero Member
  • *****
  • Posts: 651
  • Country: gb
  • Redditch, UK
Re: metal lathe thread dial
« Reply #6 on: April 25, 2017, 03:05:49 PM »
Some pictures of the screw with a ruler lined up might help.
Turns out this life c**p is just one big distraction from death but a good one. For the love of god dont give yourself time to think.
https://myshedblog.wordpress.com/

Offline bert4255

  • Jr. Member
  • **
  • Posts: 6
Re: metal lathe thread dial
« Reply #7 on: May 10, 2017, 11:47:43 PM »
ok, it is a metric leadscrew with a 2.5" TPI


Offline Pete.

  • Hero Member
  • *****
  • Posts: 793
  • Country: gb
Re: metal lathe thread dial
« Reply #8 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?

Offline bert4255

  • Jr. Member
  • **
  • Posts: 6
Re: metal lathe thread dial
« Reply #9 on: May 11, 2017, 07:24:24 AM »
Peter, I figured it out thanks
« Last Edit: May 11, 2017, 10:48:43 AM by bert4255 »

Offline mattinker

  • Hero Member
  • *****
  • Posts: 1022
  • Country: fr
Re: metal lathe thread dial
« Reply #10 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 https://www.youtube.com/watch?v=HXt4TWa382Q 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