Measuring (probable) Acme TPI
- neanderman
- Posts: 896
- Joined: Mon Jan 09, 2012 7:15 pm
- Location: Cincinnati, Ohio, USA
Measuring (probable) Acme TPI
One day, I'm likely to try making a replacement crossfeed rod for the Dual drive.
A very basic question: is this 8 TPI?
It doesn't appear to be a standard thread per my 17th ed of Machinery's Handbook as it's 0.750 major diameter.
A very basic question: is this 8 TPI?
It doesn't appear to be a standard thread per my 17th ed of Machinery's Handbook as it's 0.750 major diameter.
Ed
LeBlond Dual Drive, 15x30
US-Burke Millrite MVI
Atlas 618
Files, snips and cold chisels
Proud denizen of the former "Machine Tool Capitol of the World"
LeBlond Dual Drive, 15x30
US-Burke Millrite MVI
Atlas 618
Files, snips and cold chisels
Proud denizen of the former "Machine Tool Capitol of the World"
Re: Measuring (probable) Acme TPI
Looks like 8tpi to me. 3/4-6 seems to be "standard", but McMaster and others carry 3/4-8 Acme rod and nuts.
Re: Measuring (probable) Acme TPI
It is eight.
Re: Measuring (probable) Acme TPI
The 12" Atlas Models 3980,-81,-82,-83, and 3990, -91 are also 3/4-8 Acme on the lead screw.
--earlgo
--earlgo
Before you do anything, you must do something else first. - Washington's principle.
- neanderman
- Posts: 896
- Joined: Mon Jan 09, 2012 7:15 pm
- Location: Cincinnati, Ohio, USA
Re: Measuring (probable) Acme TPI
Thanks, gentleman.
When the time comes, I'm sure I'll have more questions.
When the time comes, I'm sure I'll have more questions.
Ed
LeBlond Dual Drive, 15x30
US-Burke Millrite MVI
Atlas 618
Files, snips and cold chisels
Proud denizen of the former "Machine Tool Capitol of the World"
LeBlond Dual Drive, 15x30
US-Burke Millrite MVI
Atlas 618
Files, snips and cold chisels
Proud denizen of the former "Machine Tool Capitol of the World"
- tornitore45
- Posts: 2077
- Joined: Tue Apr 18, 2006 12:24 am
- Location: USA Texas, Austin
Re: Measuring (probable) Acme TPI
Lead screw do not have to follow a standard.
The diameter and the lead have no strict relation like fasteners.
The diameter is chosen based on strength, flex and wear consideration'
The lead must give a practical dial. A 6 TPI would imply a dial with 166.666 division
The diameter and the lead have no strict relation like fasteners.
The diameter is chosen based on strength, flex and wear consideration'
The lead must give a practical dial. A 6 TPI would imply a dial with 166.666 division
Mauro Gaetano
in Austin TX
in Austin TX
- neanderman
- Posts: 896
- Joined: Mon Jan 09, 2012 7:15 pm
- Location: Cincinnati, Ohio, USA
Re: Measuring (probable) Acme TPI
Mauro, I fully understand the rationale for the thread pitch; the size is what I found curious.
Ed
LeBlond Dual Drive, 15x30
US-Burke Millrite MVI
Atlas 618
Files, snips and cold chisels
Proud denizen of the former "Machine Tool Capitol of the World"
LeBlond Dual Drive, 15x30
US-Burke Millrite MVI
Atlas 618
Files, snips and cold chisels
Proud denizen of the former "Machine Tool Capitol of the World"
Re: Measuring (probable) Acme TPI
What you may find curious is machining off the ends to fit. Ideally, this is done close to the chuck. At least you can get a center drill point. Suspending a long section of 3/4" Acme outside the head, calls for a fixture. It doesn't have to be massive but has to be secure. We don't want it whipping around at speed.
I guess there will be no whipping involved if it is machined at the tail end. One still needs the accurate center.
I guess there will be no whipping involved if it is machined at the tail end. One still needs the accurate center.
- neanderman
- Posts: 896
- Joined: Mon Jan 09, 2012 7:15 pm
- Location: Cincinnati, Ohio, USA
Re: Measuring (probable) Acme TPI
Good points, spro.
Given the diameter of the threads is 3/4", and that is the maximum diameter, I assume I could start with a piece of 3/4" drill rod, cut the threads and then turn the ends down to size?
Given the diameter of the threads is 3/4", and that is the maximum diameter, I assume I could start with a piece of 3/4" drill rod, cut the threads and then turn the ends down to size?
Ed
LeBlond Dual Drive, 15x30
US-Burke Millrite MVI
Atlas 618
Files, snips and cold chisels
Proud denizen of the former "Machine Tool Capitol of the World"
LeBlond Dual Drive, 15x30
US-Burke Millrite MVI
Atlas 618
Files, snips and cold chisels
Proud denizen of the former "Machine Tool Capitol of the World"
Re: Measuring (probable) Acme TPI
Apologies, ED. I misread what you were doing. I was thinking that you were doing a lead screw and as it is a standard size, purchasing a length of it. Whipping would be an issue due to the length, so an outboard support at the left side of the head might be required.
- neanderman
- Posts: 896
- Joined: Mon Jan 09, 2012 7:15 pm
- Location: Cincinnati, Ohio, USA
Re: Measuring (probable) Acme TPI
Overall length I'd just shy of 28", so I can turn it between centers and I have a follow rest.
But, yeah, something as long as a lead screw hanging out the end of the headstock would be asking for some whipping!
But, yeah, something as long as a lead screw hanging out the end of the headstock would be asking for some whipping!
Ed
LeBlond Dual Drive, 15x30
US-Burke Millrite MVI
Atlas 618
Files, snips and cold chisels
Proud denizen of the former "Machine Tool Capitol of the World"
LeBlond Dual Drive, 15x30
US-Burke Millrite MVI
Atlas 618
Files, snips and cold chisels
Proud denizen of the former "Machine Tool Capitol of the World"
Re: Measuring (probable) Acme TPI
That's a honker of a cross slide screw but that's a big lathe. I wonder why you don't purchase the ready threaded length to fit. Turning and trueing the ends is a class job in itself.