Thread dial indicator.

:laughing::laughing::laughing: I doubt that very much,but yes I don't know how yet,but something's got to give
 
8 TPI leadscrews I'm familiar with, but certainly not 16 TPI. My lathe has a 4 TPI leadscrew.

Inch threads, in the worst case, sync every four inches, and that case is very rare—usually it's every inch (odd TPI, any number on the dial) or even 1/2” (even TPI, any number or line) or 1/4" (no dial needed).

Metric thread dials are much more complex than inch ones. Metric threads are specified by length, so they only sync for the least common multiple of the thread pitch and the leadscrew pitch. For example, if you have a 2.5mm thread and a 6mm leadscrew, it will sync every 30mm (12×2.5 and 5×6). A 0.35mm thread will sync every 42mm, etc. You need something like 4–6 gears to account for all the common pitches.

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Ive found this thread quite interesting and frustrating. It has reminded me how weak my knowledge of things is. (maths).I love being a hobby machinest but not having anyone to share ideas I guess you learn by yourself and just get the job done.
In terms of thread cutting I cut ninety percent of the time a single pitch. That is 14 tpi. It is for plumbing fittings (bsp )as I am a plumber.I seldom cut threads.

But it got me thinking .My leadscrew is 6mm and most of my threads are short so I just leave the half nut closed.If Im doing metric threads I still keep the half nut closed but if its a pitch like 1mm or 1,5 or 2mm I sometimes loosen the half nut and and wind the carriage back .
So it got me thinking. I have to admit that I havnt used the thread dial for ages. So I thought I would try use it and no matter what I do I cant get it to work. I tried it on the metric setting and tried a 1,75 mm setting. It just doesnt follow the chase. This is where my maths becomes a problem. I just dont understand it.

So are there any emco owners out there who own an emco v13 with a 6mm metric leadscrew and who have a thread dial who can help me out on how to use it.
 
plunger said:
Ive found this thread quite interesting and frustrating. It has reminded me how weak my knowledge of things is. (maths).I love being a hobby machinest but not having anyone to share ideas I guess you learn by yourself and just get the job done.
In terms of thread cutting I cut ninety percent of the time a single pitch. That is 14 tpi. It is for plumbing fittings (bsp )as I am a plumber.I seldom cut threads.

But it got me thinking .My leadscrew is 6mm and most of my threads are short so I just leave the half nut closed.If Im doing metric threads I still keep the half nut closed but if its a pitch like 1mm or 1,5 or 2mm I sometimes loosen the half nut and and wind the carriage back .
So it got me thinking. I have to admit that I havnt used the thread dial for ages. So I thought I would try use it and no matter what I do I cant get it to work. I tried it on the metric setting and tried a 1,75 mm setting. It just doesnt follow the chase. This is where my maths becomes a problem. I just dont understand it.

So are there any emco owners out there who own an emco v13 with a 6mm metric leadscrew and who have a thread dial who can help me out on how to use it.
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I hope someone can help you. I must put this project on ice for now,because I have a few jobs that came in and that must be done first. Although I really want to get to cutting some gears. Good luck to you plumber man.
 
hman said:
Issue #271 of Model Engineers' Workshop (September 2018) includes an article entitled "Making a Threading Indicator for a Lathe." It's on pages 58 thru 63 and continues/concludes in issue #272 (Autumn Special 2018), pages 67 thru 69. It goes into great detail, including the required parameters for both Imperial and metric (2 thru 6mm pitch) leadscrews. I have no idea how easy it it for you to get publications from the UK where you are. If need be, PM me and I can scan and email the pages to you.
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If you are scanning these, I would really like a copy as well! I have been considering marking one for my Chinese lathe.
 
It is a single start thread and not multi start? Either way, you would be far better off making a direct copy from drill rod/silver steel then cut teeth to make a gear hob. (expensive in 40mm) For a one off to cut bronze or brass, a cheaper alternative would be use mild steel and case harden it. Because of the diameter of gear blank you will almost certainly need a worm wheel type gear that fits 'around' lead-screw (I forget correct name at present, it's concave). There are plenty of instructions and video's about making gear hobs for 'softer' materials. With a 40mm lead-screw you obviously have a pretty large machine. As for the comment about buying a NC machine, I don't know how anyone can be so asinine?????.
 
crazypj said:
It is a single start thread and not multi start? Either way, you would be far better off making a direct copy from drill rod/silver steel then cut teeth to make a gear hob. (expensive in 40mm) For a one off to cut bronze or brass, a cheaper alternative would be use mild steel and case harden it. Because of the diameter of gear blank you will almost certainly need a worm wheel type gear that fits 'around' lead-screw (I forget correct name at present, it's concave). There are plenty of instructions and video's about making gear hobs for 'softer' materials. With a 40mm lead-screw you obviously have a pretty large machine. As for the comment about buying a NC machine, I don't know how anyone can be so asinine?????.
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I have a 1.5m between centres lathe. Yes, I don't know why I should buy another lathe to solve a problem, but I don't have any ill feelings towards the member,but it was a strange reply to my problem.
 
So here it is. Firstly, thanks to all the members for your help and advise,in particular Tozguy,you helped alot.

I made an arbor and started making the gear blank.
20181029_132558.jpg
I then made a toolbit fitting the leadscrew on suggestion by Plunger and Bob Corves. It is not perfect but it will do the job.
20181029_084121.jpg
After picking the right indexing plate for the dividing head,I just double checked and marked where the teeth should be just to play safe. O I forgot to mention that I made the gear out of teflon first just to see if everything works.
20181030_110434.jpg
Then I started winging it by setting my dividing head at 8degrees to get the angle (approximately) to my leadscrew, because I want my dial to sit straight not angled,and I must say it worked out. I the proceeded to cut the gear.
20181030_131430.jpg
20181030_132904.jpg
It's not pretty or perfect, but like Bob said,it doesn't have to be. It mesh and that'sall that matters.
20181030_140118.jpg
My question is. Is there any reason to NOT use this plastic gear as the final gear rathet than brass?

I will post again during the build of the body.

Michael
 
Not really. The gear only has to turn the threading dial, and Teflon will not wear on the leadscrew as much.

I assume you have an inch leadscrew—metric leadscrews require additional gears.

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;) I guess you haven't followed the whole thread if you ask the question. No it is a metric leadscrew,this is only the first gear, I am only starting to build the dial. For the commen threads I usually cut,I will be needing a T15 & T14 gear,but I will make them as I go. About the Teflon gear, I am tending to agree with you. Thank you for your input.

Michael
 
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