Tool Caliper with broken screw

[Susquatch]

Do you intend on reusing the nut or making a new one? I have a pair of dividers that are missing an arched peace that goes between the 2 legs if you find you like repairing these. I think I have a pair of hermaphrodite calipers that is missing a piece also. should I sent them your way?

I plan to try to reuse the parts and I'd like to fix the caliper if I can. The wise choice would be pitch it and buy a new one. But I like old tools and I like to fix them if I can.

But that might change if I can't find a screw. Are your screws 90 thou in diameter?

 

[Megar arc 5040dd]

I plan to try to reuse the parts and I'd like to fix the caliper if I can. The wise choice would be pitch it and buy a new one. But I like old tools and I like to fix them if I can.

But that might change if I can't find a screw. Are your screws 90 thou in diameter?

I will go measure and see if any are that size. I have a small collection.

 

[Megar arc 5040dd]

I plan to try to reuse the parts and I'd like to fix the caliper if I can. The wise choice would be pitch it and buy a new one. But I like old tools and I like to fix them if I can.

But that might change if I can't find a screw. Are your screws 90 thou in diameter?

These are what I have. The 4 on the cutting board are names I don't recognize and cant really make out. the left 2 are missing pieces. The 7 in the middle are starrett and the one on its own is Brown and sharpe.

This starrett one is the only one with a diameter close to what you have measured. However the diameter measured across the tops of the threads measures at .121". I also noticed that the threads on all of them appear to be sharp and don't look like Acme like yours. Is it possible that your threads have worn down giving you both that flat profile across the top as well as the measurement you are getting?

These all came from ebay many years ago when I needed a pair of dividers for some layout work at the shop I worked at. When they told me to find something round to trace because the shop didn't have a compass I decided it was time to supply my own tools even if it was against policy. They also used taps as a center punch because they didn't have one of those either. Needless to say I didn't stick around there very long.

 

[Susquatch]

Is it possible that your threads have worn down giving you both that flat profile across the top as well as the measurement you are getting?

I considered this too. But the dead proof is the size of the through hole in the caliper leg. It's just slightly over 90 thou. So, no. The thread profile is deliberate.

 

[Megar arc 5040dd]

I considered this too. But the dead proof is the size of the through hole in the caliper leg. It's just slightly over 90 thou. So, no. The thread profile is deliberate.

I guess you could always try to single point thread it on the lathe

 

[jorogi]

But I like old tools

Hmmm......last time you had two words for me and they weren't nice. Damned double standards.

 

[Susquatch]

I guess you could always try to single point thread it on the lathe

I have thought about it. It would likely present challenges I have not handled before, and I don't have a steady rest that small. But it would probably be too hard on my ego. Better to just buy something. If all else fails, I might have a go at it though. I have not totally ruled that out. I'd have to buy some heavy duty depends and avoid eating off the floor for a few weeks if I do.

 

[Megar arc 5040dd]

I have thought about it. It would likely present challenges I have not handled before, and I don't have a steady rest that small. But it would probably be too hard on my ego. Better to just buy something. If all else fails, I might have a go at it though. I have not totally ruled that out. I'd have to buy some heavy duty depends and avoid eating off the floor for a few weeks if I do.

Think of the bragging rights!

 

[140mower]

I have thought about it. It would likely present challenges I have not handled before, and I don't have a steady rest that small. But it would probably be too hard on my ego. Better to just buy something. If all else fails, I might have a go at it though. I have not totally ruled that out. I'd have to buy some heavy duty depends and avoid eating off the floor for a few weeks if I do.

Prolly need a bigger jock as well....

 

[ChazzC]

I have thought about it. It would likely present challenges I have not handled before, and I don't have a steady rest that small. But it would probably be too hard on my ego. Better to just buy something. If all else fails, I might have a go at it though. I have not totally ruled that out. I'd have to buy some heavy duty depends and avoid eating off the floor for a few weeks if I do.

Come on: Joe Pie does this all the time! All you need is one of his custom follow rests:

I’m looking for a video of him single-pointing a 0-80 (I know he’s done 2-56).

 

[Susquatch]

Come on: Joe Pie does this all the time! All you need is one of his custom follow rests:

I'll watch it later today.

I'm still thinking illl buy a suitable screw if I can find one or a tap and die. I feel like that's my best bet to resurrect it.

 

[Dabbler]

I'll keep out an eye for a cheap small spring caliper that has a .080 or so screw. Then you have the parts for a nominal fee or free! At least it would work again...

 

[Susquatch]

I'll keep out an eye for a cheap small spring caliper that has a .080 or so screw. Then you have the parts for a nominal fee or free! At least it would work again...

Thanks John. The biggest issue I would rassle with would be the desire to fix both!

 

[Megar arc 5040dd]

Thanks John. The biggest issue I would rassle with would be the desire to fix both!

Then we will find you another one for parts

 

[ChazzC]

There’s a guy on H-M who also wants to single pointing a 0-80:

https://www.hobby-machinist.com/threads/how-best-to-thread-0-80.116571/

 

[Susquatch]

There’s a guy on H-M who also wants to single pointing a 0-80:

He is only cutting a very short thread. And he is giving himself multiple tries and several wall beating sessions to get the job done.

After watching Joe Pie cut small thread, he was only cutting a short length too.

However, as mentioned earlier, he did make a very small follow rest to make a much bigger thread than mine. It was an interesting process. But I think it would be much easier to modify my existing follow rest to make a small one. Here is a photo of my follow rest along with a HSS threading insert.





I pulled one of the followers. It looks like this:



I'm thinking I can make a new "micro" follower to fit my existing follow rest that would facilitate threading an 90 thou pin. Such a micro follower would incorporate a fixed corner pocket with another level of interchangeable follower tips - each made for each individual job. Basically a corner (top and rear) to hold the unthreaded rod in place. The forces of the threading tool are up and back. So the right size and location corner would do the job. In use, I would install the micro follower, then install a small blank, then mill it out with an end-mill in the lathe to fit the part I need to thread. I'd just make a new follower corner for each new job.

Joe used phenolic for his follower. I'd assume there are better materials if it's only the tip that needs replacing.

I'm also thinking it will have to be 56tpi instead of 60 cuz I don't have gears to cut 60. 54 is the finest thread my lathe will cut. No way I'm gunna make a custom gear for just this one job.

If I go this way, it would be both a challenge and fun too. I'd also have to shorten the thread engagement in the adjustment ball nut. The difference between 56 and 60 is not much, but it's enough to jamm the works up if the fit is not loose and/or short. So, I'm thinking I will drill out a third of the nut or so to make a more adaptable misfit in the threads work.

I also found both 2-56 and 2-64 SS threaded rod at McMaster Carr as well as matching ball nuts. Big money for such small parts but really inexpensive in the big picture.

Opinions?

 

[whydontu]

Good excuse to install an ELS system.

 

[Susquatch]

Good excuse to install an ELS system.

Yes, it would be an excellent excuse. But that's not for me @whydontu. I did all that kind of stuff as part of my job. Now I just want to do things manually.

Besides, I happen to like changing gears and turning handles. I have no interest in CNC or ELS.

If was going to do anything along this line, it would be to cut gears to do 60tpi.

Of course, another option would be to buy a small watch makers lathe to turn small stuff!

 

[PeterT]

Is using a threading die out of the question?

 

[ChazzC]

After watching Joe Pie cut small thread, he was only cutting a short length too.

But isn’t cool watching him single pointing 2-56 in CRS on what looks like a 14” lathe?

I pulled one of the followers. It looks like this:

View attachment 58556

I'm thinking I can make a new "micro" follower to fit my existing follow rest that would facilitate threading an 90 thou pin. Such a micro follower would incorporate a fixed corner pocket with another level of interchangeable follower tips - each made for each individual job. Basically a corner (top and rear) to hold the unthreaded rod in place. The forces of the threading tool are up and back. So the right size and location corner would do the job. In use, I would install the micro follower, then install a small blank, then mill it out with an end-mill in the lathe to fit the part I need to thread. I'd just make a new follower corner for each new job.

I like this concept: saves remaking the entire follower. If it were me, I’d use the bearing mount to attach the individual “backers.”

Joe used phenolic for his follower. I'd assume there are better materials if it's only the tip that needs replacing.

Joe used Linen Phenolic because the threads will cut into it without tending to transfer material into the threads (and he likes using this material ).

I'm also thinking it will have to be 56tpi instead of 60 cuz I don't have gears to cut 60. 54 is the finest thread my lathe will cut. No way I'm gunna make a custom gear for just this one job.

If I go this way, it would be both a challenge and fun too. I'd also have to shorten the thread engagement in the adjustment ball nut. The difference between 56 and 60 is not much, but it's enough to jamm the works up if the fit is not loose and/or short. So, I'm thinking I will drill out a third of the nut or so to make a more adaptable misfit in the threads work.

I also found both 2-56 and 2-64 SS threaded rod at McMaster Carr as well as matching ball nuts. Big money for such small parts but really inexpensive in the big picture.

But if you don’t use the original TPI you’ll need to modify the nut; if you’re going to do that you may as well up-size the diameter to make it easier to cut.

Opinions?

Hey: you were the one who (foolishly? unnecessarily?) asked for opinions!