Threading Question.

[Ken_Shea]

got thread micrometers

Priced them once, sticker shock

 

[randyc]

...That said, in 50 + on/off years of hobby machining I've managed well with out either and I do not put out junk sloppy jobs...

Can't argue with success, peace, brother ($79 for one inch thread micrometers, BTW.)

 

[Wreck™Wreck]

I agree and used wires + masking tape for years. I have a hereditary motor movement problem that causes severe tremors in both hands (it has gotten worse as I age). After dropping a wire three times before getting a measurement, I gave up and got thread micrometers

Sorry to hear that, I generally do largish work yet I still put a plastic tray across the ways with a clean rag in it under the part to be measured and still set free the occasional wire into the soup, fortunately large wires are relatively easy to find.

 

[Tony Wells]

Randy, just food for thought, but there is a way to use a single wire. Just measure the actual major diameter and do a little math. Handling one wire is much easier than 3.

 

[randyc]

... I still put a plastic tray across the ways with a clean rag in it under the part to be measured and still set free the occasional wire into the soup...

I followed a similar practice: laying a white rag across the ways, held in place with a couple of magnets. But I sometimes even have problems typing, LOL, so thread mikes are now a necessity rather than just a convenience

(My own tremors are troublesome but my youngest sister, who has the same disease as me, makes her living designing and producing one-off custom jewelry. This is career ending as her tremors worsen.)

 

[18w]

I have used modeling clay to stick those pesky buggars in place. I also have a set of thread triangles that have rubber retainer bands that fit over the micrometer spindle faces. Both can be aggravating at times.

Darrell

 

[randyc]

Randy, just food for thought, but there is a way to use a single wire. Just measure the actual major diameter and do a little math. Handling one wire is much easier than 3.

Tony, I don't think that I'd trust that method for precise measurements. You wouldn't be measuring the pitch diameter directly, you'd be measuring something like the differences in OD and PD. (The 3-wire method doesn't measure pitch diameter directly either but it's much closer and doesn't depend on the loose tolerances of the OD.)

Let's pick a thread as an example, say 5/16-18UNC-3A where tolerances are as follows:

O.D. .3038 to .3125 or a permissible variation of .0087
P.D. .2734 to .2764 or a permissible variation of only .0030

Since the O.D. can vary by almost .009 and still be within UNC-3B tolerances, it seems to me that a pitch diameter measurement based on the O.D. might measure/calculate to be within specification but in fact be considerably out of tolerance.

I sincerely appreciate your suggestion since it was clearly intended to alleviate my motor skill problems Thank you !

 

[randyc]

Randy, just food for thought, but there is a way to use a single wire. Just measure the actual major diameter and do a little math. Handling one wire is much easier than 3.

Tony, I completely misunderstood the above. You intended the single wire method to be made using measured OD, duh, not the limits of the thread tolerances. Dunno where my mind was but I apologize for the gross misconception and I'm going to look into that technique a little closer. Thank you again !

 

[Tony Wells]

That's ok Randy. I had to demonstrate it more than a few time before I convinced a few people that it was adequate. I don't use that method for making or checking plug gages, but for product, it seems perfectly acceptable. It works.

 

[RVJimD]

I may have missed it but, is there anything wrong with using a nut if you have one the correct size and TPI to check?

Jim