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Thread measurement

Lucky Shooter

Gold $$ Contributor
I've been allowed to use a Starrett No.585, 1"-2", 14-18 TP! micrometer----for learning.

Does this micrometer provide a direct PD measurement over the full range of thread pitches ?

This is a fine tool.

A. Weldy
 
Thanks Dusty.

You guys have kinda shamed me into doing better than "cut and try".

A. Weldy
Nothing wrong with cut and try. Thats the only way to get em to fit like you want. But get a glued in action and you gotta do somethin besides cut and try. It better be right the first time
 
I use a similar mic. Even if the calibration is off or it was not read direct pd, you really are just using it a comparator. After you chamber for enough actions you will find a pd that you know works for all of that model, pd does vary in custom actions. If you cut them exactly to the print you will find some that wont fit. So just keep track of what the smallest pd you have to cut for brand x and cut them to that number. The really tight thread fit is similar to threading up to the shoulder instead of cutting a relief. Its a "pride" thing that has no benefits, only potential problems.
 
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Thanks Dusty.

You guys have kinda shamed me into doing better than "cut and try".

A. Weldy
I assume it comes with a 1" standard. Check to make sure it's calibrated correctly and rock on. It takes me about a minute to swap anvils and calibrate a mic.
I still do cut and try on occasion for something new that's coming through.
 
I purchased the threaded inserts that both Stiller and the Kelbys used in their receivers. You can use those as thread checkers on some receivers. I have thread mics also when needed.
 
Some time back, I decided that I wanted to be able to measure threads for my 18 TPI action, as well as the other dimensions relating to chambering. My first move was to pick up a set of thread wires, which were a pain in the neck, three handed proposition, but doable with practice. While working on that, I posted asking for tips on how to make using them easier. I think that it was in that thread that someone mentioned bending some music wire so that it functioned as all three wires and would hold itself in position. I did, and it works perfectly. The wire is available in a diameter that is a very close match to the particular thread wire diameter is correct for 18 TPI, and being able to have it hold itself in place is a tremendous advantage. (Yes, I checked it against the wires.)

On the issue of barrel thread fit, based on conversations with some very good smiths, I have concluded that do not want a close fit. One of the most accurate barrels that I own has a fit that would probably be described as alarming by feel, but I have done the measuring, and the math and it is safe.
 
Thread wires all day long, IMO. There are handy dandy holders that you can buy to clip wires in to assist in holding. Just takes a little practice and dexterity to hold them and use the mic at same time. But the wires will give you the true location where you measure pitch diameter on the flank. The standard pee dee wires are close. True calibrated wires for the pitch will get you closer to where it is properly measured. I'd grab wires any day before the thread mics. That's me... If mics work for you that's good too. Your just threading a tenon...not too tight and not too loose is the key. After awhile, you will get a feel for fit...
 
haven't used a thread wire since I got thread mics. But they work great, especially for guys with 3 hands.
 
Who make decent thread mics that are more budget friendly for the hobbiest? Also are the ones with the interchangeable anvils any good?

Thanks
 
^^^^^^ This..... the Shars appear to be a Brown and Sharpe knock off. I handled a set and they seem very serviceable. I picked up a Browne and Sharpe set at the local pawn shop for less than import $$ so that was a nice find.
 
I use these. Simple, easy to use, and quite accurate.

https://www.mscdirect.com/browse/tnpla/01718303?cid=ppc-google-New+-+Exclusive+Brands+-+PLA_sM0E5trMw___334980939503_c_S&mkwid=sM0E5trMw|dc&pcrid=334980939503&rd=k&product_id=01718303&gclid=EAIaIQobChMIlOOZ2oqX6wIVBL7ACh0z2wlQEAQYAyABEgLmt_D_BwE

But as comparators only. I record the pitch diameter that they measure and record it for future use.

On my actions that are not glue in, I just fit By hand. As a Machinist, I know when it is pretty close.
 
Like ridgeway I use thread wires. Take 2 wires and set them on top of thread to be measured and hold them there with one side of the mic.
Take the other thread wire and slide it on the bottom of thread, between thread and other side of mic and hold it until you take up the slop, and get your measurement.

Pretty easy to do.

Chris
 
Like ridgeway I use thread wires. Take 2 wires and set them on top of thread to be measured and hold them there with one side of the mic.
Take the other thread wire and slide it on the bottom of thread, between thread and other side of mic and hold it until you take up the slop, and get your measurement.

Pretty easy to do.

Chris

Chris, the absolute most accurate method of determining Pitch Diameter is with wires. In my shop, if we must thread something where we do not have a gage, or the piece which it is mated to, we will make it standard to wires.

By the way, the easiest way to use wires is put a dab of heavy grease on the part where the wires go and stick them to it.
 
By the way, the easiest way to use wires is put a dab of heavy grease on the part where the wires go and stick them to it.
And here I thought everyone knew that. We had a short production run of a part that has 8" Acme threads and that's how we checked 'um, a dab of grease, wires and mic.
 
Since I work at a nuclear plant, we have the guy with 3 hands do it.
 
Since I work at a nuclear plant, we have the guy with 3 hands do it.
I guess his mom must have worked there to. What was her job? :rolleyes:

PS- I worked in some Nukes— Not long enough though to get much of a lifetime dose, I’m happy to say.
 

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