Calibrating STI Thread Plugs

Huntizzle23 · Jan 5, 2018

Hello all,

We recently started calibrating our thread plugs in house and I had no problem finding the formulas for inch and metric plugs, but I can't seem to find anything regarding STI gages. I'm trying to find the correct formula to determine the Major Diameter of the NoGo Member of an STI thread plug. I've looked over the B18.29.1 spec and it has how to figure out the Go Member, but not the NoGo (as far as I can see). Can anybody help me out?

Thanks,

Zach

Gordon B. Clarke · Jan 5, 2018

Have you done anything other than read B18.29.1 ?

STI Screw Thread Insert Helicoil Gage Tolerances

Added:

On rereading what I wrote it seems impolite but wasn't intended to be. I know the guy that wrote the link and I'm almost sure he'll answer questions if asked.

Huntizzle23 · Jan 8, 2018

Gordon B. Clarke said:
Have you done anything other than read B18.29.1 ?

STI Screw Thread Insert Helicoil Gage Tolerances

Added:

On rereading what I wrote it seems impolite but wasn't intended to be. I know the guy that wrote the link and I'm almost sure he'll answer questions if asked.

I didn't take your response as impolite

Yeah, I've stumbled across a few pages on that website that have been helpful. That one doesn't say anything about the Major Diameters though. Is there any other spec that I may be missing?

Also, when dealing with oversize Major Diameters, how much is too much oversize? I saw a thread where somebody had gotten back their gages from calibration and they were told that the Majors were oversize, but that they were okay to use. I was just wondering what they might be using to make that call.

Thanks for the help,

Zach

Gordon B. Clarke · Jan 9, 2018

Huntizzle23 said:
I didn't take your response as impolite

Yeah, I've stumbled across a few pages on that website that have been helpful. That one doesn't say anything about the Major Diameters though. Is there any other spec that I may be missing?

Also, when dealing with oversize Major Diameters, how much is too much oversize? I saw a thread where somebody had gotten back their gages from calibration and they were told that the Majors were oversize, but that they were okay to use. I was just wondering what they might be using to make that call.

Thanks for the help,

Zach

If you really want to know from someone that knows in depth that kind of thing I suggest you phone or email "gageguy".

I'd question how reliable a calibration lab is if I was given advice to "ignore" specs. That would NEVER happen here. Sounds more as if you're dealing with a used car salesman

Huntizzle23 · Jan 9, 2018

Gordon B. Clarke said:
If you really want to know from someone that knows in depth that kind of thing I suggest you phone or email "gageguy".

I'd question how reliable a calibration lab is if I was given advice to "ignore" specs. That would NEVER happen here. Sounds more as if you're dealing with a used car salesman

Sounds good, I'll have to shoot him an e-mail when I get some free time. I used to work in a calibration lab and I had never heard of anything like ignoring major diameter tolerances. To bump 10 or 20 millionths is one thing, but to bump tenths at a time sounds crazy

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Calibrating STI Thread Plugs

Huntizzle23

Plastic

Gordon B. Clarke

Banned

Huntizzle23

Plastic

Gordon B. Clarke

Banned

Huntizzle23

Plastic

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