When to replace thread ring gages

[mocsk3609]

when should you replace your thread ring sets? seems easy right? not so with my company.

I have adjustable thread ring gages that go out to be calibrated. (I don't have the expertise or all the master thread plugs to calibrate them. Some come back 'PASS- starting to bell' and 'adjusted 3 times: need to replace'.

Boss states 'pass-bell' still within spec no need to replace they just want more money.
Boss states 'adjusted 3 times' have them adjust it until it fails they just want more money.

Just wondering what do others do with the belling effect on the gages and the calibration vendor stating that after adjusting the thread ring gages 3 times it should be replaced 'due to maybe it will start to bell'.

My tolerances usually are +/- .005" sometimes down to .001" and the class of these gages are class X. I think the thread master set plugs they set to are made to class W if that helps. The vendor is national lab certified so I believe them but most of the time I deal with the sales agent and not the QC head.

Any insight would be great and thanks from the noob.

 

[Eric M]

To me. when your lab says "Adjusted 3 times: need to replace", that means they are worn out enough that THEY NEED TO BE REPLACED. Period. When the lab says "Pass - Starting to bellmouth", they are letting you know that these will probably need replaced soon, so start saving your money.
As for your lab "just wanting more money", I don't buy that. They get paid for calibration, regardless of whether or not they pass.
You can cut down on "bellmouthing" by reversing your ring gages each time you use them. As you know, thread ring gages are marked (typically) with the size of the gage on one face. If you thread them "marked face" first one time, then the unmarked face first the next time, you can even out the wear on your gage.
Good luck!

 

[The real Leigh]

Standard metrology practice prohibits the presence of ANY uncalibrated instrument(s) in the department or office.

Having even one such instrument can call into question the validity of ALL certs done by the department, regardless of what instrument was used.

Remove any gages that are not certified. Put them in the locker room.

Next time the boss wants a part cal'd with one of those, tell him you have no gage available.

Cal labs make more money from gages that they certify than on gages they reject.
The good ones come back next year, and next, and next... The bad ones get tossed.

- Leigh

 

[Gordon B. Clarke]

when should you replace your thread ring sets? seems easy right? not so with my company.

I have adjustable thread ring gages that go out to be calibrated. (I don't have the expertise or all the master thread plugs to calibrate them. Some come back 'PASS- starting to bell' and 'adjusted 3 times: need to replace'.

Boss states 'pass-bell' still within spec no need to replace they just want more money.
Boss states 'adjusted 3 times' have them adjust it until it fails they just want more money.

Just wondering what do others do with the belling effect on the gages and the calibration vendor stating that after adjusting the thread ring gages 3 times it should be replaced 'due to maybe it will start to bell'.

My tolerances usually are +/- .005" sometimes down to .001" and the class of these gages are class X. I think the thread master set plugs they set to are made to class W if that helps. The vendor is national lab certified so I believe them but most of the time I deal with the sales agent and not the QC head.

Any insight would be great and thanks from the noob.

When you write "adjustable thread ring gages" (plus the tolerances you give) I'm seeing the following type.

Setting Adjustable Ring Gages - YouTube

Now for the questions.

1. What thread diameter range (and pitches) do you operate with?
2. Do you also send out the adjustable thread ring gages you do have setting masters for?
2a. Do you ever send out your setting masters (you have some) for calibration as I'd consider that more relevant?
3. Adjustable thread ring gages are more expensive than "normal" ring gauges so why even have them? Varying tolerances within the same diameter and pitch?
4. Have you ever considered measuring your threads and you probably wont have to send out your adjustable thread ring gages nearly as often as you'll hopefully be away from the upper and lower limits? "Forcing" causes wear and thus more frequent calibration.

 

[PeteM]

If, as you say, there are +/- .005" tolerances on most of your threads, your boss may have a point about the starting-to-bell-mouth gages being good enough. Wouldn't be acceptable practice in a large shop, but if you're the only one cutting threads could be you'd save the newer ring gages for the .001" tolerance threads? Would also point out that a thread micrometer could handle that tolerance and be less subject to wear.

All in all, not sure the time spent keeping things straight would be worth the hassle though -- only have to screw up once (pun maybe intended) to make a new ring gage look cheap.

 

[yanshi]

I think you should listen to the calibration lab, you need to replace these thread ring gages. Calibration lab get money from calibration service, not reject the items. if you want to let things simple, you can consider solid thread ring gages, it is simple, no need setting plug gauges.
{ad removed - TRL}