Thread Mic Cal

[92Flairty]

First off I am new to this forum and hope I will learn a lot from it an the people involved. I have just started as a calibration technician so I am green on many things. My question is with a Mitutoyo 126-902 thread micrometer that i need to calibrate. Much of the information I have come across does not going in detail of what is needed to calibrated it to the OEM tolerance. So far I have been led to believe that i can calibrate it using a Davis "Roll check" model RC-755 or at least the .0625 wires. I tried with no luck. I have easy access to a Van Kuren thread wire set. I can not easily locate a procedure so I am currently trying multiple things to see if it works. I unfortunately do not have a master thread plug that i can use so the easy way is out of the question. Does anyone have any advice on how i can correctly calibrate the micrometer?

Thank you ahead of time.

 

[Gordon B. Clarke]

First off I am new to this forum and hope I will learn a lot from it an the people involved. I have just started as a calibration technician so I am green on many things. My question is with a Mitutoyo 126-902 thread micrometer that i need to calibrate. Much of the information I have come across does not going in detail of what is needed to calibrated it to the OEM tolerance. So far I have been led to believe that i can calibrate it using a Davis "Roll check" model RC-755 or at least the .0625 wires. I tried with no luck. I have easy access to a Van Kuren thread wire set. I can not easily locate a procedure so I am currently trying multiple things to see if it works. I unfortunately do not have a master thread plug that i can use so the easy way is out of the question. Does anyone have any advice on how i can correctly calibrate the micrometer?

Thank you ahead of time.

I have a zillion questions before I can even start to help. What you have is a 1-2" micrometer. Right?

1. There should be a setting master. Is there?



2. Is it a new micrometer? If not how old and is this the first time to be calibrated? If previously calibrated why no calibration instructions?

3. Will it be used for measuring component threads only? I'm assuming/hoping you know that threads have a large pitch diameter tolerance?

4. How many thread inserts do you have as each pair will have to be calibrated?

5. Are you ISO 9001 certified or similar or is it a customer "request"?

No matter how it gets done you'll need "traceability" so anything you choose to use will also require a calibration certificate. One of my own products are thread calibration plates that can be supplied with or without a calibration certificate. You could have your own made. I can tell you how but they aren't cheap to make.

The problem with the master supplied, and I hope there is one supplied, is that it's almost impossible to calibrate very accurately. It can't be done with thread wires.

 

[92Flairty]

I have a zillion questions before I can even start to help. What you have is a 1-2" micrometer. Right? Yes

1. There should be a setting master. Is there? Yes

threadmike.jpg

2. Is it a new micrometer? If not how old and is this the first time to be calibrated? If previously calibrated why no calibration instructions? Used, Has been calibrated before but extremely poor records were kept. By that I mean almost no records kept.

3. Will it be used for measuring component threads only? I'm assuming/hoping you know that threads have a large pitch diameter tolerance? Yes and Yes

4. How many thread inserts do you have as each pair will have to be calibrated? 5 pair

5. Are you ISO 9001 certified or similar or is it a customer "request"? Certified

No matter how it gets done you'll need "traceability" so anything you choose to use will also require a calibration certificate. One of my own products are thread calibration plates that can be supplied with or without a calibration certificate. You could have your own made. I can tell you how but they aren't cheap to make.

The problem with the master supplied, and I hope there is one supplied, is that it's almost impossible to calibrate very accurately. It can't be done with thread wires

If you have more questions I will answer them to the best of my abilities. Thank you

 

[TeflonDave]

With these types of gages it is important to develop a feel. Mainly because the master is a conical tip and 2 flats. And the micrometer anvil set being 2 flats and a conical tip. So after you set it you wanna measure a round helical object.

Bone up on the fundamentals of threads measurements cause using these gauges should get you a better understanding of lead and pitch. The main thing is feel, setting these gages requires a fine hand, the bottom anvil will shift position when the lock is applied. The conical point of the micrometer spindle will jam if not handled properly. For a one inch mic I found the ratchet helpful but only using one click. For another size I found the spindle feel more helpful. The main thing is to develop sameness with the setting.

After you set the same way well enough you can get into checking the calibration setting and/or at least measuring. You can use the least used plug gauges for starters.

If you take enough time going through this protocol your boss might finally break down and get you a $200 thread setting gauge for at least one mic size.

 

[Gordon B. Clarke]

Maybe just me but your post #3 wasn't easy to read. I'll get back to you tomorrow.

What pitches are the 5 pairs of inserts? When I know the pitches I can probably give you an easy certifiable calibration solution.

 

[Gordon B. Clarke]

With these types of gages it is important to develop a feel.

I disagree. Of course if you can get all to have the same "feel" then maybe, just maybe.

 

[Gordon B. Clarke]

92Fairty doesn't seem interested in what I believe is an easy way to calibrate thread micrometers. Anyone else interested?

The "trick" is that it has to be something that a calibration lab can do using their normal equipment.

Better add: No it isn't something I make or sell and to make. It would probably cost around $100 or more. Then there would also be the cost of calibration at a lab. Probably the same as it'd cost to calibrate a thread plug gauge.

 

[92Flairty]

I will try to get them to you soon as possible. I bounce around a lot so my response time here will be poor. I apologize ahead of time.

 

[Gordon B. Clarke]

I will try to get them to you soon as possible. I bounce around a lot so my response time here will be poor. I apologize ahead of time.

No problem, at least for me. Take as much time as you need / are allowed. I've made a sketch and just need an idea as to pitches.

BTW and this is important. I hope you are good at basic trigonometry. Can't do much work with threads without it.

 

[Gordon B. Clarke]

No problem, at least for me. Take as much time as you need / are allowed. I've made a sketch and just need an idea as to pitches.

BTW and this is important. I hope you are good at basic trigonometry. Can't do much work with threads without it.

My offer is off the table. Keep on bouncing.

"I'm so busy I don't have time to do anything"