G
Gordon Clarke
Re: Measuring minor diameter of internal threads - How To?
It wasn’t my intention to open a can of worms.
It won’t come as a surprise, but I agree with everything you wrote to “close the can of worms”.
My point, and it seemed to get kinda lost along the way, is that when starting up to manufacture threads, then using measurement to put the pitch diameter as close to possible in the middle of the tolerance is the surest way of avoiding most problems. Gages can then be used verify that the thread remains OK. Measurement and gages supplement each other and give the most reliable result for process control.
A company making a tender for an order, or simply manufacturing 1 off or very small series at irregular intervals, don’t always purchase the necessary gages. A shudder runs down Wayne’s spine at the thought, but he knows this happens. Anyway, especially when making a tender it is essential that you know almost exactly where within the pitch diameter tolerance the thread is. d and D1 are easily measured. Most gage companies have standard thread gages on stock, but even a slight deviation from the most used and common standard threads, gives lengthy delivery times and extra costs.
With thread pitch diameter measurement a histogram can be supplied with the tender and this usually impresses the customer, who realizes he his dealing with a company that cares. Even when delivering large quantities, measurement at receiving inspection (which, in my opinion is mistrust and a poor selection choice of supplier), requires a much smaller sample quantity that that required using gages.
I recently had an inquiry from a company that wanted to make a MJ thread with a 1.006 mm pitch. Heaven only knows why, and they wouldn’t answer when I asked, so that’s one potential customer I’m not sorry to do without.
The difficult thing about making something “idiot proof” is that idiots are so creative. :mg:
It wasn’t my intention to open a can of worms.
It won’t come as a surprise, but I agree with everything you wrote to “close the can of worms”.
My point, and it seemed to get kinda lost along the way, is that when starting up to manufacture threads, then using measurement to put the pitch diameter as close to possible in the middle of the tolerance is the surest way of avoiding most problems. Gages can then be used verify that the thread remains OK. Measurement and gages supplement each other and give the most reliable result for process control.
A company making a tender for an order, or simply manufacturing 1 off or very small series at irregular intervals, don’t always purchase the necessary gages. A shudder runs down Wayne’s spine at the thought, but he knows this happens. Anyway, especially when making a tender it is essential that you know almost exactly where within the pitch diameter tolerance the thread is. d and D1 are easily measured. Most gage companies have standard thread gages on stock, but even a slight deviation from the most used and common standard threads, gives lengthy delivery times and extra costs.
With thread pitch diameter measurement a histogram can be supplied with the tender and this usually impresses the customer, who realizes he his dealing with a company that cares. Even when delivering large quantities, measurement at receiving inspection (which, in my opinion is mistrust and a poor selection choice of supplier), requires a much smaller sample quantity that that required using gages.
I recently had an inquiry from a company that wanted to make a MJ thread with a 1.006 mm pitch. Heaven only knows why, and they wouldn’t answer when I asked, so that’s one potential customer I’m not sorry to do without.
The difficult thing about making something “idiot proof” is that idiots are so creative. :mg:
