Thanks, I just set-up a Metrology Lab at my community college but forgot about the gage block deviation chart. Will get one printed and posted. Already have temperature, humidity, lighting, and dust patricle controls in place. Keep up the videos as they are very useful when us old guys forget things, lol.
Even just turning parts on a lathe dealing with thousandths not tenths you have to watch for temperature. When you get into parts more than a few inches in diameter, you really notice it. The most extreme example of thermal expansion difference I've seen was a 1 inch shaft being inserted into a hole with a 2.5 thou interference. The part with the hole was prepped by heating with a torch and the shaft was cooled in liquid nitrogen. The shaft literally rattled around in the hole and you could see the gap with your eyes.
+theslimeylimey Are you sure it wasn't 2.5 thou, as the 25 thou would have to have about 2000 degrees Celsius temperature difference (in steel), which would mean melting?
Jaakko Fagerlund Oops, yes I did - fixed thank you. I did a quick check and the expansion would have been about 0.011" which seems to fit what I remember seeing.
I just can't believe you let that get away from you. Ha. Don, everything you have taught me is translating into my machine work. My stuff is better. Better than the rest. I now stone the edges I previously filed. It makes a real difference. I'll catch you in about 30 years...
+Kevin Gleason It comes with your gauge blocks. If you don't have it, the gauge blocks should not be used for anything requiring precision or they should be sent to a lab to verify their actual dimensions.
If you aren't in a climate controlled environment I imagine trying to hit a .0001+- would be extraordinarily difficult. What if it is 90 out on the shop floor? Is there a way to hit that tight tolerance without doing the part multiple times to find out what is expansion rate is?
+bcbloc02 That's easy, you look up the expansion factor from the material data sheet and take that in to account when making the part and measuring it.
the amount of thermal expansion becomes ridiculous when working with some plastics. Design engineers are supposed to understand materials but it seems like many don't have a clue.
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Thank you Mr Don.
Your knowledge, passed on, will always be true and relevant.
Eternity...
Thanks, I just set-up a Metrology Lab at my community college but forgot about the gage block deviation chart. Will get one printed and posted. Already have temperature, humidity, lighting, and dust patricle controls in place. Keep up the videos as they are very useful when us old guys forget things, lol.
So glad we could help, thank you for your kind words.
Such great info. We all, often, overlook it. Thanks Don!
Great advice, Don. Many thanks.
I can't thank you enough for these videos.
God bless you wonderful video thank you very much
Thanks Boss, I will not let that happen again!
great video as always!
I like this guy 💪🏻
Even just turning parts on a lathe dealing with thousandths not tenths you have to watch for temperature. When you get into parts more than a few inches in diameter, you really notice it. The most extreme example of thermal expansion difference I've seen was a 1 inch shaft being inserted into a hole with a 2.5 thou interference. The part with the hole was prepped by heating with a torch and the shaft was cooled in liquid nitrogen. The shaft literally rattled around in the hole and you could see the gap with your eyes.
+theslimeylimey Are you sure it wasn't 2.5 thou, as the 25 thou would have to have about 2000 degrees Celsius temperature difference (in steel), which would mean melting?
Jaakko Fagerlund Oops, yes I did - fixed thank you. I did a quick check and the expansion would have been about 0.011" which seems to fit what I remember seeing.
Great reminder, even by knowing this, sometimes I get screwed by forgetting or overlooking.... ;)
I just can't believe you let that get away from you. Ha.
Don, everything you have taught me is translating into my machine work.
My stuff is better. Better than the rest.
I now stone the edges I previously filed. It makes a real difference.
I'll catch you in about 30 years...
Thank you
Yes.
where can i find a deviation chart?
+Kevin Gleason It comes with your gauge blocks. If you don't have it, the gauge blocks should not be used for anything requiring precision or they should be sent to a lab to verify their actual dimensions.
If you aren't in a climate controlled environment I imagine trying to hit a .0001+- would be extraordinarily difficult. What if it is 90 out on the shop floor? Is there a way to hit that tight tolerance without doing the part multiple times to find out what is expansion rate is?
+bcbloc02 That's easy, you look up the expansion factor from the material data sheet and take that in to account when making the part and measuring it.
the amount of thermal expansion becomes ridiculous when working with some plastics. Design engineers are supposed to understand materials but it seems like many don't have a clue.
That’s the worst word you can hear in a shop “You scrapped them” makes me cringe