doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Measuring

I have a several calipers in my drawer, Dials in Inch and Metric etc. One I use a lot is a Mauser Vernier ruled in Thousandth's one side Fractions the other.

Two lathes in the shop, one a Machinist lathe I use the thousandth's side, other a wood lathe always work in fractions. Don't know why never think about it. Guess is the fraction calipers were not intended for machine shop work.

Also have a set of gauge blocks. The Vernier caliper is always right, my odd dial calipers don't always agree. Some better than others. Hard for a Vernier to go wrong nothing mechanical. It's a Home shop no inspectors.

Boats

I have always considered fractional measurements to be for the building and furniture trades. I have worked in the machinist trade for 30yrs and have always used decimal measurements in thousandths of an inch and mm. Some tolerances greater than 0.030"+or-, will be called out in 1/32ths". I have a Starrett 8" vernier that will read to .0001" but seldom use it as I have access to micrometers that are quicker to use. Another seldom used scale for large diameters is a pi tape.

Two things,

I just wanted to say that I have enjoyed every minute I have spent reading the posts provided by the seasoned, not necessarily "mature" :), machinists on this site.
Miller, especially. For more than 15 years it would seem.
I know someday everyone will be somewhere's else.
And that saddens me. But in the meantime, every day that I get to read stuff provided by the WWll or Korean War age guys, I am returned back to my days in the tool room. Half the guys spoke German, most had been refugees.

I am humbled and grateful.

As a matter of fact, I use the "drag" method to set back the shoulders of cartridges when using cheap dies. Remove the lash, 14 threads per inch, do the math, mark the die, and away you go.

Body temperature wasn't the only reason for wearing cotton gloves while handling gauge blocks. The main reason was contact with skin oil which contains acid and destroys their accuracy. Gauge blocks are also cleaned with soft cloth or chamois after use. Some people call them Jo blocks after Johansen, the man who invented them. Ford Motor Company was somehow connected with him. Some Johansen gauge blocks have both Ford and Johansen's name on them. As for sticking two together that is called "wringing".

In the shops that I worked in most of the old timers called the gauge blocks JO blocks also. I came across two used C J Johansen micrometers once, a 0-1" & a 2-3". I bought them from a lady who said they had belonged to her late husband. They were kinda dirty with a black grease but appeared in good condition otherwise & she offered them at a good price. I bought them & cleaned them up & they turned out to be the best micrometers I ever owned. I didn't ask but always suspected her husband had been an auto mechanic as he had only the 1"& 3" mics as well as a lot of wrenches etc, which ?I didn't buy. Both of them had insulating panels on the frame where you grip them so the heat of your hand wouldn't affect the reading.
Did a lathe job once which was about a 10" diameter but very thin walls in stainless, forget the exact alloy now. Tolerance was very close for that size. We had a temperature probe that could be placed against a surface to read so when I got to the finish cut I had to take its temp & then figure shrinkage to make that last cut. It worked out just right & was right in tolerance when it got to inspection.

When I first started in machine shops we had an old Sweed named Oley who wore a white shirt and bow tie and changed his shirt every day at lunch time. Know there was someone who could tell you how to hold .001!

I'm not going for one upmanship here but I found it fascinating that Sir Joseph Whitworth demonstrated instruments of his which could measure to a millionth of an inch back in 1850.
He must have worked on tools like that while he wasn't busy revolutionising engineering and production methods
I wonder what a man with his hands and mind would be capable of if he were around today.

That is in decimal form 0.000001. I would like to see that from back then.

I have spent many hours in my buddy Charlie Boswell's machine shop where he makes Comp-N-Choke and Kick's High Flyer choke tubes. I have very little understanding of the machining trade, though I play around with one of his lathes. He has Japanese CNC machines that are made by the same company that makes Citizen watches. These, among other machines there, run all day, five days a week. I texted him yesterday and asked him what tolerances they could hold, and that I thought he once told me .0005". He replied simply, "No, much better than that." Those machines are amazing to stand and watch operate. But, that precision does not come cheap.

SRH

Hi
I just thought I would post a picture of some of the Micrometres I have now put in their boxes they are now like me retired from the world of work. At the centre top is the one inch Brit Moore and Wright and at the centre bottom is the Starrett one/two inch with its one inch trial piece and bow size adjustment from your part of the world incidentally this is the only micrometre I have ever owned that could walk usually overnight to other peoples benches and sometimes toolboxes. This micrometre was given to a family member who was working on the �Rolls Royce Merlin� engines at a time when we Brits had a falling out with our German cousins by one of your Air Force Engineers and he always said that �it was like being given a gold bar and dam it he even said that they had dozens of them.� In fact when I owned it and used it at work it was given the name the �American� or the short version starting in y and ending in k I am sure you know the one because its accuracy was second to none it sort of became the final arbiter for size. It also was keeper of what the apprentices would call those �idiotic inch fraction things!� as you can see from the picture they are engraved on each side of the Micrometres bow. Left and right is the favoured Japanese Micrometre maker nowadays Mitutoyo these two micrometres are from the changeover period we Brits had to go through the one on the right is inch and the left with the thimble mechanism is milometers and after going through the angst of the changeover I will admit now that working in Metric is on the whole easier but I fought against it all the way, just shows how wrong you can be.