One of the major influences in my life as a metalworker was a retired tool maker named Charlie Blessing (left hand old dude). As it turns out I was introduced to him by one of the other master metal workers in my early career Doug Duane. Both of these guys were so much more skilled than I was I had to bring my game up just to sit and eat lunch with them and listen
'getting some oil". The only oil over there was the special insulating oil we filled the high voltage switches with. I walked across the street to meet the legend, curious as to what he was using this oil for. When I saw him he was just screwing the cap on a jug full of oil filled from a large storage tank with a hand nozzle like a gas pump. I walked up and introduced myself to him.
At this point in time is was around 1984. Charlie was probably seventy four or seventy five years old and had been retired for ten years or so. We talked long enough in that initial meeting for me to get in trouble with the boss for yapping too long. He told me to come by some time as he had some old lathe junk for the 1915 Prentice lathe I mentioned that I had.
This was the beginning of a friendship that lasted until his death in 2005 at the age of Ninety five years old. We met at least once a month and corresponded regularly by old fashioned mail and UPS. During a typical visit I would show up just after lunch time and stay for five or six hours where we talked and rummaged around in his fantastic shop in the basement. Here are some of the only digital pictures I ever shot of some of the machines he built in his home shop.
Deckel. This is a predecessor to modern CNC milling machines. Any good mold maker back then was an expert with one of these beasts. It follows a pattern with a stylus on one table and duplicated the path with a cutting tool on the second table. It can be adjusted to change the scale of the part which allows the use of larger patterns to improve accuracy and details.
The story I want to tell tonight is about a Cadillac gage. For those of you that don't know what a Cadillac gage is it is an adjustable height master for setting height gages on a surface plate. All the major gage companies made their own version of this type of height standard but for whatever reason the name Cadillac gage stuck. Perhaps the model they made was first or best version and it became the de-facto Kleenex of height gages.
In the olden days if you wanted to set a very precision size on a height gage you had to make up a stack of gage blocks then calibrate the height gage. If there were many sizes that needed to be set this quickly turned into a lot of work. Nobody ever said toolmaking happens fast. One solution was the Cadillac gage. basically a stack of one inch gage blocks wrung together with a one inch travel tenths setting micrometer head at one end. So the idea was you could quickly dial in any number up to the total height of the gage within a ten thousandth of an inch. No stacking Jo blocks together and about a million times faster. When they came out in industry they were also fiendishly expensive.
So the story goes that back some time around the early fifties Charlie and some of his fellow toolmakers decided they needed a couple of Cadillac gages. Price was a problem for them making probably three dollars a day or what ever toolmakers made in 1952. So they hatched an ambitious plan to make their own gages from scratch. Sounds pretty challenging to me even now that I know how they did it. I guess toolmakers at the height of their game think this is cream cheese easy.
So to start with they need a couple of gage blocks. Buying enough gage blocks to make the complete gages is not in the budget for these cheapskates. At this time gage blocks were quite expensive compared to what we can get today. I can buy a good one gage block from McMaster Carr for $42. To make a similar gage I would need ten or twelve blocks. Even at now with relatively inexpensive mass produced gage blocks $500 its starting to get a little painful for just part of the project so it seems logical to make your own???.
Charlie decided to make his own gage blocks mainly for cost reasons and I think he wanted a good challenge. He made the gage blocks right in his basement shop entirely with his own equipment. Starting with A-2 tools steel he machined, heat treated, ground and lapped a dozen or more individual gage blocks to make his Cadillac gage.All of this in a little basement toolroom in South San Francisco.
To start he needed to buy a couple of things. At least one gage block, and an optical flat. He may have already had the optical flat but a high grade tool purchase never stopped any toolmaker. Over a period of months he worked on his gage blocks. Painstakingly grinding them within a couple of tenths and then carefully lapping them in short sessions so the heat from his hands wouldn't expand the blocks too much. As he worked he compared the blocks to his reference standard block with the optical flat using monochromatic light. This technique is called interferometry. I don't recall the process he used for the lapping other than it was done by hand on a lapping plate that he probably made himself.
I don't know how long it took to make his Cadillac gage but as it turned out he was the only one to finish his gage out of the three or five guys that started. Several years later he had an opportunity to have a high grade inspection lab evaluate his home made Cadillac gage. He remembered being very excited about seeing how well he had done making his gage. When he finally got the report he was crushed. The inspection revealed that in the total stack of ten blocks he was two tenths short. Short was the worst thing that it could be. He is telling me this story and I'm cheering him that in ten blocks he was within two tenths. Forty years later he is still bummed out that he missed by that much. It would have been better if the stack was long, then he could have gone back in and re-lapped the blocks to bring them in. He told me after that he tossed the thing in the cabinet and never used it he was so disappointed in what he thought was a total failure.
Fast forward fifty years. I come over one day and I see the Cadillac gage taken apart on the surface plate. I ask him what gives with the gage? He is all excited because he had just read an article in a trade magazine about the long term stability of tool steels. Apparently A-2 is not perfectly stable over long periods of time and tends to GROW with age. This is enough for Charlie to dismantle the gage and check the blocks for size against his standard. It only took fifty years to finish but the job came out just fine.