This video provides a short introduction to gauge blocks and how they are used in the machine shop, followed by a demonstration of how to select and wring blocks into a stack of the desired height
Gauge blocks are ground, go through several stages of machine lapping and are then hand lapped to size. I took a tour through a gauge block manufacturer once and the final sizing area was bench after bench of women with lapping plates, optical flats and electronic gauges sizing the blocks. Tom
Once again, Tom - I learned what I needed from your vid - THANKS! Just acquired a modest set of Do-All gauge blocks and turns out I was a bit off base on how to wring them! The part about the lab-grade blocks growing together overnight was new info... amazing!
VERY GOOD instruction. I might add. Re. “dressing” a burr on a gage block by rubbing it on a surface plate lubed with denatured alcohol. You DO NOT try to “dress off” the burr as you would also remove material from the rest of the gage block surface thus undersizing the block. Using a surface plate DOES NOT remove material it pushes the raised burr back down (if it is not too bad). Also, to press the burr down uniformly you should use a figure 8 motion. If the block will still not wring, REPLACE IT. The raised burr will scratch every block it is used with.
Very interesting. I am familiar with Jo blocks but never owned a set. Knowing the process to get to a specific stack is a real time saver. Showing an easy one and a less obvious one was a great lesson.
Thanks. Just because you are retired doesn't mean you need to stop working. Now is the time you get to be your own boss instead of working for someone else. I'll be retiring in about two years and have a project list as long as my arm. Can't wait to have the time to get to them. Tom
Great explanation in this vid! I'm taking machine/industrial technology math and this vid definitely helped me get through the chapter for gage blocks! Keep up the good work!
Thank you very much for your video. I am taking the class on Inspections Technics and the two examples you gave on stocking blocks technics finally enlighten me on the matter!
It's not only air pressure that holds the blocks together ... two (or more) gauges wrung together will stay firmly conjoined even if put in a vacuum chamber and all the air exhausted. It's more a phenomenon known as covalent bonding (which also leads to the gauges getting inseparable if left wrung together for long periods of time).
Minor correction: It is van der Waals forces, not covalent bonds, that provide the inter-molecular attraction between blocks. As you move the surfaces very close together, the electron clouds surrounding each atom in the material at the surfaces start to interact, creating an "induced" dipole. This is sort of like a temporary magnet (but not really, see below) and the effect is an electrostatic attraction between the surfaces. This same phenomenon plays a role in friction too. It is important to note this is not a magnetic effect, which is a totally different mechanism. When the blocks are manufactured, the grinding process actually generates a lot of magnetism in the part, so they are totally degaussed during the manufacturing process, and sometimes during calibration.
I don't think I have seen anything on this subject, very good job. I remember the first time I put together some blocks it was amazing how they stuck together. How are they ground? Is that how they are getting that kind of accuracy and flatness by some grinding process?
I was not going to watch because it just seemed to simple of a subject. What could I possibly learn? As usual Much to be learned even about the simplest things! I just got a set that had the screw in the center to hold them together. Never would have thought you could get them to stay together with out a screw!!!! Thanks for sharing your great knowledge.
Square blocks have a hole, but can be wrung together just the same as rectangular blocks. Round space blocks also have a hole, normally threaded, but are machine grade and will not wring. They work well for machine setups that might damage gauge blocks. Thanks for watching. Tom
It's actually air pressure that holds them together. They are so flat that all of the air is evacuated from between the blocks, creating a vacuum and resulting in 14.7 psi. of force from the pressure of the air around them. Lab grade blocks left wrung together will actually grow together and become one piece. Thanks for watching. Tom
Toms Techniques Hey Tom, thanks for your reply, that is just fascinating!! I saw in the video where you had mentioned they would "grow" together if left "stuck" to one another, and that just blows my mind! Anyhow, what brought me to your page is; I am interested in finding some equipment for DIY gunsmithing and was wondering if you could point me in the right direction as far as what may be the best tools to acquire. I am interested in purchasing a lathe and milling machine. I would probably rather have manual machines, as I am of the impression that may be the most economical and best way to actually learn how to operate the equipment. Any information you can provide will be greatly appreciated! Thanks! Jeff
AccuracySpeaks I'm not a gunsmith, but if I were, I would make sure the lathe I purchased had a large enough spindle bore to pass the largest barrel that I planned on crowning or chambering. Also, gunsmithing uses a lot of unusual thread pitches, so make sure the lathe can handle them. The mill should be a Bridgeport type/size and there are many to choose from. Mine was made by DoAll in the 80's and it's a 9X49 with variable speed and an Accurite digital readout. Tom
It's really a wonder that we can afford "economy" blocks, and use them to calibrate our OTHER cheap measuring gear! Reading some old books that mention the introduction of this, that the true original Johansson block sets came to America at something like $900! Might have been a few years' pay for the guy on the factory floor there. An aside about quality and "wringing"- I once got to try a set of ceramic gage blocks in a salesroom, and it was really amazing! They just went together so easily, the impression that they were magnetic was very strong, even though they were this white ceramic material. Those are a few thousand dollars I think, which is probably a bargain even so, and still much cheaper than the 1920 originals.
The original blocks were likely purchased by quality and metrology departments at companies not individual machinists or toolmakers. Henry Ford was a big early adopter of JoBlocks at Ford Motor Co. Look at some of the early Ford manufacturing videos and you will see they were way ahead of most companies in manufacturing measurement which is key to volume mass production. It is great that now almost anyone can afford what was once very costly measurement technology.
It probably has something to do with hardness. Gauge blocks are typically made of high chromium steel, ceramic, or tungsten carbide, all extremely hard materials. I don't believe stainless can be hardened to that level.
