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Gear cutting machines with pitch error correction mechanisms

Maybe soviet sub builder lapped their gears for weeks, Westinghouse, in Sunnyvale, did not. I know people who worked there. No, they did not do that. It's oldfart horseshit. This whole thing with "lapping gears" is crap. Yes there are lappers (or were, many years ago). But they do not work the way people think. If you "lap your gears" together in your race-car tranny, all you are doing is wearing them out faster. Oh goody.
At this point I must say that I heard the story of laping for several months from my boss, who was told by his friend. That is, in fact, instead of “several months” there could well be “several days” or “several weeks”, and instead of “lapping with abrasive paste” there could be something else))))
because people nowadays only seem to know how to push buttons, and be totally competitive in accuracy with someone with a brand new Hofler for 1/100th the cost. Definitely slower but not 100 times slower.
Very cool point. After all, in fact, how much does a new Liebherr or Gleason cost now, $1 million? These are good machines for making gears 24/7 - but what if a shop needs to make 100 gears once a week? What if there are 20 pieces each?
Not every mechanism that requires precise rotation can and/or is justified in installing an encoder, servo drive and controller. I'm not even talking about any mechanical correction systems :) In many cases it will be easier and more reliable to install a conventional worm gearbox with a worm wheel of good accuracy in terms of the accumulated pitch error. Yes, Gleason will provide accuracy, I think, of the order of 1 arcsec or better - but for a damn million!
Small update. In a review of the 1969 European Machine Tool Exhibition in Paris, I found information about the Pfauter P630UP machine. This machine had an electronic correction system with optical encoders 10,000 pulses/rev. The encoders were installed on the spindle, table and somewhere in the differential circuit. Below are some pictures. Stated accuracy: +-1 micron on a diameter of 16.7 inches, or about +-1 arcsec.
img067 — копия.jpgimg068 — копия.jpg
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Maybe of interest to some... The book Engineering Progress Through Trouble (well worth reading) has a chapter titled Development of Large Marine and High-speed Gearing. Published in 1975.

Definitely lots of trouble over the years - noise, wear, breakage. Sometimes at bad moments:

"With naval ships, gear failure may occur at a vital moment after the gears have given years of satisfactory service; this happened with (HMS) Sheffield, when her gears were wrecked while she was engaging the Scharnhorst in the action in which the latter was sunk."

Engineering Progress Through Trouble cover.jpg Engineering Progress Through Trouble contents.jpg Engineering Progress Through Trouble pg 20.jpg Engineering Progress Through Trouble pg 21.jpg Engineering Progress Through Trouble pg 22.jpg Engineering Progress Through Trouble pg 23.jpg