Sunday, 8 December 2013

to cure the obscure

I picked up a bigger drill press (than my 8" Delta 11-951) as part of a job-lot of machine tools. It's a solidly built, Yamaguchi YD-350A bench top model that was actually made in Japan, with all signage lettered in English, which I'm guessing dates from about 1950. It has just 3 speeds but runs without vibration. The problem I found was the chuck runout was about .030" (measured via a dial indicator at the end of a 5" length of 3/8" drill blank). Removing the chuck from the spindle revealed that it had obviously spun out at some point, as the male and female J6 tapers were both badly scored and galled. I was able to clean up the spindle taper and read ~.0005" runout on it alone. The female taper in the chuck body, however, is proving more difficult to correct. Using a d-bit as a scraper, I was able to remove most of the raised burrs on the inside. With the chuck fitted back on the spindle, the runout was now on the order of .010"; not bad for woodworking but miserable for metal. Since I don't know how accurately the chuck ran prior to the spinout, I can't say whether this is the best it will ever be. I'm digging around for a 'known good' chuck to try for better results. If it can reach .001", I'll be more than happy.

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