I purchased a 5C Collet Chuck plain back and a back plate adapter. Two different sources and while measuring the backplate for fit the micrometer readings are very close to exact except the Chuck recess the backplate sets in is 3.740 and the backplate insert measures 3.736. Am I going to have a problem or should I make another backplate with closer tolerances?
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5C Collet
- Thread starter Capt45
- Start date
- Joined
- Feb 2, 2013
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- 3,967
if you leave a bit of wiggle room, you can lightly tap on the high spot when indicating in the chuck, thus removing unwanted runout while tightening the chuck to the backplate
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- Aug 3, 2017
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It would depend on the quality of your 5C chuck. If it is one of the really good Bernard/Bison/etc, I'd probably want a tight fit. If it is a chinesium one, I'd probably prefer to leave the backplate a little small so that you can tap it to be on center.
Good to know. My thought was I wouldn't be able to tighten the backplate enough to prevent it from shifting around. Also, the part of the backplate that inserts into the back of the Chuck measures .110, and the Chuck measures ..185. Should I spin the backplate up on the lathe and machine it to measure ~ .185? BTW, definitely of Chinese ancestry. The Chuck I mean.
- Joined
- Jun 12, 2014
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- 5,075
Lower quality backplates you usually take a skim cut with it mounted on your lathe and may adjust the step as needed. Some come a bit oversized so you can trim them down to fit the chuck. You do not want the backplate step as deep as the chuck, but I probably would go to .150-.160". I would do the skim cut to be a snug fit with the chuck mounted, and then test the alignment. My experience in the past with two other Chinese 5C chucks is both were out like 0.007" even after the skim cut and the registration step. It is hit or miss as to how well yours will be. Commonly individuals will true it up by cutting a bit more off the back plate registration step and tapping it true with the bolts lightly tightened. I did that on my Chinese 3J chuck before sending it off to rustier pastures.