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Thread: Chuck backing plate question.

  1. #21
    Join Date
    Apr 2006
    Location
    citrus heights, ca
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    2,279

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    Quote Originally Posted by Mr Fixit View Post
    Hello Group,

    Resurrecting an old post
    OK the second question. How do I get the mounting holes in the back of the chuck (they do not go all the way through) transferred to the backplate so I can drill, countersink, and bolt it to the backplate?

    Look forward to any help or suggestions. Yes I took the lazy way out on the threading.

    TX
    Mr fixit for the family
    Chris

    Hi Chris the simplest way,if I understand you ,would to make or buy some transfer screws like thees :https://www.googleadservices.com/pag...9aACCEY&adurl=

    Steve

  2. #22
    Join Date
    Dec 2012
    Posts
    508

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    Simplest way would be with the transfer screws, IF they are short enough to allow the register to locate the chuck to the plate while you make the transfer/impression.

    Another way that would work just as well would be to measure the bolt hole circle on the chuck, making sure of the proper spacing, and mark and drill the backing plate using a rule and scribe. Drill these holes oversize, to accommodate any inaccuracy in the measuring/marking-out. They should be oversize, anyway, so as to allow the register to locate the chuck without any influence from the mounting bolts.

  3. #23
    Join Date
    Dec 2015
    Location
    Chilliwack, BC, Canada
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    5,643

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    For a cast iron backing plate or a softer mild steel plate you could make transfer screws from some cup style set screws. Because you're installing them backwards I'd slot the cup screws with a hacksaw. So that'll split the round circle into more like a ( ) shape. But that's close enough to usable to use for setting your center punch for the holes. And the hacksaw blade slot will allow you to put them in and take them out with a thin flat blade screwdriver.

  4. #24
    Join Date
    Nov 2010
    Location
    Portland Oregon
    Posts
    783

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    Hey Guy's

    I mentioned my situation to a friend today that is a HSM guy too, he suggested, what about drilling the holes all the way through the chuck with a small drill and using a transfer punch to locate the holes. This is a 4 jaw that of course does not have any parts in the way of the holes to do this, if I do this, does any body see a reason NOT to? I think it might even be the most accurate.

    Let me know what you think.

    TX

    Mr fixit for the family
    Chris

  5. #25
    Join Date
    Dec 2015
    Location
    Chilliwack, BC, Canada
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    5,643

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    Quote Originally Posted by Mr Fixit View Post
    Hey Guy's

    I mentioned my situation to a friend today that is a HSM guy too, he suggested, what about drilling the holes all the way through the chuck with a small drill and using a transfer punch to locate the holes. This is a 4 jaw that of course does not have any parts in the way of the holes to do this, if I do this, does any body see a reason NOT to? I think it might even be the most accurate.

    Let me know what you think.

    TX

    Mr fixit for the family
    Chris
    Way overboard as solutions go. And there's no way to even know if the drill bit settles directly into the center or if the drill bit wanders a hair and causes the transfer punch to hit off center. It's a long way through a lot of the bigger four jaw chucks after all. Plus now you have these "do nothing" holes on the front face to catch swarf.

    What's wrong with the transfer screw idea? Of course you'd need some version which goes into and can be removed from blind holes. Or the slotted cup end set screws?

  6. #26
    Join Date
    Nov 2010
    Location
    Portland Oregon
    Posts
    783

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    You are correct BC, just another idea, as I do tend to think outside of the box most of the time. This is a CDCO 4"- 4 jaw chuck for a dividing head to use once in a while. I was thinking of using a transfer punch inside the existing screw holes drilled from the back as they go 1/2 way through the chuck, then a use a small 3/16" drill to drill a hole the rest of the way through, then a transfer punch from the face in the 3/16" hole to the backplate to mark it. I could JB the small holes when done, or drill larger holes all the way through and counter bore for longer cap screws to mount it from the front of the chuck.
    OK, I had better quit thinking about this for now, or I'm going to have a chuck full of holes and ?

    TX
    Mr fixit for the family
    Chris

  7. #27
    Join Date
    May 2015
    Location
    Somerset UK
    Posts
    2,479

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    Mention of drilling the chuck body reminded me of the Toolmex 6" four jaw independent that I bought to fit to a backplate on the Smart & Brown model A. I was extremely lucky to get the brand new chuck at a bargain price. It was made to screw directly on to a Myford spindle which is smaller than the S&B thread. I wanted the largest bore through the chuck body compatible with it working properly, so the body was fixed to a faceplate and bored for the centre and register, and then fitted to the rotary table of the mill to have four holes with counterbores added for front mounting. The chuck body was simply held on the backplate while the hole positions were marked. I just used a drill to mark the positions and then drilled and tapped the backplate.

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