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Thread: Chuck key

  1. #16
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    May 2020
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    ACT
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    27

    Default

    If you want the original item they are available from Pratt Burnerd. I'm waiting for a price bit not expecting it to be cheap. I Imagine once I get a price and pick myself up off the floor I'll end up spinning one up out of some 20mm 4140 stock. Providing you have a mill it's not a major job to make one.

  2. #17
    Join Date
    Sep 2012
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    York, North Yorkshire UK
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    Hi Guys,

    Pratt Burnard the chuck people are now part of the "600" group of companies !

    I've just bought a replacement 100 mm three jaw chuck from ARC Euro here in the UK, the chuck key that comes with it is identical in size to the original PB one.

    For the price I'm quite pleased with the quality of the chuck, the run out at the chuck jaws is less than 2/10 ths thou using a 20 mm diameter test bar and barely alters 150 mm away.

    Unfortunately I can't say the same for the pre machined Myford fitting backplate that I bought from them some time ago. I originally bought it to put a ER32 collet chuck on it. The metal was coarse and rough to machine I couldn't get a smooth finish no mater how much I tried. I ended up grinding the surface to get a good finish. Also when drilling the three holes for the M8 cap screws it was like drilling stainless steel. Horrible stuff !
    Best Regards:
    Baron J.

  3. #18
    Join Date
    Sep 2008
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    Riddells Creek, Vic.
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    831

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    Hi BJ, are you saying that the Arc Euro chuck has a runout of .008"(0.2mm)? If so, it sounds a bit much, even for a 3 jaw.

  4. #19
    Join Date
    Mar 2011
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    Southern Flinders Ranges
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    This is where things got to at the end of play today.. That and the discovery I can’t currently replicate the original flattened end of a Burnerd key on a piece of 10mm round bar because the hydraulics on my press are marking their territory too badly..
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  5. #20
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    Apr 2003
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    melbourne
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    69
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    19

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    Looking good to me!


    Quote Originally Posted by racingtadpole View Post
    This is where things got to at the end of play today.. That and the discovery I can’t currently replicate the original flattened end of a Burnerd key on a piece of 10mm round bar because the hydraulics on my press are marking their territory too badly..

  6. #21
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    Sep 2012
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    York, North Yorkshire UK
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    Hi Techo

    Quote Originally Posted by Techo1 View Post
    Hi BJ, are you saying that the Arc Euro chuck has a runout of .008"(0.2mm)? If so, it sounds a bit much, even for a 3 jaw.
    Thanks for your post, I missed a "0" off the end. I've been back and corrected it. It gets confusing swapping between imperial and metric gauges !

    I've re-edited it because I still got it wrong ! It should read two tenths of a thou ! I'm going to stop trying to come to terms with mm.
    Best Regards:
    Baron J.

  7. #22
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
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    Thumbs up Getting it wrong !

    Hi Guys,

    I thought that since I had made a right pigs ear of measuring and reporting run out figures for my new ARC Euro chuck I would re-do the measurements and take some pictures as I went along.

    13-06-2020-01.JPG 13-06-2020-02.jpg

    I used a metric dial indicator this time so I couldn't get confused with thous.
    This indicator is a 0.01 millimetre one. I started with an 8 mm diameter bar and rotated the chuck until the reading was the lowest nearest to the indicator. I then zeroed the indicator. I then rotated the chuck until the reading was a maximum.
    In this case four divisions. (1.6 thou)

    13-06-2020-03.JPG

    Then I did the same with the 20 mm diameter test bar.
    It only moved three divisions this time. (1.2 thou)

    13-06-2020-04.jpg

    Then I repeated the exercise with a 40 mm diameter bar.
    Only two divisions this time. (0.8 thou)

    I would have liked to try a bigger diameter say 50 mm but I don't have anything that big. It seems that the run out improves as the work diameter gets bigger.

    So apologies for making a screw up in my original post. Thanks also to Lex for the prod to get it right
    Best Regards:
    Baron J.

  8. #23
    Join Date
    Nov 2007
    Location
    melbourne australia
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    3,228

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    Quote Originally Posted by BaronJ View Post
    I used a metric dial indicator this time so I couldn't get confused with thous.
    .
    .
    In this case four divisions. (1.6 thou)
    .
    .
    It only moved three divisions this time. (1.2 thou)
    .
    .
    Only two divisions this time. (0.8 thou)
    Hi John,
    I think I see where the confusion creeps in. You're using a metric DI but reporting the results in thou. Why not just report the measurement in mm straight off the DI? You're adding a conversion that introduces the potential for error.
    Chris

  9. #24
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    Sep 2012
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    York, North Yorkshire UK
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    Hi Chris, Guys,

    Chris, I've used thous all my life but most on the forums seem to want measurements in millimetres. But yes you are right, trying to convert readings is causing confusion.

    A few months ago I bought a HBM 125 mm three jaw chuck and back plate. I machined the register on the backplate for a nice snug fit into the back of the chuck. At this point I couldn't measure the jaws. Anyway after drilling for the M8 mounting holes and threading the back plate I mounted the chuck. On checking the chuck body there was about 10 thou eccentricity.

    After having gone through measuring the new ARC Euro 100 mm chuck, I decided to do the same with the HBM one. Using the same setup as before, I had nearly 2 mm of runout with an 8 mm rod. This got worse as I moved to my 20 mm test bar.

    I ended up machining a further 15 thou of the register and drilling out the M8 threads to 9 mm holes and use M8 cap screws from the back. This allowed me to tap the chuck central with a plastic faced hammer. I managed to get the run out down to 3/10ths mm with an 8 mm rod in the jaws. Even so the run out gets worse with increasing diameters. With a 45 mm diameter bar the run out is just short of a whole millimetre.

    I believe that HBM is an Indian manufacturer. I certainly won't be buying another one.
    Best Regards:
    Baron J.

  10. #25
    Join Date
    Nov 2007
    Location
    melbourne australia
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    Quote Originally Posted by BaronJ View Post
    Using the same setup as before, I had nearly 2 mm of runout with an 8 mm rod.
    That's terrible.

    Quote Originally Posted by BaronJ View Post
    I believe that HBM is an Indian manufacturer. I certainly won't be buying another one.
    My experience with Indian tools hasn't been good either. Hopefully they will get their act together quickly and be a viable alternative to China.
    Chris

  11. #26
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    Mar 2011
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    Southern Flinders Ranges
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    Ready for the post office tomorrow..
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  12. #27
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    Apr 2003
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    melbourne
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    Fantastic!
    I’m so appreciative. Can’t wait to use it now. Blackened as well!




    Quote Originally Posted by racingtadpole View Post
    Ready for the post office tomorrow..

  13. #28
    Join Date
    Mar 2011
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    Southern Flinders Ranges
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    For the life of me I now have no idea where the key for my Pratt 3 jaw is
    Cant be too far away, I used it to make yours

  14. #29
    Join Date
    Apr 2003
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    melbourne
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    It’s there looking right at you! When you find it, you’ll say to yourself “ now I remember putting it there”.
    I do that about twice a day.

  15. #30
    Join Date
    Jul 2011
    Location
    Berowra Waters
    Posts
    149

    Default A file?

    Maybe just buy a 10 mm and file 0.5 off each face? Wouldn’t take very long I would think.

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