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Thread: Anyone fitted a DRO to a Bridgeport???

  1. #1
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    Default Anyone fitted a DRO to a Bridgeport???

    My DRO let me down big time yesterday, messed up a large chunk of expensive cast iron

    It seems to lose its zero point in both axis readouts, led me to machine 1.5mm off-centre line.

    I have a unit on its way but never having fitted one was wondering if there were any pitfalls to look out for.

    Its a different make than the Heidenhain on it so the mounts will need re-drilling etc.

    Then i have to find a way of recovering the damage on a 120 lump of cast

  2. #2
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    Yes, I have installed a few DRO's. One recently on my Bridgeport.

    You'll need dial indicators to square things up, and you'll need to run the table back and forth many times while doing so.

    Take your time.

    Google it and you should find much discussion.

  3. #3
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    Ok, thanks, got plenty of indicators.

    Googling now

  4. #4
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    I've stripped the old Heidenhain units off the mill and cleaned up the areas for the x and y units, shouldn't be too bad hopefully. The z axis could be a bit trickier though.

    Couldn't see anything wrong with old units, there was no oil or swarf in or on the scale units, no loose wiring, must be a failure in the main display I guess.

    One feature that strikes me as being useful on a DRO but oddly missing is this - random x y positioning....

    Instead of mounting a plate etc on the mill, aligning it to the table travel with a DTI then zeroing the DRO coordinates off the corner, just throw the work down, clamp it, then tell the DRO you want the edge you set the tool off to be taken as true, regardless if it is really running at 5 degrees angle. Then you can drill etc your bolt hole circles or holes at specific coordinates and the DRO would make allowance for the odd angle of the workpiece.

    Sounds simple to me, is it a feature known ???
    Last edited by Davek0974; 08-14-2013 at 03:39 PM.

  5. #5
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    Quote Originally Posted by Davek0974 View Post
    Instead of mounting a plate etc on the mill, aligning it to the table travel with a DTI then zeroing the DRO coordinates off the corner, just throw the work down, clamp it, then tell the DRO you want the edge you set the tool off to be taken as true, regardless if it is really running at 5 degrees angle. Then you can drill etc your bolt hole circles or holes at specific coordinates and the DRO would make allowance for the odd angle of the workpiece.

    Sounds simple to me, is it a feature known ???
    That's how my CNC PCB drill code worked. Select two holes as references, center the machine on each and the code would scale/rotate the coordinates to suit. Don't think it on a DRO.

  6. #6
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    I installed a DRO on my M-head bridgeport mill in this thread on Shop Floor Talk MB. On thing I would recommend is to remove the table to do any drilling and tapping. Clean the table and the saddle and install new felt wipers on it while you are at it.
    Also mount the X-axis scale on the rear of the table as it is better protected there than on the front, I had to make a mount for the reader head for it and the mount also is the stop to prevent the scale and its cover from being crushed. Mine was a from scratch installation, meaning the mill had never had a DRO on it.
    I had to build the a bracket to mount the Read Out on, but the installation is not all that tough to do it is just picky work.
    Dan.

  7. #7
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    Quote Originally Posted by Davek0974 View Post

    One feature that strikes me as being useful on a DRO but oddly missing is this - random x y positioning....
    Most DRO's have absolute and incremental, you switch to incremental for you random positioning.

    I fitted my scale (not a Bridgport) on the front of the table so I didn't loose any travel.
    http://www.chaski.org/homemachinist/...79d03cded38aa6

    Dave

  8. #8
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    Quote Originally Posted by Davo J View Post
    Most DRO's have absolute and incremental, you switch to incremental for you random positioning.

    I fitted my scale (not a Bridgport) on the front of the table so I didn't loose any travel.
    http://www.chaski.org/homemachinist/...79d03cded38aa6

    Dave
    Not quite what i was leaning to, EvGuru nailed it - rotated X Y positioning.

    Seems like a brilliant idea but no DRO i could find had it, would save a lot of time on some work.

    My BP had a Heidenhain fitted, the X is on the back of the table, the front has the stop bar for the powerfeed.

    Its all stripped and cleaned now, should be able to re-use a lot of the bracketry.

  9. #9
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    Ask Sir John , I think he had one on his POS before he scrapped it.

    Michael

  10. #10
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    Wow, what a pain in the backside job this is so far.

    After about four hours I have succeeded in fitting the Y axis scale, I modified the mounting subplate for the scale to fit jacking grubscrews, that made getting a good parallel easier but the hardest part was getting good alignment on the mount for the reader head.

    All is not made easier by having bad knees and repeatedly getting up from under the mill to grab tools etc is crippling me

    Anyway, the X axis seems not too bad, I will have to make a plate to pick up on the holes for the old reader head as there is no way I'm pulling the saddle off to drill and tap for new holes!

    See what happens tomorrow.

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