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Thread: How to square beam on Desktop Max

  1. #1
    Join Date
    Jun 2019
    Posts
    2

    Default How to square beam on Desktop Max

    I am seeing a substantial (at least to me) non-parallel condition on the beam on my Desktop Max.
    When cutting small parts, I can deal with it, but I was looking at needing to surface a thick piece of wood that would require me to fasten the wood directly to the aluminum table.
    Machine is less than 6 months old, I purchased it new.
    The factory seemed to think that this is within their manufacturing tolerances.
    Note that in the pics the table has already been surfaced.
    I ran a dial indicator in a circle about 4" dia, and get a .022 difference in the X axis over that 4".
    I can measure the beam on either side, and it measures .045" higher on one side, which obviously means it is not parallel to the table.
    I can also measure a .020" difference in the beam front to back; the beam is 2" wide which makes the spindle not perpendicular to the table.
    This condition means that I can not accurately surface anything unless it is on a machined spoil board.
    I searched for threads on how to fix the machine, but could not find any.
    It appears that the machine relies on screws and drilled holes for locations of components; I do not see any dowels or pins.
    If this is so, I am assuming that I can loosen screws and hope that there is enough slop in the holes to allow re-alignment. If necessary, I could open the holes.
    I am also hoping that there may be enough material so that I can drill and pin the parts together after alignment to prevent it from shifting.
    Before I start taking it apart, I just wanted to know if anyone else had done this and had any suggestions or warnings based on their experience. My biggest concern is making sure the ball screws mounts on the Y axis are able to be moved to match the movement necessary to correct the misalignment of the beam. I should not have to touch the ball screws or bearings on the X axis.

    0710191425.jpgbeam.jpg
    I am a retired tool & die maker and have access to a machine shop so I can do whatever is necessary. The construction of the machine makes me think that getting this closer to being square and parallel should not be unreasonable.
    Thanks for any advice.

  2. #2
    Join Date
    Jun 2019
    Posts
    2

    Default

    So I decided to just proceed without any outside assistance.
    What I did was to clamp a piece of maple to the bottom of the beam, the theory being that the wood would be the same plane as the bottom of the beam.
    I put a jack screw under the ends of each of the maple pieces that supported the beam.
    I loosened all the screws that attach the beam to the side plates, and by adjusting the jack screws was able to put the beam in proper orientation.
    I can sweep the spindle and now I get .002" TIR.
    To make sure the ball screw was not put in a bind, I loosened the motor and bearing blocks, ran the carriage all the way to the motor side, tightened the mounting screws, then did the same for the bearing side.

    I plan to replace all those button head screws with cap screws/washers as long as there is no interference issues, as button heads have shallow sockets and strip out pretty easily.fix.jpg

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