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Thread: Help please Z axis and table assembly dont touch....

  1. #1
    Join Date
    Jul 2025
    Posts
    10

    Default Help please Z axis and table assembly dont touch....

    I have a 48x48 Shopbot PRS Alpha.

    I have yet to get it working as it is new to me used machine.

    So I purchased a 3/4" Sheet of 12 Ply Baltic Birch, a 1 sheet of 3/4 MDF as per the directions.

    The result after drilling all those holes, and gluing down the new MDF ....

    guys z axiks.jpg
    The spindle comes no where near the table.Not close enough for the surfacing bits I have.

    The Z axis hits a hard stop and generates a driver error going as low as you can see in the photo.

    Did someone change something that I can't see that made the spindle higher or is this some weird factory customization and I am just going to have to live with gluing more MDF to the top of this sandwich.

    Thank you for your help
    Guy
    :-)


    More details:

    It came to me with a table made of MDF and a Spoilboard of MDF. The Table was 3/4, and the spoilboard was not attached constructed of 1" mdf and a 1.25" mdf.

    All of it was coming apart due to previous user saturating it with laundry detergent to try to cut brass.

    Since I could push the spoilboard and the table up and down 1/8" or more without effrort as th MDF was shot... I decided to read the directions and make a new one.

  2. #2
    Join Date
    Dec 2000
    Location
    Thorp, WI
    Posts
    2,865

    Default

    You may be able to lower your spindle by one bolt pattern, but that will short you on the top end. Most have done the plywood base, and then two layers of 0.75" MDF on top of that. The middle layer could be cut as a vacuum plenum, and then the top layer is your spoil board.
    Scott




  3. #3
    Join Date
    Jul 2025
    Posts
    10

    Default

    Quote Originally Posted by srwtlc View Post
    You may be able to lower your spindle by one bolt pattern, but that will short you on the top end. Most have done the plywood base, and then two layers of 0.75" MDF on top of that. The middle layer could be cut as a vacuum plenum, and then the top layer is your spoil board.
    Scott!
    Thank you,
    I was thinking of doing a vacuum plenum but it was another chicken and egg problem. I would need a functional Shopbot to make the plenum....

    I read the manual a little slower, and looked a my machine a little more, and discovered that there are two ways to mount the spindle holder, and whoever put this one together mounted it so that the spindle could go up farther, which means that the standard directions for 3/4 3/4 don't work.

    So I glued another layer of MDF down, and we should be able to surface and do our first ever cut today with the machine.
    Thank you,
    Guy
    :-)

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