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  1. #1
    So, what do you think of this design?

    as it's the one I'm probably going to make.
    Click image for larger version. 

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    Thoughts and constructive criticism welcome.

    It's made out of 10mm thick ALu by the way and 20mm supported rails.

  2. #2
    Hi, what do you intend to use the mill/router for? What is the cutting area?


  3. #3
    A 1050watt Kress at the moment, Cutting Area it just over A3 and 100mm High.

  4. Quote Originally Posted by jcb121 View Post
    Thoughts and constructive criticism welcome.
    I like the triangles, you get a lot of strength from a triangle.

    Can I suggest 2 small changes.

    The X axis rails have a lot more vertical separation than there is separation on the ball bushings. This introduces an awkward turning force on the nut which the bushings are poorly placed to resist. Suggest you lower the top rail and screw somewhat. Allow the Z rails to overhang at the top you are only going up there for tool changes, keep the strength at the bottom where you need it.

    Bolt the vertical risers to the sides of the Y axis aluminium sections. Connect the diagonal braces to the vertical risers with a lap joint not a mitre. Using an offcut from the vertical riser as packing, lap joint the braces to the aluminium sections. Maximise the rigidity the diagonals have to offer.

    Incidentally, 1/2" thick aluminium bar is a lot easier to find than 10mm.

  5. #5
    I think the Y-axis rails should be mounted on something stronger, ideally both on a single piece. At the moment they're on something that will twist easily, so they will still deflect downwards...
    Having them far apart is good I think, though I agree the ratio of the Y and Z rail seperations should be closer to one. Perhaps make the Z axis wider?

  6. #6
    I have just received my DIYCNC Breakout board! :D

    this may sound silly, but this is the first serial item I have ever used! I have to find an old PC now!

    Also took delivery of some M6-M12 taps.

    Exciting stuff.

    The supported rails in that picture were 250mm Long and the screw was 350mm, this allowed me to mount the screw supports above and below the supported bearings making it thinner.
    I'm now getting 300mm supported rails, this means that the screw supports will have the be inline with the rail and that the Z axis will be wider.

    would changing the ratio of Z and Y closer to 1 make it more rigid? I thought it was a bigger the better situation!

    the ratio of the new design is about 2:1

    the 2 being the Y axis.

  7. #7
    I think that ratio is fine as both of the distances between rails are reasonable, so it surely can't be worse than if they were both the same as the 1.

    What are you mounting the Y-axis rails on?

  8. #8
    probably one large bit of Alu. due to the cost of this, i'll have to make the Y Axis rails closer together to make it cheaper! then it probably will be very close to 1:1

  9. #9
    Any one know where I could find ALu 170x10x....

    I'll have to check down fromstock later today :)

  10. #10
    One large piece is best, otherwise the rails will twist.


    Imperial dimensions are more common, so you're after about 7"x3/8"... these are the nearest:

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