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  1. #41
    yes fair enough, I'm going with a single rail each side.

    I like the look of the misumi milled profile - they have it in the 45x90 size i was originally planning. Just need to figure out how to actually buy the stuff and how much it is.

    Edit - Father in Law is happy to get it through his company, now just a question of how much dolla!
    Last edited by Zeeflyboy; 19-02-2017 at 06:56 PM.

  2. #42
    Quote Originally Posted by Zeeflyboy View Post
    yes fair enough, I'm going with a single rail each side.
    It is a good decision. Now just turn them 90 degrees and place them under the table. Squaring will be a problem if you are not doing that. You would also get a more rigid machine if the rails are mounted horizontally.

  3. #43
    Why do you think it would it be more rigid?


    (3) High rigidity in all four directions
    Because of the four-row design, the HG series linear guideway has equal load ratings in the radial, reverse radial and lateral directions. Furthermore, the circular-arc groove provides a wide-contact width between the balls and the groove raceway allowing large permissible loads and high rigidity

    Personally I think the machine as a whole will be more rigid with the current setup as it allows me to bolt the frame and frame supports to the tool bed for added frame rigidity while keeping the unsupported gantry arm to the minimum length. If I flip the supports 90 degrees and set them up like my current machine then I have an unsupported bed that will flex, and I can't put the cross supports in as they would then interfere with the ball screws... unless I underslung them which would be a mounting nightmare.
    Last edited by Zeeflyboy; 20-02-2017 at 03:14 AM.

  4. #44
    Just out of interest, 50x100 GFS (high rigidity version, 6.8kg/m) milled profile works out to around 70 per metre before tax.

    Given I only need 2 metres of it that's not too bad really for a milled mounting surface I think... might be the way forward.

  5. #45
    Quote Originally Posted by Zeeflyboy View Post
    Why do you think it would it be more rigid?





    Personally I think the machine as a whole will be more rigid with the current setup as it allows me to bolt the frame and frame supports to the tool bed for added frame rigidity while keeping the unsupported gantry arm to the minimum length. If I flip the supports 90 degrees and set them up like my current machine then I have an unsupported bed that will flex, and I can't put the cross supports in as they would then interfere with the ball screws... unless I underslung them which would be a mounting nightmare.
    Yes, it would be. But there is the challenge to align all.

    The only way to align that easy and properly 100% is to rest all frame on flat surface and lift rails on paralel blocks same size and then tighten. But i assume you dont have that flat surface. So you may have to think of sth else. What i am saying here is that a design is as good as you know all steps, to finishthe machine. To figure the details meanwhile you are building it=wasted money and time
    project 1 , 2, Dust Shoe ...

  6. #46
    Thought we already mentioned that the rails would be aligned to the ecocast ground bed plate?

    I'll be using Thorlabs precision corner brackets for frame squareness (combined with the ecocast end plates and milled extrusion).

    Does that not cover the alignment issues, especially given the relatively small size of the machine?
    Last edited by Zeeflyboy; 22-02-2017 at 05:44 PM.

  7. #47
    They will be aligned left-right, not up-down , plus have to be straight up down, not wavy, same for left right, but as you said that will not be a problem as eco cast plate. 3d, means there are 3 directions that things have to be on plane
    project 1 , 2, Dust Shoe ...

  8. #48
    No, they would be aligned in the vertical plane too... ecocast bed plate could be fastened to the top and then I would insert a shim of 2.5mm between carriage and bed with the carriage at one end, clamp it in place and tighten end screw. Move carriage to other end, insert same shim again and clamp. Tighten that end screw... If required you could repeat that at several points along the length.

    Repeat on the other side and both rails are aligned vertically using the eco cast bed plate as a reference.

    The parallelism and squareness of the Y-rails would be taken care of to acceptable tolerances by the captive ecocast end plates, milled extrusions and thorlabs corner brackets, while the vertical alignment (both in X axis rotation and Z plane height) would be done in reference to an ecocast bed plate.

    What am I missing? In my head that ends up with the rails fully aligned in all axis to within the tolerance of the milled surfaces which should be sufficient for a pretty accurate machine all said and done.
    Last edited by Zeeflyboy; 22-02-2017 at 08:28 PM.

  9. #49
    Seems 100% ok what you are saying. Thats very similar to the way i thought it could be done.
    project 1 , 2, Dust Shoe ...

  10. #50
    Ok great, thanks - glad you agree with my thinking then!

    I've just done a mass analysis on the finished machine and its coming in at just shy of 190kg... I know mass is but one suggestion of rigidity but that's not far off 3 times the mass of my current machine.

    I've also taken the opportunity to change to a HGR25 rail and HGR25HA carriages on the Y-axis since there is more space now.

    Had a quote back for all motion parts, it was pretty reasonable for ground screws and HIWIN rails. Think I'm good to pull the trigger on those parts?


    Last edited by Zeeflyboy; 22-02-2017 at 09:09 PM.

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