Thread: Rain under bed

  1. #1
    I meant "Rail", as in Hiwin linear rail:)

    Hi Guys,

    I'm experimenting with different designs before I settle for one.

    Is there anything wrong with placing the linear rail under the table and bolted to the table like in this pic? (unfinished design)

    The bed is 30mm alu.I'd say chunky enough.


    Thanks


    Edward

    Click image for larger version. 

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    Last edited by Edward; 04-10-2017 at 03:46 PM.

  2. #2
    I should add, the logic of this being that the Ecocast being flat, it eliminates the problem with one plane of alignment, as opposed to fitting the rail to the extrusion on the side which would require more difficult alignment. Dual motors to go under (inside).

    Edward
    Last edited by Edward; 04-10-2017 at 04:03 PM.

  3. #3
    No problem, good way to mount them imo.
    Last edited by Zeeflyboy; 05-10-2017 at 05:35 PM.

  4. #4
    Thank you Zeeflyboy, I am inspired by your own build even though I don't think I will push it as far as buying super duper ground C3 screws:). Hmm...maybe I should bite the bullet...

    The difference is that you already have a router and therefore you want a good improvement on what you have.
    For me, this will be my first router build and I will struggle making it with my milling machine, because of the dimensions of some of the parts, though it's not impossible with a bit of patience and ingenuity.

    I was going to use a single servo motor and pulleys for the X, but after playing with various designs, I've come to the conclusion that for the sake of not much more money it is a lot easier to use two stepper motors for the long axis, like you have done.

    In fact, your design is brilliant, but I thought it would be a little bit easier to just bolt the rails to the underside of the table and get done with it. Well, it should be slightly simpler...

    I will go for the heavy duty KJN for this one, only because I have done some squaring up of the ends of the extrusion on my mill before, on 40mm, with a long 12mm endmill, and 50mm depth is probably pushing it a bit. I want to have the option of cutting my own extrusion.

    Edward
    Last edited by Edward; 05-10-2017 at 06:02 PM.

  5. #5
    Cheers :)

    Undoubtedly it is easier to bolt the rails to the underside of the Eco-cast bed as you have done.

    The only potential downside is that you are at the mercy of how straight the rail is and they do tend to have a small amount of bend to them along any significant length like that axis will have... might be worth thinking about how you will go about making sure it is running straight and true when bolted down since you don't have a reference edge to butt up against, even if it is as simple as running a piece of fishing line taught alongside and then eyeballing it straight as you bolt it down. Once you've done the master rail the other one should be able to be floated in to place.

    No different to how a significant number of machines on this forum are built though in essence, just instead of epoxy level you are using eco-cast for level and mounting upside down. I quite like the way you've done it with the small mount pieces giving you a level of adjustment for gantry width there too - something mine will be much more sensitive to.

    Will you be posting a build log?
    Last edited by Zeeflyboy; 05-10-2017 at 06:07 PM.

  6. #6
    Yes, I think I will be posting a build log, if only because you learn a lot from the criticism as you go along.

    To keep the rail straight, the "master" rail, I will use a long precision straight ruler, worth the expense, I think.

    BTW, that baby Z axis of yours is a gem, I've just seen your latest!

    Edward

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