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  1. #11
    Here are some nice pictures to get started.

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    Right now I am working in google sketchup and trying to do some design.
    Anyway can someone answer me the first question if the rails for Y are better top-bottom or front face.

    thanks.

  2. #12
    D.C.'s Avatar
    Lives in Birmingham, United Kingdom. Last Activity: 05-01-2016 Has been a member for 4-5 years. Has a total post count of 326. Received thanks 30 times, giving thanks to others 24 times.
    No problem digisoft, just a misunderstanding. :)

    Unless you already have access to a workshop you will probably have to rig something up to grind a 45 degree angle in your supports like this guy has done:

    Grinding a 45 degree angle for a linear rail with my CNC - YouTube

    One problem with this approach is that you have to use v-groove bearings as wheels and the wheels will need frequent adjustment as the rail wears and your wheels become loose. The v-groove bearings are also really expensive and hard to get hold of.
    It might be easier to use a piece of box section or square bar at 45 degrees as the rail like this:

    /\
    \/

    That way you can use skate bearings (just the normal wheel bearings from skateboards) which are really cheap, it wears down slower so it requires less adjustment and it means a lot less work to setup.

  3. #13
    OK if I have picked you up correctly you are going to make your own supported rail using the ally profile & chrome bar. First question would be what sort of equipment do you have access to because I would imagine you would really struggle to be able to drill & tap a length or round chromed hardened steel bar with DIY gear unless you already have your own workshop.

  4. #14
    Quote Originally Posted by martin54 View Post
    OK if I have picked you up correctly you are going to make your own supported rail using the ally profile & chrome bar. First question would be what sort of equipment do you have access to because I would imagine you would really struggle to be able to drill & tap a length or round chromed hardened steel bar with DIY gear unless you already have your own workshop.
    YES YES that is what I am trying to do.
    D.C. that is not a solution because I already have the ball bearings.

    I have workshop and I have big table drill and other tools. I don't have router and I can't melt aluminum :D
    Please help :)

    THANKS TO ALL!!!!

  5. #15
    I calculated the Z part and ONLY the aluminum 20mm plates will weight 11Kg. It is not included, the rails, sliders, stepper etc etc, only the aluminum plates construction. Is that too much? Should I sue thinner plates?

  6. A typical gantry will weigh in at 20 - 25kg. Without seeing a drawing of how your gantry is designed its impossible to say what the impact of making them thinner will be. Rigidity is key...

  7. #17
    Quote Originally Posted by irving2008 View Post
    A typical gantry will weigh in at 20 - 25kg. Without seeing a drawing of how your gantry is designed its impossible to say what the impact of making them thinner will be. Rigidity is key...
    Here is some unfinished design.
    Please tell me what do you think.

    Thanks.

    Click image for larger version. 

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    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  8. #18
    Going off advice given to my design, and the veiws i know others share I'd say it seems to have the right things in the right places pretty much.

    Critisism: flip the stepper motor and mount it on the back then use a belt and pulley system. This will reduce resonance, as well as other things? (correct me)
    Perhaps also mount the ball nut inline with the rails, might help give greater travel in x?

    Finally, ignorance is getting the better of me, are you really from chernobyl?
    Hobgoblin.

  9. #19
    Quote Originally Posted by Hobgoblin View Post
    Going off advice given to my design, and the veiws i know others share I'd say it seems to have the right things in the right places pretty much.

    Critisism: flip the stepper motor and mount it on the back then use a belt and pulley system. This will reduce resonance, as well as other things? (correct me)
    Perhaps also mount the ball nut inline with the rails, might help give greater travel in x?

    Finally, ignorance is getting the better of me, are you really from chernobyl?
    Hahahahahahhaa no my friend, I am not from there. I just put it like that :D
    Thank you for the help.

    Can you tell me if the Y distance of the rails (vertical distance between the Y rails) is better to be 150mm or 200mm. Y will be 1140mm long

    PS: I am still working on the Y boll-nut. I just put it like that, it is not in place.
    PSS: I was also thinking about belt and pulley for the Z but I don't have those parts and it will complicate my design. What do you think? Is there that much difference?
    All aluminum parts are 20mm tick.

    I changed the design little so the Y distance between the two axis is 150mm
    Click image for larger version. 

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    Do you think this is better?
    Last edited by DigiSoft; 23-10-2012 at 10:31 PM.

  10. Its always better to have the y-rails as far apart as you can and as low down to the bed as you can to improve torsional stiffness...

    I think you could reduce the thickness to 12 or 15mm without undue effect...

    What is the box section between the rails? material and dimensions?

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