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IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > moving gantry , where to put the tracks
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  1. #1
    Join Date
    May 2007
    Posts
    102

    moving gantry , where to put the tracks

    I found this great little frame in cast aluminium .
    I think , a very good base to build a desktop cnc router .

    I'll be using 16mm supported rails and C style lineair bearings , 1605 balnuts and screws . .
    Because quite regurarly I have to trash old medical equippement , I have an abundance of those .

    The moving gantry , x-axis , will have one or two supported tracs and one ball screw on each side .
    Each side powered by its own stepper . I'll use 2 or 4 bearings on each side .

    So I drew up some possability's to put the tracs on the frame .

    I'de like some comments / guidance of the more experianced cnc-ers on wich setup they'de prefer
    and why .




    Thx Pat

  2. #2
    Join Date
    May 2007
    Posts
    102

    Re: moving gantry , where to put the tracks

    Forgot to mention , the sides of the frame will be milled to obtain a true surface and to remove the tabs .

    The general dimensions are a bit larger then A4 or letter sized paper .

    Goal is to make a very sturdy 4 axis machine , over engineerd maybe ,
    to mill / turn wood and aluminium .

    pat

  3. #3
    Join Date
    Aug 2012
    Posts
    8

    Re: moving gantry , where to put the tracks

    I would put the ball screws inside and use the frame to mount the motors on, then there is no need to build extra brackets. the rails on the sides of course.
    The table I would make oversize to cover the rails a bit from dust. (With a over hang on each side). If it was up too me I would mill the sides of the frame smooth. I would also remove
    the rest of the aluminium inside to get a nice frame only.

    Attachment 258126

  4. #4
    Join Date
    May 2007
    Posts
    102

    Re: moving gantry , where to put the tracks

    Yes I thought of that to in the first place but that would take away the ridgitity of the frame .
    If I wanted that , I 'de better weld 4 strips together to make a "box" .

    Pat

  5. #5
    Join Date
    Dec 2007
    Posts
    2134

    Re: moving gantry , where to put the tracks

    That's a really great frame, should make a very sturdy machine. Can you flip it upside down and use the middle supports to mount rails or bearings on, and make it a sliding table instead of gantry design? This will be a very rigid machine then and with a decent spindle, you'll be able to machine aluminium.

    I'd also be using fully supported rails and bearings instead of the free hanging round rails.

    cheers, Ian
    It's rumoured that everytime someone buys a TB6560 based board, an engineer cries!

  6. #6
    Join Date
    May 2007
    Posts
    102

    Re: moving gantry , where to put the tracks

    Ian , iy's true a moving x-axis with fixed gantry will make the sturdiest machine possible .
    But that would reduce the workable x-axis by half and it's already quite small .

    So for this one , it's gonna have to be moving gantry design . .
    With offcourse fully suppported rails .

    Pat

  7. #7
    Join Date
    Aug 2012
    Posts
    8

    Re: moving gantry , where to put the tracks

    If u bolt a solid flat aluminium table u wont loose any rigidity in the frame. This is my machine base and this is what i did.Attachment 258162Click image for larger version. 

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  8. #8
    Join Date
    May 2007
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    102

    Re: moving gantry , where to put the tracks

    Nice looking machine

    why do you use a dual leadscrew ?
    With this setup you can easily put the leadscrew in the center of the sliding block

  9. #9
    Join Date
    Aug 2012
    Posts
    8

    Re: moving gantry , where to put the tracks

    I do very fine engraving and i want it to be as stable as possible.

    Philip

    - - - Updated - - -

    https://www.youtube.com/watch?v=Vsth1jq0FZ8

    Here is my machine

  10. #10
    Join Date
    May 2005
    Posts
    3920

    Re: moving gantry , where to put the tracks

    Quote Originally Posted by stragenmitsuko View Post
    Ian , iy's true a moving x-axis with fixed gantry will make the sturdiest machine possible .
    But that would reduce the workable x-axis by half and it's already quite small .
    Actually you can make the table any size you want with a moving table design. You just have to put the rails on the table. There is an obvious issue with a table that is so long it tips the machine over.

    Given that the frame as is, isn't amendable to a moving table design.
    So for this one , it's gonna have to be moving gantry design . .
    With offcourse fully suppported rails .

    Pat
    That would be the easy route. The frame, with a bit of machining seems to be almost ideal for such usage.

  11. #11
    Join Date
    May 2005
    Posts
    3920

    Re: moving gantry , where to put the tracks

    Quote Originally Posted by Sharky74 View Post
    If u bolt a solid flat aluminium table u wont loose any rigidity in the frame. This is my machine base and this is what i did.Attachment 258162Click image for larger version. 

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ID:	258164
    Nice looking machine!!! ����

    It is always good to see fresh designs in the forums here.

    As for the original poster here, I see your machine suggesting one approach that may work out very well for the frame this guy has. That is apply a solid top to the frame. If the frame is machines for the rails and the top in one setup it should be easy to achieve decent results.

  12. #12
    Join Date
    Aug 2012
    Posts
    8

    Re: moving gantry , where to put the tracks

    Hi

    If u need any help let me know mabe I can be of some use.

    Philip

  13. #13
    Join Date
    Aug 2012
    Posts
    8

    Re: moving gantry , where to put the tracks

    Thanks Wizard

  14. #14
    Join Date
    May 2007
    Posts
    102

    Re: moving gantry , where to put the tracks

    Quote Originally Posted by wizard View Post
    As for the original poster here, I see your machine suggesting one approach that may work out very well for the frame this guy has. That is apply a solid top to the frame. If the frame is machines for the rails and the top in one setup it should be easy to achieve decent results.
    Yes indeed , the top will be an aluminium t-slot plate , and the entire frame will be machined in one setup .

    I think I'll go for option E for thetracks .

    Pat

  15. #15
    Join Date
    Aug 2012
    Posts
    8

    Re: moving gantry , where to put the tracks

    Quote Originally Posted by stragenmitsuko View Post
    Yes indeed , the top will be an aluminium t-slot plate , and the entire frame will be machined in one setup .

    I think I'll go for option E for thetracks .

    Pat
    What type of bearing claps are u going to use or are u going to make your own

  16. #16
    Join Date
    May 2007
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    102

    Re: moving gantry , where to put the tracks

    I'll use the C bearings offcourse that came with the hardened rods .
    But the sliding block will be custom made on the mill .

    Pat

  17. #17
    Join Date
    May 2014
    Posts
    182

    Re: moving gantry , where to put the tracks

    If you're planning on a moving table then the rod/c-bearings will probably work fine. If you go with a gantry style setup then I'd ditch those. Since you have an abundance of them, dump them on ebay, use the proceeds to get some nice linear guides:
    LRX20 750mm Used IKO Roller LM Guide Linear Bearing 2RAIL 4Block CNC Route Hole | eBay

    You'll get much more precision, much more load handling, orders of magnitude more rigidity, and longer service life.


    That is an awesome frame by the way - are you planning on getting all sides blanchard ground?

  18. #18
    Join Date
    May 2007
    Posts
    102

    Re: moving gantry , where to put the tracks

    I don't know , the rods and ball bearings somehow feel more ridgid then the thompson like rails .
    I've also got a few of those , so I just might give it a go . .
    All sides will be surfaced and trued with a fly cutter .
    A friend does have a surface grinder , but it's far from operational . .

    I'll make sure to add some pictures when I start machining .

    Pat

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