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  1. #11
    Whydon't you put the horizontal plate of the X axis carriages under the gantry side plates. You will have a lot of unnecessary weight removed and by putting the ball nut support under the same plate you can shorten the ballscrew and the main frame (to the length of the rails). The gantry will slide above the ballscrew end blocks. It is also a good point to put the ballscrews closer to the working surface/plane.

    I think you need a plate at the back of the gantry to crate a box. Even a thinner plate will increase rigidity.

    Quote Originally Posted by danilius View Post
    What I'm wondering is if there is an optimum distance between carriages for the gantry.
    I don't think there is an optimum distance... The 20cm that you have in your project looks good to me. But I'm not an expert.

  2. #12
    If you are using Hiwin 20 long blocks/ or even short/ , 200mm between both ends from outside measured is good for your machine. 260mm is desirable for serious build and i would say ideal, and 300mm for OTT and heavy gantry and really strong and large machine. So basically with Hiwin long blocks they will be almost touching each other .

    The idea is the bit to be in that distance , looked from side. In other words the spindle overhang. But on a machine like yours even if not, its not a big deal, as bearings are much more rated than forces involved.
    project 1 , 2, Dust Shoe ...

  3. #13
    Took me a minute to figure out what you meant, but that's going to be the next change! Thanks.

    Quote Originally Posted by paulus.v View Post
    Whydon't you put the horizontal plate of the X axis carriages under the gantry side plates. You will have a lot of unnecessary weight removed and by putting the ball nut support under the same plate you can shorten the ballscrew and the main frame (to the length of the rails). The gantry will slide above the ballscrew end blocks. It is also a good point to put the ballscrews closer to the working surface/plane.

    I think you need a plate at the back of the gantry to crate a box. Even a thinner plate will increase rigidity.


    I don't think there is an optimum distance... The 20cm that you have in your project looks good to me. But I'm not an expert.

  4. #14
    Quote Originally Posted by Boyan Silyavski View Post
    If you are using Hiwin 20 long blocks/ or even short/ , 200mm between both ends from outside measured is good for your machine. 260mm is desirable for serious build and i would say ideal, and 300mm for OTT and heavy gantry and really strong and large machine. So basically with Hiwin long blocks they will be almost touching each other .

    The idea is the bit to be in that distance , looked from side. In other words the spindle overhang. But on a machine like yours even if not, its not a big deal, as bearings are much more rated than forces involved.
    Thanks for that, quite reassuring.

  5. #15
    So, having taken your sagacious advice on board, the gantry walls now sit on a block that is shared between the ballnut and the blocks. The ballscrews are essentially level with the bed. So, gentleman, in your considered opinion am I at the point where it's worth putting all the detail in now?

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  6. #16
    Quote Originally Posted by danilius View Post
    So, having taken your sagacious advice on board, the gantry walls now sit on a block that is shared between the ballnut and the blocks. The ballscrews are essentially level with the bed. So, gentleman, in your considered opinion am I at the point where it's worth putting all the detail in now?

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    Yes, looking good now.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  7. #17
    Greeny's Avatar
    Lives in North Yorkshire, United Kingdom. Last Activity: 3 Hours Ago Has been a member for 8-9 years. Has a total post count of 102. Received thanks 12 times, giving thanks to others 7 times.
    Hi,

    Something to consider might be a double plate set up when attaching the y-axis. This allows for easier adjustment.
    In essence the y gantry sides have a base plate attached to form a y-axis assembly. This can then be bolted to a matching plate that is attached to the x-axis carriages.
    See http://www.mycncuk.com/threads/10403...aver/page4/#31 & the following post for a better explanation.

    This can be seen in a very recent post of the finished machine here (post #69)
    http://www.mycncuk.com/threads/10403...aver/page7/#69

    Cheers
    Last edited by Greeny; 10-03-2017 at 08:53 PM.

  8. #18
    Good point of the double plate for easier adjustment.

    If you want a stronger machine...
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    Regarding the length of the X axes screws and the overall length of the machine I do not see why you need the frame longer than the linear rails. If you lower the ballnut mount with a spacer and move it to the back (closer to the motor) you can shorten the screw at front by at least 10 cm, having the end blocks going under the gantry base plate.

  9. #19
    Quote Originally Posted by Greeny View Post
    Hi,

    Something to consider might be a double plate set up when attaching the y-axis. This allows for easier adjustment.
    Cheers
    It's definitely something to consider as a future mod, or son-of- machine. I really like the concept. Right now, since this is my first ever build, I want to keep things as crude as possible. From what I have read I have so mucg fun to look forward too, like aligning everything, tramming and smashing through a collection of cutters. Can't tear mt hair out anymore coz I'm bald.

  10. #20
    Quote Originally Posted by paulus.v View Post
    Good point of the double plate for easier adjustment.

    If you want a stronger machine...
    Click image for larger version. 

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    Regarding the length of the X axes screws and the overall length of the machine I do not see why you need the frame longer than the linear rails. If you lower the ballnut mount with a spacer and move it to the back (closer to the motor) you can shorten the screw at front by at least 10 cm, having the end blocks going under the gantry base plate.
    Oooohh, nice one. Definitely need to give that a go. Thanks for that.

    In fact, thanks to everyone. Sop far all the advice has been spot-on and seriously helpful.

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