1. #1
    after reading a lot of threads i reached this as a startup design ..the machine will Click image for larger version. 

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    be used for engraving marble sheets (really heavy) ,for the y i will use 6mm steel sheets bent to form a cross section of 30cm *40cm,i will be using R&P sustem with gear reduction 1:5 for the steppers
    waiting for your input ...thnx

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  3. #2
    Well it looks good but there are a few things I would comment on.

    3500mm is a mighty wide gantry, it would be better from a rigidity standpoint if you have could have the axis running the other way, so the gantry only spanned 2500mm. I understand the other way offers better access.

    Is the gantry the section built from 6mm, 30x40cm? Have you calculated the strength and deflection of a beam constructed like this? Perhaps run some FEA analysis on it. Others will surely comment on this, I think 6mm will be very susceptible to vibration. Not sure but it doesn't sound like it will be sturdy enough to me.

    The way you are mounting the rails to the machine with screws is interesting, don't think I've seen that before. Clearly it would be advantageous to have that level of adjust ability. Again I'm not sure but it doesn't look very rigid to me. Have you done any calculations or tests?

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  5. #3
    Quote Originally Posted by Rufe0 View Post
    Well it looks good but there are a few things I would comment on.

    3500mm is a mighty wide gantry, it would be better from a rigidity standpoint if you have could have the axis running the other way, so the gantry only spanned 2500mm. I understand the other way offers better access.
    handling marble and counter tops is very hard so easy access is an affecting factor in the production rate and ease of handling

    Quote Originally Posted by Rufe0 View Post
    Is the gantry the section built from 6mm, 30x40cm? Have you calculated the strength and deflection of a beam constructed like this? Perhaps run some FEA analysis on it. Others will surely comment on this, I think 6mm will be very susceptible to vibration. Not sure but it doesn't sound like it will be sturdy enough to me.
    well i didn't do any calculations..actually i dont know how to do them so if you can guide me to an example or a thread that can help that would be very much appreciated.
    i thought of adding some stiffeners to the beam for inside Click image for larger version. 

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    Quote Originally Posted by Rufe0 View Post
    The way you are mounting the rails to the machine with screws is interesting, don't think I've seen that before. Clearly it would be advantageous to have that level of adjust ability. Again I'm not sure but it doesn't look very rigid to me. Have you done any calculations or tests?
    i found this system on some machiensClick image for larger version. 

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    waitin

  6. #4
    Have you build anything before? I don think so or it was not that big

    So let me help you a bit:

    -You miss some basic understanding that Box section is stronger than U profile. Eliminate from your drawing any U section. Its ideal use is for table bed.
    -Diagonal braces are more difficult to cut, almost impossible to weld and do less job than bigger box section in simple order-You have drawn 1.2 ton of a machine and i could achieve stronger machine for half the weight.
    -These bolts for leveling the rails are mistake. Eliminate them. Either do separate portal with both sides and separate table in the middle / what i would do for stone/ or lay rails directly on table sides. Raised or not.

    So basically my advise is to do separate gantry and rails and sides, plus separate table in the middle. As the HD plasma systems do it. Or read my second build from my signature, as this is the other option. My machine will happily answer all of your criteria. Plus will save you a ton of money on the build if you follow what i have done as gantry and especially for the Z. You will note that i have extremely heavy duty bed that lies directly bolted on frame and makes my machine extremely strong

    Now separate or not will depend on how many water will flow around, how heavy the stones, how you will load them, if from time to time ...


    Hope that helps.
    Last edited by Boyan Silyavski; 03-02-2016 at 06:22 PM.
    project 1 , 2, Dust Shoe ...

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  8. #5
    DearBoyan Silyavsk
    thanks for your comment and yes you are right this is my first time to build a big steel machine,mu first build was made from extruded aluminum ,the machine worked well but of course extruded aluminium was a bad choice for such application but the results were not bad as samples,and now i have a customer who liked the samples produced by this machine and want work buy on bigger pieces (the first one was max 50cm850cm) so i have to build a big machine as soon as possible.
    i read the build log for your second machine and it was very informative specially the tables for motor sizing and the epoxy technique and the beast looks sturdy (my aluminium machine was shacking like shakira),so i will redesign the machine following your log specially that when i calculated the weight of the gantry was 400 kg and post them
    i am trying to use FTA as Rufe0
    suggested to calculate stress and deflection
    just want to check with you

    1- i will be using R,P as ball screws with this length are ahrd to find
    2-i will using belt reduction system with reduction ratio 1:5
    3- i will use a shaft to link the 2 gears on the 2 sides of the y axis
    4-i am using steppers as i already have them and according to the tables they are more than enough

    thnx again for the help and the informative build log

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