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Mobile bed cnc machine, first build

Discussion in 'CNC Mills/Routers' started by Jason Harding, Sep 7, 2017.

  1. Jason Harding

    Jason Harding Well-Known
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    Jason Harding published a new build:

    Read more about this build...
     
  2. Jason Harding

    Jason Harding Well-Known
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    Got the frame together and bed mounted using 8020 liner rails
     

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  3. Jason Harding

    Jason Harding Well-Known
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    Had to fab up a pair of bearing supports for the x and y axis
     

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  4. Jason Harding

    Jason Harding Well-Known
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    Built a set of mounts for the nema 23s and flex couplers from some scrap aluminium
     

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  5. Jason Harding

    Jason Harding Well-Known
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    Got the openbuilds cbeam mounted for the y axis, using the remaining cutoff to make up the z axis
     

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  6. Jason Harding

    Jason Harding Well-Known
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    Actual build itself is complete, have a small dewalt rotozip (DW660) mounted for my spindle right now, going to finish wiring it up tonight and hopeully cut pvc as my test runs.
     

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    GrayUK likes this.
  7. GrayUK

    GrayUK Master
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    That's a good strong build there. How has it progressed since?
    May I make 2 suggestions? :rolleyes:
    One. Get yourself a couple of roller blinds to put front and rear of your table, so they expand and contract with the table and reduce the amount of debris getting into your runners.
    Two. You may not need it, but just to remove any chance of pivot on your Z axis, put another smaller X axis just above or below the existing one.
    It would be great to see a video on this machine in action! :)
    Good Job :thumbsup::thumbsup:
    Gray
     
  8. Jason Harding

    Jason Harding Well-Known
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    Hi greyUK

    thank you very much for your feedback I appreciate it. I Actually have it fully electronically functional at this point, Actually adding end-stops and mounting up the arduino and GRBL as we speak. I am hoping to do my first cut later today. I am tuning the backlash out of the 3d printed lead-screw adaptors. on my Y axis I have about a .006 variance, on my X I' running about a .003 and the Z is running about .002. If I can get my Y axis down just a little more I would be more than pleased. My target was .004 or better.

    I appreciate your observation about the vertical blind idea, I was a little concerned about the cuttings getting into the lead-screw but that's a nice ideal to minimise it.

    The Z axis is actually where I was having the most issue. Because of the smaller adaptor plate is was allowing a lot of slop when the movement was brought to tension. Exactly your observation. What I was thinking about doing without having to add more bars was to cut another plate same as whats being used on the Z axis to move the wheels further apart. and outside the Axis. I think that may be me the stability I'm looking for. as a plus I can also adjust wheel tension without having to strip the gantry apart.... again.

    Will post another pic and hopefully video at the end of the day
    Jason
     
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  9. Jason Harding

    Jason Harding Well-Known
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    Hi Grey, Here as requested, 1 min clip of the first operation of the CNC.
     

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  10. GrayUK

    GrayUK Master
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    That looks good and SMOOTH. Doesn't sound like you have noisy steppers either.
    Good Job :thumbsup:
    Gray
     
  11. Jason Harding

    Jason Harding Well-Known
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    Thanks grey, appriciate it. Alot of :banghead: but its been worth it.:)
     
  12. Jason Harding

    Jason Harding Well-Known
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    Forgot upload pic of the mounted electronics
     

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  13. Gary Caruso

    Gary Caruso Veteran
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    Jason, What made you go with the 8020 linear slides? How did they work out as far as friction?
     
  14. Jason Harding

    Jason Harding Well-Known
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    Hi gary

    Mostly my purpose in building it was available material combined with cost. The wheels and gantry systems for the openbuilds run approx $60 per side plus exchange and shipping. The 8020 linear rails cost approx $40 per side and i could pick them up over the counter (we have an awsome 8020 dealer about a 20 min drive from here)

    The second advantage to the 8020 style is that the bearings that are in them are a high cycle line. (10,000 plus movements) you can shim them to whatever you want your play to be. When they do start to show signs of wear i can cut new shoes for them on the cnc machine and as much as i would like to cannot machine roller bearings.... yet ;)

    Part of my restriction on building it was i wanted to use a single motor for the y axis as my last attempt to build a cnc machine crashed and burned because of a nema that went bad on testing and bent up my gantry (thus for the second attempt on my first build.

    Guess the answer was cause they were quicker to get and easier to maintain the actual load on them is the weight of the bed plus material /4.

    Hope that answers your question
    Jason
     
  15. Gary Caruso

    Gary Caruso Veteran
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    I guess it all depends on the vendor, that's a great price that you found, i found those 8020 slides for $60-80 per block online.. yes the real Openbuilds wheels are $$$
    I think its a good use of that system on the moving bed.
     
  16. Jason Harding

    Jason Harding Well-Known
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    I really like the open open builds design but parts are $$ when your on a budget. Have to order all my parts in small quanties and the shipping over time would be just ugly
     

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