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Problem with my cnc router

Discussion in 'CNC Mills/Routers' started by rambo800, Dec 3, 2016.

  1. rambo800

    rambo800 New
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    I made a cnc router 500 x 700mm my control box is a Arduino sheild Grbl software . I have setup up the software for the nema 17 stepper motor the steps to 10mm for x,y,z and my Grbl Controller 3.6.1 which I load the Eagle gcode. All is well when I start the cnc router and the pcb is been routing but the board track are not right and is all out of place.
     

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  2. Giarc

    Giarc Master
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    I am no expert, but it may be helpful to have a screen shot of all your GRBL settings posted. You may be off in the microstepping, or in the calculations regarding belt pitch, etc. Also a picture, or drawing, of what the PCB should look like would possibly help others in providing advice. When you tell your CNC to move 10 mm in the positive Y direction, does it move in the right direction the right distance? How about the other directions? It could be possible that the motors need to have wires swapped around if they are not moving the right way. This could be why the cutting is not happening where you want. If you use an overhead gantry like the Ox, the picture below is how the coordinates are usually laid out. This is how I did mine, and i have never had to make changes to the g-code or grbl settings and all cuts have always been done in the proper place. The front left is the x0,y0 position.
    [​IMG]
     
  3. rambo800

    rambo800 New
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    I fix the wire to the stepper motor and all 3 stepper motor are going in the right directions and steps are ok but I still have the same problem
     

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  4. Jen

    Jen Veteran
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    Rambo,
    After flipping back and fourth like fifty times between your drawing and the router track, I can see the design is literally flipped 180 degrees. I would question if one or both of your X and Y axis motors are working in reverse.
    I am new to this whole gerbil thing so I do not yet know if their travel is firmware reversible or if you need to reverse polarities to your steppers mechanically.
    Hope my input helps.
    I would slso take Giarc's advise and use a dial indicator or something to verify that the distances the axis are moving is what is expected.
    Hope his helps.
    Jen
     
  5. rambo800

    rambo800 New
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    I have found the problem as one of the pulley on the y is faulty so I will replace it soon
     
  6. Jen

    Jen Veteran
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    Justin, Duh! Yes that makes perfect sense. I thought I was viewing an image of the actual path Rambo wanted and a pen tracing of what he got. Hence my confusion.
     
  7. rambo800

    rambo800 New
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    You see my made cnc router is made of plastic parts and my son made them from his 3D printer all the list of parts for the cnc came from a web site so the pulley was plastic it work for a little why but with load the plastic pulley was slipping on the 8mm metal rod shaft.
     
  8. Giarc

    Giarc Master
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    I used threaded rod for all my linear motion. I drilled through all mounts (bearing collars, shaft couplers, etc...) and into the threaded rod with a drill slightly smaller than the 3mm threaded holes in the bearing collars and threaded holes in the shaft couplers. I then tapped these holes with a 3 mm tap and screwed longer 3 mm grub screws through the threaded holes in the bearing collars and shaft couplers into the threads in the threaded rods and motor shafts. Nothing slips. It is about as solid as a person could get. It wasn't easy and a few bits were broken, but it was worth it.
     
  9. rambo800

    rambo800 New
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    I did buy cheap cnc router on ebay which came from china no more so I got my son to search on the web and found a cnc which I can built from a 3D printer the only thing is the plastic pulley.Now I am going to put metal pulley and this will fix the problem
     

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