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Problems v carving

Discussion in 'CNC Mills/Routers' started by JamJar, Apr 9, 2018.

  1. JamJar

    JamJar Well-Known
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    Can anyone help. Im very new to cnc routers and even this forum, not even sure if this will work?
    After just recently building an ooznest workbee im having difficulty acheiving an accurate v-carve.

    My finished result does not resemble the original computer file and i cant understand why.

    Ive tried 60 and 90 bits but no joy.

    See pics below, any help much appreciated.
     

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  2. Mark Carew

    Mark Carew OpenBuilds Team
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    Hello @JamJar welcome to OpenBuilds and to learning the art of CNC :thumbsup:
    When I look at the comparison I would say that 1) your depth is a little too deep on your cut if you were up just slightly higher on your Z 0 , I would suggest bumping up your z height to half a millimeter up from zero then re-zero and try again. 2) looking at the corners where the machine changes direction I would say you have a little backlash or play in the system. I would suggest turning on your machine make sure all the motors are engaged and try to move your axis by hand by lightly moving them back and forth with your hand. On the belt system:If you get movement you need to take a look at your pulleys and make sure that they are locked to those motor shafts. On lead screw you will need to adjust the tension screws a little on the backlash nut blocks. You really do not want any moment at all there because that is where these kinds of inaccuracies come from.
    Hope this helps to get you up and running.
     
  3. JamJar

    JamJar Well-Known
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    Thanks mark.

    I have an ooznest workbee belt and screw drive machine. I was following some advice on another issue but forgot to turn my power off before trying to move the y axis and snapped a belt. I will try your advice once im up and running again.
    On another note can you try to explain what is happening in the attached movie clip so i can sort it out.

    Cheers.
     

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  4. GrayUK

    GrayUK Openbuilds Team
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    Does it always happen in the same place? Only on the same axis?
     
  5. JamJar

    JamJar Well-Known
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  6. GrayUK

    GrayUK Openbuilds Team
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    That sounds like the drive pulley is jumping the teeth on the belt.
    Can you see if that is happening when it goes wrong?
     
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  7. JamJar

    JamJar Well-Known
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    I can't see anything as its all enclosed. Ryan from Ooznest mentioned that the belt sounds to tight which could be pulling down on the motor shaft restricting it from turning. Unfortunately the belt has since snapped so i have to wait for a new one before i can test anything.
    When the machine is jogged or homing it runs at a pace that doesn't affect it but as soon as i enter a (G0) command it then happens.
    When cutting i don't hear it although i do hear a single knock noise at somepoint during a cut which results in a jump in the cut by 1 - 2mm.
    Look at the picture of some simple circles which go wonky. I have drawn a circle inside to show the difference.

    Ill get there in the end, this forum and Ryan from Ooznest are the only reason i haven't chucked it back in the box and gone back to hand tools.
     

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  8. GrayUK

    GrayUK Openbuilds Team
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    I think you would be the first person I've heard say, they never had any teething problems, from their new machine. It happens, and it can be sorted out! :)
    Here, is probably the best place for these sort of problems. We may keep asking questions, but we usually get there in the end. :thumbsup:
    What you don't want is to be trying to sort it out on your own! :banghead:
    As a thought, can you see any wear and tear on the tops of the belt teeth, where it has been skipping so to speak? :rolleyes:
     
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  9. Mark Carew

    Mark Carew OpenBuilds Team
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    There are a few things this could be but I have to say it sounds to me like it could be a loose wire on the stepper. Since the wires move on the gantry's this could be the case. It happens to me at the end of almost every build :) Its usually the wire into a wire block, tightened down, but sitting half on the insulation and half on the wire causing intermittent stalling issues.
    So I would suggest turning the power off and double check that all of your connections are sound. I would also check to be sure your fans are keeping the drivers cool on the board. If you have a driver going in and out of thermal shutdown you can have similar results.Like Gary says, all of us here has been though new machine setups and if you stick though it you will be rewarded by knowing everything about it, which challenges you to grow, learn and share more with everyone. Its really an awesome community of guys here helping one another push our own limits to better one another. Hang in there, with the help here you will get it sorted.
     
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  10. JamJar

    JamJar Well-Known
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    Just checked the belt teeth, no wear and tear. Currently checking wiring as per Marks suggestion. Need to wait for new belt before trying any movement.
     
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  11. JamJar

    JamJar Well-Known
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    Checked all the wires into blocks, in fact removed them reseated them but all were looking good from the first install. Also watched the fans for a while and loaded a job to see and all was good, both working.

    Ryan sent me a new belt and suggested not tightening as much as my previous version. This is the one that snapped when i accidentally forced the gantry movement when the machine was on. I replaced the belt and left some slack and it all works. No jumping, no skipping no noise.

    My next problem is it isnt cutting accurately. After drawing some simple shapes it cut inaccurate versions..... see photos. 20180412_181609.jpg 20180412_181609.jpg 20180412_181609.jpg 20180412_182753.jpg
     

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