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OOZnest Ox going off course (part 2)

Discussion in 'CNC Mills/Routers' started by MplsArtist, Jun 14, 2017.

  1. MplsArtist

    MplsArtist Well-Known
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    Previously, I had posted about my OOZnest 1500x1500 going off the tool path course on the 5th or 6th pass and coming to a screeching halt in virgin wood territory. Several people suggested I reduce my feed rate which I have done and now is at 75ipm with a spindle speed of 16,000 RPM (the minimum on my Dewalt 611). I'm using a 1/4" compression end mill bit and taking off approx 0.119" each pass with a climb cut.

    I thought the culprit was an incorrectly hung dust extraction hose putting too much weight on one side of the router. I reconfigured my hose supports and all looked good for awhile. I got past the previous trouble areas on my tool path and several additional pieces were being cut without a problem until it got to the 7th piece where it once again went off course and cut through a previously cut piece (Image #2 & #3 attached). This piece is in the center of my CNC work area and should have the least stress on the hose, etc. I'm now wondering if there is another factor at play.

    The pieces that I'm trying to cut are very curvy (Image #1 attached) but in Vectric Cut2D pro, I specified bezier curves during the set up process. After the latest crash I opened up the sender settings in X-ProV3 (Image #4) and discovered some info regarding arc segments and thresholds. I'm wondering if I need to adjust these settings to keep the CNC on track. Anyone have any knowledge in this area? I don't have any idea of how the last two settings should be set.

    Someone also mentioned previously that I should consider using a conventional cut as climb cutting tends to grip into the piece being cut and my Nema 23 motors might not be able to keep the pulling from causing the CNC to go off track.

    The weird thing seems to be that the course deviations are occurring in the opposite direction of the material being cut!

    Any help you can provide would be greatly appreciated.

    Image 1.jpg
    Image 2.JPG
    Image 3.jpg
    Image 4.jpg
     
  2. Ryan Lock

    Ryan Lock Master
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    Hi,

    I am not sure if this one has anything to do with feedrate settings etc. Because from your pictures that goes off course in the completely opposite direction.

    We have seen in the past issues with electrical interference cause several issues. Dust hoses are very good for building up static, one of our customers did have a similar issue, and he put a grounded metal strip along his hose, that seemed to solve it.

    Other causes could be having the USB running along side router power wires, same for the motor wires running alongside the router. So if possible keep the Router wire clear of the others.

    If you can see anything else in your setup which may be a cause, including other equipment you may also be running in your workshop.

    Ryan
     
  3. MplsArtist

    MplsArtist Well-Known
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  4. MplsArtist

    MplsArtist Well-Known
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    I have a metal wire attached to the router mount and up and through the dust hose and grounded at the plug receptacle. The router cord is in contact with the hose in several spots but is distant from the motor wires and USB cord which comes out directly from the Xpro to my laptop. The power unit is at the back of the table on its own circuit. The laptop is on its ow circuit as well. Same with the router.
     
  5. MplsArtist

    MplsArtist Well-Known
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    Ryan:
    I've attached 4 photos showing my CNC basement set up. After reading your post about static build up I think I may have one giant static generator surrounding my CNC machine in the form of large, transparent, shower curtains. The USB cord from the computer definitely touches the curtains when the router is moving. What do you think?

    I also included some other photos of my set up in case you spot other potential sources. I'm especially interested in the ferrite locations on each of the motor wires next to the Xpro.
    CNC Cutrain.JPG
    Controller.JPG
    Static wire.JPG
    Dust hose.JPG
     
  6. MplsArtist

    MplsArtist Well-Known
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    Well, I think I've been staring at the screen too long or inhaling too much sawdust lately. I did an aircut this evening of the same file to confirm everything, and it is indeed a climb cut but I indicated the wrong direction on my photo with the arrow. It should be going clockwise around the outside of the piece. This now makes more sense of the course deviation. On piece # "ADM 5" instead of following the curve cut in previous, shallower passes, this deeper cut veered off and cut into the 6th piece cut followed that channel a bit before slicing through it.

    This is exactly what's happened with all previous course deviations. It's always the last or second to last pass that is affected.

    Could this still be a case of electrical interference or is more mechanical, such as bit deflection, cutting direction, feed rate etc?l
     
  7. Ryan Lock

    Ryan Lock Master
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    Hi,

    I am not sure to be honest, just seems strange for it to go so far off course so quickly. When you connect to the xPro, which version of GRBL is your xPro running? If it is 1.1 try using UGS 2.0 Nightly build, as we have seen a few weird issues using 1.1 with 1.0.9 UGS.

    Maybe just half the feedrate, half the depth of cut, and see how it performs then. If ok then build up from there.

    Best Regards

    Ryan Lock
     
  8. David the swarfer

    David the swarfer OpenBuilds Team
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    Ditch that compression bit!

    Your cut depth is not deep enough to make use of its compression facility so all it is doing is compressing chips into the cut when deep, and is 'probable cause' for your problem.
    Please try again with a nice new 2flute spiral up cut bit.
     
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  9. David the swarfer

    David the swarfer OpenBuilds Team
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    Once a stepper motor stalls it is quite easy to turn it backwards, that it why it goes so far off course.
     
  10. MplsArtist

    MplsArtist Well-Known
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  11. MplsArtist

    MplsArtist Well-Known
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    How deep should a compression bit be on each pass?

    I did buy 2 spiral up cut bits just in case. What about cutting depth for these?
     
  12. David the swarfer

    David the swarfer OpenBuilds Team
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    I refer you to my post about this in your original thread
    OOZnest Ox going off course
    Read the article at the link provided !
     
  13. MplsArtist

    MplsArtist Well-Known
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    I just wanted to give an update on my situation. I have now done 4 sheets of 4'x4' Baltic Birch, each sheet consisting of 2-3 dozen individual pieces without error. I decreased by feed rate to 40 ipm climbcut, switched to a spiral upcut bit (as David suggested), and increased my nesting gap between pieces from 0.5" to 1.0". I had noticed that a couple of my course deviations included areas where the wall between nested pieces had been cut away and may have been a factor in the bit loosing it's way.

    My OOZnest 1500x1500 is now cranking out the pieces like a workhorse without complaint. I still need to do some fine tuning because I'm still getting a lot of chatter marks on the cuts especially on the long straight cuts. I slowed it down to 25 ipm but with very little improvement.

    I will need to cut some MDF soon as was wondering what the feed rate & RPM should be for that ( minimum speed on my router is 16,000). I've heard some horror stories about combustion etc. Any suggestions? I'm sticking with the upcut bit as David suggested and noted in the link to the article he provided.

    Thanks again for all the help everyone has provided.
     
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  14. Ryan Lock

    Ryan Lock Master
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    Glad you got it sorted. Regarding the chatter, is it at the beginning of the straight cuts? or just the whole way along?

    For MDF i run it as 2mm cut depth 1200mm min. But i think you could crank it up more than that. Spindle speed was at about 20k i think.
     

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