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Taking the CNC Plunge

Discussion in 'PRECISION-MATTHEWS' started by TomS, Aug 6, 2014.

  1. TomS

    TomS Active User H-M Supporter-Premium

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    I tried a multitude of Mach3 CV settings such as CV Distance Tolerance, bumped Look Ahead to 200 lines, made sure G100 Adaptive Nurbs CV was turned off, Shuttle Acceleration, changed speeds, feeds, cutter size, number of flutes, DOC, WOC, feed direction and spindle drive belt. No change in surface finish. Even went back and checked gib adjustment. No improvement in surface finish. I'm at a loss as to what's causing this.
     
  2. TomS

    TomS Active User H-M Supporter-Premium

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    With nothing to lose I played with my microstepping configuration to see if it had any effect on surface finish. First test was a change from 1000 steps to 400 steps. No change in surface finish. I then went the other way and tried 5000 steps. Again, no change. Next test I turned off microstepping. That was a mistake! When I started Mach I couldn't get the X and Y axis to move. The X and Y DRO's had an error message that would not go away. The message was "-1.#IND". Shut down Mach and configured my drivers for 1000 microsteps (my original setting). Started Mach and the error message was still there. After trying for 30 minutes to clear the error message I gave up and uninstalled Mach. I keep a backup copy so it was a simple matter to reload and get my smoothstepper communicating. So not a very productive day.

    At this point I'm out of configuration options so I'm back to looking at mechanical contributors. I did find that when I rotate the spindle by hand the clearance between the spindle shaft splines and the spindle drive hub splines gets loose and then gets snug. Hmmm, looks like I have some runout but I'm not convinced it's the source of my problem, yet. All this being said I disassembled the head and measured spindle shaft runout at the drive end. I got .0025" TIR. Checked the drive hub splines and got .0023" TIR. I'm still not convinced this is the cause of my poor surface finish but at this point I'm looking at everything.

    I gave up for the day because it's 100+ now and working it's way to 112 deg F. I'll reassemble it with the high spots opposite each other and see what happens. If that doesn't change anything I'll try something else.

    This is so frustrating!
     
  3. jbolt

    jbolt United States Active User H-M Supporter-Premium

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    At this point I would suggest posting in the CNC forum for more exposure. You might consider posting over on cnczone as well.

    Sent from my SM-G955U using Tapatalk
     
  4. TomS

    TomS Active User H-M Supporter-Premium

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    Good idea. I've got a couple more things to try out first. One is the runout issue I discovered yesterday. The other is a post on the Mach Support Forum that discusses having G90 and G91.1 on the same line or separate lines. The Mach forum says they should be on separate lines. My CAM program (CamBam) puts them on the same line. I've got a writeup by RGSparber that addresses this issue. Just have to read through it again to absorb and decipher all the computer geek language.
     

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