QTPlasmaC with fourth axis - rotary
- mariusl
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Marius
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- phillc54
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There is one issue at the beginning of the circle:
N0100 (o=0, pd=0.5)
N0110 G00 X14.7352 Y3.922 Z50.0 A-90.0
N0120 G38.2 Z15.00 F500.0
N0130 G92 Z[25.0 - #<_hal[plasmac.float-switch-travel]>]
N0140 G00 Z28.0
N0150 M03 $0 S1
N0160 G01 Z26.5 F100.0
N0170 G03 X18.7657 Y5.98 I0.9862 J3.0442 F2000.0
N0180 G01 X21.7803 Y14.0015 A270.0
N0190 X24.7737 Y18.6269 F1607.3831
It may be my setup but it does a complete revolution here so I changed N0110 to 270 and it seems OK.
I have pushed a test branch named phillc54/plasmac-tube with what I have so far which is only the basics. It includes the latest pipe.ngc file in nc_files/plasmac
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- mariusl
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- LesNewell
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Yes, SheetCam varies the feed rate when cutting around the corner. The exact speed for each axis depends a lot on the tube corner radius. I generally recommend that the rotary axis be capable of 200RPM and the linear axes 10m/min (400IPM).@LesNewell does the post processor take care of the faster feedrate for the A axis when cutting over the corners? If so by what ratio must the Axis be faster to be able to do a reasonable cut?
Looking at the test run there does seem to be something odd going on with the feed rates. I can see it in simulation here. I'll investigate further.
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- LesNewell
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Phill, I have attached a version of the code that includes feed on every line. It may help you figure out what is going on.
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- phillc54
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- My little rotary table is only capable of 150°/sec which is 25rpm
- LinuxCNC has poor path planning for axes other than X, Y, or Z
EDIT: I have attached a halsampler capture of the A axis velocities for the second cut from the above sim.
Attachments:
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- LesNewell
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Phill, just out of interest how do the A axis velocities compare to the first cut?
I found Mach3 works more smoothly with the rotary axis configured for 1 unit per rev instead of 360 units/rev. Do you think this would help here?
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- phillc54
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I didn't plot those, I can do tomorrow.Phill, just out of interest how do the A axis velocities compare to the first cut?
TBH I don't know if that is possible, I assumed angular joints/axes needed to be degrees.I found Mach3 works more smoothly with the rotary axis configured for 1 unit per rev instead of 360 units/rev. Do you think this would help here?
This is from the docs:
ANGULAR_UNITS = <units> - Specifies the machine units for rotational axes. Possible choices are deg, degree (360 per circle), rad, radian (2*π per circle), grad, or gon (400 per circle). This does not affect the angular units of NC code. In RS274NGC, A-, B- and C- words are always expressed in degrees.
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- snowgoer540
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- My little rotary table is only capable of 150°/sec which is 25rpm
- LinuxCNC has poor path planning for axes other than X, Y, or Z
Would inverse time (G93) help with #2 at all? I know it's common on mills to use G93 with 4/5th axis moves.
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- LesNewell
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I generally recommend that the 4th axis is defined as a linear axis rather than angular. I'm not sure about LinuxCNC but some other controls treat rotary axes differently to linear axes. Functions such as rotary axis diameter compensation or 360 degree rollover can cause all sorts of unexpected issues.TBH I don't know if that is possible, I assumed angular joints/axes needed to be degrees.
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