2 Attachment(s)
expertise needed for toolpath problem
Hello everyone,
Look at the pics to see the problem...
The first is surfacing 20lb foam with a 1/4" cutter (70% overlap) in the y axis direction.
You can see the difference in height every time it changes direction.
About 10 thou ???
The second pic is a 1/8" ballnose with a 30 thou pass in hdp foam.
Again, same problem.
Its like the z axis is somehow changing height when the machine changes direction ?
I would post the gcode but it shows static height.
Mach 3 wouldn't do that I dont think.
10HP high frequency spindle runs smooth.
Rhinocam cut speed is 80ipm.
30 for approach and engage.
Any thoughts ?
Re: expertise needed for toolpath problem
Pics aside, for anyone to really be able to help, we'd need to see your program code (gcode) bud
If the gcode is standard/validated toolpath and you are getting something else then something hardware/mechanical might be at fault :/
Problem occurs only on this part/toolpath?
Re: expertise needed for toolpath problem
If the code doesn't show a change of Z,you might have some play in the machine.If it is showing on something as easy to cut as 20lb foam it needs fixing.Additionally I would regard a 70% stepover as a high value for a surfacing operation if a good finish is sought.For a fairly good finish I would be using something like 10%.
Re: expertise needed for toolpath problem
Hi Brant - Its not software or controller. This is a mechanical issue with the machine. Backlash, joint looseness, gantry walking, tramming many mechanical reasons that need to be checked out. Peter
Re: expertise needed for toolpath problem
OK,
Here is the gcode.
I am wondering if there is an antibacklash for the z axis. Or if a contaminant could be between the nut and the ball screw.
It is very precise in its error.
G00 G49 G40.1 G17 G80 G50 G90
G20
(Parallel Finishing)
M6 T4
M03 S18000
G00 G43 H0 Z0.2493
G00
X10.2756 Y-1.0432
G01 Z0.0243 F33.0
Z-0.0007
Y0.1248 F88.0
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X10.0831
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X9.8906
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X9.6981
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X9.5056
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X9.3131
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X9.1206
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X8.9281
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X8.7356
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X8.5431
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X8.3506
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X8.1581
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X7.9656
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X7.7731
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X7.5806
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X7.3881
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X7.1956
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X7.0031
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X6.8106
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X6.6181
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X6.4256
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X6.2331
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X6.0406
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X5.8481
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X5.6556
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X5.4631
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X5.2706
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X5.0781
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X4.8856
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X4.6931
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X4.5006
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X4.3081
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X4.1156
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X3.9231
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X3.7306
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X3.5381
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X3.3456
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X3.1531
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X2.9606
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X2.7681
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X2.5756
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X2.3831
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X2.1906
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X1.9981
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X1.8056
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X1.6131
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X1.4206
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X1.2281
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X1.0356
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X0.8431
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X0.6506
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X0.4581
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X0.2656
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
X0.0731
Y18.5760
Y18.5750 Z-0.1139
Y0.1258
Y0.1248 Z-0.0007
Y-1.0432
X0.0000
Y0.1248
Y0.1257 Z-0.1139
Y18.5750
Y18.5759 Z-0.0007
Y19.7440
Z0.0243 F33.0
G00 Z0.2493
M5 M9
M30
Re: expertise needed for toolpath problem
What are you talking about? Your Z height is alternating between -0.1139 and 0.0007 constantly.
What Cam are you using? Simulation will show you this.
Re: expertise needed for toolpath problem
Yes, that is correct but if you look at the second pic you can see those two heights clearly.
The .007 has a slightly different height in the cut depending on which way the y axis is travelling.
Re: expertise needed for toolpath problem
Quote:
Originally Posted by
Brantcnc
Yes, that is correct but if you look at the second pic you can see those two heights clearly.
The .007 has a slightly different height in the cut depending on which way the y axis is travelling.
Indeed it does. Guess what that causes on the workpiece? The machine seems to be doing exactly what it is told and the question is why the instruction has been generated by the CAM system
Re: expertise needed for toolpath problem
thanks Peter,
I think so too
It's not tramming and not sure what gantry walking is ?
I know there is backlash on the x and y but not sure for z (that could explain it though)
Maybe contaminant in the nut on the ballscrew....
Re: expertise needed for toolpath problem
You seem to have missed the point described in post #6.The program is telling the tool to go from one Z height to another-which it does and the apparent gouging is the result.
Re: expertise needed for toolpath problem
Hi Brant - walking is when one side of the gantry moves ahead of the other side then the other side catches up and then again and again. Its a form of stick slip action. Peter
Re: expertise needed for toolpath problem
do not zig zag the toolpath. instead go with a 1 way feed. the action of going from climb cut to conventional makes the material suck up into the cutter. make sure the cutter is climbing on the 1 way . that should keep the pressure pushing the material away.