Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: sadistic on April 03, 2010, 10:28:20 PM

Ok we finally got our post processor correct and now our problem is setting the axis home refrences. We can run a picture but when the z axis moves it wants to either run to high on its position or run into the metal. Please help we are so close to running but have stumbled on this step.
Thanks

have you set the motor tunning for the Z axis?

Yes, we have set it to the manuals numbers from CandCNC configurations.

do you have a Z home limit switch? Are the units in/mm per turn set right

Yes and Yes. We had our limit switch wired to the down/down connectors in our board. We have switched them to the z home connectors and now we are getting a touch and go feature but it is raising up two inchs and starts cutting. Our pierce height is set at .19 in. Any thoughts and thanks a lot for all the help.

what Gcode are you using for home? G28 Z 0 or G28.1 Z 0 with zero set?

then what is the Gcode for 1st Z move

Ok we are using g28.1 and here is our gcode we just cut out.
N0000 (Filename: RE7 upper bag mount.tap)
N0010 (Post processor: MP1000THC.scpost)
N0020 (Date: 03/04/2010)
N0030 G20 (Units: Inches)
N0040 G53 G90 G40
N0050 F1
N0060 (Part: RE7 upper bag mount)
N0070 (Process: Plasma, Outside Offset, 0, T1: Plasma, 0.0394 in kerf)
N0080 M06 T1 F85 (Plasma, 0.0394 in kerf)
N0090 G00 Z0.1100
N0100 Z0.2097
N0110 X2.1023 Y2.4970
N0120 Z0.1900
N0130 G28.1 Z0.12
N0140 G92 Z0.0
N0150 G00 Z0.0520
N0160 G92 Z0.0
N0170 G00 Z0.1880
N0180 M03
N0190 G04 P2
N0200 G03 X2.2303 Y2.6250 I0.0000 J0.1280 F85.0
N0210 X1.6250 Y3.2303 I0.6053 J0.0000
N0220 X1.0197 Y2.6250 I0.0000 J0.6053
N0230 X1.6250 Y2.0197 I0.6053 J0.0000
N0240 X2.2303 Y2.6250 I0.0000 J0.6053
N0250 X2.1023 Y2.7530 I0.1280 J0.0000
N0260 G01 Z0.1100 F0.394
N0270 M05
N0280 G04 P1
N0290 G00 Z0.2097
N0300 X2.6953 Y3.8720
N0310 Z0.1900
N0320 G28.1 Z0.12
N0330 G92 Z0.0
N0340 G00 Z0.0520
N0350 G92 Z0.0
N0360 G00 Z0.1880
N0370 M03
N0380 G04 P2
N0390 G03 X2.8233 Y4.0000 I0.0000 J0.1280 F85.0
N0400 X2.6250 Y4.1983 I0.1983 J0.0000
N0410 X2.4267 Y4.0000 I0.0000 J0.1983
N0420 X2.6250 Y3.8017 I0.1983 J0.0000
N0430 X2.8233 Y4.0000 I0.0000 J0.1983
N0440 X2.6953 Y4.1280 I0.1280 J0.0000
N0450 G01 Z0.1100 F0.394
N0460 M05
N0470 G04 P1
N0480 G00 Z0.2097
N0490 Y1.1220
N0500 Z0.1900
N0510 G28.1 Z0.12
N0520 G92 Z0.0
N0530 G00 Z0.0520
N0540 G92 Z0.0
N0550 G00 Z0.1880
N0560 M03
N0570 G04 P2
N0580 G03 X2.8233 Y1.2500 I0.0000 J0.1280 F85.0
N0590 X2.6250 Y1.4483 I0.1983 J0.0000
N0600 X2.4267 Y1.2500 I0.0000 J0.1983
N0610 X2.6250 Y1.0517 I0.1983 J0.0000
N0620 X2.8233 Y1.2500 I0.0000 J0.1983
N0630 X2.6953 Y1.3780 I0.1280 J0.0000
N0640 G01 Z0.1100 F0.394
N0650 M05
N0660 G04 P1
N0670 G00 Z0.2097
N0680 X5.3977 Y2.7530
N0690 Z0.1900
N0700 G28.1 Z0.12
N0710 G92 Z0.0
N0720 G00 Z0.0520
N0730 G92 Z0.0
N0740 G00 Z0.1880
N0750 M03
N0760 G04 P2
N0770 G03 X5.2697 Y2.6250 I0.0000 J0.1280 F85.0
N0780 G02 X2.6250 Y0.0197 I2.6447 J0.0000
N0790 X0.0197 Y2.6250 I0.0000 J2.6447
N0800 X2.6250 Y5.2697 I2.6447 J0.0000
N0810 X5.2697 Y2.6250 I0.0000 J2.6447
N0820 G03 X5.3977 Y2.4970 I0.1280 J0.0000
N0830 G01 Z0.1100 F0.394
N0840 G00
N0850 X0.0000 Y0.0000
N0860 M05 M30
Newbie to all this.
Again thank you for the help.

I think a G28.1 needs tobe 0.000 because G28.1 means to find HOME 0.000 anything else, Z will HUNT for 0. On my cnc using Mach3 I know that for a fact

..
N0040 G53 G90 G40
N0050 F1
N0060 (Part: RE7 upper bag mount)
N0070 (Process: Plasma, Outside Offset, 0, T1: Plasma, 0.0394 in kerf)
N0080 M06 T1 F85 (Plasma, 0.0394 in kerf)
N0090 G00 Z0.1100
..
N0130 G28.1 Z0.12
..
As far as I know, G53 needs to be on each line where it applies. On line N0040 there is no move, therefore it does nothing and is forgotten. On line N0090 it needs to be G53 G00 Z0.11 when you want absolute Z0.11. But line N00130 should go before it, to do referencing (i.e. seek and set home position), before you do any first move. In order move to known home in Z, would read N0130 G28 G53 Z0, for example, not G28.1.
line N0090 G0 Z0.11 could go to anywhere when the machine coords are not set. Additionally, N0081 G43 H1 is missing to apply tool offset coordinates. M6 doesn't do this. Missing G43 H1 too makes the Z move hazard. (Your post processor might not know about G43 Hn)

I'm a newb also so bear with me. When you "ref home" on z doe it ref home properly and zero out? Did you set your "switch offset" in your Sheetcam post to the proper height?
Just my 2 cents worth.
Mike

Depends on whom you ask..
Yes our Mach3 does home properly when we press the "Ref All Home" button, and it will set the machine coords to "0" properly. We did the required correct setups in Mach3's config>Ports And Pins and config>Homing/Limits. And our mill delivers referencing signals (actually limit switch signals). I can go with you thru the details. I can't help you with Sheetcam.