[AmplifiedLight]

Hi all,
I'm using a 4.25" long 3/8" end mill for clearing thick stock. At the beginning of the job when the rapid movement to the start position happens, the z drops down below stock 0 and cuts it's way to the start point. At the end of the job it does the same when it returns to home. I fixed the issue at the beginning by adding a G1 Z0.5 command before the move to the starting point, but at the end of the job, adding the same command before the move to home doesn't work and the tool moves down below 0 and cuts it's way home. I'm using a Chinese 3 axis 1325 cnc router with Xulifeng Mach3 motion control card, Mach3 on Windows 10, generating toolpaths in Fusion 360. This is the only tool that I have this problem with. I'm milling 3" foam and I set z0 using the paper method since the probe won't fit under the tool. About 3" from collet to end of tool. It's dropping down about .8" below stock 0. Does this have something to do with tool offset compensation? Does Mach3 have a limit to how long a tool it can compensate for? It runs the rest of the program fine with appropriate retract and clearance heights. Anyone have any ideas?

End of program:
X16.6695 Y23.3403 Z-0.4923
X16.669 Y23.3397 Z-0.4878
X16.6688 Y23.3395 Z-0.4833
Z0.6

G28 G91
G90
G1 Z0.5
G28 G91 X0. Y0.
G90
M30

[dazp1976]

Hi all,
I'm using a 4.25" long 3/8" end mill for clearing thick stock. At the beginning of the job when the rapid movement to the start position happens, the z drops down below stock 0 and cuts it's way to the start point. At the end of the job it does the same when it returns to home. I fixed the issue at the beginning by adding a G1 Z0.5 command before the move to the starting point, but at the end of the job, adding the same command before the move to home doesn't work and the tool moves down below 0 and cuts it's way home. I'm using a Chinese 3 axis 1325 cnc router with Xulifeng Mach3 motion control card, Mach3 on Windows 10, generating toolpaths in Fusion 360. This is the only tool that I have this problem with. I'm milling 3" foam and I set z0 using the paper method since the probe won't fit under the tool. About 3" from collet to end of tool. It's dropping down about .8" below stock 0. Does this have something to do with tool offset compensation? Does Mach3 have a limit to how long a tool it can compensate for? It runs the rest of the program fine with appropriate retract and clearance heights. Anyone have any ideas?

End of program:
X16.6695 Y23.3403 Z-0.4923
X16.669 Y23.3397 Z-0.4878
X16.6688 Y23.3395 Z-0.4833
Z0.6

G28 G91
G90
G1 Z0.5
G28 G91 X0. Y0.
G90
M30

Your issue could be the G28
That tells the machine to go to its MACHINE coordinate home position. This is completely different to your WORK coordinate 0 position.
If this had not been set properly (or at all) it will go to wherever it thinks it is.

[AmplifiedLight]

Your issue could be the G28
That tells the machine to go to its MACHINE coordinate home position. This is completely different to your WORK coordinate 0 position.
If this had not been set properly (or at all) it will go to wherever it thinks it is.

The machine coordinates have been set correctly. I guess that could be it, but I wonder why this issue doesn't show with any other tool. Every other tool goes to safe retract height before travelling.

[CNCRim]

Hi all,
I'm using a 4.25" long 3/8" end mill for clearing thick stock. At the beginning of the job when the rapid movement to the start position happens, the z drops down below stock 0 and cuts it's way to the start point. At the end of the job it does the same when it returns to home. I fixed the issue at the beginning by adding a G1 Z0.5 command before the move to the starting point, but at the end of the job, adding the same command before the move to home doesn't work and the tool moves down below 0 and cuts it's way home. I'm using a Chinese 3 axis 1325 cnc router with Xulifeng Mach3 motion control card, Mach3 on Windows 10, generating toolpaths in Fusion 360. This is the only tool that I have this problem with. I'm milling 3" foam and I set z0 using the paper method since the probe won't fit under the tool. About 3" from collet to end of tool. It's dropping down about .8" below stock 0. Does this have something to do with tool offset compensation? Does Mach3 have a limit to how long a tool it can compensate for? It runs the rest of the program fine with appropriate retract and clearance heights. Anyone have any ideas?

End of program:
X16.6695 Y23.3403 Z-0.4923
X16.669 Y23.3397 Z-0.4878
X16.6688 Y23.3395 Z-0.4833
Z0.6

G28 G91 <<<<< G28G91Z0
G90 <<<Remove this
G1 Z0.5 <<<Remove this
G28 G91 X0. Y0. <<<<<< X0 Y0
G90 <<<Remove this
M30

Switch back and forth with the absolute and increment mode, in this case is unnecessary. I like to kept program in absolute so at the begin of the problem, the safe line is G20G17G90G80G40 to cancel pretty much everything out.

- - - Updated - - -

Hi all,
I'm using a 4.25" long 3/8" end mill for clearing thick stock. At the beginning of the job when the rapid movement to the start position happens, the z drops down below stock 0 and cuts it's way to the start point. At the end of the job it does the same when it returns to home. I fixed the issue at the beginning by adding a G1 Z0.5 command before the move to the starting point, but at the end of the job, adding the same command before the move to home doesn't work and the tool moves down below 0 and cuts it's way home. I'm using a Chinese 3 axis 1325 cnc router with Xulifeng Mach3 motion control card, Mach3 on Windows 10, generating toolpaths in Fusion 360. This is the only tool that I have this problem with. I'm milling 3" foam and I set z0 using the paper method since the probe won't fit under the tool. About 3" from collet to end of tool. It's dropping down about .8" below stock 0. Does this have something to do with tool offset compensation? Does Mach3 have a limit to how long a tool it can compensate for? It runs the rest of the program fine with appropriate retract and clearance heights. Anyone have any ideas?

End of program:
X16.6695 Y23.3403 Z-0.4923
X16.669 Y23.3397 Z-0.4878
X16.6688 Y23.3395 Z-0.4833
Z0.6

G28 G91 <<<<< G28G91Z0
G90 <<<Remove this
G1 Z0.5 <<<Remove this
G28 G91 X0. Y0. <<<<<< X0 Y0
G90 <<<Remove this
M30

Switch back and forth with the absolute and increment mode, in this case is unnecessary. I like to kept program in absolute so at the begin of the problem, the safe line is G20G17G90G80G40 to cancel pretty much everything out.

[machinehop5]

...sub-programs in inc---to rinse and repeat...tictactoe and thx moe and joe

[mactec54]

Hi all,
I'm using a 4.25" long 3/8" end mill for clearing thick stock. At the beginning of the job when the rapid movement to the start position happens, the z drops down below stock 0 and cuts it's way to the start point. At the end of the job it does the same when it returns to home. I fixed the issue at the beginning by adding a G1 Z0.5 command before the move to the starting point, but at the end of the job, adding the same command before the move to home doesn't work and the tool moves down below 0 and cuts it's way home. I'm using a Chinese 3 axis 1325 cnc router with Xulifeng Mach3 motion control card, Mach3 on Windows 10, generating toolpaths in Fusion 360. This is the only tool that I have this problem with. I'm milling 3" foam and I set z0 using the paper method since the probe won't fit under the tool. About 3" from collet to end of tool. It's dropping down about .8" below stock 0. Does this have something to do with tool offset compensation? Does Mach3 have a limit to how long a tool it can compensate for? It runs the rest of the program fine with appropriate retract and clearance heights. Anyone have any ideas?

End of program:
X16.6695 Y23.3403 Z-0.4923
X16.669 Y23.3397 Z-0.4878
X16.6688 Y23.3395 Z-0.4833
Z0.6

G28 G91
G90
G1 Z0.5
G28 G91 X0. Y0.
G90
M30

In your program you move the Z0.6 and then you move it down to Z0.5 the whole end of the program is kind of messed up

End of program:
Z0.6

G28 G91
G90
G1 Z0.5
G28 G91 X0. Y0.
G90
M30

Check what settings you have for the G28 in Mach3 this is in the Config Tab under Homing / Limits these G28 positions can be set to where you want the machine to go if they are 0.0 then they have not been activated, if this is setup you just need to use a G28 by itself and the machine will move to whatever you have set in the G28 Boxes

You can test this out in MDI with just using G28

G28 is not ideal to use in a program so try this below

This is all you need at the end of your program
G0Z.6 The last Z move this can be any number you need to park to clear your work or do a Tool Change
G53X0Y0.
M30

[AmplifiedLight]

Thanks, the code is generated by Fusion 360's mach3 post processor. I'll give your suggestion a try. But I still don't know why this is an issue in the first place since it's only with this tool. Is there a length limit that Mach3 can handle?

In your program you move the Z0.6 and then you move it down to Z0.5 the whole end of the program is kind of messed up

End of program:
Z0.6

G28 G91
G90
G1 Z0.5
G28 G91 X0. Y0.
G90
M30

Check what settings you have for the G28 in Mach3 this is in the Config Tab under Homing / Limits these G28 positions can be set to where you want the machine to go if they are 0.0 then they have not been activated, if this is setup you just need to use a G28 by itself and the machine will move to whatever you have set in the G28 Boxes

You can test this out in MDI with just using G28

G28 is not ideal to use in a program so try this below

This is all you need at the end of your program
G0Z.6 The last Z move this can be any number you need to park to clear your work or do a Tool Change
G53X0Y0.
M30