Z FeedRate Problems

[ednspace]

I am generating some of my first toolpaths with MadCam. I have problem where by what ever I have set for XY feedrate gets transfered to Z when I post process.

In other words if I set XY feedrate for 50 ipm and Z for 10 ipm when I post process Z moves are at 50 also.

Is this normal???

I am using a taper bit, planer finishing, with a bounding curve. Tool paths look correct, machines fine, except when it does first Z moves, my machine I suspect, misses steps because of speed of move and then the work is hosed.

If I just change F50 to F10 on the first Z move will this work to fix?

What about where it calls both an X and a Z at the same time, like line N8 below? Will the Feed rate be recalled from the first time I used it with Z only as a single move, or would you have to separate out all your Z moves so they stand alone.

Also is there a way to get the post processor to add some free lines, so line numbering goes N10 N20 N30 etc... so you can insert some of your own code.

Thanks for the help,
ED

Top of GCODE program generated by MadCam (I am unsure how to tell Version)
N1 G40 G90 G64
N2 M6 T1
N3 S5000 M3
N4 G43 H1
N5 G0 X0.255 Y0.210
N6 Z0.125
N7 G1 Z0.044 F50
N8 G1 X0.210 Z-0.000 F50

[Dan B]

Hi Ednspace,

Your post is not set up correctly. Take a look for the "feedz" variable. I'm going to guess that it's not there. You probably have "feed" instead. Here is an example of how it should look:

*RAPID_APPROACH*
N"lnbr""x""y""z"F"feedz"
*END_SECTION*

compared to:

*FIRST_CUT*
N"lnbr""x""y""z"F"feed"
*END_SECTION*

With the "feedz" in the approach section, your Z feedrate will be applied there, not throughout the path. If you want to do that, you can experiment by trying the "feedz" variable in place of the regular "feed". Not sure if you're going to get the results you want though.

As for the second part of your question, I've never found a way to change the default line numbering. In WorkNC I number the lines by 2's so it's easy to add a line. However, you can still do it manually by using decimals:

N1 G40 G90 G64
N2 M6 T1
N3 S5000 M3
N4 G43 H1
N5 G0 X0.255 Y0.210
N5.1 X0.265 Y0.220
N5.2 X0.275 Y0.230
N5.3 X0.285 Y0.240
N6 Z0.125
N7 G1 Z0.044 F50
N8 G1 X0.210 Z-0.000 F50

Hope this helps,

Dan

[ednspace]

Thanks Dan for the info on decimal line addition and the ZFeed info.

I ended up restricting the Z axis feedrate through my control software which is EMC. This way I can never exceed axis limiting velocity with Gcode. Probably should have done this to start with

Also, I discovered a tool table file, which I think may have been the real culprit for my problem. There were tools listed as 1, 2, 3, etc... The same numbers that I was using in my tool definition in MadCam.

Its my guess that the EMC control software was grabbing these tool definitions and doing offsets on the tools I had selected in MadCam. Or at least, I suspect. After the changes the part cut correctly, all is well.

I am still a little confused about feedrate, and actual ipm travel of each axis when both are called at the same time. I guess its a straight line?

Like say you start at 0,0,0 and move:
G1 X10 Z1 F50 (Would move the Z axis down slowly as it moves to X)

verses
G1 X1 Z10 F50 (Would move the Z axis down quickly as it moves to X)

For now it works again, thanks for your help
ED