Who knows Python (FreeCAD PostProcessor)
17 Nov 2023 00:59 #285675
by blazini36
Who knows Python (FreeCAD PostProcessor) was created by blazini36
FreeCAD has experimental 4th axis support but it's basically hidden. Since it's really the only CAM game in town for Linux I tried it, the previewed toolpath looks pretty good but the rotary (A) axis output is bad.
I realised if I output in millimeters, the A axis output is fine, it looks like degrees. My machine is setup in inches so when I output the inches gcode the A axis output is basically divided by 25.4. So I need to get this postprocessor script to ignore the A axis when it's converting to inches. I'm not a Python guy so I'm looking for help here.
I realised if I output in millimeters, the A axis output is fine, it looks like degrees. My machine is setup in inches so when I output the inches gcode the A axis output is basically divided by 25.4. So I need to get this postprocessor script to ignore the A axis when it's converting to inches. I'm not a Python guy so I'm looking for help here.
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17 Nov 2023 08:04 #285707
by Aciera
Replied by Aciera on topic Who knows Python (FreeCAD PostProcessor)
I'm not a python expert either but I don't see anything that looks like unit conversion in that script.So I need to get this postprocessor script to ignore the A axis when it's converting to inches.
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17 Nov 2023 09:26 #285712
by blazini36
Replied by blazini36 on topic Who knows Python (FreeCAD PostProcessor)
AFAICT your right, looks like it's passing the inch argument back to Freecad and it's doing the conversion. I figured maybe something could be passed to tell it not to convert the rotary axis, or at the very least multiply the rotary outputs by 25.4 to convert it back to degrees.
So I need to get this postprocessor script to ignore the A axis when it's converting to inches.
I'm not a python expert either but I don't see anything that looks like unit conversion in that script.
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17 Nov 2023 09:55 #285714
by tommylight
Replied by tommylight on topic Who knows Python (FreeCAD PostProcessor)
There is also BlenderCAM, single word, but i have no idea what it does.
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17 Nov 2023 10:06 #285717
by Aciera
Replied by Aciera on topic Who knows Python (FreeCAD PostProcessor)
Actually I think I was wrong, looking at this again I think I may have found the conversion part after all:
When processing the 'A' word then 'param' would be equal to 'A' and 'pos' would be the angle value (wrongly getting divided by 25.4) so may be you could add an if statement that would multiply the pos value by 25.4 IF param == 'A'.
pos = Units.Quantity(
c.Parameters[param], FreeCAD.Units.Length
)
outstring.append(
param
+ format(
float(pos.getValueAs(UNIT_FORMAT)), precision_string
)
)When processing the 'A' word then 'param' would be equal to 'A' and 'pos' would be the angle value (wrongly getting divided by 25.4) so may be you could add an if statement that would multiply the pos value by 25.4 IF param == 'A'.
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17 Nov 2023 10:13 #285719
by Aciera
Replied by Aciera on topic Who knows Python (FreeCAD PostProcessor)
Maybe something like this as hack and slash attempt:
pos = Units.Quantity(
c.Parameters[param], FreeCAD.Units.Length
)
if param == 'A':
pos = pos * 25.4
outstring.append(
param
+ format(
float(pos.getValueAs(UNIT_FORMAT)), precision_string
)
)
The following user(s) said Thank You: blazini36
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17 Nov 2023 18:09 - 17 Nov 2023 19:14 #285763
by blazini36
Replied by blazini36 on topic Who knows Python (FreeCAD PostProcessor)
Hey that actually works, that's great man thanks. Since I use inches it works out but I tested it without the --inches flag and it still multiplies by 25.4 so if using mm this one would have the opposite problem.
Is it possible to have that if statement consider the --inches parser argument?
Didn't mention it in the first post but the A-axis Gcode FreeCAD was outputting also ran -180 to 180. I don't know if that's normal or if LinuxCNC can be configured to use that setup. Mine is setup as "wrapped rotary" and it will travel infinite degrees in either direction. The code it was originally outputting looked like it would travel halfway around the part and then travel back in the other direction on my setup. One of the guys on the FreeCAD forum fixed that in the PP script so it now outputs 0-360 then returns to 0 for the next pass, it looks more convincing now.
So this is the current script with Aciera's changes as well as what bmsaus4ax on the FreeCAD forum did.
Is it possible to have that if statement consider the --inches parser argument?
Didn't mention it in the first post but the A-axis Gcode FreeCAD was outputting also ran -180 to 180. I don't know if that's normal or if LinuxCNC can be configured to use that setup. Mine is setup as "wrapped rotary" and it will travel infinite degrees in either direction. The code it was originally outputting looked like it would travel halfway around the part and then travel back in the other direction on my setup. One of the guys on the FreeCAD forum fixed that in the PP script so it now outputs 0-360 then returns to 0 for the next pass, it looks more convincing now.
So this is the current script with Aciera's changes as well as what bmsaus4ax on the FreeCAD forum did.
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Last edit: 17 Nov 2023 19:14 by blazini36.
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17 Nov 2023 19:25 #285768
by Aciera
Replied by Aciera on topic Who knows Python (FreeCAD PostProcessor)
Sure try this:
else:
pos = Units.Quantity(
c.Parameters[param], FreeCAD.Units.Length
)
if param == 'A' and UNITS == 'G20':
pos = pos * 25.4
outstring.append(
param
+ format(
float(pos.getValueAs(UNIT_FORMAT)), precision_string
)
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17 Nov 2023 21:26 #285781
by blazini36
Replied by blazini36 on topic Who knows Python (FreeCAD PostProcessor)
Hey much obliged,
That seems to do the trick for mm and inches. I think I can run this output after I manually fix the feedrate.
Gonna post this on the freecad forum as well since it might be helpful.
That seems to do the trick for mm and inches. I think I can run this output after I manually fix the feedrate.
Gonna post this on the freecad forum as well since it might be helpful.
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