Invert Axis For Opposite Hand Parts

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10 years 2 months ago #79500 by fc60
Invert Axis For Opposite Hand Parts was created by fc60
Greetings,

Many years ago (early 1980"s) when I did my time on the CNC machines, most of the machines had a switch to "Invert" an axis for an opposite hand part, very common in the aerospace business.

Is there such a feature within LinuxCNC?

Cheers,

Dave

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10 years 2 months ago #79503 by Todd Zuercher
Replied by Todd Zuercher on topic Invert Axis For Opposite Hand Parts
No, I don't believe there is any dedicated way to do this (simple G-code). But I think there could be ways you could work around the limitation to get something that might work for what you intend.

IMHO
In this age of CAD/CAM generated code, this sort of feature has become rather obsolete. (Usually easier and safer just to regenerate the code.)

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10 years 2 months ago #79505 by Todd Zuercher
Replied by Todd Zuercher on topic Invert Axis For Opposite Hand Parts
Such as this, if you're a little creative with your G-code you can make a file that can be fipped simply by changing a parameter value like this.
Code:
#1 = -1 (Set #1 = -1 to mirror 1 for normal) #2 = 0.0 (offset for X mirror axis) #3 = 3 o100 if [#1 EQ -1] #3 = 2 o100 endif (1/4" End Mill) G0 X[#1*4.244+#2] Y5.0743 S17300 G0 Z1. G1 Z0.75F100 G1 X[#1*3.8212+#2] Y4.8068 Z0.F200 G1 X[#1*0.8875+#2] Y3.091 G[#3] X[#1*0.8256+#2] Y2.9831 I[#1*0.0631] J-0.1079 G1 Y0.9725 G[#3] X[#1*0.9506+#2] Y0.8475 I[#1*0.125] J0. G1 X[#1*6.818+#2] G[#3] X[#1*6.943+#2] Y0.9725 I[#1*0.] J0.125 G1 Y6.4148 G[#3] X[#1*6.8802+#2] Y6.5232 I[#1*-0.125] J0. G[#3] X[#1*6.7549+#2] Y6.5227 I[#1*-0.0622] J-0.1084 G1 X[#1*3.8212+#2] Y4.8068 G1 X[#1*3.7348+#2] Y4.7563 G1 X[#1*3.2944+#2] Y4.519 Z0.75 G0 Z1. %

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10 years 2 months ago #79506 by eFalegname
Replied by eFalegname on topic Invert Axis For Opposite Hand Parts
Flipping parts is a very normal daily procedure in cabinetmaking, it's a shame that Linuxcnc lacks this feature.

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10 years 2 months ago #79528 by Todd Zuercher
Replied by Todd Zuercher on topic Invert Axis For Opposite Hand Parts
The problem with running code flipped is that it also reverses the milling direction. That can be a big problem with wood, where climb milling might be required to prevent corners from chipping.

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10 years 2 months ago #79557 by fc60
Replied by fc60 on topic Invert Axis For Opposite Hand Parts
Greetings,

Forgot to mention, Boeing had a large assortment of Left Hand cutters. So inverting the axis for the opposite hand part just meant using a left hand cutter and editing the M3 to M4.

Cheers,

Dave

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10 years 2 months ago #79564 by Todd Zuercher
Replied by Todd Zuercher on topic Invert Axis For Opposite Hand Parts
I forgot to mention the above code modification was done to a regular g-code file in 3 find and replace steps using Notepad++ (using regex replace commands). first step modified the X commands to multiply them by #1 and add the offset, 2nd was to multiply the I commands by #1, and 3rd was to make the G2 words variable. It could easily also be done on the fly while opening the file with a script.

I still think it is more trouble than it's worth. We have 7 or 8 machines that do have the capability, to run a mirrored files, and in over 15 years we have never once tried to use it.

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10 years 2 months ago #79612 by cmorley
Replied by cmorley on topic Invert Axis For Opposite Hand Parts
I could really use an inverted axis option on my lathe... it has a tool turret on both sides of the center line.
i would use it everytime the lathe was used.

Chris M

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10 years 2 months ago #79616 by Todd Zuercher
Replied by Todd Zuercher on topic Invert Axis For Opposite Hand Parts
I would think that something useful could possibly be done with some careful Hal trickery and some custom M-codes, But I'd have to think about it a while to iron out the details. I wonder if the problem has already been solved by someone. Some time searching the archives may prove fruitful.

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10 years 2 months ago #79620 by tommylight
Replied by tommylight on topic Invert Axis For Opposite Hand Parts
Just thinking out loud here,
What if .......a pyvcp button with the added python script that would get the values from gcode ( outer most values ), invert them adding "-" and then offseting all that for the values it got from gcode, so everything falls in place ????
I wonder...... but i do not have the time nor did i do actual programming in a long while.

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