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View Full Version : Output arcs using R not I,J?



LongRat
06-19-2007, 03:05 PM
I'm having some problems cutting G2/G3 arcs on my rotary axis. Basically I am using Sheetcam to generate standard X,Y plane G-code, then using a text editor to replace all the Ys with As to use my A axis. Works fine until I,J arc centre words come up, then the REAL Y axis starts to move and not my A. I figured if I used the "G2 R..." notation this problem would go away - is there a setting that I can change to effect this, or does it require a different post? Currently I use the standard Mach2 post with no other problems.

Thanks

locost_cam
06-20-2007, 03:47 AM
Mach cannot handle X-A arcs. Arcs have to be on the X-Y, X-Z or Y-Z planes.
To get around this you need to break the arcs into lots of short line segments. Go to c:\program files\sheetcam\posts. Make a copy of the post then edit the copy with a text editor. Look for

function arc()

Delete the whole function and replace it with this one:

function arc()
arcasmoves(0.1)
end

If the line segments are too long, reduce the number. While you are digging into the post, look at function rapid() and function move(). In both functions, change " Y" to " A".

In SheetCam, load the modified post and away you go, no more editing the G-code.

Les

LongRat
06-20-2007, 01:35 PM
Les, many thanks. Makes my life much easier.

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