Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Pegasus on November 10, 2006, 11:38:59 AM
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HI everyone,
I am in the process of surfacing my table on my 3DRouters.com 4x8 gantry CNC machine. I went into the Rectangular pocket wizard and gave it the dimensions of the travel limits and to mill down to a depth of .01" (delta of high and low points on the table).
My question is this: It mills along just fine from the inside-out but on two corners it seems to "get ahead of itself" and runs a diagonal from say, the long travel from the X axis to the Y travel when approaching the corners. This only happens on two corners and they are opposite of each other.
It is almost like it doesn't complete the run down the X axis before it wants to run up the Y axis (as an example). Here is a crude ascii art of what I'm talking about:
/------------------------------------------------------------------|
| |
| |
| |
| |
-------------------------------------------------------------------/
(Where the "/" are the corners being missed).
I wonder if there is something in setup (ramping?) that is set to fast?
Any and all suggestions would be appreciated
New to Mach 2 in Houston ::)
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Is it just at the last (outside) corners or does i happen on each pass as it moves out?
Have you checked for backlash or loosness in your y axis?
Hood
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Hood,
Thanks for the help. It happens on each pass as it goes out, always on the same corners. I don't have any slop in any of the axis and the other two corners cut just fine.
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What does your code look like for the corners, is it a G2 or G3? It is just that it looks like backlash on one axis and backlash would only affect two of the corners.
What kind of size is this diagonal? Have you tried cutting a circle to see if it comes out round or squint?
Hood
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Hi Pegasus,
I don't see why It would only do it on 2 corners but with high feed speeds, CV mode and settings can cause this. Does it do it in Exact Stop Mode?
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It happens when transitioning during G1 mode from a long cut down the X axis to an immediate Y cut, i.e;
G1X0Y0
G1X10
G1Y10 (arc happens during this transition)
Looking at it closer I wouldn't call it an actual slant or diagonal, It is more like a smooth arc to join the Y axis intended direction. X never fully gets to G1X10 before it begins the curve to join the Y axis.
Thanks again for your help
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Have you tried it in exact stop mode. Allso, g 61 is Exact Stop And g 64 is CV.
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Let me give that a shot and see what happens.
Thanks!