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Offline BR549

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Re: cutter comp
« Reply #10 on: October 19, 2011, 09:28:22 PM »
it IS not ILLEGAL AS IS. Unless that was changed, just not the best idea. Art had it working well in most respects. The real problems are deep in subs where it gets totally lost .

People also don't understand it is not an auto function it has to be planned for and sooner or later the comp has to be unwound from the process OR it mysteriously shows up elsewhere when you are not looking (;-).

Years ago I beat the dog snot out of the COMP testing it in ways I would NEVER even program it just because someone might(;-).

The last series of comp code I tested was really nice. Don't know if it made it to the  M3 versions or was held for Mv4.

If you have an example of the comp code  switching sides I would love to see it. It would make a good test sample for future testing.

(;-) TP

Offline simpson36

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Re: cutter comp
« Reply #11 on: October 20, 2011, 02:58:11 AM »
If you have an example of the comp code  switching sides I would love to see it. It would make a good test sample for future testing.

I ran these on my office computer which just got updated to XX.50 yesterday and it looks like there have been some fingers in the cookie jar. Comp is even more bizarre now! Now it is switching sides even on connected arcs. This example shows how MACH inserts tiny arcs . .  a bonus. Another new behavior is that there is no separation between the original and comp toolpaths, Note the tool diameter and also note the scales. First screen shot is with both axis at -1 scale. Second screen shot only one  axis at -1 . . BOOM!   That is opposite of what it was doing in the earlier version in the shop. The behavior in the earlier version is also different in that the comp arc started on one side and endied on the other side of one of the long arcs that make up the sides of this part. If I changed the scale from -1 to -.999, it still switched sides, but at a different location on the tool path where I could live with it, so I did that and got the parts cut. As I siad, I do not use comp much at all, but typically, I find that comp seems to work OK on simple unscaled toolpaths, especially closed paths, but if you go 'outside the box' . . . it can get  ugly.

I cannot release the G-code on this part. If this occurs on releasable code, I will be happy to provide the code. I understand it is difficult to debug without a repeatable example, sorry. I just came in to add some new video links to my 'mini machining center' thread and thought I'd poke around a bit and see if I could be useful, however I am unsubsribing now. I hope my comments were helpfull, but just do not have time to participate in-depth on forums.  :(

« Last Edit: October 20, 2011, 03:14:07 AM by simpson36 »

Offline ger21

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Re: cutter comp
« Reply #12 on: October 20, 2011, 07:13:01 AM »
Without seeing the code, it's impossible to say what's going on, but here's a few things.

1) Setting the scale to -1 doesn't work properly in all version of Mach3 even without comp. Only in the last year has this been fixed to work without comp.

2) From the looks of your toolpath, I'd say that you have duplicate lines of code at your transition points, or very, very small segments at those points that are messing up the comp. I saw this the other day, and it was due to bad g-code, and not comp's fault.
Gerry

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