I'm having an issue with circles. I've attached the example files. It seems that the more segments I use on the circle, the squarer it gets?? In SketchUp, the circles look better as the segments increase. Which is what is expected. But, when the gcode is created and viewed in Mach3, you can see that higher segment count results in square circles. Now, these are relatively small circles (.375 diameter). I'm cutting holes in 1/8" plywood where ball bearings will be inserted. I cut initial samples out of 1/8" foam for testing and the higher segment count circles are rounded squares. What am I missing/doing wrong?




Attached files CircleTest.cnc (15 KB)Â CircleTest.skp (200.5 KB)Â

 

Does anyone have a comment on this? Or is this just something strange going on in Iowa?

 

I've not had a chance to look at it myself, I'll try later on tonight, however I'm not sure I'll be much help.

 

Looks like definitely something strange going on. And I got no answer, as to why, but easy to fix. 1st you don't need that many segments. With a hole that small, you figure 48 should do you. But you say I want a perfect hole. Well, I advocate using arcs, anyways. That means don't explode or phlatten them. Check out this video:
viewtopic.php?f=98&t=1732#p16956
If you preserve your arcs, then the gcode will actually draw arcs instead of line segments. I've made a new 500 segments circle for you and also a circle with only 6 segments. For some reason inside cuts, need more arc segments than the outside cuts you see in my video. So I would suggest min of 6-12 segments for inside cuts.







Attached files CircleTest_modified.cnc (31 KB)Â CircleTest_modified.skp (244 KB)Â

 

kyyu, thanks for the input. It seems you're saying that for an inside cut, fewer segments are better. You mentioned don't explode or phlatten the circle. If I don't phlatten the circle, it produces the "sewing machine" type gcode. Well, that seems to have been fixed somewhere along the line. I see that it no longer reacts that way. What do you mean by don't explode? Does that mean that after you group the object prior to producing gcode, you can't explode it without changing something relating to the circle? Thanks again for your input.

 

If you select the circle, right click on it, and select explode curve, it will turn it into line segments. You can explode a group without affecting the arc/circle segments.

Tim

 

Yes, what navionflyer said. Don't right click and explode the curve itself. I checked the command and it actually saids "Explode Curve". It's fine to explode a group. And likewise, do no use phlatten on an arc/circle. I think it redraws everything, but now you just have line segments and not longer an "arc". Even though it looks the same. If you right click it and click "Entity Info", skechup will tell you what it is. For example, an edge (aka line segment), arc, circle, curve, etc... If arc or circle, the phlatscript/gcocde will draw it as a true arc; not the way you see it in skechup, which is represented by line segments. So basically, protect those arcs and you don't need the high segment count to get perfect circles.

I don't know what to tell you about the it doesn't work if you don't phlatten it thing. I went through those phases also. 1st I thought everything needed to be welded and then next I thought everything needed to be phlatten. But I don't think that, anymore. If phlatten or weld fixes it, then it's probably something else that you did, that really fixed it. I mean phlatten could actually fix something, but it's unlikely that you can draw something not flat, especially if it so simple. I seriously doubt that even if I drew something extremely complicated, any of it could be not flat. I almost never use it, anymore.

-Kwok

 

Did you mirror any of the circles? If so, the "sewing machine" issue might be a result of a reversed face. Check out this thread http://www.phlatforum.com/viewtopic.php?f=100&t=1863&p=18337#p18337 for details. Kwok has a very informative little video in there.

Tim