Tool trajectory doesn't match contour selected

[Anonymous]

Hello everybody, When I try to do a 2D contour on a piece I design, I got an issue with the trajectory of the tool, it doesn't match the contour selected, its very disturbing... see the attachement Does anyone have an advice ? thanks !

[Steinwerks]

There's no attachment.

Without seeing anything, are you used to using In Control cutter compensation?

[Lambodesigns]

I'm having the same issue.  It is a simple part that I'm cutting out of cardboard for a "Cardboard Classic" as part of our end of season here at the mountain. Craft can only be made of cardboard and duct tape so it is nothing complex.  I'm just learning 360 and we do this for a group of 5th graders as a full blown engineering project so I combined the two together so we could all learn something.  This part is part of the neck of a coke bottle and the inside radius is off by a lot.  I saved the piece off as a solo part and repeated the CAM and followed the contour exactly as expected.  Not sure if my work flow caused a problem (just learning 360 so there is a lot of undo involved) or something else but it seems to be the same problem the OP is talking about so probably not an isolated case.  

BTW.... I didn't really notice the toolpath being off until I read this.  My real issue that I was trying to find an answer to was that the tool path was very jerky as it hit all the points along the curve.  I've played with tolerances and made it better but not exactly smooth.  Setup is running Mach3 (mach3 post processor) with gecko 540 driving nema 23 motors and CV on and all options off.  Other parts seem to cut very smooth but not this one:(

I've tried to add a screencast that shows the issue.  Still new at all of this so hopefully it works.  Gotta say 360 has been nothing but impressive so far. 

[Lambodesigns]

Second try:( 

[Steinwerks]

@Lambodesigns : Was this an imported part or designed in Fusion? There was a thread not too long ago regarding a very similar issue where the part was designed in Rhino.

That said, is your part selected in the CAM Setup?

[Lambodesigns]

100% fusion designed.  No other sw involved. I made the part by using some conic curves and then an offset to get the width.  The slots were just lines on the sketch and it followed that contour with no problem.  It is the one that was created with the offset that is the issue if that helps?  

Not sure exactly what you mean by "part selected in cam setup" but I did define the axis, size, etc. for the part in the setup so I think the answer is yes.  .For each different part there is a separate setup.  Not sure if that is the right way to do it but other than the one tool path being off it seemed to work and I got all the other parts cut out yesterday.   Same way I did it for the solo part that looks to work just fine. 

Here's the link to see what the other parts look like.

http://a360.co/1RyIAGm 

[Lambodesigns]

Sorry.. I've saved the file since that link was created so it doesn't show what I wanted it to... I'll have to wait to change it since I just got a load of lumber to unload and it just started to snow.  Probably be a couple of hours.  

[Lambodesigns]

Link should show the full skeleton of the bottle now.  

[Lambodesigns]

Well it looks like there are 2 parts doing something similar.  I copied this one over to be a separate part but this time it didn't fix the problem.  My construction path was create a circle, put a conic curve on it for a cutout and then duplicated it around the edge of the circle.  From there I did an extrusion at an angle to look kinda like a bottle cap.  From there it was just trying to do a 2d contour to cut it out.  The original conic curve was not duplicated and was cut a lot deeper.  The other pattern curves cut perfectly.

[Anonymous]

Hello , sorry here is the capture of my issue which seems the same as lambodesign The part is 100% from fusion too

[Anonymous]

can't manage to attach my png image to the message ....

[Lambodesigns]

A little more info from what I found this afternoon.  I was going to cut another of the ribs and the tool path was so far off the part was almost cut in two (almost 4" wide) so this was a huge error.  Since I had a gaggle of 5th graders coming I had to go with plan B and exported the DXF of the sketch so I could use sheetcam.  Well.... the DXF matched the toolpath so I had to use Corel to correct the DXF and cut the part.  So to me that points to the CAD portion of this equation because 360 CAM wasn't involved in the generation of the DXF.  Looks like the CAM is just following the sketch pattern which doesn't match what the sketch looks like if that makes any sense and if I was bet'n on something I would say there is an error somewhere in the conic curve portion since everything else seems to be spot on.  Either that or I'm doing something wrong which is entirely possible.  The 5th graders are gone so I'll do some more looking to see if I can figure anything out.  

[Lambodesigns]

Looks like the conic curve is causing the issues with the CAM for me.  Did some sample shapes using conic curves, splines, arcs, etc and they all seemed to work fine except the conic.  The bigger the conic curve the more prononced the deviation from the contour.  Redrew the part that was so far off using splines instead and it worked great.  Curious to see if this is the same issue for @Anonymous. 

Only did one sample on the cnc cutting air but it looks like the spline removed the jerky motion too.  Not really enough testing to say for sure but I'll be looking into it some more.  Not sure how much snow the mountain got today but I'm guessing the arcs I'll be making tomorrow will be on the slopes:)  

[Anonymous]

Well I tried a new form with conic and curve and indeed the trajectory goes banana when i try CEM

[Anonymous]

Any one got an answer to that ?

[HughesTooling]

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@Lambodesigns wrote:

BTW.... I didn't really notice the toolpath being off until I read this.  My real issue that I was trying to find an answer to was that the tool path was very jerky as it hit all the points along the curve.  I've played with tolerances and made it better but not exactly smooth.  Setup is running Mach3 (mach3 post processor) with gecko 540 driving nema 23 motors and CV on and all options off.  Other parts seem to cut very smooth but not this one:(

I've tried to add a screencast that shows the issue.  Still new at all of this so hopefully it works.  Gotta say 360 has been nothing but impressive so far. 

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I've seen this problem a few times with 2d ops and it's been down to the 2d op trying to add corner rounding on external\convex curves. See this post. You will find using a 3d op like contour with smoothing enabled will give a far better tool path.

Mark

[Lambodesigns]

Dang.... that link is going to take way more time to digest than I have time for today. Good stuff though and I'll have to spend some time with it. Thanks.