Design issue

[Anonymous]

Just getting started in cad and cam software. Fusion 360 seems to be great! I am in the process of designing a simple picture frame and unfortunately in the model format some foreign object keeps popping up out of no where. when I try to draw out something. I've tried redrawing the same thing multiple times and it keeps happening in the same area and I can't understand why. When I go to cad and try to create a tool path this obstruction prevents things from being carved out like I hope. I would be very thankful if someone could explain to me what I am doing wrong and how to correct it.

[jeff_strater]

@Anonymous,

This could be just a graphics glitch, and not a geometry problem at all.  Can you share your design here so we can take a look?

Thanks,

Jeff

[Anonymous]

Thank you Jeff. I may have neglected to mention that I am also new to posting things on forums. How do I share this design with you? 

[Anonymous]

http://a360.co/2AXFuez

[jeff_strater]

Thanks for the model.  It does look like it is a graphics issue.  You can tell if you use Section Analysis to cut away the model:

I think the underlying geometry is good.  You should be able to use CAM on this model, I think.  It sounds like this is causing a problem with the toolpath?

Let me have the graphics team and the CAM team take a look at this and see if we can figure out more about the issue.

Jeff

[jeff_strater · Accepted solution]

While we wait for those teams to investigate, I did stumble on a workaround.  You basically have to split the faces where the bad geometry occurs.  In this case, there are two areas, so I did two split face operations:

This seems to fix the graphics glitch, even though it leaves a couple of unnecessary edges in the model, the geometry should be OK.

Here is a screencast of how to do this workaround:

Jeff

[paul.clauss · Accepted solution]

Hi @Anonymous

I had a look into your CAM model today and have some thoughts on a workaround I wanted to share - it may allow you to ignore the faceting issue in the model while making the part. 

The first workaround that I found was that reducing the toolpath tolerance parameter to 0.002" in the affected area eliminated the issue. This suggests that this is a faceting issue - it could be that the faceted copy of the model created with a tolerance of 0.002" (used for the CAM toolpath generation) is tighter than the default modeling tolerance. I reached out to Jeff about this and it looks like the ASM team will be looking into this - thanks for bringing it to our attention!

Decreasing the tolerance may be undesirable as it will increase the size of your g-code files. You could manage this by increasing the Smoothing Tolerance, or the other workaround would be to pattern the toolpath from an unaffected corner of the model. I have shown this, along with some other thoughts on toolpath setup for this model, in the screencast below. Feel free to reach out if you have any questions!

[Anonymous]

Jeff and Paul

      I had no idea that these things were even possible. This has been very helpful and has taught me a lot.  Thank you guys so much.

[jeff_strater · Accepted solution]

Just learned from our graphics team about yet another workaround - this turns out to be a tolerance problem, and if you increase the level of detail for that body, the problem will go away:

Jeff