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From: Michael Gibson
Hi Supagoat, it's a little hard for me to figure out which one is the boolean problem. Is one you marked with the arrow is the one that you're having trouble with the slicer?
What mesh settings are you using for the STL export?
I don't see anything wrong with the geometry in that arrow-marked one, but the issue may be that your slicer does not like to have very thin areas in it, like this spot here may be thin enough that it is deciding that the polygons there are close enough that it considers that they are touching each other:
Does the slicer have any tolerance values you can adjust?
If it doesn't like such thin sharp shapes you might need to have a pretty small chopped off flat piece at the end rather than a razor sharp point like that.
- Michael
Image Attachments:
supagoat_stl.jpg
From: Supagoat
It was hard to describe so I made a video demonstrating the problem:
(fixed the URL)
https://youtu.be/nYwWqQHxZKQ
From: Supagoat
OK I think I may have found a workaround. If I trace the outer profile as well as the inset in the form of a C, and then separately make a rectangle to close it and make a D shape, then I loft that curve and rectangle separately and then boolean union the lofts together it appears to work. A little labor intensive but not too bad.
From: Michael Gibson
Hi Supagoat thanks for the video, I did a closer examination and it looks like there may be an anomaly in the back inner curve here:
There are a couple of spots where the curve is making a sudden tight bend in shape, these spots:
It would probably be good to try and get the original curves to be a little simpler and smoother than this, without this type of sudden changes in shape in highly localized areas. That's not generally good for offsetting.
This is the spot that seems like it may be a problem especially:
You can see there where the curve's control points do an abrupt reversal of direction. I'm not entirely sure but it may be that the curve is back-tracking on itself or very close to back-tracking in that spot. I think that's what may be messing up the boolean.
One way to make this shape without doing a boolean is to do 2 lofts as you did, but with "Cap ends" turned off (unchecked) so the ends are open, and then select, then select all 4 curves and run Construct > Planar, that will build 2 end caps and now you've got 4 surfaces that can be glued together using Edit > Join. Doing a boolean will attempt to intersect surfaces with each other and that backtracking area is probably confusing the boolean.
But even with the non-boolean method that area may generate polygons that are back-tracking as well so it would be good to get the curves smoother and more simplified I'd think.
- Michael
Image Attachments:
supagoat_curves1.jpg
supagoat_curves2.jpg
supagoat_curves3.jpg
supagoat_curves4.jpg
From: shayno
Hi There
I think also that because the inner surface that you boolean out shares the same surface as the outer you sometimes get a conflict.
If you move the inner profiles .1 mm outside of the outers then you get a clean cut as its not trying to cut a surface from a surface on the ends.
Also you get a better result if the inner and outer curves have a similar number of control points, also Offset can throw up some confused curves with way too many control points , I often rebuild them to simplify it.
You can also sweep the inside curves longer than the outer solid to cut with
cheers
shayne
Image Attachments:
2018.04.26-15.28.02-[3D].jpg
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