Problem Trouble getting a solid subtract to function correctly


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Thread: Trouble getting a solid subtract to function correctly

  1. #1
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    Default Trouble getting a solid subtract to function correctly

    Hello, I've been messing with this for a couple of days so maybe one of you can give me a point in the right direction. Created a profile, used revolve to create basically a 360 degree corrugated cylinder, round on one end, coned down on the other. The solid looks great. Created a cube which lies beneath the cylinder so the cylinder rests half in and half out of the cube. Essentially this is to be a two part cavity mold of the cylinder negative. Half in top, half in bottom. The solids subtract feature seems to work correctly but it's only showing the outline of the solid. When switching to transparent it shows the cavity is there but switching back to non-transparent the cavity disappears and the outline reappears. When I try to cam the part it ignores the cavity but not the outline. I do notice that the original profile line for the revolve still shows up on the solid even though the cad of that line is inactive. Thanks in advance. Bobcad V28.

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    Default Re: Trouble getting a solid subtract to function correctly

    Be easier if you can upload your BobCAD file if it isn`t a prorpietry design, just put it in a Zip file (Not RAR) and on your reply use the "advanced" option and attach the Zip file to it.

    In the meantime have you tried clicking on the area that is outlined and using the "unstitch" option under the "utlities" tab, if it will work you should then be able to delete that surface and the cavity should be open, sometimes works when there is an issue with the Boolean subtract

    Regards
    Rob



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    Default Re: Trouble getting a solid subtract to function correctly

    Just as an addition to the above a little "workaround" with Boolean subtract issues, another way to do what you want (I think) is to use the "slice" facility to cut your shape in half (I only did a 180 revolve for the example) and then extrude the flat face so that it stands higher than the surface of the block to be cut, you will have to use the Boolean "add" to add the extruded surface to your half shape so it is a single solid, now it should subtract OK.
    Is this what you want to do ??
    Trouble getting a solid subtract to function correctly-boolean-example-jpg
    I have done a example program for you so you can see better what I am talking about, just go through the steps in the CAD Tree and try to duplicate those steps in your own program and see if it helps, the BobCAD Boolean can be a bit "picky" with solids

    Regards
    Rob

    Attached Thumbnails Attached Thumbnails Trouble getting a solid subtract to function correctly-boolean-example-jpg  
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    Default

    Yes. That's pretty much the idea. I'll give your suggestions a shot in the morning and see how it goes. I just did this a few days ago with another similar shape and everything went semi smooth.



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    Default Re: Trouble getting a solid subtract to function correctly

    I tried this several different ways today. I did finally get it to subtract but the result was pretty funky for some reason. Here is the .bbcd file.
    Edit: I did notice one of my lines on the rotate was a bit short across the top. Still same result when lengthened to center.

    Attached Files Attached Files


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    Default Re: Trouble getting a solid subtract to function correctly

    Hmmm, your geometry was a bit off, where the segments met the lines crossed each other instead of joining, I re-drew the geometry and I also found that one end of the geometry was higher than the other end, they have to really be the same.
    Trouble getting a solid subtract to function correctly-test-bad-geometry-jpg
    Anyway with a little TLC I have modified your file and managed to get it looking pretty much OK now.
    Trouble getting a solid subtract to function correctly-test-modified-jpg
    So have a look at the attached file and see where you go from there, could be a starting point for you

    Regards
    Rob

    Attached Thumbnails Attached Thumbnails Trouble getting a solid subtract to function correctly-test-bad-geometry-jpg   Trouble getting a solid subtract to function correctly-test-modified-jpg  
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    Default Re: Trouble getting a solid subtract to function correctly

    Geeze. And I'm usually the one showing people how their geometry isn't clean. Note to self: quick trim doesn't trim so good. Thanks for the help brother. I knew it was going to be something simple.



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Trouble getting a solid subtract to function correctly

Trouble getting a solid subtract to function correctly

Trouble getting a solid subtract to function correctly