Union Negate keeps adding glitchy extra faces

I am trying to negate a build of wedges and normal parts from another part, but it keeps adding faces between the parts even though there is no space between them

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Is there any way to stop it doing this or to just remove these faces? I am unable to overlap the wedges with the parts or it won’t look the way I want it to

You will only need to overlap by a couple of studs, this shouldn’t affect the look and will rid these one or two stud thick faces you are seeing.

Your solution is make the negate parts bigger. For example;
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You’ll union the red part by blue negate part, but there’s an issue;
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They are overlapping, and this make extra faces;
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So you have to make negate part bigger like this;
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And done!