Boolean Union Problems after ExtrudeSrf

In the attached file, I started with the red “solid.” Then I did extrudesrf on the tops. I am unable to do a boolean union with the extruded closed surfaces with the red surface that they were extruded from. The green sliver surface in the between the purple and blue will union.

I can union the extrusions together. I can also split red with that union and the union with red and join. However, I am curious why do these cause such a problem with boolean union?

Could this have something to do with the triangular shape of the sides?

BTW. Is there a command that will do A split B and B split A in one operation?


Problem Extrude.3dm.zip (18.5 MB)

do you want all the present geometry to be joined into one closed object? if so, just subselect the facing surfaces delete them and use join. boolean operations failed yes but dont rely on that too much.

Problem Extrude.3dm (14.0 MB)

here @Helvetosaur posted a python script which does the split part splitting all involved geometry with each other. maybe that helps.

Thanks, I’ll try the script. My issues is that i need to do a lot more with the upper part before joining. This is the simple case.

If I take things to the next step by trimming the extrusion, all hell breaks loose if I try to split.

Problem Extrude 2.3dm.zip (12.6 MB)

My opinion. Forget boleans and extrusions and generate surfaces and polysurfaces from curves. Then make Join.
It is never a good idea to cut an extrusion

-Simon

hey jim, if you want others to keep helping you it might be better if you reply to their posts directly or quote them or use @ with the user name to address them, i dont always look back into all topics even though i try.

the hull surfaces are still far too heavy, you dont seem to take any response serious towards that. anyway for the last model the case would be pretty clear and easy to do, just duplicate those 2 edges and split the faces deleting the facing surfaces and join.

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but as you see here you have a bunch of microsurfaces which are not particularly helpful and create naked edges. you may have to take a step back here and try to get clean boundaries otherwise not even join will do that for you.

“the hull surfaces are still far too heavy”

What do you mean by “heavy.”
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You should have been able to predict split would not work. . You are trying to manually emulate a boolean that failed and you should expect the manual process also will fail. Why are you surprised?

The simple way to do this is don’t even think about booleans. Just build the surfaces that contribute to the end result and join them.

You are building surfaces that don’t contribute to the end result and then getting stuck trying to figure out how to get rid of those surfaces. If you do find that you have a surface you don’t need don’t try split to get rid of it. Just delete it.

Number of control points is large. For your hull surface in this thread the number of control points is extremely large.

“Number of control points is large. For your hull surface in this thread the number of control points is extremely large.”

I’d be curios to know why this produces so many control points. I have stripped this down to the minimum that curves that will produce the desired shape.'I have other surfaces with more frames and none comes out as complex as this one.

Problem Bow.3dm (4.6 MB)

Mostly because you use a tolerance dependent surface creation tool using an extremely tight tolerance. I doubt that anything this big could be manufactured to tolerance of less than 1/4"

You should be able to make this a lot simpler.
bow.3dm (437.9 KB)

“I doubt that anything this big could be manufactured to tolerance of less than 1/4"”

The original tolerance for the hull was 1/16".

Those engineers of the 1930’s were amazing, especially considering their lack of computers.

“You are building surfaces that don’t contribute to the end result and then getting stuck trying to figure out how to get rid of those surfaces. If you do find that you have a surface you don’t need don’t try split to get rid of it. Just delete it.”

The problem is there are three different configurations that can occur here: No bulwark (in which case I need those surfaces) and two different bulwarks.

If the temperature went up 10 degrees the overall length of the bow would increase by ,more than 1/2" an inch. How could the engineers possibly expect the shipyard to hold a tolerance of 1/16" for the entire hull?

Was that the accuracy of the build, or the precision of the dimensions/offsets on the plans?

With a nominal accuracy of 1/16" = 0.0625 a reasonable absolute tolerance would be 0.01 or 0.006 rather than 0.001.