Esteemed gentlemen,

I present a union problem. I have tried a few different tricks, but nothing seems to make the union work. Any hints or advice?

My thanks in advance,

Todd the Otterman

Hi Yen,
Here is a file I did, though I changed it up a bit. If the pipe dimensions dont work for what you want then I'll explain what I did.

The 2 pipes in your model are actually very slightly "Intersecting". THis is throwing a tiny little sliver into the mix where the 2 pipes meet and touch the building.

Also the to ends of both pipes just bairly touch each surface. These should "punch through" a bit to get a good boolean.

Hope that helps,
Burr

[EDIT] I posted a file that had an anomoly in the short pipe, I fixed it and replaced it here. If you got it fast please redownload this fixed version. [EDIT]

Hi Todd, yeah like Burr mentions one issue is that pipes just barely graze one another, that can sometimes be bad for booleans.

Here's a screenshot of this part:






That may be better to have them either aligned to one another or possibly slightly separated rather than having a very thin intersection, thin slivery intersections can then generate little tiny surface slivers which tend to cause problems.


Then actually a bigger problem is with the joints of the pipe:




If you look there you can see that there are some edges internal to that joint. They are all joined up to one another, but if I use Edit/Separate to break this into individual surfaces and move them apart a bit, you can see what is happening there:




So actually something went wrong with the booleans for the pipe elbows it looks like, that then made an object that has a kind of self-intersecting internal part to it, which is going to pretty much hose booleans with that object after that.


Those can probably be repaired, I'll give a try in a bit.

- Michael

When I extracted the edges of the pipes to use to rebuild them, they were this weird "misshaped circle. Thats why I just made new ones.

> Those can probably be repaired, I'll give a try in a bit.

I'll still take a look later, but it looks like Burr has you covered already, thanks Burr!

- Michael

Your surfaces are a bit of a mess....try re-constructing the pipes using cylinders/spheres (watch the seam lines & how they might intersect with the main body) then boolean. Alternatively, sketch a curve on Centreline and fillet edges slightly bigger than your pipe radius and use sweep1...thats how it would be made for real anyway ;-)

HTH

:-( cannot attach my file

Thanks for the help, guys.

How odd that the pipes were freaky. They were vanilla sweeps of a simple circle over relatively tame paths.

Hey carter thanks. I used square line segments and then filled the corners with spheres. Silly me.

Nice pipe!

Burr

Hi Todd - you can run into problems like this with sweep where you have a bend in your path where your profile curve has a larger size (larger distance away from the path) than the radius of the bend.

Here's an illustration of this kind of thing:




Notice how when trying to sweep the line above along the curved path, that because the line is longer than the radius of the bend, it gets all bunched up in that area? That's a similar kind of thing as what you're running into here.

This same kind of problem can apply to several different functions that work by keeping things a constant distance or perpendicular arrangement from a path curve, including Sweep, Offset, and Fillet.

Here's the similar kind of area from your pipe:




So that is going to end up doing a sweep of that large circle around that small arc, like this:



Or as viewed in 3D:




As that circle sort of marches along that path, it will make things like this:



As you get more of them, you can see how that kind of a shape will be generated:





Instead of doing a circle there, you may need to do something like just the "outside" 180 degree arc so that you can avoid that self-overlapping to the inside part.

- Michael