Subtract Problem

Okay, this one is driving me nuts. The big object needs these cylindrical objects subtracted from it. As you can see, it's almost done. But this line of objects that are still out hovering in space just will not subtract correctly.

To do this test, move the hovering objects (just one is fine) toward the large object 2.75 units, then attempt to subtract the small shape from the big shape. Notice the glitch in how the large object renders? ALL of the other shapes that are ALREADY subtracted were done precisely the same way, but this small row that are left just will not work properly no matter what I do.

I've tried exploding the large object, then recreating the solid with surfsculpt...then trying the subtract again. No effect. I've tried subtracting the large object FROM the smaller ones (to redefine their shape closest to the large object) and THEN retrying. No effect.

The odd thing is...when you zoom way in, it looks correct. But zoom out, and there's the glitch. It even has this behavior in viewports.

Here's the file: https://mega.nz/#!md912YqL!wq9S8DIJWjpvppN233vDBcmH6iXk1G77AaDXgxCBTxg

No one has any ideas on why this is happening?

Is there a reason you did not attach your file here?

I believe the file size is 1.4MB.

Yep, it was slightly too large to upload to the site.

In the theory of Boolean operations it is possible to do a series of valid Boolean operations and an object that has a surface dangling in space of infinitesimal thickness. To get rid of this invalid surface a process called regularization is performed to provide a valid solid. In practice, with real CAD systems, Boolean operations must check for this issue. Due to numerical errors, these dangling surfaces may not be processed correctly in the regularization process in AutoCAD.

I tried a series of tricks to get the subtraction to yield a valid result including the rotation of the objects in 3D before doing the subtract. I tried exporting the model to 3ds Max where the dangling faces can be removed but this was too much work.

Another interesting approach I took that had some success was to create a solid mass the encompassed the problem area. I then made two copies of the two pieces and for one set did a Boolean Intersect and for the other set did a Boolean subtract. For the result of the Boolean Intersect I successfully subtracted the 10 slotted solids resulting in the following:

I then unioned the two pieces together resulting in the same problem you found.

To help me isolate the problem piece of geometry I undid the previous union and sliced the insert in half and unioned only one half of it. As you can see in the following picture the bottom 6 slots unioned nicely.

I then went to union the final piece which yielded some problems as can see below.

A little more experimentation may help you to find the problem piece of geometry.

Good luck!

~Lee

It is AutoCAD glitch. No problems in Rhino and BricsCAD:

It is AutoCAD glitch. No problems in Rhino and BricsCAD:

Would there be a way for you to resave this to .dwg format after doing the subtract, or would that just re-introduce the anamoly when I opened it in CAD again? I'd really appreciate it. Thank you guys for the responses. It's good to know I wasn't going nuts and that it really is a software issue.

Would there be a way for you to resave this to .dwg format after doing the subtract, or would that just re-introduce the anamoly when I opened it in CAD again? I'd really appreciate it. Thank you guys for the responses. It's good to know I wasn't going nuts and that it really is a software issue.

Just giving my last post/question a bump.