Boolean Fail

Rhino Rhino for Windows
1

I’m trying to make a keychain holder for a bicycle Schrader/Presta adapter. I got the adapter in Step format from GrabCAD here. https://grabcad.com/library/tubeless-presta-valve-adaptor-1

However, when I tried to BoolenDifference it failed. Rhino says both objects are valid. Thoughts?

Boolean_fail
Boolean_fail2137×1131 294 KB

BooleanFail.3dm (4.6 MB)

2

cool idea!

fails here too-
it looks like there are several seams that are very very close to the edges of the trim.

exploding and trimming surface individually typically shows where the problems lie as the trims get funky too.
could simply be how the imported part was made, or other weird tolerance thing

anytime I have to deal with this type of stuff I simply explode the part and trim manually.

3

Thanks, Kyle. I just trimmed the threaded part a small amount at the bottom to remove the area noted, and then it booleaned. No idea why it worked. I’m winging it here.

Boolean_fail02
Boolean_fail022137×1131 254 KB

4

that’s the surface that was misbehaving here… no idea what is causing it… reasons I suppose. Always proceed with caution using imported parts from elsewhere.

fwiw, lowering it .01” made the boolean work… >shrug<

image
image692×656 73.8 KB

5

image
image1501×1152 194 KB

 Edge Tolerances: 0.000 to 0.008
    median = 0.006 average = 0.005

… might be a problem…

if you explode and untrimall the thread - you see some crazy surfaces.
I strongly recommend to do not build helix–like surfaces - many operations a likely to fail (project, trim, boolean …) as pulling and projecting is not unique.

a good approach (at least with my experience) is to only build half of a turn and repeat / array it:

… @theoutside there was another topic, where moving the part a small steps gave a solution… cant find it at the moment.

kind regards - tom

6

the thread you downloaded is not nice.
already having a closer look shows some wavyness:

image
image1501×1152 82.3 KB

here is a solution that follows my approach mentioned above:

BooleanFail_reworked_tp.3dm (4.8 MB)

the final part has

Edge Tolerances: all smaller than 0.000001

:nerd_face:

the dense cv s are inherited by rhino s helix command.
you can rebuild the curves on layer section_crvs with Degree 5 and 6 CVs - this will be within 0.003 and should be within most production tolerances…

kind regards - tom

7

Disappointing. I’ve found GrabCad models to usually be better than other sites. At this point, I feel creating threads is beyond my skills.

I’ve reinstalled the BoltGen, which seems to be working. Thoughts on using that plugin to create threads for purposes like this?

8

don’t model threads, download files of fasteners from mc master carr- they tend to be quite high quality and in my experience here, Boolean well in Rhino.
I keep a whole set of m1 to m12 bolts I downloaded from them that I use anytime I need threads.

9

Thanks, Kyle. I discovered that McC had models of all their products a while back. When I work, (rarely these days) we use a lot of McC products, so it’s good to add the actual item for construction. However, with this, I was originally unable to find the correct threads in my first search. Then a search for items used on tire valves produced models I could modify that had the correct thread.

Amazing how such a simple model turned out to a major learning experience. Final model here. Bicycle Presta/Schrader adapter keychain holder. by KaisoArt | Download free STL model | Printables.com