why can't I move/align a nut with a bolt?

[jamie.q.white]

Fusion 360 just hangs.  Beachball. Nut and bolt imported from McMaster-Carr.  Ugh. Frustrating.

Here's the downloadable file:

http://a360.co/1ClEWoa

Thanks!

-jamie

[jeff_strater]

Thank you for sharing the model.  I can reproduce the problem and the dev team will take a look at it.

Jeff Strater (Fusion development)

[jamie.q.white]

update: I can create a joint (rigid or revolute) but not move or align the nut to the bolt.  It seems like I should be able to move or align. I moved a set of washers into position after import.  Why not the nuts?

[jamie.q.white]

Hi Jeff,

Thanks! It is really nice to know I'm not going crazy.  Time for a coffee...

My internet was hung for a while: I can creat a joint, but still can't move or align.  Weird.

-jamie

[jeff_strater]

This is a very interesting problem, to be sure.  What I observed is that if I delete all the joints, I can move things, but it is VERY slow to move the bolts.  It is not clear why this is the case.  I suspect that this is the root cause of the whole problem.  With the joints in place, moving one bolt will try to move several bolts together.  The rate that I see a single, unjointed bolt moving makes me think that if you waited long enough, everything would eventually move.  I'm not saying you should do that, of course.  This is a very simple model, and should be able to move just fine.  We will get to the bottom of it...

Thanks for making my Thursday just a bit more interesting!

Jeff

[jeff_strater · Accepted solution]

OK, now I see what is going on...  You have contacts turned on in this model:

Yeah, that will kill performance in a hurry.  Especially in a model like this, where there are lots of tangencies.

Personally, I don't use contacts, except in rare cases.  They don't perform well, and they are not really all that accurate.  I would just use Joint Limits in this case.

If you turn off all contacts, your model will move fine.

Jeff

[jamie.q.white · Accepted solution]

Hi Jeff,

ah, thanks.  I had no idea that contacts were so detrimental to performance.  I tried to create just a "contact set" between one set of bolts and slots.  Did I do it correctly.

More generally, I was trying to check the bolt positions in the slots. The movement is a titch over 2 in center-center due to tolerances (2.121" or something).  What is the best way to keep the bolts in the slots to see how the bolts move?  I could not figure out how to do it with joints.

-jamie

[jeff_strater · Accepted solution]

The best way to do this is with Joint Limits.  You need to set the limits so that it keeps the bolts in the slots.  The workflow is not as wonderful as it could be, but you can get there.  The Align command can help.  The basic idea is to use Align to put the joint in each of its extreme orientations, then take note of the joint value in each orientation, then set the min and max to those values in the Edit Limits command for that joint.

Here is a screencast of me doing this with your model, for one of the joints:  http://autode.sk/1Ppl6Se

Jeff

[jamie.q.white]

Hi Jeff,

Just getting back to this after other tasks took over; thanks a lot for help and the screencast.

I'm still learning what are the best (or for me maybe it is the "least bad") ways to do things in Fusion 360.

-jamie