topic Re: Can't get joint origins to snap to center of hole anymore... in Fusion Support Forum

Can't get joint origins to snap to center of hole anymore...

SavedByTheLamb — Sun, 22 Aug 2021 00:17:28 GMT

Hi,
I can't get joint origins to snap to centre of holes any more, and it's winding me up lol.. I used to be able to hover over and it would snap to the centre of the hole, but now it puts the snap point out from the hole, for seemingly no good reason... What on earth is the problem with it please?..

..

Re: Can't get joint origins to snap to center of hole anymore...

jhackney1972 — Sun, 22 Aug 2021 00:20:48 GMT

Attach you model. If you do not know how to attach your Fusion 360 model follow these easy steps. Open the model in Fusion 360, select the File menu, then Export and save as a F3D or F3Z file to your hard drive. Then use the Attachments section of a forum post to attach it.

Re: Can't get joint origins to snap to center of hole anymore...

SavedByTheLamb — Sun, 22 Aug 2021 00:34:16 GMT

Hi, here is the file.

Re: Can't get joint origins to snap to center of hole anymore...

davebYYPCU — Sun, 22 Aug 2021 01:30:27 GMT

Click on the cylinder wall, will snap to the end or centre as desired, unless I am missing something.

No rod or axle, so can say much more.

Might help....

Re: Can't get joint origins to snap to center of hole anymore...

SavedByTheLamb — Sun, 22 Aug 2021 02:11:58 GMT

Hi, thanks.
I just clicked to make the end of the hole highlighted - right clicked - and selected "Axis through cylinder/cone/torus" and now I can snap the joint origin where it should be...
I was able to snap to the right point before, and I never selected that axis through thing, so I must have done something else that allowed for it to work then...

Oh, that only worked for one tube. Need to find a way to put that axis through all of them.
I managed to select all of them and use the construct -> axis through thing and it did all of them.

Ugg, nope. I rotated the rings and now the snap point if off again...

I don't think that is the right way to do it...
______________________
It's something to do with the circular pattern I think. Because I can snap to the right place on the original holes; it the copies that are being annoying...

Re: Can't get joint origins to snap to center of hole anymore...

davebYYPCU — Sun, 22 Aug 2021 02:07:39 GMT

Might help with full description of the end game, I have no trouble developing a snap point by selecting the cylinder wall. There was no axle or rod, but you can make virtual as built joint, with the model as is. I don't think I have ever created / used a work axis.

Did you check the Circular pattern, I figure it has not completed as required, 2 rows of holes and not 4, in 180 degrees.

Might help....

Re: Can't get joint origins to snap to center of hole anymore...

SavedByTheLamb — Sun, 22 Aug 2021 02:28:06 GMT

Yeah, I dunno. Something is up with the circular pattern. Some were suppressed on purpose. I took off the suppression so holes go all around, and some I can get the joint to snap in the right place and others I can't. It's stressing me out, I give up for now, it's too late...

Re: Can't get joint origins to snap to center of hole anymore...

davebYYPCU — Sun, 22 Aug 2021 03:28:49 GMT

3 things here that would give grief,

Faces and not Feature,

The hole command goes right through, so 8 times pattern will put two hole sets in the same place.

Suppress is disabled now, but there is only 2 rows of holes.

Works with hole Command - changed depth to 15.00

Feature select Hole in Timeline, 8 and full angle, Adjust, Suppress or adjust the angle / count.

Might help....

Re: Can't get joint origins to snap to center of hole anymore...

SavedByTheLamb — Sun, 22 Aug 2021 10:56:07 GMT

Hi,

I opened that last file and looked at the hole command and changed extent to distance, and it says 29.999cm. That should be 30cm. I dunno why it's taking off 0.001cm... Maybe that is flagging part of the problem...

I've changed to using a circle extruded rather than made with the hole command. Changed to using features, and a -45 degree copy with the circular pattern. It's still being weird... The original cut is fine, but the copy refuses to let me snap to the middle of the hole.

Re: Can't get joint origins to snap to center of hole anymore...

jeff_strater — Sun, 22 Aug 2021 12:47:09 GMT

@SavedByTheLamb - A couple of things:

you cannot snap to the center of the "circle" here, because it is not a circle - a circular hole through a cylinder produces a complex curve:
you can select the cylinder and snap to the endpoints of the virtual cylinder.
if needed, hold down CTRL (CMD on Mac) to "lock in" that cylinder, so you can pick any of the 3 snap points
note, though, that the JO is at the end of the "virtual cylinder", and will not lie in line with the face:

so you will have to adjust the point so that it is closer to being in line with the faces

I did not have any trouble at all adding a JO to any of the cylinders here, original or patterned

In theory, the type of pattern (face vs feature) should not matter at all here. In general, if you are patterning geometry, use Face or Feature/Optimized for efficiency. Feature/Adjust can be very slow to compute, and should be avoided.

Re: Can't get joint origins to snap to center of hole anymore...

SavedByTheLamb — Sun, 22 Aug 2021 13:43:55 GMT

"You cannot snap to the center of the "circle" here, because it is not a circle - a circular hole through a cylinder produces a complex curve:"

This is going well over my head. I can snap to the centre point, and flush, on the originals. They are all circles so far as I can tell. It's not a circular hole through a cylinder. It's a circular/cylindrical hole through a load of rings...
(Edit: Sorry I think I just "got" what you meant about the circle not being a circle. Because the hole is cut out of a curved surface, not flat. But that makes no difference to the fact I can create a joint origin flush with the original holes, but not the copies of those same holes...).

Why can I put a point flush with the hole on the original cut out hole, but not on the copy?.. It makes no sense. What is the difference between them that makes the virtual cylinder flush on the original but not on the copy?..

Why is the "virtual cylinder" longer than the actual hole?..

I think maybe the first time I did it when it worked, I made all the rings components before cutting the hole. Maybe that made the virtual cylinders flush with the holes... (EDIT: I just changed the order and it makes no difference..)

BTW I have not been using the "Assemble - joint origin" command. I am using the "Assemble - Joint" command. If that makes any difference.

"I did not have any trouble at all adding a JO to any of the cylinders here, original or patterned"

Do you mean you could get a joint origin flush to the face, on any of them?.. I can get a origin point on any, but the copied ones will not go flush.

Re: Can't get joint origins to snap to center of hole anymore...

jeff_strater — Sun, 22 Aug 2021 13:40:15 GMT

"This is going well over my head. They are all circles so far as I can tell. It's not a circular hole through a cylinder. It's a circular/cylindrical hole through a load of rings..."

I've forgotten the math here, but the intersection of two cylinders (your "rings" and "holes" are both cylinders) is not a circle. It is, for lack of the proper mathematical definition, a "potato chip" curve. Joint Origins can only snap to the center of a true planar circle.

"Why is the "virtual cylinder" longer than the actual hole?.."

I'm not sure how the extents of the cylinder are computed, but it is guaranteed to include all of the geometry of the trimmed cylinder.

"Do you mean you could get a joint origin flush to the face, on any of them?.. I can get a origin point on any, but the copied ones will not go flush."

I do not see any difference in behavior of the original or the patterned versions. No, you cannot get a flush JO on any of them. The larger the cylinder, the closer it will be, but none should truly be flush.

Re: Can't get joint origins to snap to center of hole anymore...

SavedByTheLamb — Sun, 22 Aug 2021 14:24:21 GMT

"No, you cannot get a flush JO on any of them. The larger the cylinder, the closer it will be, but none should truly be flush."

It may not be perfectly flush on the original hole but it looks like it is. It's probably as close as possible. Whereas the copy is way off... And both holes are identical in shape, so something else is causing the original to snap flush, and the copy to refuse to do so.

That picture is a merge of 2 separate screenshots while hovering the cursor over the hole, that is how both joint origins are able to be seen at the same time...

Re: Can't get joint origins to snap to center of hole anymore...

jeff_strater — Mon, 23 Aug 2021 12:19:30 GMT

ah, OK, that helps a lot, and actually describes the problem pretty well, so thanks. It all has to do with that virtual cylinder I described earlier. It seems the virtual cylinder is much tighter on the original than on the pattern instances. This is something we can look into, definitely.

Re: Can't get joint origins to snap to center of hole anymore...

SavedByTheLamb — Mon, 23 Aug 2021 16:42:40 GMT

I wish I new what on earth I did the first time to make it work.
I just got rid of the pattern and tried to manually make a new hole from a 45 degree plane, and it's still refusing to let me make the joint origin flush... So it's not the pattern creator that's doing it; it's something else...
____________
Just managed to do it by cutting the first hole, then rotating the whole model 45 degrees and then cutting a new hole as the first one.

I'm sure it shouldn't be this hard to do something this simple...