Tangent constraint puts parts in inverse alignment

[Vagulus]

I have posted this problem before and it resolved itself.  Now it is back again and no matter what I do it persists.

Obviously, I want the outer face of the bearing (1)

to ride on the inner face of the cam track (2).  How do I achieve that?

This time, the frame with the cam plates has been converted to an IPT (simplified part) whereas previously I was working with an IAM and all the associated constraints.

FTR I am working with AI Pro 64-bit, build 284, release 2018.3.3 on Intel QuadCore i5-3470 CPU @ 3.20GHz, 32 GB RAM, running MS Windows 10 Home v. 1803, build 17134.228 on an MSI B75MA-P45 motherboard.
It was assembled by Net Solution Computers of Morley, Western Australia, and has RealTek High Definition Audio and a SAMSUNG U28D590D VDU driven by an NVIDIA QUADRO K620 Video Card.
I have Windows Defender and Malwarebytes as Anti-virus with Firefox and Skype running in the background.

Thanks

[Vagulus]

Sorry, I forgot to add the files.  The IAM in which I am working is AE-008-0000.

[Vagulus]

Another thing I forgot, the rod with the bearings on it.

I hope that's the lot

[jhackney1972 · Accepted solution]

Go into the assembly and edit the Tangent assembly constraint and then choose the opposite solution.  It will jump to the other side of the track.  I will also move to the other side of the assembly but can be move around the track freely.  I am using Inventor 2019.1.2 so it would not help you to zip it up and send it back.  Take a look at the screencast.

[Vagulus]

That's what I did last time but it did not work yesterday.  This morning I did a Repair on AI and that led to an update.  When I did the flip trick this morning it worked as you said.  It is, to say the least, somewhat erratic.  I can move the rod but it will often pop back to where it was when I release the LMB.  Anyway, that's an improvement but the plot curdles.

When I add in the Drive Assembly I need the inner bearing on the rod to ride in  the radial slot.  Previously I used a Transitional Constraint

and the two constraints working together mean that rotating the drive makes the rod move backwards and forwards in the slot.  The outer bearing follows the cam, the inner one stays in the slot.  Now, accepting the constraint pictured above gets me

this.

This is really annoying .  I have had this working using IAM files instead of the Simplified IPTs.  I shifted to the IPTs thinking that I would have less constraints for AI to worry about in an animation.  This current incarnation of the model only has half a dozen or so constraints instead of the dozens its equivalent had in the past.  Things should be better.  It's obviously a case of, "What can possibly go wrong!"

Anyway, can you help with how to get both constrains working?  Thanks

[jhackney1972]

I am not exactly sure if you are asking "How to drive the cam rod around the track" or not but that is what I am going to show you.  I would make an invisible part that you can drive around the center of the assembly.  This invisible part will have a slot in it, the same size as the cam rod, that will be constrained to it using a tangent constraint.  I then would create an angle constraint to use for driving the invisible part which in turn will drive the cam rod around the track.  It is not perfect due the acceleration curve, but it works well and maintains the cam in the track.  Take a look at the screencast.

[Vagulus]

Thanks for that, I appreciate your taking all that time, but that is, in effect, what I am doing.  The flange at the ends of the Drive axle has four slots

which are to do the same job the slot in your invisible part does.  Two of those rods, with bearings, ride (transitional constraint) in each of these slots - we are getting a little complex here .

This is a temporary IAM called LoadedDrive.iam and the rods move backwards and forwards constrained within their slots.  So far so good.

Now the bearings at the ends of each of these rods have to ride in the cam slots (I have been using a tangent constraint).  This is Test.iam.

My problem occurs when I try to apply the tangent constraint

between the small outer bearing (1) and the face of the cam track (2).  I just get

.

I think my assembly logic is correct, it's just that AI18 doesn't want to attach the tangent constraint.

Is it a problem with assembly sequence?  Should I use a different constraint?  Is Inventor just having a Bad Hair Day?

[Vagulus · Accepted solution]

I finally got this to work.  I am forced to the suspicion that AI18 deciding to work might have had something to do with closing down the PC overnight and starting afresh in the morning.  I don't know why that would matter, but I wouldn't mind some comment on the idea.  Does AI have ghosts in live memory which are only laid by a computer reboot?

Anyway, here's how I got it to work:

1.  Make the drive (axle and flanges) invisible.

2.  Place rod with bearings.

3.  Constrain YZ plane of the rod to the centreline plane of the Frame.  This controls movement side to side and also the alignment parallel to the axle.

4.  Tangent constrain small (outer) bearing at end of rod to the face of the cam track.

5.  Make drive visible.

6.  Transitional constrain larger (inner) bearing at end of rod to the slot in the drive flange.

7.  Repeat from 1 for all eight rods.

Tedious but successful - up to a point.  If you get too enthusiastic with the speed at which you rotate the drive then AI throws a tantrum.