Yet another "Some positions cannot be resolved due to joint conflicts" post.

[skudd.com]

I'm losing my mind. I've resorted to calling out Autodesk in my Imgur post and on Facebook because this is such an annoying problem.

I've been trying to build and rig a W12 engine. I've done an I-5 and a V-8 with no issue, so I know the basic things behind it all should work. A W configuration is really not too much of a deviation from a V configuration either. At most, I have to put some extra thought into how I build certain components.

First go around, I got the block roughed in, the crankshaft, the piston, connecting rod, and wrist pin, and I tried to put them all together. The block was set to ground, the crankshaft to rotate within the block, the piston to rotate on the wrist pin, the wrist pin to rotate on the connecting rod, the piston to slide in the bore of the block, and (this is where the problem came in) the rod to rotate on the journal of the crankshaft. 

All these joints previewed just fine while I was creating them. Things rotated and slid where they should, until that last OK button was clicked. 

What doesn't make sense though is that when I did a single cylinder configuration, it worked fine.

I did the same sort of mockup with the offset bore as well, and it worked just the same.

The only thing relevant in the log files is the same message that I got in the UI:

20190303T172534 W New Alert message. Tooltip: Selected joint type will result in conflict, Short Message: Selected joint type will result in conflict, Long Message: Selected joint type will result in conflict

This has happened with 3 different main assemblies, the most recent being the most correct in terms of block geometry. 

If you want to see my Imgur posts, they are at the following URLs, and include lots of screenshots, a few memes expressing my anger, and lots of words about what I was doing.

I'll also update the most recent post to include links to my different files, as there are a few that are different from what's linked in the posts.

First Imgur thread: https://imgur.com/a/9IvD3bd

Second (most recent) Imgur thread: https://imgur.com/a/qm5yr39

[davebYYPCU · Accepted solution]

Try changing the last revolve to Cylindrical, if it works, your likely to find an alignment problem.

Might help....

[TrippyLighting]

Three different assemblies  and no posted model ?

Please export as .f3d and attach to next post, or share the public link.

[skudd.com]

Not surprising that you didn't see them. I didn't really think many people would click through and read all the things I've posted in the Imgur threads.

Anyhow, here are the public links:

My first model can (still) be found here: https://a360.co/2IXmnWO
The most recent assembly is here: https://a360.co/2IRZWC7

The discrete models that make it up:
- Block Rev 1: https://a360.co/2EpW85G
- Block Rev 2: https://a360.co/2Teji9d
- Block Rev 3: https://a360.co/2EsoQ5T
- Crankshaft: https://a360.co/2IMM8ZJ
- Crankshaft Rev 2: https://a360.co/2TbzuYW
- Connecting Rod: https://a360.co/2T9W2JN
- Piston: https://a360.co/2ILgaNr
- Wrist Pin: https://a360.co/2ExGKEe
- Piston Assembly (Includes: Piston, Wrist Pin, Connecting Rod): https://a360.co/2T9QMpo

The mockups I did are:
- First one, straight bore: https://a360.co/2Tft1fI
- Second one, offset bore: https://a360.co/2TckOZr

[skudd.com]

Grumble grumble. That did it.

Now to figure out what the misalignment is.

[TrippyLighting]

I started following the first link in the post and see that you derived the single components into the assembly. What is the reason you are using "derive" instead of "insert" ? 

It's not inherently wrong, but it is more "data heavy" than inserting or even creating the whole assembly in one file.

Generally, in any design you should \not have bodies at the same structural level with other components such as in this sub assembly.

Body 1 and body2 should be components.

You BOM will be incorrect but can get away with this from an assembly standpoint more easily if you apply a rigid group joint to the enos assembly by right clicking on the root component in the browser and selecting the rigid group joint.

Make sure "include child components" is selects.It should be the default.

The component counter in the joint UI shows 5 selected because there are 5 origins in that design including the top level. Rigid Group joints lock the origins of the involved components together in space. 

In your subassembly (at least in this one so far) you are using position capture features to move part into position. Don't do this. Use assembly joints to assemble the parts in the subassembly.

Ground the Connecting Rod directly after deriving/inserting it Ito the assembly, or better create rigid group between it and the top level origin. Make sure in this case that "include child components" is disabled. This will look the part firmly to the top level origin in this design.

Then as you add components assemble as you go! Your timeline should look like this (without position capture features):

I'll continue to look through this and see what I find

[TrippyLighting]

I can see now what you use derive. It is to work around some of the structural and design issues creeping up in your design. However this is going to catching up with you sooner, rather than later 😉

As mentioned previously, using the position capture feature with components to create a parametric design is not a recommended workflow. You use that extensively in the Crankshaft and that is likely one source of the lack of precision.

If you must use the move feature, at least use the body move feature and use the parametric version of it (translation-only and rotation-only). 

Edit: It's not the precision that is the problem. It the lack of it being parametric that makes the hard to follow or correct if it needs to be changed.

[TrippyLighting]

Not going to edit that post again. That position-capture-with-components technique is the precision culprit thats should be avoided. All other distances on the crank shaft are exactly 3.5". Just this one isn't.

If you use revolute joints to assemble the piston assemblies to the crank shaft and then cylindrical joints for the pistons to the cylinder heads, here's your problem!

[skudd.com]

Well, you gave lots of feedback and I really appreciate that.

Let me address the points you made though:

1. "Insert Derive" vs "Insert" - If the latter is the same as dragging from the data view into the current model, then my issue there is the inability to define joints or hide components in the main assembly. I'll poke around at it more after I get my desktop going again, but from the experiences I've had with the drag-and-drop approach, it didn't work out at all.
2. Rigging in the sub-assembly - Yeah, I thought about that too, but for some reason I opted to define the joints in the main assembly. I'll give it another shot later, but that's my reason for that.
3. The crankshaft is no longer using that particular model, but in order to get it built the way I wanted it, the same issue existed. I ended up using cylinder joints for it, but that still feels like a dirty hack. 
   1. The way I ended up modeling the crankshaft the second time around was to define the crank journal shapes, then copy the body along the axis. I want to try a couple other things to avoid the moves showing up in the timeline, but I haven't really taken the time to do that yet.
   2. I don't get why that measurement isn't dead-on though. Is the precision of the various things like moves and extrudes not on-par with everything else?