topic Re: Brand new to Motion Studies, and having an issue in Fusion Support Forum

Brand new to Motion Studies, and having an issue

blave549 — Tue, 11 Oct 2022 21:18:18 GMT

I worked through a YouTube tutorial yesterday on animating a sort of engine. When I use Animate Model things work as expected: https://www.youtube.com/watch?v=9d5mPKrxrkU. But when I try to put together a Motion Study, after a certain number of degrees of rotation of the crankshaft Joint, the piston "falls out" of the cylinder:

I would expect Animate and Motion Study to work more or less the same -- is this not correct?

thanks,

Dave B

Re: Brand new to Motion Studies, and having an issue

jhackney1972 — Wed, 12 Oct 2022 01:31:12 GMT

The Forum users would need your model to try and give you a good answer. Please attach it. 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: Brand new to Motion Studies, and having an issue

sutherland- — Wed, 12 Oct 2022 08:08:10 GMT

Hi @blave549

Have you tried to capture position before performing any Motion Studies and Animations?

Re: Brand new to Motion Studies, and having an issue

blave549 — Wed, 12 Oct 2022 16:18:22 GMT

Thanks for your reply. I have to admit that I don't know that function, so I will research it and see if it helps, and report back. I've been wondering what those icons were for 😀.

cheers,

Dave

Re: Brand new to Motion Studies, and having an issue

jhackney1972 — Wed, 12 Oct 2022 16:25:40 GMT

I will ask again, could you please attach your model. The model can be used by the Forum users to try and define your issue and give you a possible solution. In my earlier post, I gave you the process for sharing.

Re: Brand new to Motion Studies, and having an issue

blave549 — Wed, 12 Oct 2022 16:30:45 GMT

I wanted to try Capture Position as recommended before having anyone spend time on this. It doesn't seem to help. Design attached.

thanks,

Dave

Re: Brand new to Motion Studies, and having an issue

jhackney1972 — Wed, 12 Oct 2022 17:45:31 GMT

Motion Studies have a tendency to run too fast. To make your run correctly and as slow as possible, you want to first select the Revolve joint used for rotation and Drive Joint to 0 degrees. Then create a Motion Study using this joint and set step 100 to 360. Then when your run it on a repeating basis it will be as slow as possible.

Your original Motion Study did not do a thing, it was set for no rotation at all.

I have attached your model but remember it is an F3Z file as you supplied me with one. If you are not careful, you will clutter up your Cloud Folder with duplicate models and make a mess. I would suggest creating a trash folder and upload it to it so you can remove it easily.

(view in My Videos)

Re: Brand new to Motion Studies, and having an issue

blave549 — Wed, 12 Oct 2022 18:25:48 GMT

I didn't realize that the Motion Study I was playing around with wasn't saved in that file -- my apologies. If I set a study point to 150 degrees, the piston will drop out of the cylinder before I even play the study (I played around with the number and it doesn't seem to be a specific one, but typically >= 140 degrees). I have been playing the study at minimum speed.

If I edit the crankshaft-to-connecting rod Joint, it shows zero degrees and the crankshaft is shown as being perfectly vertical.

But when I close the Joint dialog, it shifts to another position.

The other moving parts all show 0 degrees for their Joints.

Thanks for your ongoing support!

Dave

Re: Brand new to Motion Studies, and having an issue

jhackney1972 — Wed, 12 Oct 2022 19:40:13 GMT

I have recorded a video to explain the difference between the Edit Joint and Drive Joint commands. Also I explain how to use Joint Limits, on the slider, joint to keep it ALWAYS within the cylinder but not interfere with its motion caused by the crankshaft.

(view in My Videos)

Re: Brand new to Motion Studies, and having an issue

blave549 — Wed, 12 Oct 2022 21:12:52 GMT

Thank you so much! I will dig back into this tomorrow.

Re: Brand new to Motion Studies, and having an issue

blave549 — Mon, 17 Oct 2022 19:59:49 GMT

John, thanks so much for taking the time to make the video!! That's just above and beyond. I haven't had a chance to try what you suggested, but I have to admit that I never even noticed or researched the Drive Joint command (duh). I knew about the limits command, but not in this context.

I will mark this as solved -- have a great day!