topic Re: Assembly problems with rotation - Inventor 2019 in Inventor Forum

Assembly problems with rotation - Inventor 2019

Anonymous — Fri, 24 Apr 2020 15:14:33 GMT

Hi all,

So I have designed and built a prototype but now need to correctly assemble it, motion and all, so I can then open it in CFD and simulate the airflow, all of which is completely new to me and I am dreading CFD as I've tried it and didn't get it at all! So, I know how to align everything fine and set certain times of joints and constraints etc, but I can't seem to get everything to rotate together!?

As you can see in the pic, it all starts at the bottom with this axle from a motor spindle sticking through the base, (screwthread with the top red rotational arrow,) and a fan that is locked in tight due to a good fitting. I can align it all perfectly, but just can't get it so that when I rotate the axle, the fan rotates with it. The thing is, this continues upwards for quite a few parts to follow! The "axle" is actually a number of parts with other discs that all, in real life, screw in to each other and rotate together with the first axle.

So, what relationship do I need to include that makes the fan spin once I spin the axle? And then, when I put the next piece on top which I am simply doing face-face as I do not have time to figure out how to genuinely simulate screw thread attachments, how do I then get the next parts to rotate too? (Literally just imagine a cylinder cut in two. Then mate the two faces back together which is easy enough, but done in a way that when you rotate the bottom half, the top half rotates with it.)

I hope that all makes sense. It is a super, super important element for obvious reasons - the whole thing rotates but is many parts screwed together so if I can't make this work, I have no model, and no simulation, and the project is dead in the water. 😞

Any help would be greatly appreciated thanks!

Re: Assembly problems with rotation - Inventor 2019

JDMather — Fri, 24 Apr 2020 15:23:13 GMT

Attach your assembly here.

What version of Inventor are you using.

Mate Planes or Insert with Lock DOF (as appropriate).

What software will you use to do the analysis?

Re: Assembly problems with rotation - Inventor 2019

mcgyvr — Fri, 24 Apr 2020 15:31:21 GMT

Yes Inventor now has an option to "Lock Rotation" when using the insert constraint or if you didn't use that then assuming you constructed those parts centered about the origin planes (you should have) then you simply use the origin planes of each part with a mate constraint to tell them to stay together.

Good luck with the CFD.. Remember garbage in = garbage out so its very important that if you expect to be able to get a realistic output from it then you must be well versed in it and ensure that all of your loads/forces/flowrates/frictions,etc... are very well understood and match the real world as best as possible..

Re: Assembly problems with rotation - Inventor 2019

Anonymous — Fri, 24 Apr 2020 15:38:34 GMT

Hi JD,

Unfortunately I can't attach it as it is confidential. What is "Lock DOF?" I've tried mating the planes, but then when I rotate one, the other does not rotate. I am quite surprised, it seems like it should but it just doesn't. It's the first time I've done it so it shouldn't be an issue with settings... I will also be using Autodesk CFD for the analysis.

Thanks.

Re: Assembly problems with rotation - Inventor 2019

JDMather — Fri, 24 Apr 2020 16:05:15 GMT

Make up a dummy assembly and Attach it here.

Re: Assembly problems with rotation - Inventor 2019

Anonymous — Fri, 24 Apr 2020 16:34:32 GMT

Ok, so there are three sequential parts there. The fan is a tight fit in real life, a little off in the model but that shouldn't matter, and if it does, I can change it. In real life it sits on the "shoulders" of the axle just below the screwthread so that it is a tight fit cylindrically and then the shoulders and flat faces kee it aligned and make sure it rotates with the spindle. Then the first axle spacer screws down on to the screwthread and also obviously rotates with it. For ease here I have just mated the two faces obviously.

The problem is that I can get it all to line up. I can even get it so that the individual parts can rotate on their own, but I can't get it so that I can rotate the spindle at the bottom, and everything from the fan upwards rotates too. I hope that's clear?

Re: Assembly problems with rotation - Inventor 2019

JDMather — Fri, 24 Apr 2020 16:52:38 GMT

An assembly must include parts.

Re: Assembly problems with rotation - Inventor 2019

Anonymous — Fri, 24 Apr 2020 17:11:17 GMT

Hi, sorry but I don't understand? What I just attached includes 3 parts? I can also attach/join/constrain them all perfectly ok with no error messages saying their are no parts? Sorry can you explain please?

Re: Assembly problems with rotation - Inventor 2019

mcgyvr — Fri, 24 Apr 2020 17:18:02 GMT

@Anonymous wrote:

Hi, sorry but I don't understand? What I just attached includes 3 parts? I can also attach/join/constrain them all perfectly ok with no error messages saying their are no parts? Sorry can you explain please?

What you see includes 3 parts because those parts are located on YOUR computer so the iam file can access them..

When we download the iam we ONLY have the iam and do not have access to the ipt files because they are on your computer..

An iam only links to the ipt and subassembly iam files inside of it and does not include them in itself.

Zip up all the ipt files and the iam and attach the zip in the future..

But..

This is the lock rotation (DOF = degree of freedom) button he is talking about.. Its accessible with insert constraint selected..

Re: Assembly problems with rotation - Inventor 2019

JDMather — Fri, 24 Apr 2020 17:28:28 GMT

@Anonymous wrote:

What I just attached includes 3 parts?

A part file has the extension of form *.ipt

I do not see any *.ipt files attached?

Where do you live, I'll come over and get them.

Oh wait a minute, governor says no, can't do that.

You will have to send them electronically.

Re: Assembly problems with rotation - Inventor 2019

Anonymous — Fri, 24 Apr 2020 17:35:14 GMT

Ha ha! Ok yeah I just read the other guy's response too sorry, please find attached. Hopefull that works.

Re: Assembly problems with rotation - Inventor 2019

JDMather — Fri, 24 Apr 2020 17:38:26 GMT

I don't own a rar extractor - I have only Window OS for zipping/extracting folders.

Re: Assembly problems with rotation - Inventor 2019

Anonymous — Fri, 24 Apr 2020 17:41:34 GMT

Sorry, please find attached.

Re: Assembly problems with rotation - Inventor 2019

JDMather — Fri, 24 Apr 2020 17:43:18 GMT

I will take a look at your assembly...

Re: Assembly problems with rotation - Inventor 2019

JDMather — Fri, 24 Apr 2020 17:46:26 GMT

Mate YZ to YZ and you should be good to go.

Re: Assembly problems with rotation - Inventor 2019

Anonymous — Fri, 24 Apr 2020 17:58:10 GMT

Sorry can you just clarify exactly what you mean by the please? All I think of there is the axes of the whole work space?

Re: Assembly problems with rotation - Inventor 2019

Anonymous — Fri, 24 Apr 2020 18:35:14 GMT

Ignore the other response, I just saw the video ou posted which nails it thankyou! Massive help that was and very much appreciated. Are you any good with Autodesk CFD?