topic Inconsistent Relationships with linear motion components in Inventor Forum

Inconsistent Relationships with linear motion components

Anonymous — Fri, 12 Feb 2016 14:17:12 GMT

Hi Everyone,

We are roughly a year into Inventor and there is one problem has been more problematic than any other. Inconsistent relationships. We use alot of slides that are constructed of linear guides (THK, Hiwin, Etc.) or complete guided linear actuators purchased from vendors (Parker, Festo, etc.). We seem to almost ALWAYS run into inconsistent relationship issues with the linear guides. This is our current process: Download the linear guide assembly from THK (STEP), save as Inventor file, constrain the blocks that move to the rail, then insert this assembly into our main assembly. We then will usually constrain the rail to it's mounting detail, then make it flexible and create applicable posiitions (showing slide forward and returned, etc).

At some point from then on as our assembly progresses, we eventually start getting "inconsistent relationship" errors and they point to the constraints that we made WITHIN the linear guide assembly, i.e. the blocks to the rail.

Is there some known issue with a flexible component that when you have it in an assembly and then set up positions it just doesn't like it?

Could there be issues with importing STEP or IGES files, and using them as flexible to show motion?

Thanks for any suggestions.

Ron

Re: Inconsistent Relationships with linear motion components

JDMather — Fri, 12 Feb 2016 14:22:01 GMT

Can you attach an example assembly that exhibits this behavior?

Are you running Quality Check on the imported geometry?

Are you using Origin Planes rather than part faces to constrain?

You mention both Flexible and Adaptive - are you using Adaptive only when really needed?

Re: Inconsistent Relationships with linear motion components

Anonymous — Fri, 12 Feb 2016 16:55:00 GMT

Ok, first silly question...How do I get the assembly attached here with the parts as well (excuse my ignorance, never attached a working assembly before).

Was not even aware of a Quality Check feature. Orignally I believe we were constraining the parts using the planes, and when we started to see the issue, we started to try and mate faces to faces.

Re: Inconsistent Relationships with linear motion components

blair — Fri, 12 Feb 2016 17:08:19 GMT

Care must be taken if using the Flexible option within IAM's. If you are dragging the "Flexible" items into different positions, you can drag the items faster than your system can calculate the constraints/limits within Inventor.

This allows flexible IAM's to become sick with respect to constraints. Either drive the range of motion through driven constraints or use iLogic with sliders to control the range of motion.

Re: Inconsistent Relationships with linear motion components

JDMather — Fri, 12 Feb 2016 17:14:28 GMT

If all of the files are in one folder - simply right click on the folder and select Send to Compressed (zipped) Folder. (delete the Oldversion folder first)

Attach the resulting *.zip file here.

If the parts are in different locations - from the assembly file go to Save>Pack and Go, we don't need all the libraries and temlpates, so check/uncheck as appropriate.

If the *.zip file is greater then 7 Gig, post back for instructions on how to upload to A360 Drive and make public link to download.

Re: Inconsistent Relationships with linear motion components

Anonymous — Mon, 15 Feb 2016 14:12:26 GMT

Here is the assembly.

Re: Inconsistent Relationships with linear motion components

JDMather — Mon, 15 Feb 2016 15:19:18 GMT

I didn't get the error with your file.

But -

I would use the existing Origin workplanes in the parts to constrain, rather than creating new workplanes or using part faces.

Are you working in a mixed unit evironment (inches and mm)?