topic Problem with changing sketch dimensions in Fusion Support Forum

Problem with changing sketch dimensions

Radischen — Mon, 01 Jan 2018 23:07:54 GMT

Hi there,

I’m a beginner and I’ve got a problem with changing a dimension (d104) in Fusion 360. I couldn’t find an answer in the internet. The dimension already exists, but I have to add 30 mm to it. And Fusion always tells me that that’s not possible: Failed to solve. Please delete or modify the following constrains/ dimensions: d104 : 120mm. I just don’t get what I’m doing wrong. I can edit other dimensions in the sketch. It’s probably a stupid little mistake.

But when I’m already writing a post here, I’ll add two other questions:

Why is the slot with the dimension d152 not fully constrained?

And why do center to center slots delete the dimension you’re setting when you’re creating them?

The file I’m talking about is attached.

Thank you in advance.

Re: Problem with changing sketch dimensions

laughingcreek — Tue, 02 Jan 2018 02:17:24 GMT

The sketch solver still has some kinks that need to be worked out. This is an example of one. It happens when additional geometry and constrains are added after a dimension. The additional constraints act to lock the geometry in the initial configuration, but don't throw an error about being over constrained. That doesn't happen till you attempt to change the original dimension. It's sort of a circular reasoning problem.

I would consider not warning about being over constrained sooner in the process to be a bug. @jeff_strater, what do you think?

Attached is a screen cast pointing to the 2 collinear constraints and the chain of dimensions that is causing the problem. deleting one of the co-linear constraints allows you to change the dimension d104.

Don't know the answer to your other questions. I'll note that dimensioning between the arc center points of the slot instead of dimensioning the line between them does make the slot fully defined. But I don't know why dimensioning he line doesn't achieve the same thing. It seems like it's fully defined that way also. Maybe a bug also?

Re: Problem with changing sketch dimensions

FrankCao — Tue, 02 Jan 2018 03:10:46 GMT

Hi antonio.roeder,

Thanks for reporting this issue. I think this should be a bug in Fusion sketch solver. Now I have reported FUS-37691 internally to track it and have sent it to our development team to take a look.

Regarding the question of "Why is the slot with the dimension d152 not fully constrained?"

I feel this should be a bug too. I don't feel this slot has more degrees of freedom. FUS-37692 is reported to track it.

About the question of "why do center to center slots delete the dimension you’re setting when you’re creating them?"

This should also be a bug and we will try to fix it soon.

Regards,

Frank

Re: Problem with changing sketch dimensions

Radischen — Tue, 02 Jan 2018 17:47:12 GMT

Thank you a lot, I edited my sketch like shown in the screencast. That solved the issue for now.

Re: Problem with changing sketch dimensions

Radischen — Tue, 02 Jan 2018 17:51:18 GMT

Ok, thank you for the information. I’m looking forward to the update.