topic Re: CANNOT CREATE ARC LENGTH IN IPT SKETCH in Inventor Forum

CANNOT CREATE ARC LENGTH IN IPT SKETCH

avaya2012 — Wed, 07 Jun 2017 20:49:57 GMT

First off, I am using Inventor Pro 2017. I have had this issue a few times in the past and know a work around but would like to figure out my issue. I am drawing a piece of bent pipe using a sweep and a shell. I want to add the arc length to the bend as a driven dimension so I can get an overall length, but Inventor is not allowing me too. The error box pops up and says "Failed to create arc length dimension." Most of the time I get the error that reads "Adding this dimension will over-constrain the sketch. Choose Accept to create a Driven Dimension." My work-around is to create another sketch and throw my driven dimensions in that which works fine.

It actually won't even allow me to create an arc length as a standard dimension in the original part sketch.

Why is it not allowing me to create this driven dimension? This part was created in an older version of Inventor but is migrated. I can create a new part and get all the dimensions I want.

Thanks,

CWW

Re: CANNOT CREATE ARC LENGTH IN IPT SKETCH

TheCADWhisperer — Wed, 07 Jun 2017 21:02:36 GMT

Can you attach the file here that is exhibiting this issue.

Are you attempting to (driven) dimension a sketched arc - or are you attempting to (driven) dimension a Projected arc?

Try setting the Driven Dimension flag before dimensioning the arc.

Re: CANNOT CREATE ARC LENGTH IN IPT SKETCH

avaya2012 — Wed, 07 Jun 2017 21:03:26 GMT

It is a sketched arc. Basically the centerline of a pipe with 65° or bend. So two straight lines, an arc connecting them, and a few construction objects.

I have tried setting the radius of the arc, deleting the dimension, and creating the arc length as a standard dimension with no luck.

Just attach it as an .ipt file? I have never attached parts here before, just screenshots. I am done for the day so will get your next response tomorrow.

Re: CANNOT CREATE ARC LENGTH IN IPT SKETCH

avaya2012 — Wed, 07 Jun 2017 21:05:57 GMT

OK, it looks like my attachment is there. Let me know if it works or not.

Re: CANNOT CREATE ARC LENGTH IN IPT SKETCH

TheCADWhisperer — Wed, 07 Jun 2017 21:16:01 GMT

This one is a strange one.

I would perhaps attribute the issue to the fact that the original file was created in 2008, but my testing was inconclusive.

I created a new fully defined arc in a new sketch and had no trouble with driven dimension.

I went back and changed the arc in Sketch1 to construction and then sketched a new arc over top the original sketch and could not dimension.

I deleted the original arc and placed a new arc and could not dimension as driven dimension.

Re: CANNOT CREATE ARC LENGTH IN IPT SKETCH

johnsonshiue — Wed, 07 Jun 2017 22:47:06 GMT

Hi! I see the issue now. The behavior depends on combination of constraints and dimensions. Arc length dimension may require more degree of freedom to solve correctly. I will need to work with project team to understand this behavior better.

Many thanks!

Re: CANNOT CREATE ARC LENGTH IN IPT SKETCH

rhasell — Thu, 08 Jun 2017 00:01:35 GMT

The sketch is in an overconstrained condition.

Delete the one coincident constraint, and it will allow you add the arc length dimension. Instead of the co-incident, replace it with a collinear constraint.

Refer to image below.

Re: CANNOT CREATE ARC LENGTH IN IPT SKETCH

Anonymous — Thu, 08 Jun 2017 10:20:06 GMT

Arc length as a driven dimension in Inventor does not work. Have tried it a few times in 2014 and even as a driven dim the sketch cannot be changed until you delete the arc length dimension. I am using 2016 now and have not tried it but do not expect any better results.

No help in your case since you work with pipe but I work in conveyors and arc length helped calculate belt length. Now I model the belts as sheet metal so I get a flat length.

Re: CANNOT CREATE ARC LENGTH IN IPT SKETCH

TheCADWhisperer — Thu, 08 Jun 2017 14:00:32 GMT

@Anonymous wrote:

Arc length as a driven dimension in Inventor does not work. .....

Could have fooled me - can you post an example?