Extruding a fully constrained sketch

[Anonymous]

Hi,

I'm having trouble extruding a fully constrained sketch. The sketch is a cross-section of a hollow cylinder that is splined on the inside surface (see attached part file). The line segments that create these splines seem to be grouped together because moving one line moves the others, however the sketch will not extrude.

I can't use the coincident constraint button to group the lines because they don't separate from each other. I also tried to use the close loop button but was unable to select all the necessary lines.

Any help on how I can extrude this sketch or make an equivalent sketch that is easier to extrude would be appreciated.

[Anonymous]

While in Sketch mode right click on your sketch in the browser and run Sketch Doctor. You will see your problem.

[japike]

If you delete your sketch pattern and make closed loops of your splines before patterning, it works fine. I wouild also consider using a feature pattern for the splines instead of a sketch pattern.

[Anonymous]

Thanks.

I tried doing this but had trouble making closed loops - I wasn't able to click on all the lines. So I used the sketch doctor and it said that multiple sketch points existed at the origin but then it wouldn't combine them because that would over constrain the sketch.

[japike]

What version of Inventor are you using?

[Anonymous]

Inventor Professional 2012.

I made the splines an almost closed loop before making the pattern (I couldn't close the end points because I don't have a closed boundary until I make the pattern). Then after doing the pattern I closed the end points using the sketch doctor, although it made my sketch no longer fully constrained.

Also the sketch doctor said I had overlapping curves but I don't think I do because I drew each arc starting from where the previous one finished. I was able to extrude the sketch though. Hopefully I don't have any problems making an assembly with this part.

[japike · Accepted solution]

I'm using 2013 and don't have 2012 installed so I can't send the part. But, you might be able to see what I did in the attachment. I made the highlighted geometry a closed loop before patterning. I would normally make that area a seperate extrusion and pattern the feature.

[Anonymous]

Thanks, I can see what you've done.

[Anonymous]

Thanks, using the sketch doctor helped.