Patterned Sketch won't close

[ninjarunner1007]

I've run into this problem with different sketch types when curves cross each other and are trimmed, or when patterned sketches are coincident. The problem I'm having is that I'm creating a ratchet wheel and I'm patterning a sketch in two parts so that the spacing for the teeth line up. What I do first is draw the angled line of the tooth, do a circular pattern of 20 teeth around the origin, an then create an arc from the bottom point of each line to the tip of the next line to create the back of the tooth. When I try to extrude it, it says the loop is not closed, but when I do the repair, it says it overconstrains the sketch and is not possible. I've tried creating this profile using a center circle that intersects the bottom of the teeth and it does not work either. I was able to make the profile I needed by making one tooth, extruding it, patterning the feature, and then creating a circular sketch in the middle and extruding it. The problem with this (aside from requiring additional steps not needed in other programs) is that when I needed to go back and change tooth dimensions, it can't rebuild the sketch.

I attached two different sketches of the non-closed profile as well as the solid ratchet piece that I made using the pattern feature command that has the teeth that can't be easily edited.

Thanks for any and all help.

[JDMather]

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@Anonymous.berger wrote:

I'm creating a ratchet wheel and I'm patterning a sketch in two parts so that the spacing for the teeth line up. I attached two different sketches ...

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Sometimes the Sketch Doctor will fix these patterns, but -

it is almost always better to create simple sketch (right click on your complex pattern sketch and select Show All Constraints) and pattern feature rather than sketch.  (Inventor has to figure out all those sketch constraints.

There should not be any significant problem editing sketch, feature and pattern.

I don't see any attachments here.

[ninjarunner1007]

Thanks for the tips but the problem still persists. I did do the single feature and pattern it, but its sketch can't be easily edited.

I tried the sketch doctor, and it says there's extra points and open loops. However, when it tries to repair the sketch, an error message shows up saying that it will overconstrain the sketch and so it cannot be done.

I'm not sure why the attachments didn't show up, is there an upload step that I'm missing? I tried to attach them again, maybe they'll show up this time.

Thanks

[JDMather · Accepted solution]

All 3 files you posted have patterned sketch.
I would never pattern sketch for a part like that.

Count the number of constraints in my sketch.               Count the number of constriants in your sketch.

I just realized that the .241 is redundant and wrong.

See attached ipt file.

This could be why your sketch failed.

You have an appoximation dimension rather than exact dimension.

Rather than use an approximation you should use a function of the number of teeth.  (that is actually 360° the 3 got cut off in the window)

[ninjarunner1007]

Thanks for the help.

While the drawing you illustrated is much simpler, I still think the sketch pattern feature has some problems. That redundant dimension was only used in the one solid model file (RW2) but in the two other sketches, it was not used and the spacing was determined by the patterned sketch itself. 95% of the constraints are just the pattern constraint for the sketch geometries, which should not make the sketch open (or unrepairable).

[sebastafoya]

yeah, having to deal with this kind of problems is just stupid to me

[JDMather]

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@sebastafoya wrote:
yeah, having to deal with this kind of problems is just stupid to me

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Yes, I never have to deal with this kind of problem - because I don't create this kind of problem.

Do you have a problem you need help with?

If so, can you attach your file here.