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over-defined sketch
kingsley_izima
Member Posts: 5 ✭
in Drawings
My sketch says it's over-defined and I can't figure out why. None of my constraints throw any error and I don't hav any blue lines, arcs, or points.
Please let me know why I'm still getting this error.
https://cad.onshape.com/documents/c41bf88704b55a0e07ce0ab8/w/c763dac8e4c74d54d1832945/e/1b567800de1b5be6c26c1727?renderMode=0&uiState=677d64625a75b67ae306d7b3
0
Comments
I believe that your sketch is UNDER-defined not over-defined.
I would recommend working on more complex sketches with "Show constraints" turned on.
The two ends of the R46 arc looked like they want to be tangent, but they aren't. Even after fixing those and reworking the constraints a bunch of times, I couldn't find the unconstrained geometry. The sketch solver gets weird sometimes with things that were created from offsets and fillets. I tried getting rid of the offsets and adding reference lines to make all the "offsets" equal manually. I was still baffled why this was unconstrained.
I went back to a basic principle, which is to put your layout in a separate sketch and then hang all the "offsets" and tangents off of that. In doing so, I found a bunch of hidden (covered by other sketch entities) points which were likely created during offsetting and trimming to create fillets. I deleted those, and was able to make everything constrained. I'm sure that the layout sketch and your front view could be rolled back into a single sketch, but separating them is probably better practice to keep things more manageable.
https://cad.onshape.com/documents/646f8abfd3573a2de3c6f26d/w/df652c88e6e878ee3eeb7df2/e/777907623d5ddcf88ba4cbc9
@kingsley_izima
I used "transform" tool to move objects off to one side, and discovered strange, under-defined artifacts left behind at the center points of the three lower circles - only you can answer where they came from. Also a weird point keeps popping up at the top left circle on the circumference at about 2 O'clock. There is a horizontal constraint at the top of the 44mm dimension leader to the other end of the arc (is it really supposed to be there?). I suspect the 44mm dimension is not accurate, and there are missing parallel constraints at the 28mm & 29mm areas - these are just the ones I found, and I still didn't find what's really wrong.
Because this sketch is not terribly complicated - my suggestion would be to take any notes you need , then erase and start fresh, being careful not to infer any bad constraints. It's all that unneeded, hidden geometry that's giving you the trouble - best not to put it in there in the first place. Try to use good sketching practices - the 2nd time is always quicker, and it happens to all of us.
maybe the sketch inspector tool can aid in finding duplicate and overlapping lines in a future update…. 😉😉
@kingsley_izima
@S1mon said The two ends of the R46 arc looked like they want to be tangent,
SIMON recognized the problem
In the GIF below - the sketch laid over the drawing has everything tangent
The GIF will repeat. If you don't see the GIF , then click below