projected curve

joerg_haas

Hi

why doesn't regenerated the prpjected curve in
https://cad.onshape.com/documents/3853a2680da33876296aeca7/w/4afdb79d3cc9fb9d2679b267/e/cd03e5f00a79cf73486e1084
thanks
joh

paul_chastell

Projected curve is a relatively simple feature. It takes the two sketches, extrudes them and intersects the extrusions to get a curve. If that results in a self-intersecting result or more than one result it will fail. I edited your doc and extruded both sketches. The visual intersection between the gray and the blue is where the curve would be. In this case the surfaces fail to intersect for a short interval near one of the ends, causing it to fail. In general touching at the ends is valid, it is the slight over-shoot of one of the curves (plus its return to touch at the end) that causes the issue here.

michał_1

It looks like original curves can't touch each other:

NeilCooke

At the top of sketch 2 there is an inflection (meaning the curve goes back on itself). This would create a curve that self intersects and fails (imagine extruding 2 surfaces and trying to trim one with the other).

NeilCooke

Maybe I was a little hasty with that last post. Self intersecting curves give multiple results. Perhaps a gap is required (I will ask later when HQ wakes up)?

NeilCooke

I was able to recreate something simpler with touching curves that worked. Must be a self-intersecting issue. Stay tuned. 

paul_chastell

Projected curve is a relatively simple feature. It takes the two sketches, extrudes them and intersects the extrusions to get a curve. If that results in a self-intersecting result or more than one result it will fail. I edited your doc and extruded both sketches. The visual intersection between the gray and the blue is where the curve would be. In this case the surfaces fail to intersect for a short interval near one of the ends, causing it to fail. In general touching at the ends is valid, it is the slight over-shoot of one of the curves (plus its return to touch at the end) that causes the issue here.