Projected curve fail

matias_ramirez · February 6

I am following a timelapse of how to create the mandalorian helmet in onshape, it is an old video and the UI differs a little, but it is manageable. this is the link:

https://youtu.be/iUQScBx-InQ?si=BBDtbfhSbmYR7PD7

I see in the tutorial, the guy created a front plane and a sketch in there, and then a right plane and a similar sketch there.
Then with the projected curve he is able to create a intermediate sketch selecting the lines, but in my case it is fails.

In the picture I am selecting the orange lines from each sketch plane, and then I hope to get the green one, but not happen.

this is the part where he uses the projected curve perfectly:
https://youtube.com/clip/Ugkx2w-rGIFo808Eq-b6FT5yFH7EVXeuEDhY?si=7Cb7_qstyrDE_H0r

What is the reason? it works for the guy with the time lapse.

thanks for your time

martin_kopplow · February 8

Projected Curve worked for me the other day. There are certain conditions, though. Maybe you could share a file of yours where it does not work, so we could help.

Image: https://us.v-cdn.net/5022071/uploads/editor/7m/qh1jhueqccis.png

https://cad.onshape.com/documents/f5478b892985b6d7289f6be7/w/66a73f174e112e9f1fb76571/e/917d80d3c252463864fb1105?renderMode=0&uiState=65c4aae20d033b564fa76cd5

matias_ramirez · February 15

hello, thaks for your answer. this is the document: https://cad.onshape.com/documents/7a48a6bc8cd52d276652720a/w/e00a5c506aa0f6d2aafcaa8e/e/63a8ac1759f340f5bb1815a7

matias_ramirez · February 23

martin_kopplow said:

Projected Curve worked for me the other day. There are certain conditions, though. Maybe you could share a file of yours where it does not work, so we could help.

https://cad.onshape.com/documents/f5478b892985b6d7289f6be7/w/66a73f174e112e9f1fb76571/e/917d80d3c252463864fb1105?renderMode=0&uiState=65c4aae20d033b564fa76cd5

I shared a link with my project, could you check please?

martin_kopplow · February 24

@matias_ramirez

I'm sorry I didn't read this any earlier.

Image: https://us.v-cdn.net/5022071/uploads/editor/bg/63fxek0bi9ay.png

https://cad.onshape.com/documents/87e8311bdb0fcdb5085c7a09/w/58ee85b3824c93ef66d3fb21/e/c2c0634fe76da7af9afffb33?renderMode=0&uiState=65da288d6cd98047c2ef690f

The point here is that - even if you made the end points on the same height, one curve of each of the couples in your sample has a portion the reaches higher up than the other curve. That means: No intersection is possible, for it takes two to intersect. In my sample, I just constrained the upper vertex handle to horizontal, and that did the trick. Now the end points are also the max Z. Look at the Plane 4 (upper point), which I added, to see where the limit is. If you want the curve to climb above that limit, you'd need to create a plane or vertex on the horizontal tangent, as a Z-reference for the second curve.

matias_ramirez · February 26

@martin_kopplow to be honest, I did not understand anything hahaha. Could you explain me if I were like a boy of 8 years? I speak Spanish and even trying to use google translate, I am lost.
Sorry thousand time

martin_kopplow · February 27

@matias_ramirez, I'm also no native english speaker, so we've got the double language barrier to climb over.

It is simpler than it appears, though:

If you look at your sketches, you'll find that on Sketch 2, the two curves go higher up, before reaching their top end points, than their projection partners on Sketch 15 do. Obviously, the program cannot compute a 3D intersection curve, when the projected curves don't intersect properly.

To analyze, try rebuliding the intersection using extruded surfaces:

https://cad.onshape.com/documents/209b21556d92e626bd1d24c3/w/81b16dd08dc3350585daeaec/e/2543114bff2e3ae585f56f02?renderMode=0&uiState=65de2a7dd680c14d088bb871

Image: https://us.v-cdn.net/5022071/uploads/editor/nj/exx6iyjq0j7o.png

Note the (yellow) intersection curve stops before it reaches the edge of the extruded face. That is the point where the second curve is too high to allow a fully defined intersection, as visible in this close-up:

Image: https://us.v-cdn.net/5022071/uploads/editor/ig/5e2k4embz0ou.png

Bring the second curve down a bit (like I did in my previous sample), or the fist up, and it'll work as expected.

matias_ramirez · March 1

martin_kopplow said:

@matias_ramirez, I'm also no native english speaker, so we've got the double language barrier to climb over.
It is simpler than it appears, though:
If you look at your sketches, you'll find that on Sketch 2, the two curves go higher up, before reaching their top end points, than their projection partners on Sketch 15 do. Obviously, the program cannot compute a 3D intersection curve, when the projected curves don't intersect properly.
To analyze, try rebuliding the intersection using extruded surfaces:
https://cad.onshape.com/documents/209b21556d92e626bd1d24c3/w/81b16dd08dc3350585daeaec/e/2543114bff2e3ae585f56f02?renderMode=0&uiState=65de2a7dd680c14d088bb871
Note the (yellow) intersection curve stops before it reaches the edge of the extruded face. That is the point where the second curve is too high to allow a fully defined intersection, as visible in this close-up:

Bring the second curve down a bit (like I did in my previous sample), or the fist up, and it'll work as expected.

thanks for your answer!
I was able to understand what you said, but I am not able to get the projected curve.
I extruded the surfaces as you explained, and the intersection is quite pertect, but it does not work