adding non-planar holes into a curved surface

Andrew_Netherton

I am trying to figure out how I would put a series of holes into a curved surface.  The surface is a flange off of an inclined plane that is at an angle with respect to the axis of the curve.  You can see an example in the model below:

https://cad.onshape.com/documents/137547d8c29926caf9a25cff/w/fae9d09a918dbffcb6e6d8d1/e/007b84dfa9b77331494d0c4a

I am trying to put radial mounting holes for an exterior panel on the orange face that are at the midpoint of the flange at their location.

So far I can't see any way but to do each one individually, but I have to imagine there's a better way I simply don't know about.  (Been on Onshape professionally for only 5 months now.)

glen_dewsbury

Something like this?
https://cad.onshape.com/documents/fde7beb02d869a73f1d45706/w/9557b07e898fd3b84dbbe29a/e/9ca6f11ac19caf00147c80d9

glen_dewsbury

Something like this?
https://cad.onshape.com/documents/fde7beb02d869a73f1d45706/w/9557b07e898fd3b84dbbe29a/e/9ca6f11ac19caf00147c80d9

Andrew_Netherton

Very much exactly like that @glen_dewsbury! Thank you!  Now to reverse engineer what you did....

S1mon

You may find some useful tricks in here too:
https://www.youtube.com/watch?v=B0GLmOJVqho

ian_gardiner

Hey Andrew! How do you feel after 5 months of professional Onshape use?

Andrew_Netherton

Hey @ian_d_gardiner! While I'm glad I made the switch, there are still a few areas that are frustrating, like the lack of 3D sketches, and Frames not being as fully-featured as SW Weldments.  Mostly I just need to get more active here on the forum so I can learn more from others.  I'm definitely not going back, I just need to persevere and learn!

Andrew_Netherton

@glen_dewsbury I tried to implement your solution this morning, but the offset curve is not behaving the same way.  Your curve offset axially along the circular surface, whereas when I try it, it doesn't.  It seems to try to determine a best fit circle, find the axis of that, and offset, which results in the curve actually being buried under my surface, not on it.  Perhaps instead of an offset curve I should try an intersection curve?



I'll fully admit that the sample I gave was simplified, but I figured it was close enough - maybe not!

glen_dewsbury

Curious. Here is a screen shot from offset curve when I select. Yours looks chunky like low resolution of the selected edge. If that is true it can be verified by changing view to high quality during the operation. Assuming you have a smooth curve to start with and not an angled edge.
Did you view the video S1mon posted? Greg Brown's videos are very helpful.

Andrew_Netherton

I did review the video, there's some customization there that I'm not up to speed on.  Yes, my image is rather "chunky", it's usually better but that was a quick zoom in to show what the curve was doing, it's a graphical thing, not representative of actual geometry.

I've just discovered that I had to flip the direction of the geodesic offset to get my curve on the correct face.  Perhaps now I can progress further!

glen_dewsbury

BTW Did I mention flip direction? 

Andrew_Netherton

I'm taking the shotgun approach now, flip everything, try every option!

What I'm attempting now is going inside-out, starting on the inside of the flange and going out, only because the panels on the outside are not being very accepting of my offset curves.  Better to go from the inside and "through all", I figure.

Andrew_Netherton

Partial success.  My offset curve is working, my hole is working (except with the sheet metal part on the outside, that's a Support ticket currently), but now that I've managed a pattern all along said curve, my holes look like this.  Well, not the first one, or the last, but around the back they're decidedly skewed.  Is there some method to tell the patterned holes to keep their axis parallel to a given plane, or some other such constraint?

If there's not enough context in the image, the axis of the hole is severely angled compared to the flange face.  The fact that it's not going all the way through I can manage, but the angular misalignment is a head-scratcher.

glen_dewsbury

@Andrew_Netherton
Note that in my original hole pattern I used 2 offset curves then added a 3d fit spline between the 2 ends. 3D fit spline with only 2 inputs is a line. The end of the line was used as a mate connector for the hole. That made it perpendicular to the face at that point. See sketch 7 for second curve.

Andrew_Netherton

I got there through slightly different means, but I used a similar process to get a mate connector at the start of the pattern.  I suppose the difference is yours actually works and mine doesn't.  I missed the detail that yours is a 3D spline, however.  Mine is only a sketched line.  I'll try that and see if I gets me to where I need to be.  Thanks again!

Andrew_Netherton

The 3D spline technique worked as well as my sketch did, but unfortunately no better.  I'm going to see if I can simplify this somehow.

Thanks for the assistance everyone!

glen_dewsbury

@Andrew_Netherton
I had another go at this after seeing the problem you still had with holes not normal to surface and came up with this. Hope it helps.
https://cad.onshape.com/documents/fde7beb02d869a73f1d45706/w/9557b07e898fd3b84dbbe29a/e/9ca6f11ac19caf00147c80d9