I am new to nurbs modeling. I like it a lot. I have been trying to model a sheet metal stamped wheel caster for weeks. I have tried many different ways. the latest is boolean union of a cylinder with a box and subtracting the shape. I still have awkward transitions, especially the shrink surfaces and blends. I Maybe this model should be laid out flat like a blank sheet metal part and bent. Really stumped. Looking forward to have you model geniuses would tackle this. As always thanks in advance for your help.
Enclosed screen shots of the caster, and my Rhino file.
Hello- how accurate do you need to be? I ask because in your file, the objets that are circular or cylindrcal have different centers and none of them so far is at 0,0,0. I think the whole process will be easier of you get that all lined up and concentric on the origin.
If you have no known dimensions and are reverse engineering from the drawing only you can do things like place a bunch of points on a circle in the drawing and get a true circle from those (Circle > FitToPoints) which you can then use as a reference for the radius - but I’d draw a new circle centered on the origin, using the first circle just as radius info.
It does not have to be very accurate, you are correct that things are sloppy, I am really after the process. Solids as opposed to lofts etc. I just keep thinking about how to model this. Thanks Pascal.
Dude please I am trying to learn Nurbs modeling. I do not need a caster. It is a stamped part, hard to model the shrinkage. But thanks for the lead to McMaster.
Still, if things are not concentric etc as expected, other operations may suffer - it’s just good practice to make sure things are trued up and centered even if the thing is not for manufacture.
It is #2, and I am not reinventing the wheel, I am learning how to blend compound shapes together using nurbs. It is useful when designing. You got a gazillion videos on nurbs modeling. I just thought I would take something from scratch a stamped part which is difficult to blend and try to model it. I watched the video on the car hood by the Australian, and there were microscopic blends and lofts and tween curves, it was amazing. That is a learned skill.
You solved the biggest problem that I was having, it was blending the back to the front. I kept coming up with holes from the top blend to the side. It was maddening. I would fill the top go to the side fillet and there would be a blank spot. It is the area in green on your drawing. How did you model that? Was it a loft? And how did you get the curves from the two shapes? Using edge curves, which I have never done.
I meant to include more in the model i posted earlier.
Here is a better file: WHEELx2.3dm (735.3 KB)
I made the cyan as a revolve of the magenta curve. The pink parts are from your surfaces. They could be made as an extrude. Then I used FilletSrf to connect the pink and the cyan parts. After trimming with the fillets, I trimmed the whole thing with the red curve from the right view.
If you want to add thickness to this model, you should do that using offsetsrf before trimming with the red curve. Then after that you can extrude the red curve and use that to trim.
Curious did you do the filletSrf in sections. Because I did the top and had a gap from the side. I could not get it all around. You used curves all around the fillet?
Each fillet connects exactly two surfaces. If you run FilletSrf command and click on each pair of surfaces you can make every fillet in that string of fillets with FilletSrf.
if you want a slightly faster way to make all the fillets at once you can use the script described below:
