I’m self taught and have only been leaning for about 3 months, so this could be a very basic question. I’m attempting to create a part using reference geometry.
The seat on the left of image is the original part I’m using as a reference.
The center part is what I’m attempting to create. the edges of this part don’t quite meet up cleanly. I come from using SolidWorks, so the the finer points of cleaning up part and edges are still lost to me, but that’s a different topic.
I decided to start from scratch for the sake of practice and learning. the part on the right is as far as i got. this will be a fiberglass part so the object needs to have 2 degrees of draft from bottom to top. I’m not sure the steps need to ensure it has that draft uniformly around the whole object.
That is the only reasonable way to do this in Rhino. However you are off to a terrible start. In Rhino you should not try to model the part without draft and then “add draft” to that.
.
You should not do it that way in solidworks, also. The model in the middle demonstrates what a mess swx makes when you do it that way. Rhino’ draft angle analysis will show you where the errors in that model are.
Ideally you should model the part using flat tangent lines and arcs that you use to create drafted surfaces with the Rhino command ExtrudeCrvTapered. That will give you the best quality surfaces. In your file the original part is tipped 1.5 degrees. That doesn’t matter really but it will make it easier if you rotate the part 1.5 degrees so that the direction of pull for the draft is going straight up.
One of the things you have to decide is where you want to hold the dimensions. Usually it will be either at the top of draft or at the bottom. It looks like you are trying to hold the dimensions in the middle. So given that this is how i would add draft: seat mockupx.3dm (2.8 MB)
The way I did it (SplitAtTangents=No) produces a single surface which allows the whole thing to easily be extended since ExtrudeCrvTapered doesn’t have a bothsides option. You can use DivideAlongCreases command to turn it into a proper polysurface,
Thanks for quick feedback, this is is being used on a boat so the 1.5 degree needs to be there to represent the tilt of the deck. non-uniform shapes on a random angles, all no fun. I think the ExtrudeCrvTapered might be just what i need!
yeah but is there any reason to make modeling the draft more difficult then it needs to be? As I understood it the draft is required so that the part will draw properly when molded. How it fits with the deck is a separate problem.
Yes. And if you can arrange it so that all the surfaces that need the 2 degrees draft so that the part will pull easily when molded are made from planar curves composed of tangent lines and arcs the process for creating this part should be fairly simple.
I stress this because if you don’t use planar curves composed of tangent lines and arcs as your inputs for ExtrudeCrvTapered then you will get crappy surfaces and the whole process becomes a whole lot more difficult.
