I've not seen this "open polysurface" problem before

rhino5

#1

Usually the extrusions of the tooth profiles join up without any issues. I don’t know what I’m doing differently other than this is a larger diameter gear than I usually work with and it has an almost flat pitch angle. I’ve looked at Analyze>Edge Tools>Show Edges>Naked Edges but have no clue how to use that to solve the issue.
Any help would be greatly appreciated.
https://1drv.ms/u/s!AvbRThajlgqAhhIrQZBfg0eEKbL5


#2

it is supposed to be open, its only closed when it creates a closed volume with surfaces from all sides. how will you proceed with this is, it going to be a metal or rubber gear ribbon? the only thing it needs is a volume below or above it then to become a closed object.


#3

I thought so. I tried extruding it to the back cone apex but that didn’t work.

I’ll keep plugging away at it. Thanks for responding RichardZ.


(David Cockey) #4

A naked edge is an edge which belongs to only one surface. A closed surface or polysurface will not have any naked edges. Conversely an open surface/polysurface will have naked edges. First step in determining what is causing an open rather than closed surface/polysurface is to find the naked edges.

Start ShowEdges and a panel pops-up. In the panel there is a box for selecting the edge display color. Pick a color that is different than you model. Click on Naked edges under Show. Now the naked edges will be displayed and the number of edges and naked edges will be shown in the command line box. Look at the naked edges and determine what is needed to eliminate them.


#5

Are you trying to make something like this?
Large_Bevel_GearX.3dm (6.5 MB)


#6

Precisely, jim. Thanks. At the moment the notification of your reply hit my inbox, I was in the process of attempting to:

  1. Transform>Stretch>BothSides the polysurface symmetrically along the X-axis

  2. Extrude the polysurface to the apex of the back cone

  3. Trim the resulting “stretched” solid using conical surfaces I’d generated as well as a planar surface below.

I wasn’t having any luck extruding the polysurface. How’d you do that?


#7

If I understand you were trying to make the sides of the gear by extruding all those little surfaces to a point.
That’s seems like a recipe for disaster to me. The shape of the sides are cones. If you make the cone shape that way each cone will be composed of more than a 1000 conic bits. There are numerous ways to make the sides as single trimmed surfaces there is no good reason I can see to make it fractured into thousands of tiny surfaces.

I don’t think ExtrudeSrfToPoint works with polysurfaces. If you use it on the exploded teeth surfaces it will produce thousands of internal surfaces as well as the outer surfaces that you are trying to make into a cone.

I made the side surfaces using the Loft command. One surface by lofting the red circles and the other by lofting the blue. I then extended the surfaces using ExtendSrf command. After that Trim and Join can be used to connect the side surfaces to the gear surfaces.

You could also make the side surfaces by using the Cone command or you could extrude a circle to a point. Make the cone so that it extends past the teeth on both sides - that way you can trim off the side you don’t want with one clock of the mouse.


#8

Awesome! Thank you! I’ll try that.


#9

jim, that is so cool! I cannot thank you enough. BTW, trim didn’t work for me, so I went back to look at Visual Tips for a refresher on the Trim topics and from there tried Split and Join! Voila!

I’ll try the Cone command and/or extrude a circle to a point for the pinion.

I love Rhino because it is awesome and so are folks like you who help a newcomer like me out.