Solid Union driving me crazy!


#1

How can you verify that several extrusions can be boolean unioned? I am trying to make a bevel gear. I created a single tooth and then polar array to create the 43 finished teeth. But I can’t combine them and I can’t see what the issue is. See the simple source file attached for what I’m trying to do.

BevelGear.3dm (1.3 MB)


#2

first of all you created a little micro hole, so your array was probably a little shifted if thats not intended, but i believe not because its really small having them flow into such an aperture style.

so if all that is ok for you and even wanted then you can explode the elements and delete the inner walls where they touch manually tooth by tooth and join them all together.

quickly achievable with a clipping plane like here

otherwise i would recommend building that up from scratch with an open element which you quickly join together in the end for example.


#3

Thank you. I did not intend to have the micro hole. I extruded to a point and the ending point was supposed to be at x=y=0 but perhaps not or perhaps the outer circle was not centered although I created them that way.

I understand what you are saying with removing the inner walls and I know about clipping planes but I’m not sure what the illustration with the clipping plane is showing?

I have the curves for the end profile but I’m not sure how I would “open” it and extrude. I have been using Rhino for a few years and am pretty proficient on many things but I still run into the occasional issue like this. In fact, on this part, the surface for the tooth face originally extruded “inside out”. I had to change the direction
: Analyze->Direction of the curve in order to extrude it correct side out. I still don’t understand why but that worked.


#4

Ok, did a little experimenting using your recommendation. I unjoined the tooth profile curve and then polar array just the top parts of it to create this:

I selected them all and used Join and get a single surface. I thought I should use the surface edit tools like Match or Merge but neither worked.

Now, I actually intend to have a flat bottom (the “disk” you see) instead of the tapered bottom in my original post. This seems to be getting me closer to that. I also polar array copied the bottom edge to create the 43 sided figure you see in the drawing and joined them. Oddly that was an open curve. So I closed the curve and then used Patch to create a surface for the bottom:

But now I need to figure out how to close it all up as a solid.


#5

You just need to draw one surface -> ArrayPolar -> Join everything.


#6

the clipping plane was just to show a quick method how to get rid of all the inner walls fast. but since you have to build that up once more you can forget about that part it seems anyway.

yes i just wanted to suggest that but the lower part you keep from the curve. just delete the sides like here and extrude them to the point. you can also array all the curves till they build the circle and extrude then.


#7

RichardZ, that is basically what I’ve done as shown in the 2nd screen shot above. Now I can’t figure out how to fill in the opening around the perimeter.

@MarcusStube - I’m not sure what you mean? I think that’s what I had originally done that didn’t work.


#8

just do what he suggests additionally for the front surface and you can join all together including the extrude lines. or you only take the front surface array which you can join together and extrude the boarders from it to the point.


#9

I’m struggling to figure out how to join the correlated “cap” and the flat multisided disk to create a solid. Nothing I’ve tried works.

I also had tried your suggestion RichardZ of keeping the bottom segment, extruding to a point and then polar array. I’m having the same issue with figuring out how to join the top and bottom into a solid. In fact, once I had done it this way, I realized I didn’t need to include that bottom segment in the extrude to point and instead simply polar array and join them to create a flat bottom surface like in the drawing - which is actually what I want.


#10

yup i must say i was a bit a concerned if that was going to be a structural gear the center would´ve become crazy thin. so you can create a second point for the lower surface or you make it flat. one idea is since the curvature of the upper part is as round as the lower part you could just simply loft the perimeter up and trim it off join it all together done. that means deleting all the old front surfaces.

if it still does not work maybe post an updated file or at least the initial curve that we can help you.


#11

BevelGear2.3dm (4.9 MB)

Ok, here is basically everything in one file. I ended up patching one of the tooth profiles to make a surface and then polar array copied it. I then joined these to create the outer perimeter surface. I was then able to join this to the top and flat bottom. So all “seemed” ok (la on words pun intended) but there is something wrong with the resulting solid - it is in the file. I analyzed it but I didn’t see anything odd. But when I create a mesh (this is for 3D printing) I get a weird artifact “web” between teeth and an open mesh.

The two cylindrical surfaces are intended to be used to boolean split the gear to end up with a big hole in the middle and vertical outside surface. I get a failure trying to spit the gear though. Most likely related to the issue I get with the mesh?


#12

Layer 13 has the mesh so you can see what I mean about the web.


#13

i have found that minimum one maybe more has double front surfaces at least in the old file still. that may join together but leads to severe problems like maybe your artifact.


(Pascal Golay) #14

I’d use a revolved surface for that outer surface I think.

@Michael_Hackney see how this approach works for you: BevelGear2_PG.3dm (1.5 MB)

-Pascal


#15

I found and removed the double front surface.

@pascal - isn’t that what I’m doing - revolving the surface (polar array)?


#16

or revolve yes. nope Michael you used array thats something else.
and the curve which you used to create the upper point i assume, is also not precise.


#17

I think I’m going to have to rethink this. Everything I do results in open meshes or artifacts. I started with an open source mesh (STL) and traced the tooth profile. The gear itself is perfect for my project but I need to rework it - the hub and a few other elements. But the tooth profile is not perpendicular to the X-Y plane so I’m trying to reconstruct something slanted that needs to be polar array copied 43 times and it just ain’t working. One would think that in 2017 there would be plugins or an app (affordable/free) to generate simple bevel gear profiles. I can easily construct a simple spur gear but the stuff I’ve seen on creating a bevel gear from scratch is daunting.


#18

Is this what you are trying to get? BevelGear_re.3dm (2.2 MB)


#19

Yes with the matching pinon in a specific size. Where did you find this Marcus?


#20

Wow, I see that it is my gear done right! I just have to learn how to do stuff like this.