Bevel on a hole inside of a cylinder


#1

Hi, I looked through similar question, but haven’t found advices of how to do what I’m trying to do. I’ve intersected two cylinders and get a hole in the one of them (look at the picture, pls: http://tinypic.com/r/sct0ds/9).

  1. The problem is that I need bevel on the edge of the hole and I have no idea how I can do that. I’ve tried to use cones, but this way bevel has different length: up and down of the hole look wider, than left and right sides of the hole. I’ve tried to search through plug-ins, but there are too many of them.
  2. Another question about the same scene is that after intersection I’ve got some nasty artefacts (looks like shaded triangle faces) on the cylinder and it looks like there is no way to clean that up - no edges, no nothing (http://tinypic.com/r/sg4v4j/9).

I would really appreciate any suggestions of how I can do that or what plugin I could use.
I’m using SketchUp Make 15.0.9349.


#2

You understand, of course, that the distorted-looking bevel is actually correct. That’s how it would look if you machined it out of bar stock.

Still, you can achieve what you want by simply distoring the cone producing the bevel to counteract the curvature of the surface. In the following picture I made the cylinder and bevel contrasting colors for clarity:

When you look at this bevel straight on, it appears round although it actually isn’t:

-Gully


#3

@Gully_Foyle, thanks a lot for the response. I’ve successfully used this method. The only thing that concerns me is that I have to do scaling without any measurements. I mean that hole radius is exact (I have a measurement), but cone that corresponds to it has to be scaled by eye and I’m afraid I may loose precision. So, I wonder if there is any way to do it precisely.

On the other hand, I’ve discovered, that in real life (I model guitar head) it’s actually not round over the circle. I’m talking about pegs - they’re “done” using non-scale cone. I haven’t seen that, because pegs are really small and the bevel really thin there.
Although for the sake of learning how to use SketchUp I’d still want to know how I can do that.

I tried to use parallel projection and standard views left and right to scale the cone to a circle I’ve created for that, but the result is still non precise. I’ve discovered that separate cone gives a little bit worse result, than the cylinder with sort of cones on both ends (before intersection). The reason is that it’s hard to collate edges on cylinder (hole) and cone.


#4

Whereas this is an interesting exercise in projection geometry and SketchUp technique, it begs the questions “how would one create that hole in the real world?”, and “why?”. Machining it precisely would likely be just as difficult as drawing it precisely in SketchUp!


#5

@slbaumgartner, excellent question! =)) I’ve got the same one after spending couple of days trying to figure how to model that.


#6

Not sure how exact this is (because i fear math), but you can use Fredo6’s RoundCorner on that geometry (hole through a round surface).


#7

It’s not real. It’s actually a saddle shape. How can you be concerned about the precision of something that doesn’t actually exist, or that is at best an optical illusion? The whole point is how it looks to you, not the true mathematical intersection between a conoid and a cylinder. You can have precision (as in fidelity to reality), or you can have an optical illusion. Choose one.

Edit: Strike that. You could certainly measure across the bevel both horizontally and vertically as you fiddle with the Scale tool. When you get the two measurements the same, you will have arrived at your destination.

I guess the real-world equivalent to that would be to walk around the rim of the hole with the world’s smallest router.

-Gully


#8

Well, It’s definitely not possible (or close to not possible) to make such a thing using drills, but nothing stops you from printing that, then making a mould and then finally cast it in metal to actually have it… real. So, I can’t agree on just one, I need both :wink:
Even if I’m completely wrong with making it in metal, it’s still a good exercise to know SketchUp better.

@TheOnlyAaron,
thanks for the advice, I will try.


#9

The only down side is the RoundCorner does not work if the cylinder is at all deformed… I tried on the peg below, but ended up using Gully’s method…


#10

or using a de-buring tool…

john


#11

I’m not exactly sure what you just said there, but it looks to me like the tiny hole in a guitar tuning peg–at least this one–has a normal-looking bevel, and by that I mean the intersection between peg and bevel is non-round. Observe:

-Gully


#12

Maybe I’m not understanding what’s at issue, but if you use a double tube you can specify the exact circles you want. The skinned bevel isn’t part of a cone.


#13

@Box, this looks like what I want, but I can’t figure out what did you do to get from left model to the right one. Here is what I have, I mean I can delete the double tube and have my hole through, perfect circle around it on a surface of the curved cone, but I don’t know how to create the bevel from here.

I’ve tried to scale the tube, but I’m getting pretty nasty artefacts. Bottom radius is ~2000mm, so there shouldn’t be any round errors.


#14

I think @Box used Solid Tools, Split and Union, to get the desired shape.


#15

Probably just performed the two intersections and used Curviloft to skin the opening.

-G


#16

Yep Gully got it. Intersect, delete excess including the face between the circles, scale the inner tube then Curviloft to skin.
Technically impossible to machine, but no problem to print or cast.


#17

I love the way SketchUp sages understand each other :wink:


#18

@Box, finally I’ve made it. Thanks a lot!