Bevel with Follow Me not working on complex body?


#1

Hi all.

I am new here, and I hope my problem has not been discussed elsewhere, but I could not find it.

Here is my problem: I try to bevel a body. That works well with few subdivisions, but to get rid of the straight lines, I have increased the number of subdivisions. Now the beveling does not work anymore.
What can I do?

Thanks,

Florian


#2

I can just confirm that I’m seeing the same results as you. I’m sorry I don’t have a bullet proof solution for you but I think there are a few plug-ins that probably could do the trick. I tried Round Corner from Fredo6 tools and that seems to work a little bit better although I had to erase a few faces with that tool as well.


#3

…a funny thing is, if you draw the shape or bevel on the outside of the shape it all seems to work so maybe that’s your workaround.


#4

120 segments for an arc is way, way too many for nearly any imaginable purpose, certainly for a surface whose only job is just to sit there and be looked at. There are many adverse consequences to using more segments on curves, arcs, and circles but hardly any upside.

First, do not judge the the smoothness of an object’s appearance if the object is just a 2D outline. Once the curve is incorporated into a shape, and the shape extruded, you will see that number of segments doesn’t play nearly as great a part in apparent overall smoothness as other factors, including uniformity of mesh size. When you look at a 3D object whose curved surfaces have been softened/smoothed, it’s really hard to discern individual facets and very hard to tell the difference between a surface consisting of a hundred facets or five hundred. Or a thousand. The only time the number of segments really makes a difference is when you are looking at a curve in profile, as at the end of a cylinder.

You must reset your expectations as to what constitutes a suitably smooth curve. Seeing segmentation sometimes in somes views is inevitable. Get used to the idea.

The alternative is a big, massive, unwieldy model that gobbles up system resources, makes your computer move at a crawl, and is subject to mysterious failures, especially on intersections.

When you use Follow Me to extrude a curved profile along a curved path, the number of facets on the resulting surfaces increases exponentially as you increase number of segments on 2D curves. The resulting surface is made up of thousands of teeny, tiny faces. The more faces make up a surface, the smaller they are. The smaller a face is, the more likely is is to fail to form. Faces with any dimension less than about 1mm simply do not form, and cause holes and voids in the surface, or torn, uneven-looking intersections. Sound familiar?

Make better models: try using the default number of segments on curves. Constantly look for opportunities to reduce the number of segments. Never increase them without a specific, compelling reason. Do not judge the appearance of a model, especially its “smoothness,” based on 2D shapes.

-Gully


#5

A bit of specifics added to what Gully wrote: when your shape turns a corner and the segments near the corner are small compared to the profile you are extruding, SketchUp can’t make a clean corner because the profiles along the short segments protrude completely through each other.


#6

Thank you all for your comments.

If I ever succeed, the object shall be CNC machined in a pretty large scale. That’s why I thought I need that many subdivisions.

Gully_Foyle, I understand your reasoning. But does that mean that this kind of object just can’t be crated with Sketchup? Or is there any solution how I can get a smoother arc AND a bevel?

Martin, what do you mean by “outside of the shape”? Will give “Round Corner” a try. Thanks!

Regards,

Florian


#7

Depends on what you mean by “this kind of object.” If you can’t tolerate segmented curves, dwell marks, and tesselated surfaces, you’re going to have problems with SU models, since those are inherent to SU’s method of representing curves and curved surfaces. As I said, you reach a point in increasing segmentation where you run into so many associated problems that it’s either not worth it or not doable at all. However, you may be able to find a sweet spot, or at least a good tradeoff between, say, quality and stability (or managability).

You haven’t mentioned what sort of material you’re using–obviously, tiny flats are not a big deal on a piece of wooden furniture you’re going to sand anyway, whereas, I can see how they would be a big deal if you’re CNC machining steel or aluminum. Also, as Martin said, technique may play a role in some situations. (Maybe “outside the path” may be clearer; you don’t want an extrusion to double-back on itself. Butterfly-wing overlap errors may occur.) It’s possible your model is okay but needs to be cleaned up a bit. Maybe you should upload it.

Sorry to sound so imprecise and uncertain about this, but you are working at the place in SU where science and Voodoo intersect.

-Gully


#8

Upload model=>The classical use of the follow me tool the extruded face must be perpendicular to the profile at start.


#9

Took some time to find this but may be of interest. Discussions in 2011 for moulding door and inside corner problem. I have not follow over the years and do not know if later version has fixed http://sketchucation.com/forums/viewtopic.php?f=15&t=40974


#10

This is what I meant by adding the bevel on the outside of the model.


#11

Thanks again.

Martin, great idea, but strangely, it does not work for me either:

I keep on trying.


#12

You may be missing the fact you have set the arc to 120s, so when you draw the small arc it is still creating 120 segments so the combination of 120 by 120 is making very tiny segments which are making the faces fail to form.

If you really feel you must have that many segments you will need to scale up to get the faces to form then scale down again.

On the other hand, I imagine you aren’t directly connected to the cnc machine from sketchup, you must be outputting drawing to the relevant software for the machine.
If you export 2d plans as 3d models the curves will export as true curves.


#13

Model the object BIG then scale down.
You haven’t revealed how big the part is other than “a pretty large scale” which doesn’t mean anything.
Perhaps working in meters would be large enough and then scale the model down to mm when finished.

If you wish to extrude an exact profile then it must be perpendicular to the path at the start.
Drawing the extrusion profile on the end of the part as you did; means the profile is not perpendicular to the first segment of the path.

That leads to the question @lacina118 of why attempt to model the part with such high detail in 3D when it’s merely a 2D flat part? All you really need is a 2D tool path, not a 3D model.

Ha!
Calling upon the spirit of Doctor John may indeed help when contorting SU beyond its practical limits.

@lacina118
It can be done. What use it has is uncertain.
No plugins or religious rituals were used in the process.


#14

The Follow Me tool works on a planar path. To use the function of Follow Me on a non-planar path try FollowMe and Keep or Upright Extruder. Note you may need to rotate the model 90 degrees so those plugins will work correctly. It could also be modeled flat and later bent with Shape Bender

It’s also possible to subdivide models after you make them. The plugin Artisan is one tool that will let you do that. It also has a tool to let you select which edges should remain crisp.