How to create a curved face from curved edges


#1

I’m modeling a coffee table, and I have essentially a board with dimesions 12" x 4" x 1/2". On one corner, I’ve shaved off a curve. This worked, problem is that somehow I lost part of the face on the 1/2" side, and don’t know how to create a curved face from these edges.

How can I create a curved face along these curved edges? See model here, I’m looked at the curved non-face going towards the leg from the left. Coffee Table.skp (196.9 KB)


#2

I’m not quite clear as to what you are asking, but I note that one of your boards has some of the geometry in a group while some of the geometry that should be included is outside the group. Don’t know if that matters.


#3

You can reconstruct the curved surface by stitching the vertices around the facing curves as shown on the following picture.

The way to construct parts like that is to draw the complete profile flat and then just Push/Pull to thickness. Don’t "shave " it after you’ve extruded it or you make the task unecessarily difficult.

-Gully


#4

I don’t think thats directly my issue. If you start from standard view right and orbit so the curved edge of the leg is facing you, you’ll see 2 curves cut out of the side pieces coming in towards the leg. The one on the short side is missing a face. I’m trying to recreate that face to make it look like that other one.


#5

@Gully - So at this point the easiest was is to create all those sub-faces, then smooth them over? Also, I know the kinked edge is wrong, but am unsure how to correct. Also, I’m not seeing all those segments on the top part…

Noob here.


#6

Well, “easiest” isn’t always best. Easiest is to just leave it as it is, but that clearly isn’t good enough.

The best thing to do at this point is start over. And if you have to start over three more times to get it right, you should. You could spend hours fiddling with the thing to “correct” it, and that really is misused time. Your time is much better spent practicing to do it correctly in the first place.

A bit hard to miss. Each of those dots represents a segment. Six per curve would be plenty.

-Gully


#7

The easiest way to get that surface back is to copy/move the one from the other piece.


#8

To answer one of your questions, you aren’t seeing the edge endpoints because you aren’t using a style that shows them. You also need to turn on View->Hidden Geometry if you want to see the cross-wise smoothed edges.

I agree with Gully on this: your model shows enough flaws that you would be well served to start over and do it better. Here is a list of issues I see and suggestions on how to address them if you start over:

  • The details of the cutout in your model are drawn at sizes that seem like you attempted to make them nice fractions of an inch and missed by just a little. For example, the upper curve is 0.315561" wide, which is just a bit off from 5/16 (=0.3125). Similarly, it is 0.208824" tall, not quite 3/16" (=0.1875). The flat and the lower curve are close, but not quite 1/8". The straight part from the leg to the upper curve is close, but not quite 1 11/16". Try laying out the locations by creating guide lines and/or points and typing values into the VCB to get them exactly where you wanted. Then use inference engine snaps to the guidelines while drawing the curves. Use the VCB whenever you need precise placement or lengths in SketchUp, else you will build models with tiny glitches that are hard to see, tedious to fix, and that cause mysterious errors until they are fixed.
  • The upper curve and the flat between the curves have way too many facets (as Gully noted). This is particularly troublesome with the flat, since it is actually planar and could be drawn as a single face (if you view hidden geometry, you can erase the interior edges and leave a single face). But whatever tool you used to draw the upper curve also used far too many sides. You can reduce the number of segments used by the Arc tools by typing something like 6s into the VCB while the tool is active. Whatever tool you used to draw the upper arc should have similar options.
  • The upper arc and the flat do not meet at a nice tangent, causing a corner. The final arc segment meets the flat at an angle of about 23.3 degrees, making it visible even with smoothing. I assume that was not intentional? Notice how much nicer the edge between the flat and lower curve look despite the lower curve’s much smaller number of segments! Try drawing the curves using a tool that understands tangency, such as the two-point arc tool, or the traditional Bezier spline tool extension. If you did use a Bezier tool, you need to read up and practice to understand how to use it correctly, as assuring tangency is one of the features of Bezier curves.
  • As others have observed, you have some peculiar combinations of grouped and non-grouped geometry on the same part. For example, the lower curve on both aprons is duplicated inside and outside the group, which serves no useful purpose. This suggests you need to learn and practice some more on when and why to create groups (or components, which would actually be better in this model since presumably the table will have two pairs of identical aprons in the end).
  • As others have already observed, these aprons are perfect candidates for drawing first one side outline and then push-pulling to thickness. That technique would avoid the sort of issue you encountered with the non-filled face curves, though you may need to soften/smooth edges afterward.

#9

To follow up, here’s an animation of how I would draw that apron (starting with a 19 1/2 by 4 rectangle pre-drawn, and assuming the flat was a failed attempt to make a 5/16 curve at the top). Oh, and I just went with the default 12 sides instead of reducing it to 6.


#10

I did basically the reverse, drawing then extruding the board, then using arc tools on on surface and using push/pull to pull (intrude?) away the not needed portion. I also didn’t erase edges like that, but instead tried to smooth them away.

Also, while everyone’s points on practice and learning are understood and I’m sure correct for serious use, I am a beginner using this for fun, so I’m learning from your comments, but I’d rather not start over, my flawed model is “good enough” for this case.


#11

View hidden geometry! I’m aware of the option, but didn’t realize I had anything hidden that mattered. Thanks, exactly what I needed to know.


#12

Based on the number of requests here for help, I think the consensus is that it is safer to draw a shaped flat face and push-pull it to thickness rather than to draw on the surface of a rectangle and push-pull openings through it. Both ways work, but there are fewer problems with the former way.

Not to offend, but while trying it out for fun is exactly the right time to throw away a bad example and start over to learn a better way! As you can see from my animation, there is hardly a lot of effort involved!


#13

There are three flavors of “hidden”. View->Hidden Geometry affects all of them.

-There is plain old “hide”. This tells SketchUp not to display the edge.
-There is “soft”. This tells SketchUp to treat the two adjacent faces as a single surface. There is a visible, sharp change in shading where the two faces meet even though the edge is not drawn.

  • There is “smooth”. This tells SketchUp to shade the adjacent faces as if they form a smooth curve across the edge. However, the edge is still visible unless it is also soft.

What isn’t visible in my animation is that I was holding down the option key (I’m on Mac, ctrl on Windows) while erasing those edges. That softened and smoothed them, it didn’t actually erase them. If you erase instead of smoothing, faces will disappear.


#14

That helps, thank you.

Also, I’m thinking it might be cool to get this model right, especially so
I can send it to one of the 3D printing places. I assume a model with
small flaws like this would print funky. So I may indeed start over.


#15

It’s a lot more fun and satisfying getting it right than not even if nobody else ever sees it. Here’s another approach to modeling the part in question:

-Gully