Need Help Smoothing Out This Model


I’m working on a curved staircase in sketchup. I followed this tutorial: but provided my own image, which was more curved.

I’ve tried searching on Google and just experimenting on my own, but I can’t figure this out. I’m not entirely sure how to describe what I’m doing (I’ll provide images), which is probably why I can’t find it on Google.

I started with a 2D image, with the outlines of the stairs, used PP to get everything in position height-wise. Following the tutorial had me move the bottom of the stairs up and then draw lines between the bottom corners to form the curve. This made it come out really jagged, which I didn’t like.

Eventually I came up with the idea of removing all the stairs from a frame, welding each outside curve together and using the move tool to move one end to the correct height. I was stoked with the results - until I realized that this caused the curves to distort. One edge was lower than the other, which would have made the stairs slant to the inside. I need them to be level.

Please help!

@Gully_Foyle Ack, I’m sorry! I hit back in the middle of writing this, and forgot to put that part back in. I’m trying to build a curved staircase, and I don’t want there to be a wall that goes all the way to the ground.

2D Image I’m using:

Here’s the look I’m trying to achieve:


It would be far more useful if you were to provide a detailed description of exactly what you’re trying to achieve instead of taking us step-by-step through a procedure you’ve already told us doesn’t work. Better yet, show us a picture from the internet of a staircase like you’re trying to make.




It looks like the ‘Show End Points’ option is turned on in the style you’re using.

If so, that’s a good part of the problem – since it exaggerates all of the end points of each line segment of the curve.

this option can be toggled off in the edit style menu, edge settings, or for that matter you can just lower the emphasis value for it.

Low line segment count can also affect how smooth a curved line appears in SketchUp, and increasing this value can help out as well. . . but then I’m not sure you need to do this in your case. And you probably already know about line segments, and how SketchUp handles curves anyways.


In most “spiral stair” tutorials, the idea is to make one tread component and then duplicate it so that each tread is identical working up the spiral.

However if each tread is different, I would recommend a slightly different approach:

  • Make a “master” group for the bit you want to step on
  • Use move and [alt] to copy it in one movement from the ground to the topmost tread
  • Type in [/ nn] where nn is the number of steps you want
  • Rotate and position each group to line up with the helix you already have (using the “intersect” tools might help)
  • Drop the riser from one group to meet the tread from the one below.


Here’s some images of the modeled staircase, with a full length wall. I wanted to make a curve that I can copy onto the face of the modeled staircase, and then delete the areas underneath it, to make a smoother curve underneath the stairs.


I’m not completely understanding your problem. I’m not sure what all those lines are from, but they are making your model bloated and fragile. If you are using lots of segments on your arcs thinking that will make them look better, it won’t necessarily have that effect but it will add to the model’s complexity and susceptibility to failure from all kinds of causes.

In the following example, the curves of the stairway footprint consist of twelve segments each, which is the same as the number of stairs. Try to keep your geometry spare and taut, if that makes sense.


Oh, drat. Okay, now that I’ve seen the picture you added, I’ll go back and modify this to include cutting off the bottom. Back anon…

…Okay, here’s with the bottom cut off:



Thanks Gully! This helped a lot =)


Here’s what I’ve come up with, but it’s really complex:

You mentioned simplifying the footprint to make the model cleaner, but since SketchUp can’t PP curves, how would I get the stringers (triangle parts on the edges) to have a width?


your face normals, are completely messed… i would strongly suggest to right click any of the white faces then click “orient faces”


What if you share the file? To see how you built the stairs. And to see what can be simplified.


Ok, sure! Thanks for the help =) There’s some hidden geometry where I started working on a possible railing, but I’m not married to it.

stairs8.skp (1.2 MB)


I think that’s actually two different things. I would say the main way to reduce edges is to make the sides of the stairs straight instead of curved. I’m thinking that each stair is a segment of the overall curve.

Also, I really dont know what all that funny gridwork is on the sides of the stringers, but it has the undesirable effect of creating many, many internal faces, which bloat the model and look very strange.

I’ve attached a quick version of the stair in which I’ve made the stair sides straight as I described, simplifying the footprint. Also, to give the stringers width (thickness), I’ve used the plugin Joint Push/Pull, which is one of those indispensible plugins whose action is very difficult to duplicate by hand. I suggest you head over to SketchUcation and pick up a copy. Here’s a picture (and I’ve attached the model as well):

Now, also, there are some construction details that aren’t right. For one thing, the tread on each stair should rest upon the riser, and the treads should overhang the risers with a bullnose leading edge. You appear to have the treads inset into the frame of the risers, weakening the structure. Here’s a picture in which I’ve shown this bullnose on the two bottom stairs:


curved stair.skp (221.5 KB)


Thank you SO much! I’ll take a look at your model right away.


One last question (I hope), how would you put a bottom on the stairs? I tried using ‘Beizer surfaces from curves’, since the edges aren’t planar, but it adds a LOT of vertices. Any suggestions?


Actually, I showed a bottom on the stairway in my second picture above. I did that one by hand-stitching, which is simply connecting all the involved endpoints in a zig-zag triangualr mesh.

It turns out, though, that the From Contours Sandbox tool works pretty well, and it’s quick and easy (except you may have to clean it up a bit). The following picture shows a bottom made with From Contours. I made a copy of the outline from the stringer groups, surfaced it, grouped the new surface, and moved it back into position, like this:

You could achieve about the same result using Curviloft, if you have it (well, if you don’t, you should, although you should also learn to use hand-stitching).


By all means, ask as many questions as you wish.


Heh, so my instincts aren’t completely useless! I made a zigzag of triangles going up the back on my first one, but thought there might be a better way. Got the new bottom done now =)


Hardly surprising, since this is one of ■■■■ Sapiens’ three major instinctual behaviors, which are:

  • Eating
  • Procreating
  • Drawing zig-zags




This is a bit off-topic, but is there a way to add a menu command to a toolbar? IE, if a plugin adds a menu command ‘create face’, but doesn’t come with a toolbar, is there a way to associate that command with an icon and place it in a toolbar? Or add a hotkey?


You can assign a shortcut for a plugin. To see the plugin in the list, you have to select something you can use the plugin for (for your example: select some edges to create a face for).


Thanks! It’s been really bugging me, loosing time looking for menu commands =)

Here’s the newest version, with a banister and spindles.

The bottom had to come off, because I changed the width of the stringers. I’ll add it again later.

The base staircase model is much simpler now. No more crazy patchwork. The exterior faces are all white instead of blue.

I think I want to remove the base from the spindles, either by making the stringers a bit wider, or the spindles a bit narrower.

The banister is a bit plain, might do something more with it.

I decided against bullnosing the stairs, as sturdiness doesn’t matter for my application.

Are there any problem areas?