Why does my model render backwards?

TrackRoller09.skp (376.7 KB)

So how do I use the current SketchUp to create an item with concentric bands and have it printed properly? What I attempted was:

  1. Create the 4 circles
  2. Create the axes thru the center point
  3. Erase the lines to make the basic shape and erase the faces for the holes
  4. Pull the first level
  5. Draw circle for the depressed area and pull
  6. Draw the next outer circle and pull both to size
    … repeat for 5 & 6

Previous versions filled in the holes either partially or fully, and left out one of the indented stripes.

My technique obviously doesn’t work. What is the proper way to create this image?


Can you share the SKP file?

My first guess is that you have faces reversed but I can’t tell from your screen shot. From the description of your process, reversed faces would be likely.

SKP is right there next to the pic

Sorry. Didn’t see it. opening it now.

OK. So not reversed faces. There are internal faces that need to be removed.

Does this one work the way you expect it to?
TrackRoller09.skp (366.2 KB)

I seems to have worked! Thanks!!!

So how did you fix it? I see you put it in xray to find the inner faces, so how did you erase them?

I made a component of the wheel first. I noticed it wasn’t shown as solid in Entity Info so I ran Solid Inspector2 (Extension Warehouse) to identify the problem. Xray made it possible to see the internal faces. To fix it, I clicked the Fix button in Solid Inspector2 but if I was going to do it manually, I would have selected the outside surface of the wheel and hid it temporarily. Then I would have selected and deleted the internal faces before unhiding the outside surface.

Better workflow would be to avoid creating the internal faces to begin with. If I were drawing that from scratch I would use a cross section profile and Follow Me around a circle to get the wheel with the grooves. then I would draw the shape of the openings between the spokes and push them through to create the voids. This would result in a solid as soon as it’s made into a component.

By the way, do you want the spokes to be wider out toward the rim? Is the wheel supposed to be 19.1 mm thick? Are the grooves supposed to be 1.1 mm wide?

I see an issue that can create problems. When you drew the circles you didn’t drag out all of them on axis. This means vertices on the edges of the circles don’t align. Best practice is to always drag out the radius of circles on an axis so you are consistent.

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Interesting. I have yet to master the “Follow Me” tool. It kinda works for me about 25% of the time.

What does making a component of the wheel do to help?

I have tried pushing out the holes and that seemed cumbersome and fairly effective. Not perfect, though… Trying one other idea at the moment but don’t have high hopes for it. Didn’t work.

I will have to grab Solid Inspector2 and give that a whirl.

I felt the spokes gradually getting thicher

  1. looks better
  2. easier to create

Yes, 1.1 wide grooves is what I want, they are to test two 1mm widths at 9mm apart (N-Scale track)

Thanks! You’ve been a great help.


Maybe you need a little instruction?

Mainly for this, it allows you to see that SketchUp considers it a solid so you should have an idea whether or not it’ll work for printing. You could also use a group although there are a lot of other features of components that can be leveraged.

Make sure you also get the current TT_Lib support files.

OK. I was doodling and I did this. I used the method I described before.

What are you doing with the N-scale track? Are you hand laying it?

Someone asked me to create a track roller for HO and Tram track so I played around with it. As long as I kept a solid center, everything was fine. Adding the spokes for a cheaper product was the problem. (Save $3)

I recreated it by pushing out the spoke voids and Solid Inspector said it was fine. Shapeways finally liked it, too…

I’m not hand laying track, but that is the intent, as well as simple verification the track is good.

Your doodle was one of my first attempts at the spoke design.

Looks like the Inspector didn’t need TT_Lib. Both are now installed.

For the FollowMe, Yeah, I need instruction. Most of the instructions/videos don’t do what they say. Some instructions actually have a step that doesn’t exist. Now that I have Ver17, I’ll try it again.

By the way, one of the problems I’m having with circles maybe you can answer. If I want to draw a circle on the blue plane (I’m over a hole) and the circle is oriented for a different plane, how to I change it’s orientation before drawing?


Ah… I see.

I was thinking that making the spokes thinner, like I have, above, would reduce the amount of material required even more. Maybe not significantly, though.

I’ve been thinking about hand laying some N-scale track, too.

How does your roller work over turn outs?

Many of ThomThom’s extensions require TT_Lib but I didn’t remember if Solid Inspector2 does. Safer to have it if you get any of his other extensions, anyway.

Maybe we could connect for a little one-on-one. Drop me a PM.

After you get the Circle tool, hit the up arrow key on your keyboard. This will lock the tool in the right orientation. (Right for red, left for green, up for blue)

I remember my Dad had a jig for hand-laying HO track. It was a plate with two slots in the bottom and holes adjacent to the slot at one end for setting the tiny spikes. As I recall the slots were sort of D shaped so that curves could be done up to a limit radius, which helped prevent cars pulling off the inside of too-sharp turns.