STL Import and Hole Punching



Hey everyone. I’m really new to SketchUp. I’m really into it and have been using it for 3D printing. I have a project where I’m going to use some threaded rod to drive the below gear. The gear below is exactly what I need. All I have to do is punch a hexagon shape hole in the center so that I can place a threaded nut in there. But that’s the problem, this is an imported STL file and it’s not acting like any other design I’ve created in SketchUp.

I cannot figure out how to punch a hole through this design. Any help would be greatly appreciated.

[Selection Toys] Trying to Reverse Inside Faces

Here are 3 ways in order from least expensive and time consuming, to a $10 plugin or SketchUp Pro.

Free, model doesn’t need to be solid - Draw a hexagonal cylinder intersecting the model where you want the hole. Select all > Right click > Intersect with model. Select and delete the extra portion of the cylinder and center of the model. If the model isn’t solid, use the Solid Inspector plugin or Netfabb to repair the model for 3D printing.

Using BoolTools plugin, model should be solid - $10 get it here. Group the model, making sure it’s Solid, Draw a hexagonal cylinder intersecting the model where you want the hole. Group the cylinder, also making sure it’s Solid. ‘Subtract’ the cylinder from the gear using BoolTools.

Using SketchUp Pro, model should be solid - exact same steps as BoolTools, except using the native Solid tools!


I’m guessing that gear isn’t very large, in which case it already contains a lot of small geometry. Before using any of the techniques @d12dozr suggests, scale it up by maybe 100 (could require even more), do the operation, and then scale it back to real size. Otherwise you are going to run afoul of SketchUp’s handling of new small edges.


Thanks guys. I’ll give your suggestions a try after work today.


Some further thoughts:

That image shows a massive spiderweb of small triangular geometry, typical of stl. Looking at the top surface (the bottom is no doubt similar) it is evident that the stl used a large number of very narrow triangles to join the top faces of the gear teeth into the overall top of the gear. You could easily delete these and redraw the top face in SketchUp - it is happy with any shape of planar face and does not need to triangulate. Particularly near the center (where you want to work!) getting rid of all those narrow triangles will make your life a lot easier!


Worked like a charm. Thank you. I deleted the top and bottom. Drew a line to make a face them I was able to push/pull to punch a hole.