Extrusions as components?

Can an extrusion be saved as a component?

So far, I’ve been able to save the general shape that cuts an opening into one face, but the shape sits on top of the face rather than into it with no extrusion occuring.

I’ve also just saved an outline of the shape as a component and then tried to place that on my main shape and then select inside the borders of my component to do a push/pull but that has also been unsuccessful.

It sounds like you are mixing up extrusion and intersection.
Post an image or the model so we can see what the problem is.

Yes, of course.
An extrusion is nothing more than geometry resulting from the process of extruding and selected geometry can be made a component.

The best way to create a hole-cutting component is to create a single temporary rectangle.
Orient the rectangle logically and model the object on that face, including the hole you wish it cut.
If you’re modeling a hole-cutting window, orient the temporary rectangle vertically, like a wall.

When you’ve finished modeling the object, don’t delete the temporary face.
SketchUp will use that face to automatically set the gluing plane for your hole-cutting component.
Simply drag a L-R selection box around the just the object and make it a component.

Setting the gluing and cutting plane of a component — SketchUp Help

The only question you’ve asked is quite clear and easy to answer.
The description of what you’re trying to create isn’t so clear.
It will help us help you if you’ll post a picture or a simple model file.

I quickly created a bunch of circles and extrusions to set up an example of my situation (not actual stuff I’m working on).

With your mention of “intersection”, I tried to intersect the component with the main model. At first, I had no success. But when I removed the component from the model, it left behind a circular imprint that could be altered with the push/pull tool!

This could work for me but if anyone has a more streamlined method, I’d be interested in your feedback.

P.S. I noticed the final extrusion on the far right has a faceted interior. When viewed in wire frame mode, the extrusion seems to match the others. Do I need to be concerned about this? Eventually these holes will be cut with a CNC router and the tolerances will be specific and tight.
extrusions.skp (84.4 KB)

Sorry, but your example file doesn’t make it clear to me what you are trying to accomplish, how you are going about it, or what is the problem. The example cylindrical indentations in the top of cylinders are trivial to draw in SketchUp, so could you explain a bit more why they are causing you grief?

When you intersected the component with the top of the cylinder, the new edges you created are exactly co-located with the face edges of the component, so you can’t see them until you move or delete the component from that position. Because they were created by intersection, SketchUp doesn’t recognize them as a smooth circle, only as a polygon. So when you push-pulled them, the corners created edges. You can smooth these edges to make them look the same as the others (if you turn on hidden geometry you will see the same kind of edges in the other holes as well).

For export to CNC you need to be aware that unless you export a model to certain formats (I believe dwg or dxf?) all circles and arcs will export as polygons and polylines, not smooth curves. That is the way that SketchUp represents such curves internally.

As I stated previously, this was a simplified representation of the problems I was facing with my project. The simplified representation was created after reading the response from “Box” and reflects the solution to the problem with the intersection of face with model solution on the right most model in the attached example.

The actual shape of the extrusion in my project was custom made, not easily repeatable, and as a result, was saved as a component to save time.

I think I solved the problem after reading the response from “Box”. Sorry about the confusion.

Thanks for the info regarding smoothing the lines on the extrusion. I am indeed going to be exporting to .dxf for CNC production. Do I understand you correctly, that means I don’t need to worry about smoothing the lines?

SketchUp will export an arc or circle as such only if it is still recognized in the model. You can check by clicking on a single edge of the arc or circle. If that bit is all you get, it has been broken into segments. If you get all of it, check the entity info to see whether it is listed as an arc or circle and whether the radius is still known. If not, the abstract geometry of the circle or arc has been lost and all that remains are the segments. That is, SketchUp has forgotten the initial origin and radius.

In you sample file, the indent you made via the intersect technique split the circles into segments.

I’ll let the experts chime in. I think I recall reading about a plugin to recover a circle from the segments, but I can’t remember what or by whom.

Another workflow: Draw the 2-D outline of your extrusion, that is the bottom face without push-pulling it to depth. Select this face and its outline by double-click and move a copy onto the target surface. It should merge with the target face to split it. Then push-pull to depth. I believe this way will preserve arcs, unlike the intersect method.

For example:

The intersect command creates lines of intersection in the current modeling context.
I gather from your model you want to efficiently create repetitive recesses, not just lines of intersection.

You need only model one of the recesses.
Make the recess geometry a Component with cut-opening (aka hole-cutting) properties.
Bring instances (copies) of the component from the Components Browser.
You can explode the components after if you wish. The hole they cut will remain intact.

See the attached model file:
Recess Component.skp (59.0 KB)

That’s exactly what I was looking for! I tried the sample that you included and it worked great. Now, I will try to recreate it using my shapes and see if I can do some debugging. But first, some lunch, then a bike ride to suck some fresh air into my brain cells.

Thank you everyone for your help today. With this incredible software and great community support, I know I’m in the right place to work on my project.