Need to "cut" a groove in a cylinder

The greenish “piston” object in the lower LEFT of the image below is a solid object (by SUP specs), and I’d like to be able to “cut” an additional groove into the face of the cylinder… similar to the one that is cut into the bottom edge… that is, all the way around, but not cutting all the way through the wall of the cylinder… just a groove. Much like the groove in the object on the lower right (circled in red).

I’d like to not have to start over with the drawing (if possible) and I figure there “must” be a simple way to do this!

I included 2 additional views of the object in question just to present how the piston is constructed.

I’d like to maintain the object as a verified “solid”. Is there a straightforward way to do this that I am missing?
Been struggling with this one ;-o

(I’m expecting that this might be a “Duh” moment for me :wink: )

You can use the section tool at the center to extract the cross-section:


Move the original to another layer and hide it. Then use the cross-section to draw the new groove:


Using a circle with the same number of segments and orientation, use the Follow Me tool to create the new groove and reverse the faces (if necessary) so that the blue-gray (inside) is on the outside:


Use ^X to cut/copy the object and open the original grouped geometry. Use the “Edit >> Paste In Place” option to insert it into the original:


Delete the outer surface of the new groove:



If the groove is going to be the same you can select the groove geometry (drag left to right in the elevation) and “ctrl move+copy” to new location then delete face.


Jim… thx very much for the detailed solution! I had not used the Slice tool before (still in the learning stages) It took me a few attempts to get it to work… but it did… THANK YOU!

wow!.. thx for the vid. I would swear I had tried this process several times but kept running into issues… but I tried it again and presto! Must be adding ctrl to the move process. That worked well. Many thanks!

glad it did, it might be useful to go into “x-ray” (wireframe) mode when you make the initial selection to see that you have selected what you intended to select because when you select from left to right (as opposed to dragging right to left) only geometry bounded by the selection marquee is selected and it may be that one little piece was missed?

… didn’t realize there was a difference in the drag/selection direction!
Remembering back on it… I think my initial problem was I hadn’t cleared out much of the extra internal geometry that was created in my initial mucking around with the shape… and I was selecting several internal bits that were throwing the whole drag/copy process off. Even in X-ray mode… it kinda looked “normal”… but you know those little faces crop up everywhere!

Thx again!

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