Need tips on aligning and centering

[SomeDay]

Hello,

Picture this, if you will. I have a 3 inch thick wall. I cut an octagon out of the wall and reduce the size of the octagon to be smaller than the hole it was cut from. After moving the octagon around to other locations in the model, I decide to move the cutout back to the wall it was cut from.
I want the face of the cutout to align (be coplanar) with the wall it was cut from and I want the cutout to be centered (i.e., equal spacing at all edges).
I know that I can fuss around and get it where I want it, but I can't help thinking there must be a better/more direct way to accomplish this.

Thanks in advance.

[TIG]

It'd be easier to picture this with a picture... but here goes...
If you made the Octagon as a native Polygon [or even an 8-segment Circle] it should have a center-point that you can 'infer'.
With the Move tool hover over the copy's edges and move the cursor towards the center, that should become a snap option, pick that. To relocate it exactly over the 'parent', again get an inference to the center of the parent and snap to that. The two should now be concentric.
Grouping the copy would prevent it sticking to other geometry unnecessarily and allow easy rotation about and edge etc and its relocation... Explode the group to merge geometries later as desired...
If it's not a polygon/circle then you need to add a guide-point at the center of the parent and the copy, if the copy is in a group the cpoint will move with it...

[Mike Lucey]

The first time you made the octagon 'cut out' you should have cleaned the unwanted surrounding surface and put it on a layer for on / off. After that you can pull it out, and do what you want with it

[SomeDay]

Thanks Mike and TIG,

How do I add a guide point?

Thanks.

[Gaieus]

Pilou, it was about how to add a guide point at the centre of a polygon.

Under Window > Preferences > Extensions, enable all sorts of things (I cannot remember now which enables this feature). Restart SU and now if you right click on the perimeter of any polygon, circle or arc entity, you get this menu item.

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[pilou]

I have read only the last post

[Gaieus]

I know (as I know you)

[pilou]

With the Tape measure tool but it's more easy with some plugin like Projection by Didier Bur

[pilou]