How do I centre extruded solids?


I am having trouble centering an extruded Solid with respect to an other solid.

The problem is that after you have Grouped the extruded shape to form a Solid, if I then click Select and left click to select the solid, you get a blue bounding box around it.

However this blue bounding box does not have any useful geometric attachment points (e.g. Midpoint) and when you click Move, and then mouse-over the parts of the blue box, you don’t seem to get the same control points that you do for say a simple cube.

Instead what I get is a little purple ball with popup saying “Endpoint in Group” appears, but there is no obvious way to select the object by a MID point on the solid.

Four red crosses also appear, but if you click on them the protractor appears after which point you can only change direction but not Move the solid object.

You are correct. SketchUp’s inference system finds points based on actual geometry, not the bounding box (the blue box). It will find points within the component or group without opening it for edit, but if there is no geometry at the center point you wish to align, there will be no inference. One solution is to edit the component/group and place a guide line at the center. Then you will be able to get inferences based on that guide.

the circle has a centre point , can you use it?


I had a perfectly good guide line going down the centre of my object but I had to remove it because Sketchup stopped me from forming a Solid if it was still there. [sigh]

[Aside: I still don’t get why Sketchup developers couldn’t put inference points based on the geometry of the bounding box! It seems that as soon as you create a Solid - which is surely precisely what one is trying to model most of the time, much of the best functionality evapourates!]

Good point - I’ll try…

But presumably I need to Explode if first, yes? And then move it out of the way again before I re-Group to make a solid, yes?

The problem was the thing you refer to was an edge, not a guide. Loose edges will prevent something from being solid, but a guide will not. Create guides using the tape measure tool.

And, no, you don’t need to explode to get inferences from geometry inside a component or group.

Guides not Edges. OK got it - thanks

PS One thing: After I have re-grouped my Solid, is there any merit in then grouping the Guide in as well so that it moves wherever the Solid goes?

There are so many ways to skin a cat in sketchup it’s too confusing to learn them all at once.

@Box I assume that’s an extension/plugin? “Centering” doesn’t appear on the standard context menu?

Another thing to consider is that some simple planning ahead can make things easier. If you’d drawn the circle for the path centered on the origin and the shank of the hook centered on the green axis, you could easily move the block you’ve drawn and center it with the center of the hook. The midpoints of its edges are easier to find than the vertices in your hook because of the huge number of segments in the hook.

Or, you could have just drawn the block centered from the beginning and avoid having to center it afterward.

Lots of options.

I moved everything away from the axes because I found it impossible to see any edge running down an axis, because the axis over-wrote the edge! Hmm maybe that was a mistake…

If you will need that reference again, there is no problem with putting it inside the group or component. The only issue is that you will need to open the group/component for edit before you can get rid of just that one guide (Edit->Delete Guides will delete all of them regardless of context).

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You could temporarily turn off the axes in the View menu or edit the style to make the edges easier to see. Again there are options

Ya gotta love Tim Toady (aka TMTOWTDI - There’s more than one way to do it)!

So so many ways.
SD Mitch has a plugin that will stack a bunch of shapes by their centers. Or align them to their edges…
You can’t learn everything in one sitting.

As a total newbie my feedback is that yes, yes, there may well be plenty of ways to do things. But all I can tell you is that there are plenty more ways that one might reasonably have expected to work… but which fail to do so!

I don’t think I have ever come across software that is at one minute inspiringly brilliant, and the next so irritating!

Anyhow I’m mainly here to do some work not fix the software. Hey-ho.

I would use TIGs center point plugin in this case to create a cpoint as a reference point…