Newbie question: how to position objects accurately and erase unneeded circular lines in SketchUp 8?

[EDIT: short answer is to first do all the “SketchUp Fundamentals” courses at …]

I know how to size objects accurately (type size after drawing), and move them accurately first by moving in red axis (then typing number) and green axis (typing a number). But the only way I know to have their location be exact is to draw them at the origin, then do two moves, and further should it touch any other object it combines with the other object and there’s no way to move it without corrupting the previous shapes.

As an example, let’s say we want a 20x10mm oval with two circular ends, centered at the origin.

So to make a 10x10mm rectangle with lower left corner at -5, -5, I draw it with lower-left corner at 0,0, type “10,10” to size accurately, then select it (space bar, lasso) , then go in move mode (M) drag it left a bit (mouse drag with right-arrow to constrain move to red axis), and type “5” to make the move 5mm. Then I repeat to move it down the green axis another 5mm, thus centering it on the origin. Surely there’s an easier way to do it?

Likewise I want a 10x10mm circle centered at 5,0. I draw a circle around the origin, diameter 5mm (click origin, drag a circle, type “5”). I then select it (space, lasso) and move it right 5mm (M, right-arrow+drag, type “5”). Then I move with copy, 10mm left, producing an infinity-type shape. But is there an easier way?

Now combine the two. I draw and position the rectangle first. Then I draw the first circle. Looks fine, but sketchup assumes they’re a fancy combined object and I can no longer move just the circle. So I draw the rectangle… then move it up the green axist a memorable amount (20, say), draw and position the circles, then move the rectangle back down 20. Again, easier way?? [EDIT: select one circle, right-click, and select “make group.” It will no longer attach to other drawing that touches it. If it makes sense for your object to have sub-groups, leave it as such. Alternatively, ungroup it once the fiddly editing is done.]

Then the final step: erasing the unneeded internal circular lines. Sometimes when I click them in select mode, it selects the whole curve I want to delete, basically intersection point to intersection point, and I hit delete. But other times it just selects a single facet (of the 24, say, sides I’m using to approximate a circle) and I have to select and delete many many times over and over. Easier way?

You need to spend some time with the tutorials at the Campus.
This will help you get an understanding of the fundamentals, which your description makes clear you haven’t yet.


OK, I’m looking at the course “SketchUp Fundamentals.” If this isn’t the one you meant let me know, and thanks for the pointer!

The learn things Box pointed you to will help a lot. It’s been a while since I looked at the videos, and I can’t remember if the arc tool tutorial shows that there are help tips to tell you when you have created a half circle. Here’s a screen recording that shows that I tapped a modifier key to make the rectangle be drawn from the center, I got the exact size by typing 10,5, and I made the ends by using the 2 Point Arc tool and watching for when it snaps to the half circle position. I do end up having to erase two unneeded internal edges! But that didn’t take long.

Problem is for some reason the OP is using SU8 which doesn’t have the rectangle centre option.

Thanks, I hadn’t checked the profile other than to see if my Mac status bar things may be confusing for a Windows user. Hopefully they are using the web version, though of course that will lead to other confusion while trying to follow the learn videos.

In particular, look at making components (or less usefully, groups) to stop geometry sticking together.

Draw something, triple click it to select all of what you’ve just drawn, tap the letter g to make it a component. Give it a meaningful name in the dialogue that opens. Change the component’s axes if needed, make sure the box Replace selection with component is checked, then click OK (or Make component- I’m on my phone so can’t remember which it is).

The default component origin is at the corner nearest the origin (lowest x, y , and z in the component) and is often fine. But it may be more useful for a circular component to place the origin at the centre of a circle or arc on its base or top.

Then draw the next ‘thing’ and make a component of that… and so on.