I can't use Follow Me on very large arcs



I need to create a “channel” in the middle of a very large arc - 180 degrees from the foot to the other foot, which is over 1,300’ away.
I tried to do this in sections since I could not see the starting square when the full arc is onscreen. But it stopped working about halfway up each leg, dropped faces, and skipped empty space before starting the extrusion again. It also crashed twice (bug reports sent to Sketchup). Is this too much for the Sketchup engine?
I tried copy and paste, but with angling each section…well, you can imagine this is a bad result.
I have no choice about the dimensions, and the arc really have to be done as a single geometry with 172 segments in its 180 degrees.
What is to be done?


Pre-select the path, get the Follow Me tool and click on the profile.


Ah, how do you pre-select the path? How do you click on the profile?


Use the Select tool to select the path (arc). Then after getting the Follow Me tool, zoom in on the profile if you need to and click on the face.

Why don’t you start with something a little smaller to get the hang of it and then move on to the main project?


Well, it is easy enough to do in a small project, kind of fun actually. But it balks on a large arc and that is what I need. Also, I need the channel running through the middle of the arc. By “profile” you mean the starting box at the foot of the arc which I am supposed to extrude upwards?


The profile is the section of the channel.

The arc path is 1300’ on the chord.

How about if you share the SKP file. I can give you more definitive direction.


Inner Arch and Trough.skp (285.8 KB)

OK, here it is. As you will see, I am attempting to join a second “half” arch to the channel that will run between the two, but moving a 1,300’ arc into place is rather hard! Anyway, I’d rather start over and use the proper technique with the follow me to make it clean.


Yes, but facing in the opposite direction, downward, and with a 9.5’ wide arc on either side.


Also, the arc, as you will see, should be inset into the underside of the arc, flush with it.


I’ll look when I get home.


I’m not able to understand from your sketchUp model and your description what it is you are actually trying to accomplish. Do you have a some photos or something that you could share?

And maybe some dimensions for the arc and the profile.


OK, the arc is actually the underside of a much larger structure, which I’ve more or less made good progress on. I have to do this part first since it’ll determine what space is left over for the rest. I intend to paste this arc into the underside of the structure. I also have to lay tracks on the outer edge of the arc, and there are corresponding track about 11’ curving under each of those sets (4 total then). It’s a bit hard to explain, and I’m not ready to share it yet. But the channel is the main thing now and it is holding up my big plans for the rest…
The arc I sent you has the dimension between the feet that I need, though I think there’s a mistake in the last 35’ or so on the left side.
Thanks for all your help.


How high is the arc supposed to be? There appear to be two arcs crossing at a shallow angle. I can’t determine from your model what the cross section of the extrusion is supposed to look like either.


Yes, the “twin” arcs were all I could think of to get the channel to run between them, but as you can see, moving them in sync is next to impossible. I really need the channel to run down the middle of a single arc.


Can you show me a cross section of the channel? And again, give me some dimensions so I can redraw the arc properly.


It should be in the .skp file I sent you, but you’ll have to zoom way in and get under the arc to see it. I even colored it, prematurely…


All I can see is a rectangle and a surface with no thickness.


Inner Arch and Trough.skp (281.9 KB)
I"m reattaching the file. It is a view from the top down of the split arc. I need them merged together with the upside down channel between them. Thanks…


Well, I really want to do, and learn how to do, it right. I have more of this sort of thing.


I’m sorry. I still don’t see what the cross section of the extrusion is supposed to look like. Even looking at it from the top. Why don’t you just draw the shape of the cross section for me and give me that SKP file?