I have been using sketchup for a while now but still have trouble with sizes when rolling

Say I was to make a tube and wanted it to be out of 6mm Depron, if I draw the tube and then flatten it (unfold it) do I use … The outer skin ? … the inner skin ? … or somewhere in-between ?

I have tried the inner skin and it turns out too small, I have tried the outer skin and it turns out too big … PLEASE … what do you guys use??

Lockey

 

Use the inner skin.

 

Thanks Tiger, but the inside skin seems to always be a little small, I asked the question on another forum and a couple of guys seem to think 1/3 is about right

Lockey

 

If you want to make a tube of, lets say, 3" you draw a tube of 3" and unfold it. Once you make the tube it will not be too small on the inside. The inside edges will touch perfect. The outer edges, making the outer diameter, will not touch. If that precision is important to you unfold the outer diameter and sand a bevel to both sides. When I make my planes I don't care that much for the 100% precision, it's only foam plane LOL, and I use the inside edges. I use it when I make the skin for buildup wings.

 

Most times it isn't too important to be exact, BUT sometimes when you need to match parts together it is .. see pic

Lockey