Difficulty getting two solid objects to union

I have two objects that both show as solid groups, a cylinder with an internal thread.

I have tried making them next to each other and with a slight overlap, but I can’t get them to merge into a single solid.

Any ideas?

spiral7b.skp (1.3 MB)

just select both the solids and right click solid tools - union

There are two issues causing this to fail.
Firstly your internal thread geometry doesn’t match up with the outer ring, so when you ‘Union’ there will be gaps where things don’t line up, making it a non solid.
Turn on hidden geometry and you can see where things miss.

You also have a tiny edges problem which will create a non solid.

So either make the thread larger or the ring smaller so the faces fully intersect where you want them to join.
Then Scale up by 10 and run Union, you should get a solid. Then scale back down.

1 Like

It worked!

I made the cylinder with an inner diameter slightly smaller than
the spiral.

Scaled up 10x, union, then it formed a solid group of the outer

Scaled down by 10x.


Thank you.