Ken,
It's best to get a watertight model, but the great thing about OneCNC is it will cut it even if you don't have a watertight model.
And your right if it dosen't say watertight it isn't.
By the way you can only get watertight by using the "merge" and NOT the union.
So sometimes you have to use the union to remove the inner parts then disconect and merge. Did that make sense?
And believe me you will get a handle on this. Like anything else, it takes time to get your mind in tune with this solid's thing. Sure is easy and fun when you do.
