Noob question about Rhino generated stl files

I have bought a Prusa i3 to learn the basics of 3D printing with, and have used Rhino on and off in the past for some modelling.

I've got the machine printing quite well now, but have just used simple calibration models downloaded here and there.

My first simple design was a plain box, open topped, 160x55x25mm roughly with 3mm wall thickness. A bit like a supe simple cattle water trough if you like.

Using Repetier and Slic3r, when I loaded it it said there were difficulties, and when sliced just produced a solid box with huge amounts of lines and layers!

I modelled it in Rhino 4, and saved it as an .stl

Am I doing something basically wrong? Or will Rhino not make good .stl files?

Sounds like you don't have a water-tight model. I'm trying to remember the commands off the top of my head as I am away from home - but if you make sure the cube is closed by using the 'Join' tool. Also by using the 'what' command that will tell you if you have a closed object. Hope that helps a little.

A good way to go around it would be drawing the cube and using the 'shell' command as that produces nice solid models.

Thanks for the reply, I managed to identify what was going on and it really was a noob mistake!
When I shaded in Rhino, the grey shading made it appear that the box was watertight, as there was little contrast bewteen the surfaces. I wasn't familiar enough with the slic3r viewports to know what was going on!

After some head scratching I'm on the right track now! :-)

No worries, I'm glad that it has been solved. Good luck with the printing. :)