> "Archimedes screw" is actually a device for lifting liquids. I think you
> mean "Acme screw", which is typically the leadscrew device used on
> flatbed applications like lathes and mills

Dave, quite correct. I do recall it as Acme thread now you mention it

A source I found some time ago was the mechanism on old windows
at a building materials recycler. Not exactly top quality metal, often
brass-ish, but they did work and are a complete unit

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist