Luis:
>> I always wandered about clearances, how close coupled do you guys think
>> is the screw to the wall of the tube?
>> As anyone found any design notes on designing and building one/

Carl:
> On the say 6' diameter, might be 1/2" or more. THese are not made to
> aircraft engine tolerances, more like a structural steel fabricating
> shop, and that screw is somewhat difficult to shape and weld together
> with any real precision. Usually there is no machining of the screw O.D.

To start off one MAY be better off winding some sort of tubing around
a centre core.
Result will be a guaranteed leak proof pump at any angle less than
vertical. Volume pumped per turn is related to tube diameter, core
diameter and angle.

Simple to play would be garden hose.

Easy to make but more robust would be eg copper tube - possibly anneal
before bending.

Impressive would be exhaust tubing.

I can imagine a multi section design using injection moulded segments
joined together to make whatever length is required.

I sense a Coke can based design aborning.


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