Does any know where I can find (online, preferably North American continent) an aluminium tube with an OD of 0.75" an ID of 0.44" or less and a diameter tolerance of .005 or less? 
TNX
Google aluminum tube, lots of hits, for example
Read the spec sheet for tolerances. 0.005 feet? inches? yards? I'm sure one of those units can be made to work 8)
I wouldn't expect it to exist either. You're talking about tolerances that are as tight as DOM steel tubing in a material that has double the coefficient of thermal expansion. Something like this would have to be machined.
So... are you building a non-ferrous firearm?
Well I searched for hours yesterday, but to my surprise, I could not find ANY 0.75" OD tube with less than 0.5" ID!
This is for a hot-melt (250°F) glue nozzle. I wanted Al for its thermal conductive properties. I even considered brass, but I could only find sources the right size in India and China.
I finally ordered a DOM tube from onlinemetals.com this morning. I can live with a slower warm-up time, it is just not ideal.
Thanks for the help though!
Get some .75" solid bar and have it drilled down the center.
Rob
Yes that could work too! Thank you.
How Long? Getting a piece of 3/4 aluminum bar and drilling and reaming would not be a major problem, depending on how long you need it. Could even force a 7/16 ball bearing down it to burnish the ID and make it smoother.
Thanks kf2qd. I already got my DOM steel tube, but I will bear that in mind for future needs. The length was about 9 inches.