alloy tube bending

"Brian Whatcott" a écrit dans le message de news: snipped-for-privacy@4ax.com...

I have bent a lot of Al alloy tubing, and would recommend the eutectic alloy to fill the tube. But before putting it in your bending jig, rub it with soap. Proper soap is grandma's, yellow cubes, no perfume, no additive. Don't forget to wash it off afterwards. Cleaning the eutectic alloy after bending is not simple (heat the tube, and as soon as the alloy is half gone, wash the tube with hot water, until everything is gone. I don't know what you mean to use that tubing for, but a tiny drop of eutectic flowing inside may spoil the day, and perhaps more. At the price of the stuff, the alloy must be reused! To use sand you must put the tube in a vertical position, slowly pour the sand in the tube lightly hammering the outside to make sure the filling is ok (no air bubbles) when it is ready, heat it to around a 90°C-100°C, rub it with soap, and bend it. The sand must be dry, and you will have a much easier problem to get rid of it afterwards. The sand must be pure silica (no beach sand) Many art foundries still use it. We have been using that method to bend steel tubes, and pipes all the way to

36" and 4" thickness, smaller light alloy and copper tubing. The pipe was vertical, spinning on a revolving stand, with three pneumatic hammers were knocking on the pipe to ensure even filling. I forgot to say that if you can fill the tube without sealing the bottom end first, it is because the sand is not dry... yours robert hirschel

I should also have mentioned internal bending springs - these hold the pipe against collapse, yet can be pulled out (with difficulty)

Brian

Dear Brian Whatcott:

Same for external springs. They'll keep the tube from collapsing all the way, but can be hard to remove.

David A. Smith

If the usual methods don't work, consider anneal/ bend /heat treat. Expensive....

Brian Whatcott