forming trumpets

[philpullan]

hey guys thought id pick your brains on this 1 . im wanting to form a trumpet so far im not sure of the large size yet the tube its to be made from is 50mm ive looked on youtube to see if theres anything on there but nothing i think i could replicate
is there a way of doing it other than on a lathe ?

cheers for any help
phil

 

[hotrodder]

Diameter of large end and length of the thing will play a big role. If we're talking thin wall tube and the change in diameter not massive then (depending on dimensions) can be done with a hammer and dolly. Limitation would be the diameter of the large end i.e. how far the metal can be stretched before it splits

place end of tube over convex dolly and hammer (combination of on dolly to stretch and off dolly to move metal) while rotating tube. As the tube stretches you can reach further inside. Made an air filter housing several years ago that incorperates a velocity stack made with this method. Due to dimensions i rolled a cone first rather than starting with tube and then stretched the large end forming a bell mouth