Member postings for Carl Wilson 4

Edited By Carl Wilson 4 on 27/06/2017 20:40:43

Hello John,

Thanks for the information. I can get hold of a set of rolls that can cope with 2.5mm thick aluminium. So I can re-jig my design to account for the available tools (have a decent margin on safety factor) or I can use a bit of extra grunt for the extra 0.5mm.

Thanks for all the posts. I can get a set of rolls that will cope with 2.5mm thick ally plate relatively easily. I had already considered the possibility of turning the part from a large blank, and indeed i may still do this. Just looking at all the options.

Carl.

Thank you very much for all the replies. John, it is Metal Craft I was thinking of but they don't seem to do a suitable machine. I seem to remember seeing a set of rolls that you could fit into a bench vice that could be then stowed when not in use.

Duncan, your plan is sound, however I would like to get hold of a set of rolls because I may want to do more such work in the future and also I might get my calculations wrong! It is far less embarrassing to have to go back and make another part myself than to have to ask someone else to do it again!

Ian - I think I may have used the wrong terminology. I meant that I need to fabricate a truncated cone. I looked at the caldera cones on the net and they seem to be some sort of camping stove, like a Trangia. I thought the term caldera was the name for a truncated cone shape. What my truncated cone is for is a rocket engine nozzle. It will be 3mm thick 6082 plate.

A few years ago now I was in a shipyard where a new cone shaped fairing for an azimuth thruster was made. The ship that the thruster belonged to had lost the original part in an accident involving a large submerged log off the coast of Equatorial Guinea. The fairing was made from 1 inch thick steel plate. the cone was laid out in the flat on the plate using standard sheet metal techniques. Then the pattern was profile burned out. The resulting bit of plate was then rolled in a large set of powered rolls. Once the cone was formed, it was seam welded while still in the rolls - the rolls being the perfect jig to hold the part while it was welded. Then one end of the bearings for the rolls were removed - the rolls being designed to do this - and the cone was slipped off. When I say slipped off I mean using an overhead gantry crane on to a waiting forklift. The cone must have weighed a quarter of a ton.

So I was thinking about doing this but on a much smaller scale. Although I would not weld my cone in the rolls because I think I'd like to joggle the seam and TIG weld it on both sides to get a nice strong joint. TALAT among other places recommend this type of joint in aluminium plate.

I will keep looking for a set of little rolls.

Thanks again,

Carl.