Bending without bending rolls

I am making the cladding (cleading?) for my loco. I have a piece of .020" copper 26" by 6" to wrap the firebox in a U shape. I don't have access to bending rolls so I intend to bend it over a suitably undersided paint tin. I need to put a 3½" hole in the middle to clear the manfold. If I put the hole in first I am worried that the copper might crease rather then bend? On the other hand, how could I make the hole after I've bent it?

Any suggestions as to the best way to proceed would be much appreciated.

I would bend the cladding first then

You could use a Dremel type grinderette - but wear goggles as copper in the eye is VERY DANGEROUS.

If you had the Dremel jigsaw attachment, that may work, but its a bit expensive just for 1 job.

ive never clad a boiler in copper before...brass, even wood but never copper? surely its not a great idea?

I was sold the copper by an ME Trader because they didn't have the specified brass in stock. They told me that the only disadvantage of using copper instead of brass was that it was more susceptible to damage eg kinking. I have already lagged the boiler barrel with the same copper material, and painted it, with no obvious problems. I'd be interested to know what the potential problems are before I proceed any further. I should perhaps add that both the boiler and the firebox cladding are over 3/16" ceramic insulation.

Denis.

Firstly you must drill all holes before rolling also you must if there is a very large

hole pre drill all round roll then after rolling cut your large hole keeping in mind you must have done all your blue, marking out and scribing. Regarding a set of rolls it If you are a member of an ME society I am sure that they have either one or a member has whom I am sure will be delighted to help you.

I have been doing a lot of research into mouldable ceramic materials and will be publishing my findings soon.

its just so soft? smooth, like velvet almost! and conducts heat rather well,

My suggestion would be to bend first then drill holes. If the holes were drilled first the copper would be weaker where the holes were and you may not get an even bend, possibly even a kink. It is also more difficult to locate the exact position of the holes if they were cut before bending. A card template could be made and adjusted to the hole location and then this transfered to the rolled copper. Anlealing woud help the copper to form more easily.

Hi Engine

I hate to dissagree with you the articles in ME by Dag Brown on the 7.25g Anna ( I built one) Dag recomends the method that I sugested but there must be careful marking out.

Kind regards

Bob

On the traction engines that I have made I have rolled first and then done the cutouts for the same reason Engine Builder gives, though they were all brass.

J

Many thanks for the various suggestions. I eventually chain-drilled the 3½" hole and then bent it over the paint tin. I then released the big hole (which itself was nicely bent) and trued up the hole using a rotary sanding drum - worked a treat!

Many thanks