Numberplate box

[david7441]

Hi
I?m new here and I would welcome some advice on a project to make a new rear numberplate (license plate) box for the car I am restoring. I can cope with the box part but it?s the fancy bit that shows that I need the advice on. These things are very hard to find in a descent condition so repair or a remake are my best options. The metal is thin in places and has quite a few holes. It is worse than it looks in the photos. The whole thing is like two semi-circles connected top and bottom with straight bits (see photo 1). This is made up of two main pieces soldered together (a swaged piece plus a separate lip at the back ? see photo 3) plus cross pieces. I can cope with the cross pieces and the simpler lip at the back, but the tricky bit is the swaged surround that shows. I guess the original (steel) was pressed with dies.
My idea is to hammerform it ? possibly out of brass as I imagine that?d be easier to shape than steel. I was thinking of using some two inch thick maple offcuts I have for the form and clamp the brass to the top and hammer it INTO the form ? it has quite crisp corners, and I thought this way I?d get better corners than using a male mould and hammering round the former. Plus I?d be stretching the brass and not trying to shrink it. Will maple be hard enough for the former? The diagram shows a cross-section and is to scale, with the hammerform indicated one side to show what I intended.
I have done some basic hammer forming before but wonder whether this will work. Is this a realistic way of making this or am I doomed to failure? Is there a better way?
Any help or suggestions of better ways of doing this appreciated. I have basic metalwork tools, a lathe and a heavy duty swaging machine but can?t see I could do the curved ends with that, even if I could get the sides straight.
My alternative is to try and repair it by reinforcing the back side with steel sheet cut and shaped to fit, and fixing it on somehow. I fear that if I have the original blast cleaned there will be little left.
Thanks
David

[Gene_Olson]

David,
I'm just taking a guess here, but I would try making it in 4 pieces.
the two sides and the two ends.
the sides could be hammerformed.

I would have the sheet folded in a break to the width of the bottom flange and then use a piece of steel the thickness of the first step up to the curved cove section to clamp/bolt it down to the form. With it secured like that, the forming should go fairly easily.

for the ends, I think I'd try turning a plate on the lathe to match the inside and then bolt a sheet on the narrow end with a holder plate right to the edge. Then I would try spinning it on the lathe and if I had trouble with that, I would make a few raising passes around the circle to raise the edge to a 45 cone and then hamerform it down. I would make a couple special tools for that, a dull polished 90 deg (slightly less) "chisel for setting the corners and a polished concave planisher to smooth the curve.

then it would be cut and paste with the pieces to assemble.

of course, somebody else probably has a better idea.

Good luck.

[1969robinhood]

Actually Gene....that sounds like a pretty good approach to me...although it would be my choice...it will involve considerable work for a newbie like myself...

[Boogiemanz1]

Gene I think your way will certainly work, I just wonder if it might not be easier to spin out a die on the lathe and press the ends as a circle with the die, into a rubber pad, If it needed additional detail, use the die as a hammerform .........john

[david7441]

Thanks Gene for the suggestions

Four pieces sounds a good idea. I guess my idea in one piece getting it to stretch round into the ends is expecting rather a lot.
If I spin the ends round an internal former am I going to get good corners on the outside of my finished piece? Aren't they going to round off?

Thanks for the help
David