Fabricating a Battery Box

[Tscott]

I've been restoring a Triumph Spitfire on and off over the last few years for my father in law. Up until now it's been mostly mechanical restoration. New bushings, bearings, etc. but I've now reached a point where I get to actually fabricate some parts. I've got limited experience working with metal. My last 2 restoration projects were a boat and a corvette so fiberglass has been my medium of choice but I've always wanted to fabricate in metal.

Last night I decided to dive in head first. The previous owner of the car decided to patch the rusty battery box with fiberglass. At roughly 3/4" thick it's pretty messed up and pretty well adhered so a new box will be needed. I could buy one but making it will be more fun.

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The box itself is pretty complex piece with vertical ridges running top to bottom. The ridges probably serve to stiffen the box but I'm going back with 22 gauge which is thicker than the existing box, so I decided I could do away with them. with limited metal working tools I decided my best bet would be to build a form in the shape of the box and to beat the metal over it.

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A few layers of plywood later I had a shape roughly equivalent to the box. To get the radius bends at the bottom of the box I broke out the router and took the sharp edges off all the corners.

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To keep everything in place, I used a few screws to attach the flat stock to the form.

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I used my body hammers to form the metal to the contour of the form. At the corners where the metal needs to shrink I make some relief cuts and hammered one edge over the other and followed that up with a quick cut form the angle grinder to cut off the excess.

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That's as far as I got last night. So far so good though I've decided I need a few more tools to make it easier. I ordered an 8" bench shear this morning to assist in cutting the panels. To get this far I had to use a set of hand shears and I managed to cut myself pretty good while attempting the long straight cuts I needed. The bench shear should also come in pretty handy as I start cutting patch panels for the rest of the body.

I'm open to any pointers. As stated I'm fairly new to fabrication and just sort of fumbling my way through based on what I've seen others do in the past. I should get a little more time tonight but without a shear I hesitate to attempt any more long straight cuts as my finger still hurts.

Tom

 

[rlitman]

What are the odds that a steam tray pan bottom (which is already deep drawn) would happen to be the right size for your purposes?

http://www.bigtray.com/c3-19740-steam-table-pans-hotel-pans.html

 

[Tscott]

What are the odds that a steam tray pan bottom (which is already deep drawn) would happen to be the right size for your purposes?

http://www.bigtray.com/c3-19740-steam-table-pans-hotel-pans.html

It's probably pretty close and could be made to work but this is more fun. I also need to rosette weld this thing back into the car here.

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I've only got a mig and no experience welding stainless.

Tom

 

[matt_i]

Have been doing some duct work and a hand nibbler which approximates a double-shear is much nicer as it doesn't require one side of the cut to "curve" by the cutting edges. Just a little "kerf" is ejected.

The hand nibbler may not be able to do 22ga but I'm pretty sure the powered ones fall into that range.

 

[racingtadpole]

You should be able to planish those corners out and not have to relief cut them. There isnt much metal there to pucker out, so you should be able to get it to shape without too much hassle.
Have a look on YouTube for flow forming videos, there's a heap of good ones.

My other suggestion if you have air available, is to get a pneumatic hammer, its heaps faster..

If you want to really challenge yourself, try flow forming the entire panel from one piece...

 

[MP&C]

^^^^ agree with rtp. Since you'll be welding the sides onto the tray bottom, the corner slits aren't too much sweat, but as this is "more fun" you may as well learn something new with it, right?


Here's a video in hammer forming a no-weld corner. Basically the tuck that forms is all your excess material gathering, keep hitting what becomes the high spot (the tuck) until all the excess gradually works itself into the corner.

 

[jimgood]

Cool project. I'm glad to see that you're trying to make it.

Is it possible to make the entire box out of one piece without welding; i.e. flange and all? Would the order be to form the box then the flange? And is there a risk that there could be too much stretch in the corners of the flange that it will split or should enough metal have gathered in those corners from the box forming process to compensate for that?

 

[jackson1701]

^^^^ agree with rtp. Since you'll be welding the sides onto the tray bottom, the corner slits aren't too much sweat, but as this is "more fun" you may as well learn something new with it, right?


Here's a video in hammer forming a no-weld corner. Basically the tuck that forms is all your excess material gathering, keep hitting what becomes the high spot (the tuck) until all the excess gradually works itself into the corner.

Robert, You always make it seem soooo easy. Thanks for always sharing your skills with us!