Bending metal bars.

[Steve Webb]

Not really transaxle specific but its for the GTV so I thought I'd slap it in here.

The rear spring pans on the car have worn through, not all the way round just in a couple of places. Its not all corrosion, mainly is just because of the friction between spring and pan.

So I've picked up some 30x2mm and 16x2m bar to patch it up. Now, bending this bar along the 'easy axis' (bend in the 2mm plane) is pretty straight forward.

But is there a way to bend in the 30mm plane, or an I going to be cutting through 80/90% bending and welding to get a rough shape?

I'm guessing heat and violence is going to come into this somewhere.

[wrinx]

It's quite easy if you can knock up a DIY jig and the material is soft enough. If it's bright metal it'll be harder than the stuff with mill scale on it...you'll be limited with how tight the bend can be though.

If it's really small you'd be easier chopping the circle from 2mm plate with a jigsaw and metal blade (I've cut 10mm like that!) then grinding it to the finished size.

These jigs will give you some ideas....

This is what you want to achieve I think,


Basic idea, hold the material and bend around a former.


Simpler version, just move the pegs to hold the material and bend around another. Bend every 10mm or so bit by bit.




wrinx

[Steve Webb]

Indeed that is exactly what I was after, cheers, my only worry is that the bar will twist as its only 2mm thick. Although I'm sure I can sort something to prevent that.

Time to dig through the scrap box and see whats to hand.

[wrinx]

If you make the jig base large enough you can make sure the strip is kept flat as you bend...although 2mm will be easy enough to sort out if it does curl up.

wrinx

[Steve Webb]

Made a small jig up this afternoon with some scrap bits and pieces, looks like its gonna work in theory, just need to change a couple of parts to make the bending easier and keep the bar flat to the jig.

[wrinx]

Piccies...

wrinx

[the wombat]

Interested in this. Useful info here.

[Steve Webb]

Well I'll try and get some pics when I've made the changes.

Looking closer at the pics wrinx posted, it seems the important part is keeping the inside edge of the bar flat to the base. Looks like a notch in the inside roller is the easiest way.

Oh and bending bar in the flat direction is much harder than you would imagine, everything needs to be aligned 100% or it all starts bending in odd ways.

[wrinx]

Looks like a notch in the inside roller is the easiest way.

Yes, a step about half the width of the materiel should be enough.

What diameter are these circles, would it be easier jigsawing them out of sheet?

wrinx

[Steve Webb]

Yes, a step about half the width of the materiel should be enough.

What diameter are these circles, would it be easier jigsawing them out of sheet?

wrinx

I'm beginning to think that now. But to be honest I spotted new spring pans somewhere that just need to be welded onto the A frame. Not that expensive so I think I might go down that route instead. Seems a better way of sorting out the problem rather than bodging up whats there. Especially given the quality of my welding of thin materials.

[Steve Webb]

Page 52 on the pdf shows the parts I'm on about. It will be much easier to cut the old ones off and weld a new pair on.

http://www.myalfa.eu/katalog/english/1/Alfetta.pdf

Got new bearings and all new bushes for the rear so should end up with a factory fresh rear end.