Shrinking a flange

[madkayaker]

Used to make tray keys at the college for folding the edges of cable tray to make swept bends and they were just a length of flat bar with a cut near the end will see if I have one to photograph anywhere

 

[Terrapin]

Great 'how to' post. I forget that a lot of these basic skills are getting lost to all but a few these days. However, I always find it amazing that in the more remote/poor locations (I visit Asia quite frequently) the back street metal workers have fantastic skills borne out of necessity and the lack of power tools. I have seen a guy take a front wing off a car and beat it into shape to fit a completely different model - and it was extremely well done!

Apprenticeship memories .......

• Soap/Fairy liquid on aluminium - heat until it goes black - your ally is annealed.
• Chalk on your file to help prevent aluminium clogging it.
• Paraffin to lube alloy when turning

The list goes on ………………..

Did anyone have to file a perfect cube out of a piece of round bar or chisel a keyway by hand

Happy days

 

[droopsnoot]

I have the same problem, when I start hitting the tucks all it does is straighten the panel out again. I did have a small amount of success but nothing controllable. I did buy a shrinker when someone posted a link on here to a bargain, so I all but gave up on how to do it by hand. I doubt the shrinker would handle 1.5mm plate though.

 

[Paul.]

Well he came back today for another piece, this trailer is turning into a bit of a patchwork job, this is just a flat plate with a return going round a radiused corner, just to make a safety edge and stiffen it a bit,

Cut out and bend lines marked


Straight bends pulled up on the folder


Trade secret time, gently define the line of the curve with a narrow cold chisel, not to cut it but just enough to weaken the metal and make it bend where we want it to.

Back on the dolly as before, just another suitably sized piece of old bar from the odds & sods box, I don't normally work with rusty bar, but it does the job,


Then to finish it off use the dolly on the inside pressing down on it with one hand against the bench, (or clamp it if you want) and dress the flange up square, sliding the hammer along the bench to keep it square,


And thats it

 

[Paul G]

Don't get me going on shrinking.

 

[Shox Dr]

it that a mud guard?

 

[stuvy]

it that a mud guard?

id guess its for a 60's trumpet or bsa?, either way its looking good

and thanks again paul as i was scrolling down i thought how the hell is he gonna do that!

 

[outofthefire]

Don't get me going on shrinking.

If you heat the hollows up then rest the low point on your dolly and work round the edge of the hollow gently with your hammer they should start to shrink. Dont hit the metal directly on the dolly with your hammer or you'll start to stretch the metal. Heat will help them shrink.

 

[Welderpaul]

How thick is the material Paul?

 

[Paul.]

How thick is the material Paul?

1.5mm,

 

[CRB]

Learn, learn and learn some more.

 

[steviec_lj]

Need to get me some solid lumps of steel to use as dollies! Awesome work, I have some arches to form!!

 

[CRB]

I have a VW LT. it may have an MOT but there is plenty shrinking and stretching to do.... especially the lower windscreen corners!

Learn, learn and learn some more.

 

[Paul G]

After some gentle persuasion and wiring the edges it looked like this. (see pic)

It's a 1.5mm thick aluminium rear wheel arch on my Lotus Seven.

Paul G

 

[CRB]

Geometric mat

 

[hotrodder]

I have the same problem, when I start hitting the tucks all it does is straighten the panel out again. I did have a small amount of success but nothing controllable. I did buy a shrinker when someone posted a link on here to a bargain, so I all but gave up on how to do it by hand. I doubt the shrinker would handle 1.5mm plate though.

There are bigger ones that will but they still have lots of limitations... a couple of grand + on something like an Eckold HF100 (and if you want a pair of stretching dies too that'll getting on for be another grand) will get you a shrinker that doesn't rip the surface to within an inch of it's life, will handle 16swg mild steel and has a throat depth of 4". Still need to know traditional methods to turn curved flanges though, they just speed things up and offer more precise control once the part is roughed out

 

[droopsnoot]

Yes, I meant mine specifically, I have seen some other heavy-duty ones. Mine is just about at it's limit shrinking 18swg, but as that's all I'm using it for, it does the job. The marks are annoying, true, but can be cleaned off quite effectively.

 

[julieanncharters]

After some gentle persuasion and wiring the edges it looked like this. (see pic)

It's a 1.5mm thick aluminium rear wheel arch on my Lotus Seven.

Paul G

from what was looking like a cluster f-ck to a piece of art.
nice.

 

[Paul G]

from what was looking like a cluster f-ck to a piece of art.
nice.

I've told you ten million times not to exaggerate,


but thanks anyway.
Paul G