How to make U-channels out of glavanized sheet metal?

Hi,

I want to make U-channels from 0.65mm galvanized steel plate.
The U-channels will be use as edging on metal cages.

The U-channels need to have following dimensions:
20mm on both sides
Internal width; 3.5mm
Length varying from 300mm to 1000mm

I can't use plastic or rubber as animals will chew on it.
I am in the market to buy a pan brake but most of them can only fold up to 135 degrees and I need to be able to bend to 180 degrees
A hemming tool isn't good either as it just flattens the material.

Can somebody tell me how this is done with sheet metal tools?
I want to make them myself as I need to be able to make variants to the design.
Thanks for your help.

Luc

Making these accurately requires a sheet metal bender - for a 1m length this is a machine that costs several thousand dollars

Most home made folding jigs will stretch the metal and will make the channel Bow so producing 1m lengths could be problematic.

However if you wish to persist then I would sandwich the metal strips between two pieces of 3.5mm thick angle iron leaving 23.5 mm of metal showing and clamp everything together firmly using strong clamps spade about 150 mm apart. In addition, camping them onto a bench or in a vice would also be a good idea.
Then use a wooden mallet to progressively gently fold the metal around the lip of one of the angle irons. By progressively I would bend it over by no more than 5 mm - once the whole length has been bent over by 5mm go back and bent it another 5 mm etc.
Of course you will need to move the clapms

My guess is it will still bow but the slower the progression the less it should bow.

Perhaps a magnabend?

Thanks BobL for your reply.

However I am in the market for a pan brake and I do know they cost around the $3500.00 mark. I want to buy the machine as I want to start off a bit of a production. If it would be a one-off I could indeed use a hammer and a mandrel. The machine I'm planning to buy will have a operable folding width of 1300mm at a thickness of 1.6mm.
I am just after the sort of machine to buy who can do this kind of job.

I have tried a magnet pan brake at work and it can make U-channels but the lowest internal width is about 10mm, which is too wide for my needs.
Cheers,

Luc

Hi .RC.,

Thanks for the suggestion. Yes it was a Magnabend I used at work. The minimum channel width I could achieve with that was just over 10mm.
Cheers,

Luc

Hi Luc,
I believe it may be possible as I have achieved a bend of similar dimensions be on a 135 degree bend angle machine while in the education system.
Not a full 1metre length, mind you,but I have folded around 300mm length (but with unequal leg lengths).

The trick was to partially bend both bend lines, then bring one to 90 and place the bend with the insert ( as described in a previous post) under what I would describe as the hold down member. The hold down is used to then squash down / bend the top flange down on insert. This was fiddly to engage the hold down and if I remember some manual dressing was required to pull the flange down and keep the insert in position so the 90 bend formed for the upper flange.

Its been a few years, but I know it can be done but all the finer details are fuzzy.I would be having a talk with a sheet metal work tradie before rushing out and buying a pan break on my say so. One of the other Industrial arts teachers was an ex sheetie and showed us the little tricks and short cuts.

The sheeties will set you straight on how it can be done.

Grahame

I just tried this on a Magnabend and found that it can be done although it is not ideal and the longer the length of bend the more difficult it becomes. I substituted the standard 16mm thick clamp bar for a piece of 3mm thick flat bar the same width as the standard bar to maximise clamping area and then just folded it over 180 degrees. Short lengths worked well but a piece around 600 wide required extra clamping.

Hi Techo1,

That is good to hear!
If that is the case I probably need to make up a jig that involves the original clamping bar but bolt on an edge of angled iron of 3mm all over its length.
I will have a better look into this once I'm back in the workshop.
You've been a great help there and thanks for trying it out :-)
Cheers,

Luc

If I only needed a short bit I'd fold it as much as possible in the pan brake (135 degrees or so) then put a piece of material of the gap thickness in the v and use the folder to then squash it down the rest of the way. 0.6mm material won't cause a problem with that method.

Michael

0.65 is not a heavy gauge .
How accurate or sharp for better words do you need the edge to be.
I my self ,would be bending it over sandwich between some clamped timber DAR hardwood.
Using a panel beaters slapper (yes that is what there called a bit like a small bat with one face having a slight crown in both directions covered with s strip of leather)
I have one but its in Ballarat and I'm in Melbourne .
To push the edge over before trimming it up with s dolly ,and planishing hammer.
That's how we use to make up rust repair panels for restoration work on cars sills arches. Etc.
Sorry for all the panel beating terms ,comes from being an old panel beater.
Hope that helps in some way

I agree with what Michael said, have done this many many times. As you're going to have your own folder, the 3mm insert piece could be made as an insert, that can be bolted as a semi permanent arrangement, instead of trying to hold it in place.
Kryn

LRAT, if you have a fair bit to do it might be worth your while to build a roll former, https://www.youtube.com/watch?v=mhAfO2zQr5I
It wouldn't have to be a heavy industrial machine such as in the yoowie clip, you could likely bend your strips
to 135 deg and then finish them in a reasonably small/lightweight homebuilt rollformer

shed

A hydraulic press might do what you want but you would have to make or have made punch and die for the profile that you need. I used to use a No:5 fly press to put 1/4" inch wide "U" shaped bends in 1mm aluminium, but then they were only 9" inches long. The female die had a tapered profile but the punch was a simple flat bar. Neither were hardened but wax was used as a lubricant.

Guess it comes down to quantity and how serious you are. One Hydrabend we had several years back did have the correct bottom former for a very narrow U - not that it was ever used as I recall - probably in the 5/6 tonne range and could take a full sheet, 2.4m. At the other extreme, John Heine did produce a simple manual bender that with the correct upper and lower mandrels could produce what you're after if you're only got short legs each side. Only ones I've seen are 1 yard wide though, but maybe larger exist?