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Thread: 90 degree bending

  1. #1
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    Default 90 degree bending

    I have to make lots of little matchboxes and have gone down the casting route and failed. The box and cover fit together perfectly when they leave me but once cast they don't fit at all.

    I've decided that the best way forward is to get the inner tray cast and to make the outer sleeve from sheet metal. I've decided to make the sleeve in 2 parts, each with a 90 degree angle and to then solder them together around some sort of former which is the same size as the inner.

    Really, my question is in 2 parts -

    1. What is the best way to bend the metal? It has to be quick as there will be a lot of them to make. No scoring and filing. I've looked at the Axminster mini brake http://www.axminster.co.uk/sieg-miniature-shear-brake. Does anyone have this or similar?

    2. What is the best material to use as a former when I solder the 2 L-shaped pieces together? I was thinking of cutting down fibre board but the stuff I've used in the past is quite soft and crumbly.

    Many thanks.

  2. #2
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    Default

    Have you looked at the Bonny Doon brake bar for the press? I've not used the Sieg press brake, but I've used others; for the really cheap option Axminster do some vice jaw attachments, although they're a bit limiting. All but the BD approach will mark the outside of the bend, BTW. Fingers on a brake are handy for doing boxes - you don't always want the full length of the brake bar.

    Thoughts on formers - the ceramic fibre board I have isn't all that soft (subjective, of course); you could cut a soft firebrick to size; a hard firebrick is a bit of a heatsink (as is the mouldable firebrick). Could you not wire the pieces together while on a former and then remove it? Tack welds help too

  3. #3
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    Dubai (originally from Brighton UK)
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    Just my 5 cents worth - If I have to wire tricky shapes together, I tend to super glue them first, then wire - the super glue burns off when you heat for soldering.

  4. #4
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    Default

    I did look at the Bonny Doon brake bar and maybe that's the way to go. I just wasn't sure how accurate it was, as if the metal moves slightly in the press it'll send the whole thing out of alignment. There might be some way of taping it down.

    I tried wiring the pieces together but as soon as I remove the inner former, the whole thing moves.

    Where did you get your ceramic fibre board Peter, it may be better than mine?

    To be honest, I wish I'd never started this process as it's turning into a nightmare!

  5. #5
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    Thanks Paul. I think wiring and superglueing may work.

  6. #6
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    I *think* mine came from Purimachos in Bristol (name has changed since then AFAIR). I bought a pallet load of refractories from them a while back and have gradually worked my way through it.

    All of the brakes suffer if the piece moves; with the press you can at least check alignment readily before bringing the pressure up - or make a jig if you're doing repeated pieces. Are you making the legs of the L oversize for a t joint or are you being precise and making butt joints?

  7. #7
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    I'm making them oversize for a t joint.

    I don't think I need a pallet load!

  8. #8
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    The other way would of course be to score and fold; it'll give a sharper corner.

    *Everyone* needs a pallet of refractory materials, surely?

  9. #9
    Join Date
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    I am not sure of how many match boxes you are making Carole, but back in the past when I was making rectangular cigarette lighter cases by the dozen, we arranged to have 16 inch x 2 inch strips of metal that were the correct width of the L shape half, scored by an engine turner along the angle bend line. Nowadays I am sure that there are CAM machines that could do this for you. Then we just pierced the strips to size and bent then on a steel block, filed a bevel along each solder join then used binding wire to hold the two angles together while soldering. The lighters were cheaper silver versions of the rectangular lighters in the centre of this photo.

    Click image for larger version. 

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    James
    Last edited by Goldsmith; 20-11-2014 at 10:31 AM.

  10. #10
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    Mar 2013
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    How about a metal bending tool like the one Durston has just released Carole?

    It's got a die that'll allow you to form perfect 90 degree bends, or alternatively use a scoring tool to form the creases if the filing approach is going to take too long for you?

    Nick


    Sent from my iPad using Tapatalk

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