The Craftmans Shop > Model Engineering

Sheetmetal Bending

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vtsteam:
I just clamp angle iron in a single vise for pieces up to 6" wide in gauge that thin. For wider stuff you can inset a piece of theavy angle iron into your bench edge, with tapped holes, and add a second piece with slots and bolts at convenient spacing as the clamping face.

I do understand, though, if you have invested in a cnc laser capable of cutting metal, you want to get use out of it, so why not? It won't save time, and you'll still need something to keep the bent legs flat, like any of the angle iron or vise suggestions. I don't think it will affect the bend radius which will be determined by the uncut dashes.

I do believe it will weaken your piece, but in model engineering, strength may not matter -- up to you. Well, you say you will weld (or solder) after, so that would not necessarily apply. I would think a groove would be better than dashes for bending through, but maybe that can't be done on your CNC laser. Simplest fastest and strongest would be an unwelded bend as Norman said.

If you are making kits for sale/production, I can see the reason for trying this to make it easier to bend by users wihthout shop equipment, and also pre-marking the cut all in one CNC operation.

Anyway, yes you can do it, no it wouldn't be more efficient for a one off, and would be weaker unless soldered or welded, but perhaps there are other reasons to do it that you have -- including fun with lasers.  :beer:

Yorkshireman:
Most of the parts are something like boxes 32 x 16 x 5 mm (26 'spacers' in a model of a rail car).
I think awemason's method will work best. If I scrape a 90 deg. V-groove on the inside, I will get nice sharp bends and reproducible outside dimensions, and 'reproducible' is the keyword here.
Johannes

RussellT:
If someone is doing the laser cutting for you it might be worth asking how deep they could engrave a line on the fold.

Russell

Fergus OMore:
As a 'Manure' student, I picked up double distinctions in City and Guilds Motor Vehicle Restoration and the trick is to fold with sharp edges on your vice or whatever rather than fiddle about. Dammit, it's pan folding, nothing more. The sharper the edges on your former, the better the fold. If you want razor sharp edges, then use the Mig but you'll probably blow holes in the edge until you get enough experience.

Simply settle for the easy pan folding stuff. Joining, by all means use the Mig but with a spot welder attachment if you haven't got a real spot welder. It's a modified Mig nozzle- no more.

What you have got to realise is that if you put too much heat in, your one milli stuff will probably distort and have to be stretched or shrunk which is a whole new ball game.

You've heard of  or heard oil drumming-? That's it.

Regards, good luck and I need that rest!

Norman

Lew_Merrick_PE:
Johannes,

When I need extremely accurate bends in sheetmetal, I place a pair of vee notches on either end of the cut.  Sometimes I place them in "ears" that can later be cut or ground off.  Then, when locating in the bending fixture, I can use a pair of sharps to line everything up.

Unless you are doing vise-based bending I am not sure how much value a dotted line would be.

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