Thread: How much muscle needed bending 2.1 m of 3mm steel on panbrake

I'm a bit late to this discussion but here is a list of tonnage require for bending plate
cheers

There are two parts to this question. Tonnage to bend will depend on the material thickness - from memory it is related to the cube of the material thickness. That is, if a 1mm piece takes X units to bend, a 2mm thick piece will take 8X units. Doubling the width of the sheet (that is, the length of the bend) will double the force.
The nasty part about bending wide sheets is that the bending device beams will deflect. This is (again from memory) related to the length of beam to the 4th power. If the beam deflects a proper bend will not form. Therefore while a pan brake may be able to bend a 1m wide sheet satisfactorily (say it takes Y tonnes of force), a sheet twice as wide will take 2Y tonnes but to hold the integrity of the bend, the brake will need to be at least 16 times stronger to resist the forces.

Attached is an add from Home shop machinist for people wanting to do similar things to you. The interesting thing is the folded corners of the table. Instead of a solid bend it has been slotted (I think someone else suggested this)
Scan (Medium).jpg
If you make your bend say 90% open space, then obviously the force is reduced by 90%. While you will still need a wide folder it will only be resisting 10% of the bend force so will not need to be as solid - you may even be able to get away with something home made if your slots are big enough. Welding up the corners post bend is possible, but I don't know how a weld with 'normal' wire would look on corten. It will rust but maybe at a different rate or in a different way.

Michael

Thanks for the chart Gazza, a lot of force in bending an innocent peice of 3mm.

Thanks for the maths info Michael. That hits home the benefit of reducing the thickness at the bend line, as suggested in a previous post. How I would achieve this cut is another matter, need a consistent depth all the way along (without going all the way through LOL).

Seeing a photo of the slot cuts has confirmed my worries of that method. First the visual appearence of the slots, and something else I just thought of is when the light is switched on at night, it could shine through the slots. Glad you posted that photo, saved me physically testing it out in the workshop.

Cheers,

Keith.

Hi Michael,
Interesting picture, I hadnt given any thought to the pattern going around the corners, you'd just need to be careful what the pattern was doing at the corners or funny things would happen when it was folded. Is it meant to be a seat? there is very little metal holding the top and at least one leg in place. You first

Stuart

I think it's meant to be an outdoor setting table. You'd need to make sure you were drinking pints and not spirits though.

Michael

I'm always looking at potential patterns with a view to the strength. Some patterns, although looking good, leave a miniscule amount of metal holding a big chunk in place, you could literally push with you finger and stuff it up. That photo looks like a table to me and often they put a sheet of safety glass on top. A seat would need a different pattern for strength.

That photo looks like it's from Plasmacam. I know of one cnc electronics manufacturer that really get peeved off with the way Plasmacam makes everything seem so turnkey in plasma cutting. They try and get the message across that if you buy one of their tables you'll be making money in no time (by making tables like that for instance).