Which (press) brake for sheet metal folding?

[nctnico]

I hope somebody has some hands on experience with cheap (press) brakes for folding metal and can share some advice / experience.

For an upcoming project I have to fold some thin (1mm) aluminium sheet. This has to be done with some precission so I started looking for a good tool to do this. One avenue I looked at is to get a second hand one but even the very old ones fetch quite a bit of money. An additional handicap for me is that space is limited so I'm restricted to a benchtop model. 24" / 605mm is wide enough for now. When I make something from sheet metal, my go-to material is aluminium but I don't rule out using sheet metal (likely 1mm at most).

So far I have found 3 variations...

A low cost one like this:


I worry that the construction isn't stiff enough to make clean, consistent bends when trying to fold wide sheets. I've seen some people modifying these to add more stiffness. But I'm not looking for yet another project.

A medium cost one:


This looks a bit more sturdy than the lower cost version with the added flexibility of having removable fingers so it opens up the possibility to making odd shaped objects out of sheet steel /aluminium. Provided the fingers stay in place while bending... I may like to bend up to 3mm thick aluminium sheet at some point.

And a more expensive version which seems to come in 2 versions; with or without extra supporting L profile. I don't quite see what the additional purpose is of the extra L profile.





Since I'll need to move the brake to/from the bench before and after use, the weight is also an issue. The 3rd option typically weighs around 45kg which is more than I'd like to lift but I can probably work around that. The difference between the medium (2nd) option and the 'more expensive' 3rd option is that the 3rd model typically had set screws to -I guess- eliminate play from the hinges and the hinges are double instead of single.

All of the models above are relatively cheap and are definitely not precission engineered / manufactured. One way to look at it is to buy the cheapest model and just write it off after the project is done. OTOH if the more expensive models are actually good tools then the project at hand could be a good reason to buy a piece of equipment that lasts me a long time.

So the question is: what would be my best value for money?

[jpanhalt]

1) None are press brakes.
2) The first is a cheap, typical brake.  If you need to make a box, it won't work, because it has a fixed width.
3) Bending aluminum is easy.  Bending anything except dead soft (or maybe 1/2 hard) is trickier as you have to maintain a certain radius or it breaks.  There is also a lot to learn about setbacks for precision bends.

Have you consulted a shop for cost to do it for you?

Edit: Oops.  The second to fourth options look like box brakes.  They can make a box.  Probably either will work.  I can't tell whether they have an adjustable setback, but that is not absolutely needed.  You can bend a sacrificial sheet at the same time to provide the radius.

[nctnico]

For the project at hand I need very specific angles which may need going back & forth a bit depending on how accurate I cut the material. I basically need to make a pyramid with a square top and a rectangular base. Having a workshop do that is likely not going to work out time & money wise.

Your note about the setback did give me some extra input for Google which came up with this video which shows that the 3rd/4th models do have an adjustable setback:

[langwadt]

For the project at hand I need very specific angles which may need going back & forth a bit depending on how accurate I cut the material. I basically need to make a pyramid with a square to and a rectangular base. Having a workshop do that is likely not going to work out time & money wise.

how strong does it need to be?  if it is only thin aluminium you can probably bend it by hand if you make a score line on the backside if the cuts

[jpanhalt]

Set back is important, particularly with harder alloys when you need a bigger radius.  So, now your choice is down to two.  They also look similar.  I don't understand the need for mobility.  Some tools can be mounted to custom pallets, which are then easily moveable up to a ton or more. 

For a box or pan, you will need fingers that add up approximately to the width you need.  The ShopFox seems to have more fingers, which might be helpful, but it doesn't have the single large fingers.  If you get the finger widths, you can see whether the 4th will suit your needs.  I have a similar, but considerably older PEXTO.  None of its fingers are more than about 3" or 4."  More fingers is probably an advantage.  Are additional fingers available for either?  Both are probably made in China, so spare parts might be hard to get.  ShopFox is sold by Woodworkers Supply that has brick and mortar stores in the US.  I don't know about the other brand.

[nctnico]

Thanks for your suggestions!

The reason I want mobility is due to the very limited space I have. I have a shed that measures about 2.4 by 2.8 meters. Most of the floor space is already taken by a workbench, drill / mill, tool storage cabinets and materials I like to keep dry. For sure I could free up some more space by cleaning out some stuff (some that has collected under the bench) but it wouldn't mean creating enough floor space to have a brake setup permanently (even if I would use it regulary). So I'd likely need to put the brake somewhere where it is out of the way when not used but still in a place where it can be lifted onto the bench without breaking my back.

Getting different / replacement fingers looks like a challenge indeed. Maybe some can be found on Aliexpress / Ebay. If push comes to shove, I could use my mill to reduce the width of a finger but that would 'ruin' it forever.

[jpanhalt]

If I get a chance, I will get some photos my brake.  It is "portable" but mounted to a fairly heavy steel stand.

You mentioned previously that you were trying to make a pyramid shaped something.  What are its dimensions?  When I had my repair shop, I made a small press brake.  It was sort of like an arbor press but with a bottle jack in back to apply the force.  That is what I used for small, precise bends.  I used my finger brake for larger stuff like making engine baffles.  Do you have a welder?  For the homemade press, a drill press/mill and welder would be needed.

[nctnico]

The base of the pyramid shape I want to make is 50cm by 33cm (say 20" by 13"). Or to be more precise: my plan is to make a square tube that ends (tapers) into a pyramid shape. I want to achieve that by making 4 plates. Two for top and bottom and two for the sides. I want to use an L shaped profile to bolt / rivet the side and top plates together. All in all it is not exactly small.

I did come across a DIY press brake kit on Ebay BTW. I could do welding at my father's place (he is better equiped to work with steel anyway). Then again, that would become a project on it's own.

[jpanhalt]

For what you describe, a finger brake is probably more appropriate. 

The biggest thing I made with the press brake was about 8" long.  I used a 12" long die made from 1" square cold roll and a modified piece of commercial anvil for the radius I needed for 2024T3 aluminum.  McNeilus Truck (which made 60% of the concrete trucks in the US at the time) was nearby, and the father of the clan ran a scrap yard with all sorts of neat stuff including tool steel, at $0.10/lb.  I got a lot of neat stuff there. (circa early 1980's).

Pictures, I hope, tomorrow.

John

[connectTek]

https://www.kangindustrial.com.au/products/kaka-30-in-sheet-metal-brake-3-in-1-shear-brake-roll-combinations-20-gauges?variant=26504892744&currency=AUD&gclid=CjwKCAjw-rOaBhA9EiwAUkLV4ubLiHM1B6xyp5iU3TEZPffAOGuSjZAiNht2suIPIClSbwXnlnOXFRoCLZwQAvD_BwE
I have one of these, they are great, they also come in a 360mm version

[jpanhalt]

I finally got around to taking a picture.  It is a PEXTO (earlier Peck, Stow, and Wilcox) brake.  Picture is poor quality as it weights 150 to 200#  and is hard for me to move.  Moved to my barn circa 2010 and not used yet.  Rigidity is very important, particularly if the 1 mm aluminum is a hardened alloy.

What aluminum alloy are you planning to use?  How do you plan to cut it?  1 mm hard aluminum (e.g., 2024T3) will be difficult to do with a hand shear without curling.  For that aluminum, you will need to cut and then dress with a file before bending. A shear would be far more appropriate.  I have done 0.031" by hand (0.8 mm), and it is not easy.  Also, for 1 mm, T3 aluminum you need a bend radius of at least 5/32  or 4 mm (i.e., at least 4x thickness).

[nctnico]

Your brake looks like a good quality one. I wish I good find something like that in a smaller size for a decent price. Pity you are not using it.

The aluminium I bought is the regular, cheap soft stuff (by the look & feel of it). I bought it in a professional building supply store that is nearby. At least I have no reason to believe it is hard to work with in any way. But I'll make some test bends to see what happens first.

For cutting I plan to use a circular saw with a trapezium blade. That way I can keep the aluminium flat (and perhaps stack several plates to keep sizes exactly the same). I do have a shear (Peddinghaus size 3 IIRC) for sheet metal but that does not always keep the metal flat (especially at the side where the blade moves). It works much better than a hand shear though 

[jpanhalt]

Sawing aluminum (in fact even steel) will work with the right blade.  First time I saw that being done was a 2" thick aluminum block on a typical Delta Unisaw in the 1980's using a carbide blade.  It amazed me as I had always thought a band saw was needed.

You shouldn't have any problems.  PEXTO is/was one of the American name brands for sheet metal work.  All of my stuff was bought used, but that market is drying up.

As for alloys, the 2xxx series is used a lot in aircraft.  It is hard and doesn't weld easily (2024 can be spot welded). More common commercial alloys are 6061 and 6063, which are not as hard or difficult to work. Both are readily welded.  For your project, I would probably go with one of them (most likely 6061) unless you already have your material.

I have also used 3003 which a local shop called "half-hard."  It is easier to work with than dead soft aluminum yet is still quite soft and easily bent.  It has few advantages over the 60xx alloys, except easy bending.  I only occasionally use it because it is so soft. There are, of course, several other alloys.

Would love an update when your project is done.

[nctnico]

Yes, I frowned as well when I helped a family member cutting large aluminium sheets on a circular table saw. But he explained that it is possible with the right saw blade. Since then I've been cutting aluminium, bronze and brass using a circular saw myself.

I'll post some pictures for sure as it is a test chamber for electronics. Likely a project that interests others as well. I agree about the super soft aluminium being bad to work with. Recently I broke a 3mm milling bit because I didn't see it had filled up AND didn't apply enough lubrication -sigh- (I use Relton A-9 for aluminium per suggestion of this forum).

BTW: I have decided to order the 4th option (the 'Cowley'). Maybe I'll use some tackle contraption to move it around. Or at least lift it onto the workbench.

[Neepa]

The first brake I would consider absolutely unuseable if you want to achieve any precision.

During my apprenticeship we extensively used floor standing manual brakes to make all kinds of profiles for our projects. Bending 3.1364 T0 from 0.8mm up to 1.2mm and that was doable with a manual machine using a 3 or 4mm radius.
Those brakes were 1.2m across and could theoretically handle 3mm thick Al or 1mm/2mm thick Steel. However I wouldn't try it with one though. The biggest cast iron behemoth we had which could do 2 Meter wide sheets was only capable of 3mm as well.

At 3mm thickness the radius would need to be somewhere around 7mm+ to prevent the bend from splitting when the material is stretched around the bend. I would consider outsourcing such a job at that thickness. A hydraulic bending press would be more suited than trying by hand.

Doing it be hand is also quite a fiddly process if you want the length to land within 0.2mm of your desired dimensions. Any warpage in the sheet will result in an uneven crooked bend. Meaning you have to ideally adjust the brake for each sheet to get even results. That is if you can adjust the brake which none of the shown brakes have as far as I can see.

To properly adjust one the moving bar has to be variable in its distance from the holddown fingers when the bar's top surface is at 90° to the holddown surface. The sheet should fit vertically through the slot with just a tad of resistance without wiggle room between the fingers and the bar.

[nctnico]

Meanwhile the brake has arrived. The setback is adjustable like in the video I found. The weight is also not a problem; I can move it around just fine. I tried some bends and it works OK but I'd like to have an angle indication on it. I tried some 90 degree bends as a quick try but ended up bending too far.

[nctnico]

I've added a protactor to the brake to see the angle with some accuracy:



I took the pin that forms the hinge out. It is some kind of high carbon steel but not too hard. It was easy to drill a hole in and thread it.

[jpanhalt]

Emery metal has it own spring back.  5° is a good starting point -- at least that was the case with usual thicknesses of 2024-T3 aluminum and close to 90° bends.

[coppercone2]

cut out a acrylic circle and glue the protractor to it and mount that because it looks like dodge city