Metal brake: 1/2" OD bend radius?

[anythingyoucanimagine]

I have a small ~40" manual/hand brake. I just drew up and cut out cardboard for airflow baffles surrounding an air compressor. Is there an easy/cheater way to bend 18ga sheet metal to something like a 1/2" or maybe 5/8" radius?

I've never done this before so I'll do test pieces. I understand there will be complications with measurements and bigger bend radius as well as at corners, etc. I'll practice, practice (screw up a bunch) but just don't know what to use on the brake to give me the bigger bend radius.

Thanks. (and yes I did Google)

 

[dr_clyde]

On a finger brake you would put a radiused finger(s) on it, then set the apron gap to sweep wide enough to clear the new dies.

It’s a pain to set up.

You will get a bigger radius than your die. I would start with 3/8” or 1/2” tube slit to fit over the fingers, and set the gap as wide as it will handle, then sneak up on it.

Alternatively you can “bump” bigger radius bends by making lots of smaller bends in a row.

 

[bullnerd]

Some brakes you can weld a pipe to a flat bar and clamp it under the fingers, but you need a lot of adjustability.

How wide is the panel?

You can also make one that basically mounts to the end of your bench, too hard to explain, Id have to find a picture. Might be in the Fournier handbook. You have that right?

Found it,make the roller mounts adjustable and start small like was said above. Obviously there is a million ways to do it, this is just one.

https://i.pinimg.com/originals/0e/32/b2/0e32b2bb18a7cd752be2f8e47c786a38.jpg

 

[anythingyoucanimagine]

Thanks dr_clyde and bullnerd. I made it but it's basically an exact clone of the 36" HF brake. I don't have dies but happy to make something. Bullnerd, the panel is 12" wide so it should be fine on the 36" brake. This is just an air baffle going around a compressor. Doesn't need to be exact/precise. I'll grab some bar stock or maybe black pipe and weld it to a flat bar like you suggest. I'll figure out a way to make that work. Dr_clyde, yep I get it that the bend radius will be than the die radius. The inside radius of the workpiece will be slightly larger and the outside radius of the workpiece will be much more bigger. (not proper English)

Bullnerd I like that bench bender with the rollers. Did you make that? Then what? Just use different size rollers? I like that a lot thanks!

 

[kazlx]

Only 12" wide and 16g you can probably do easily with a press brake style if you have a press. It would be pretty easy to make a form. The style like bullnerd posted would work pretty good as well.

 

[sberry]

If its lighter can often simply hand bend over the edge of a bench for 1 off jobs.

 

[bullnerd]

Thanks dr_clyde and bullnerd. I made it but it's basically an exact clone of the 36" HF brake. I don't have dies but happy to make something. Bullnerd, the panel is 12" wide so it should be fine on the 36" brake. This is just an air baffle going around a compressor. Doesn't need to be exact/precise. I'll grab some bar stock or maybe black pipe and weld it to a flat bar like you suggest. I'll figure out a way to make that work. Dr_clyde, yep I get it that the bend radius will be than the die radius. The inside radius of the workpiece will be slightly larger and the outside radius of the workpiece will be much more bigger. (not proper English)

Bullnerd I like that bench bender with the rollers. Did you make that? Then what? Just use different size rollers? I like that a lot thanks!

No, that's not mine, just a pic i found for an example. I did have one, but I lost it in a shop fire. Mine was a smaller version of that. Used strut shafts for the rollers/die.

 

[jsaw]

I have used the jaws of a vise and used the cross peen of a hammer to "massage" the radius to the shape I needed.
mark a line on the workpiece where you want the bend,
start with the jaws open 3/4 " , keep the line centered between the jaws, and slowly massage with the hammer while moving the workpiece . could also grind an old chisel or even a piece of flat stock to a radius and use that

 

[MoonRise]

12" wide and 18 gauge sheet steel and a ~5/8" bend radius and not really a critical dimension and just a one-off (or two-off )?

Just roll it by hand around a small diameter round pipe/bar or the edge of a bench. Done.

 

[4 FN 27]

On a finger brake you would put a radiused finger(s) on it, then set the apron gap to sweep wide enough to clear the new dies.

It’s a pain to set up.

You will get a bigger radius than your die. I would start with 3/8” or 1/2” tube slit to fit over the fingers, and set the gap as wide as it will handle, then sneak up on it.

Alternatively you can “bump” bigger radius bends by making lots of smaller bends in a row.

Following the Dr's orders here is all you need to know to bump increment form this part using a finger brake and 10 hits as we call them in the business assuming the Inside Radii will come out to approximately 1/32.

The flat view on the right is showing the actual center of the Bend Line which can be hard to pic up on a Finger Brake...but not impossible if you establish a zero with a drop piece of metal. This will take a little patients, a ridged backstop and a pair of Calipers to use to make the incremental changes of .082 for each 9° bend. An extra hand helps with this part.

The view on the left breaks down like this:

The Pink Color is the actual geometry of the metal formed.

The yellow dashed line is the theoretical Neutral Axis where the material neither compresses or expands (I use .44 on Cold Roll Steel).

The Red Lines (small line through the material, intersecting just beyond the outer material surface) locate the outside apex of each bend.

All dimensions on the left are Outside Apex.

The first bend would be the bend at 1.231 followed by the 1.149 and so on. This way the part will be feeding at you.

If the legs grow or shrink that means you are not getting a true 1/32 Inside Radii. You should be able to hold +/-.010 doing this this way but everything has to be perfect.

Give it a shot...

 

[theoldwizard1]

Minimum bend radius is a factor of the material (different steels and aluminum have different minimum bend radius) and the thickness of the material. Very little to do with the equipment.

 

[joe49]

Go to page 26 in the link.
https://books.google.com/books?id=ViUmhImu630C&pg=PA30&lpg=PA30&dq=fornier+radius+bends&source=bl&ots=3WeL2WReVi&sig=ACfU3U3FRiLBpJ-voHI7qz5RrB8_cGHgMQ&hl=en&sa=X&ved=2ahUKEwia_tmJrqbjAhWZKs0KHVq4BaQQ6AEwC3oECAkQAQ#v=onepage&q=fornier%20radius%20bends&f=false
Make a T dollie and a wooden *******.

 

[hawkeye2]

How about slicing a tube lengthwise, 1” conduit would be close to what you want.

 

[mrolds88]

One other thing I would do on your brake would be to bolt on a piece of angle to the apron. That would extend it out and keep from kinking your work piece

 

[EdT]

For an air baffle you could certainly use much lighter material and, as suggested above, just bend it over a piece of pipe or tubing.