radius nosebars for bending brake

[Harold Line]

Good morning all. I'm looking at a 48" bending brake from King Canada. Looks like a decent piece of equipment but the nose bar is sharp they don't offer a radius nose bar. I don't want to have to machine the original nose bar. Does anyone have any ideas on how to do 1/8" radius bends or how to modify a machine like this to do 1/8" radius bends?

Thanks for your help.

[CraigCantwell]

If it's the 48" x 16Ga one, places like Mittler Brothers have replacement fingers with different radii available that should fit. Most of these units are direct copies of early Pexto's.

https://www.mittlerbros.com/mittler-bros/sheet-metal-brakes/ultimate-box-pan-brake-fingers.html

[Harold Line]

Hi Craig. Thanks for the note. I looked at the Mittler Bros product. Very nice but more expensive than what I'm looking at. I'malso in Canada so shipping is $$$. Their radius nose bars don't fit the unit I'm looking at. https://federatedtool.com/king-48-x-12-ga-floor-model-box-pan-brake-kc-bp4812/

[bigdog]

Use some shim stock between the nose bar and your work piece. Back the nose piece off an additional radius from the bend line. In your case you'd need .125" stock but that probably won't handle the zero radius without cracking so maybe try 4 layers of .032". Once the shims are bent, you can reuse them for other bends. They only need to be as long as the bend you are making.

[Harold Line]

Will give that a shot bigdog.Thanks for the tip.

[Ken Mercer]

Harold,

I found a .125" X 1" X 6 ft. piece of architectural aluminum in the Aircraft Parts section at Home Depot. Filed down the radius and it's been working like a charm for years...

[vondeliusc]

Use some shim stock between the nose bar and your work piece. Back the nose piece off an additional radius from the bend line. In your case you'd need .125" stock but that probably won't handle the zero radius without cracking so maybe try 4 layers of .032". Once the shims are bent, you can reuse them for other bends. They only need to be as long as the bend you are making.
My thought was basically the same. What we do, is use 6061-O (soft) and shear off a hunk about 1" wide and bend as tight as possible; putting some narrow 90 degree bends along the length allows the formed part to grip the fingers. Depending on the radius required, you can use various thicknesses of material and multiple layers like bigdog indicates.
An example is for a 1/16" radius in 2024T3, a hunk of 0.032" 6061-O about 2" wide by 18" long has 1/4" flanges bent up on each long edge, and then bent tight with the sharp fingers; then tapped closer with a hammer on the bench. Then a second similar piece 2.375" wide with similar 1/4" flanges, then bent tight using the 1st piece seated on the nose of the sharp fingers, then tapped closed tight on the first piece. The flanges allow you to push the pair over the fingers and stay there, and using proper setback, the 2024T3 can be bent with no fracturing.
And practice.
Good luck-
-Christian