Looking for Brake Press Ideas for Large Radius Bend

m_ridzon · Oct 29, 2021

I'm just a weekend hobbyist. I have access to a large press to bend sheet metal (e.g., my project is 3/16" thick steel). However, the press does not have a die set to make a large radius bend. In other words, it will only make bends with a tight radius. But my project needs a 1" radius. I'm looking for ideas to for how to get this large radius, without having to go buy a die set.

For reference, the attached Google image kind of shows what I'm trying to do.

(So far, I have not been successful tracking down a local weld/fab shop that could make the bend for me)

Thanks in advance!

neilho · Oct 29, 2021

How long a bend do you need to make? Thru how many degrees?

Rob F. · Oct 29, 2021

How long is your bend? If not to long you can just make a top die out of 1" round bar by tacking some 1/2" flat bar to it (so the machine can hold it).

m_ridzon · Oct 29, 2021

The bend needs to be 90°. The length of the bend is about 1.5'.

I like the idea of round bar with some flat bar tacked to its top. What about the bottom side, under the steel plate? Will a "V" shape do okay on the bottom side?

kustomizer · Oct 29, 2021

m_ridzon said:
The bend needs to be 90°. The length of the bend is about 1.5'.

I like the idea of round bar with some flat bar tacked to its top. What about the bottom side, under the steel plate? Will a "V" shape do okay on the bottom side?

I would be afraid of splitting the V

Garwood · Oct 29, 2021

m_ridzon said:
The bend needs to be 90°. The length of the bend is about 1.5'.

I like the idea of round bar with some flat bar tacked to its top. What about the bottom side, under the steel plate? Will a "V" shape do okay on the bottom side?

You're way overthinking this.

Punch made of roundbar push material into V. Width of vee is important it matches your punch so you can get to 90

Rob F. · Oct 30, 2021

Like garwood said, the width of the vee just needs to be wider than 1" so the 1" top die can get down inside it to give you 90º bend.
Only 18" long it is a no brainer to make the top die, if you can get a short piece of 1" round. Cold roll would be nice but not critical.

Mcgyver · Oct 30, 2021

can we assume very low quantities since its a hobby? (with anything, quantity is as important to the solution as material and dimensions)

top die is easy, and the bottom doesn't have to be a long ground V die. When required for a short run we fabricate specialty dies like below and it works. Width of the bottom die has to suit material, thickness and radius of bend

However if you've got a shop that has the tooling and will do it, there's your solution

m_ridzon · Oct 30, 2021

Great ideas folks! I think I can get this done with these tips! Thanks!

kustomizer · Oct 30, 2021

Rob F. said:
Like garwood said, the width of the vee just needs to be wider than 1" so the 1" top die can get down inside it to give you 90º bend.
Only 18" long it is a no brainer to make the top die, if you can get a short piece of 1" round. Cold roll would be nice but not critical.

He wants a 1" radius meaning a 2" bar, way too wide to use any "V" die I have ever seen, but that don't mean they don't exist

m_ridzon · Oct 30, 2021

kustomizer said:
He wants a 1" radius meaning a 2" bar, way too wide to use any "V" die I have ever seen, but that don't mean they don't exist

You are correct in that I need a 2" diameter bar. I'm going to inspect the vee that's currently on the machine and see if it will work. But nevertheless, you make a valid point that it needs to be wide and able to handle the pressure.

DDoug · Oct 30, 2021

kustomizer said:
He wants a 1" radius meaning a 2" bar, way too wide to use any "V" die I have ever seen, but that don't mean they don't exist

My neighbors press brake has 4" and 8" wide bottom dies.

kustomizer · Oct 30, 2021

digger doug said:
My neighbors press brake has 4" and 8" wide bottom dies.

I like to make parts I can walk around with 2-20 of them in my shirt pocket but I do enjoy the hell out of watching the folks that run that big stuff.

DDoug · Oct 30, 2021

Cincinnati mechanical 400 ton press brake, with a pit for the lower die holder.
The whole place shudders when in motion.

kustomizer · Oct 30, 2021

Well, by golly gee, that there's a press brake, or break depending on who is setting it up. Mine was 56 tons mechanical and scarry for me. I have one of these now, it is more my speed

MCritchley · Oct 30, 2021

digger doug said:
Cincinnati mechanical 400 ton press brake, with a pit for the lower die holder.
The whole place shudders when in motion.

Mechanical! That would be intense to run.

We had a 60 ton we called the widow maker, it was faster than our hydraulic presses- good for production

Garwood · Oct 30, 2021

kustomizer said:
He wants a 1" radius meaning a 2" bar, way too wide to use any "V" die I have ever seen, but that don't mean they don't exist

I use a 4" V die section on my friends 100 ton regularly bending 1/2" steel. It just about kills two of us getting it in the machine even with the forklift, but it's sure nice to have.

mhajicek · Oct 31, 2021

K-zell Metals, Press Brake Bump Forming - YouTube

Bondo · Oct 31, 2021

You cant "really" bend a 90* bend with a radius in a standard 85* V die. To use a 2" round punch with 3/16" material, you would need roughly a 4" die. You need a very strong bottom die that can handle wall pressure to do the final 5*.

Your best bet is to build a custom die set with 3 rounds like what was previously posted. This allows for the pressure to be applied in the proper locations to do a 95* bend which will flex back to 90*.

That custom die set in the OP first post is CRAZY expensive. I priced out a 12' set for my brake for 1/8" stainless and it was in the 20k range, and that was 4 years ago pricing. Best dies for stainless though.

Sent from my SM-G960U using Tapatalk

m_ridzon · Nov 22, 2022

Where there's a will, there a way. It took a while since life got in the way, but I built my own jig and was able to bend the plate. It worked out great!

Looking for Brake Press Ideas for Large Radius Bend

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