# Thoughts on making a sheet metal brake?



## FlyFishn (Mar 4, 2021)

I am contemplating the idea of making a sheet metal brake. I don't know much about bending sheet metal but I have made some small projects (boat console and some other things) with a cheap brake from Harbor Freight. With the gauge metal I made the console out of, for example, the HF brake was too light duty for bends resembling anything of quality/crispness. 

So some design considerations that are in my head at the moment are:
- Ability to put more crisp bends in sheet metal
- Ability to clear 5-6' of width
- Ability to bend complex bends (think 5 sides of a box - bottom and 4 sides as well as 90deg Z bends)

Looking at how the HF brake I have works - the mechanism doesn't seem very difficult to replicate. With heavier metal and some design changes the basic function of it (the clamped piece on the fixed table and hinged press plate) is easy to make. However, I am not sure if there is a logical way on that style press to do complex bends. The kind of brake that mounts to an H frame hydraulic press with the piece being pushed in to a V block, to me, makes more sense for being able to make a complex Z bend, but I don't know how crisp a bend could get. The V block would also mar the outside of the bend (the metal pressed against the V block).

As for generating the pressure I have 2 ideas. 
1. Bottle jack. I have a 4-8 ton and the one on my hydraulic press could certainly be used as well - its a 20 ton. 
2. Lever. This, preferably, would be powered by a bottle jack, but it would be conceivable to use a long bar or a bar with a cheater pipe, but I think a jack would give me more precision/finesse. 

Is my idea crazy and off-the-rocker? Or is there any merit to making my own machine? Does anyone that has good experience with sheet metal work have any words of wisdom on the subject?


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## aliva (Mar 4, 2021)

First off you have to determine the max thickness you may want to bend. The thicker the material the beefier everything has to be. not being an expert on brakes, I would think a finger brake would be the way to go. With fingers of various widths. Enough to cover the entire length of the brake. The fingers will have to be removable and  tough, hardened and then annealed.
I'm sure others with more experience will chime it.


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## JimDawson (Mar 4, 2021)

A press brake style is the easiest to build, and probably in more common use than is a finger or pan brake.  You can put fingers on a press brake for working inside a box.

The V and V-block does not really mar the outside of the bend, the V-block just needs to have rounded top edges.  Bends are as crisp as you want, final bend shape is a function of the V and V-block shape, and final force.

I made a small, 6'', press brake out of a 7 ton, electric wood splitter.  I also have a 28 ton, 48'' hydraulic press brake, and am in the process of consulting on a 48'', 20 ton all electric CNC press brake.  The CNC press brake project started out as a finger brake, but that idea was abandoned in favor of the more conventional press brake style.

Of course there is merit to making your own machine, it's a fun project and can be as simple or as complex as you want.


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## finsruskw (Mar 4, 2021)

I bent up these items a few years back with my homemade  press brake and dies.
Power seat floor pan sections for a '57 Chrysler 300C.


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## projectnut (Mar 4, 2021)

Here's a link to a thread about one I built a while ago.  This one is adapted from a set of plans for a 12" wide one.  The original plans are in post #3.









						Sheet Metal Brake
					

This is a project I've had in the works for a couple years.  I didn't work on it on a daily basis, or even a monthly basis for that matter.  It's been sort of a fill in thing for when I had a few extra minutes to spend in the shop.   With the recent "social distancing" recommendation I felt it...




					www.hobby-machinist.com


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## stupoty (Mar 5, 2021)

The kits from swag off road look good and might provide diy ideas 









						SWAG 20 TON Finger Brake Heavy Duty DIY Builder Kit
					

Heavy Duty 20 TON Finger Brake Press DIY Builder Kit Press Brake kit comes un-assembled, you do the final assembly and welding. Designed to fit the Harbor Freight 20 ton hydraulic press Item # 32879 & 60603. Press brake kit includes an adjustable back stop for accurate and repeatable bends. The...




					www.swagoffroad.com
				




Stu


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## aliva (Mar 5, 2021)

stupoty​I looked at the 20 ton finger brake, The spec indicates it can bend 5/8 plate, I don't believe it.


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## Ken from ontario (Mar 5, 2021)

I thought about building a press brake style brake a couple of years ago, the turn off for me was the cost of material, I should have thought about it when I was employed and had full access to all kinds of left over or scrap steel, if you do have access to inexpensive or scrap metal , think heavy duty and big capacity, make it at least 30" long ,reinforce it enough to be able to bend minimum 16Ga mild steel at full length.
IMHO, every DIYer at some point thinks about a sheet metal brake or wishes to own one .
One option is to buy one from HF on sale and build it up and make it beefier, that is still a fun project and it may cost you ( depending on where you live) less than building it from scratch and pay and arm and a leg for material.


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## Flyinfool (Mar 5, 2021)

The force needed is a combination of material being bent, length of the bend, material thickness, and V die opening.

Here is a calculator that will give you the required tonnage for the bend.








						Load Calculator — Cincinnati Incorporated
					

The CINCINNATI Press Brake Load Calculator will calculate the tonnage to form a part with the variables of material type, vee die opening, bend length, and material thickness inputted.




					www.e-ci.com


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## stupoty (Mar 5, 2021)

aliva said:


> stupoty​I looked at the 20 ton finger brake, The spec indicates it can bend 5/8 plate, I don't believe it.



Yeah it does seem incredible.  I did find a person on you tube using it for quite substantial thicknesses but 2 inch widths.






Looks ok though compared to a lot of cheaper pan brake options, although you have to have a press available to use it with  

I like the concept of this one but don't like the 1.5mm (1/16th) bending limit.






						Manual Steel Plate Bending Machine Light Metal Brake Bender - AliExpress
					

Get plate bending machine with free return and fast delivery. All metal construction, antirust and durable. Find products of machinery accessories with high quality at AliExpress.




					www.aliexpress.com
				




Stu


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## FlyFishn (Mar 6, 2021)

stupoty said:


> The kits from swag off road look good and might provide diy ideas
> 
> 
> 
> ...


That is an excellent starting point. Aside from the dies, I could fabricate that pretty easy.

Now my wheels are spinning because I need to bend 60" material for my current project so my gut tells me go bigger - like 72". The 20 ton HF press is the one I have. I could use that as a base and make a new table + top frame + jack stabilizer, then use the same sides, feet, and hardware (I replaced the bolts with grade 5's from Fastenal last year).

Edit:
The stabilizer bar would be a moot point on the wide brake. The top of the brake that holds the dies is on a track so there is no need to stabilize the jack separately, provided the pin or bottom of the jack is attached to the top of the brake where it won't lift out/away = dual function, as opposed to separate parts with separate functions.


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## FlyFishn (Mar 6, 2021)

Flyinfool said:


> The force needed is a combination of material being bent, length of the bend, material thickness, and V die opening.
> 
> Here is a calculator that will give you the required tonnage for the bend.
> 
> ...


According to that chart, .125" thick 6061-T6 aluminum 60" wide takes 18.57 tons to bend with a 1.5" V opening. The .125" is overkill for my current project. I got a recommendation of .090", but that was with the caveat of the bent sheet metal serving as a sort of unibody frame. I am not going that route - I am putting the bent sheet metal portion on top of a rigid C channel frame which means I can go much lighter on the sheet metal. So if I go down to, say, .050" or .063" then that would be that much less force required to bend it. .050" x 60" would be closer to 4 tons.


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## Flyinfool (Mar 6, 2021)

You also need to watch your bend radii, 6061-T6 is a bit on the brittle side, you will want a radii of about 3 material thicknesses to avoid cracking.


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## stupoty (Mar 7, 2021)

FlyFishn said:


> Aside from the dies, I could fabricate that pretty easy.



I was really suppressed as I had initially been looking at replacement die / knife sets from folders to maybe use in a diy folder and saw that a lot of manufacturers list them as mild steel.

I had presumed they were hardened but maybe they could be made from gauge plate and be quite good.

Stu


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## finsruskw (Mar 7, 2021)

Good grief man, hold that camera still will Ya!!
Makes me nauseous just to watch that.


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## FlyFishn (Mar 7, 2021)

Thinking....... That is a dangerous proposition, you know? 

What are the physics behind how crisp a bend is? 

Reason I question it is, from what I see and what I have experienced with my cheap HF brake, is that the crisp'ness of "bend" depends on how much pressure can be generated close to the exterior radius of the bend. 

That is, in the reverse, the further away the pressure is from the exterior radius of the bend the less crisp the bend is. 

To verbally illustrate this - with the HF brake I have the part of the brake that pivots with the handles that bends the metal is only rigid enough for very light gauge metal. The thicker the metal the more the levered part of the brake flexes during the bend. That flexing takes the force further and further away from the exterior radius of the bend with the stiffer metal (thicker or different grades requiring more force to bend). The result is the metal next to the bend exterior radius ends up getting bowed.

How do you control where the pressure is on a press style brake so as to maintain crisp bends - and adjust that for different grade/thicknesses of metal? Is it simply the opening width of the V - provided the same dies are used (same tip/radius on the tip)? Or is there more to the process?

I am mostly wanting 90deg bends for the time being, but I want the flexibility in the brake idea here to be able to make any angle in "light gauge" sheet metal - with a crisp bend. I realize greater than 90deg bends (under 90deg interior angle) are going to be more difficult. 

While I am at it I think I'll make a narrow brake for the normal width of the HF 20 ton press for thicker bracket type metal of only a few inches in width at the bend. I don't want to limit myself to using the wide set up for heavy bends. My intent with the wide set up is to be a specialty set up specifically for sheet metal work - were my HF press falls short. Though, I imagine 95% of my pressing needs (automotive/mechanical, metal fab/bending) would be handled with the original 20 ton press frame as it sits - a very good bang for the buck from HF, by the way - so long as yours comes with the plate steel press plates, not the cast iron press plates. The cast iron ones have larger radius edges and look like sandpaper, plate steel has sharper radius edges and are smooth. Cast iron plates can shatter under high loading and shock loading.


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## Flyinfool (Mar 8, 2021)

I guess the fist question is just what are you referring to as "crispness of the bend"?
There are many variables to play with to get various results.


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## JimDawson (Mar 8, 2021)

FlyFishn said:


> How do you control where the pressure is on a press style brake so as to maintain crisp bends - and adjust that for different grade/thicknesses of metal? Is it simply the opening width of the V - provided the same dies are used (same tip/radius on the tip)? Or is there more to the process?



All of the above.  The V width requirement is mostly a function of the material thickness.  The thicker the material, the wider the V must be.  But having said that, you can make perfect bends with slot rather than a V as long as you can control the height.  My press brake has a micrometer adjustment for the shut height.  We just stuff the material in and adjust the height until we get the bend we want.

Here are couple of pictures of my ''wood splitter'' press brake.  I used this until I bought a real one.  I threw this one together for a couple of specific jobs.  






This is what we have now.  48'', 28 ton hydraulic.  Shown with a special crimping die we built for a project.  Micrometer adjustment is on the lower left.


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## aliva (Mar 9, 2021)

I tried the calculator for 5/8 plate with a opening of 3.125' . 130 tons. So a 20 ton bender shown in the link won't do it. False advertising.


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## FlyFishn (Mar 9, 2021)

Flyinfool said:


> I guess the fist question is just what are you referring to as "crispness of the bend"?
> There are many variables to play with to get various results.


By "crispness" I mean a sharp, small radius bend where the sheet on either side of the radius is flat  - not bowed requiring extra tooling to make "flat".

Though, I would throw in there that in some cases larger radius bends might be desired down the road. In that case I would say the same thing regarding "crispness" where the sheet on either side of the radius is flat, not bowed.

Perhaps a better term might be "accurate" as opposed to "crispness"?

In the project I have in mind at the moment the smaller the interior radius the better. I know I can't get a sharp crease akin to an extruded piece, but I don't want an interior radius of as large as .125" either.


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## Flyinfool (Mar 9, 2021)

The radii of the bend is determined by the nose radius of the die. 
For a press brake to make nice accurate bends you need to use a coining die, air dies are not as accurate. 
A box and pan brake will make nice bends as long as it is heavy enough to not flex while making the bend.


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## Cheeseking (Mar 10, 2021)

Flyinfool said:


> The radii of the bend is determined by the nose radius of the die.
> For a press brake to make nice accurate bends you need to use a coining die, air dies are not as accurate.
> A box and pan brake will make nice bends as long as it is heavy enough to not flex while making the bend.



Bend radius is determined by the v-die opening for a given material thickness when air bending. 
Specifying IR smaller than .63 x material thickness (on mild steel) is considered “sharp” and poor design practice.  

Air bending is extremely accurate provided you have the proper equipment and tooling. We do it all day long.


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## Chips O'Toole (Mar 11, 2021)

I have a SWAG brake on a 20-ton press with air. It's fantastic. It will not put a 90-degree bend in 16" of 1/4" steel, however. I tried to do it, and I got maybe 30 degrees. Maybe heat will help. The site advertises 16" of 1/4" steel. Can't promise that my press isn't the issue. It's from China, after all.

It does bend very heavy metal compared to most factory brakes, however. I have no doubt that I could do 10" of 1/4" plate. I have made big pans from 11-gauge steel with no problems at all. Try that with a 24" Grizzly, which maxes out at 12" of 18-gauge.

Given that factory brakes only bend steel which is about like car bodies, which you could bend just as well with a hammer and blocks of wood, the SWAG brake seems like a phenomenal tool for the price.


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## Cheeseking (Mar 11, 2021)

It will take every bit of 20 tons but using a die with proper v opening you can bend it.
Quick check of a common force chart shows
1/4” mild steel will require 14 tons per foot using a die with 2” V opening. It will require at least 1-3/8” bent flange length and you’ll get approximately a 5/16” inside bend radius.


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## CNC_noob (May 9, 2021)

aliva said:


> stupoty​I looked at the 20 ton finger brake, The spec indicates it can bend 5/8 plate, I don't believe it.


The specs indicate it but only a small piece; not the full width of the brake.  I’ve not tried it on my brake, but there are videos that show it being done.   I have. 20 inch SWAG brake using the HF press kit and it works nicely and have no reason not to think it would bend a small width of 5/8 steel. I just don’t have any need to bend something that big.  
This thread is talking about building a 6 Foot brake and so there are some multi bottle jack brakes on the swag site as well as some kits that might help With that design idea.
I for one would love to make a 6 foot finger brake.  Unfortunately, I do not have the shop space for it.


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## CNC_noob (May 9, 2021)

FlyFishn said:


> I am contemplating the idea of making a sheet metal brake. I don't know much about bending sheet metal but I have made some small projects (boat console and some other things) with a cheap brake from Harbor Freight. With the gauge metal I made the console out of, for example, the HF brake was too light duty for bends resembling anything of quality/crispness.
> 
> So some design considerations that are in my head at the moment are:
> - Ability to put more crisp bends in sheet metal
> ...


I would think using c channel steel cut to order in the style of a press brake would be pretty easy to design and put together within a few days with some welding.  The metal likely will be heavy enough where you will need a system to hold them and move them and I would imagine the brake will be too heavy to move once assembled.


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