Finger Brake: Useful Tool or Waste of Money?

[SteveHGraham]

I want a finger brake. I have realized that there is a lot of expensive stuff out there which is only expensive because someone else had to bend it. I have also realized that the generic mobile bases that are available from retailers are inferior to simpler things that can be made by drilling and bending metal. When you make a mobile base that has to fit a thousand machines, you have to add features that weaken it, clutter it up, add to the cost, and make it less useful.

Anyway, an outfit called Swag Offroad makes a finger brake kit for the Harbor Freight 20-ton press. I already have a project in mind for this thing. I have a 325-pound band saw that has a rectangular base with 4 predrilled holes in it, and I want to make two 3/8" bars to go under it, come out, and extend upward and out to take casters.

I have never used a finger brake. The web is full of videos of people putting this kit together, but nobody seems to be making videos of themselves making projects with it. That makes me wonder if it really works. For example, how do you locate things in it? You could ruin a lot of steel, trying to get a bend in exactly the right place.

It's easy to get excited about a tool and then find out it doesn't work well in reality. Case in point: I thought I might get a small plasma table, and then I researched other people's experiences. Apparently, you spend 90% of your time trying to make the tool work, and you will probably ruin more parts than you make. I don't want to buy a finger brake and then be unable to use it.

I like the Swag brake because it bends metal which is actually thick enough to be useful.

https://www.swagoffroad.com/SWAG-20-TON ... _p_86.html

[rrnut-2]

That looks good. I think I will get one. Thanks Steve for the info.

Jim B

[John Evans]

If you are trying to bend 3/8 X 4" I think you will be disappointed . Normally use a press brake 50 ton up. Looked at the link ,radius of the bend is rather large ! Large radius' are easier to bend. Link also says welder needed. Learned to weld yet ?

[SteveHGraham]

I can't weld, but I picked up some 5-minute epoxy the other day. I'm sure it will work just fine.

I'm more worried about the accuracy than the tightness of the bends. For a lot of projects, a bend that isn't terribly sharp will do the trick.

Their site says the radius of the bend is 110 degrees, which makes me wonder if they know what a radius is.

Glad to provide the link, Jim. Now I can sit back and watch you try it.

[Russ Hanscom]

A finger brake is usually intended for thin metal. For bending thick stuff, I use a V block and hydraulic press. There are tables for locating the bend, considering the bend radius. I am getting ready to bend some 3/8" x 3" flat bar for a rolling base for a new large drill press. Doubt a finger press would touch 3/8" stock.

[SteveHGraham]

I'm just trying to find out how hard it is to locate bends correctly.

[Rich_Carlstedt]

Its not hard to learn, but first a word
Most all metals have whats called "Spring Back"
This relates to the Tensile strength and hardness of the material
For example , you may have to bend material 100 Degrees and when the die is opened, the material becomes 90 degrees
Spring Back is also affected by the radius of the bend ( nose Radius) on the punch.
A excellent way to figure out what you will see is this method.
Say you want to bend a 1/8" thick piece of 10 x 10" steel to a 90 degree angle at the 5" center line .
Cut off a piece of THE SAME material and make it only say 1/2" wide ( No specific for the test) and at least 7 inches long (More later on why the length) . Mark the 5 inch line and when placed in the Die, Mark the edge of the die on the test strip ( say your die is 2 " wide, then you would have a mark at the 4 inch depth. NOW, when the fingers come down (punch) , the 4 inch mark will move inward..no problem --continue until you think you have your bend - Two things here, either use a dial indicator to find this point ( depth of the punch) ..or you can do what I do, I first place a round steel rod in the bottom of my die before hand ( say 1/4" ie) and run the punch with the material down till it stops. MARK where the 4 inch mark is on the die !.
Now when you lift the punch ( Finger) you can see how much bend you have ( say 80 degrees) , You then remove the rod and put a smaller one in the die or decide to go another .010" on the dial indicator...Now you can place the material back in the exact place ( using the recent marks) and go for the next 10 degrees to get to 90. When you hit 90, you will see or learn how much deviation you need to get your bend... so to bend at the 5 inch line you may need to have a line at 4 7/8" and the 4 inch reference line becomes 3 7/8" and THIS LINE will be used whenever you make a bend to determine where the bend occurs and how much "allowance" you need.
If you overbend , then 2 things to do
Start another test piece or "shock" the bend.
All bends have stress, and a good procedure for all is to shock the bend by hitting it "hard" with a hammer in the direction of the bend or dropping it on the floor . Again the shock force must be a right angles to the bend itself. ( Think of the bend like a post in the ground and you strike the top of the post)

The test piece should generally be long enough so it completely straddles the die , plus extra because the stock will be "drawn" in as the bend occurs and should always touch the V edges !!

Rich

[warmstrong1955]

Bend allowance....I use this:

Bend Allowance.pdf

(479.68 KiB) Downloaded 322 times

Actually, I built and use a Excel spreadsheet based on this equation, that will convert the formed shape I want, and it calculates the flat pattern for me. Much faster than thumpin' keys on a calculator.

As far as a finger brake, if you are making boxes, or enclosures, like instrument panels, then yes, they are a necessity.
Regular bends, for brackets & mounts....a simple brake will do.
So it depends on the parts you are building.

[choprboy]

I have a 4' finger brake, the folding type not the press type, and I use it all the time for making shelves/boxes/etc. Extremely handy. But there is a lot of guess work as the final location of the bend depends on the material type, material thickness, and the distance between the finger and folding point. Use some scrap for test bends, a bit of guess work, and then go for it... Folded up some 30" wide x 60" long sheets of 16ga to build a box, measured, tested... still came up about 1/8" long on one leg and 1/8" short on the other leg though.

I would think the press brake would be easier to use as the center of the bend is the center of the brake die (usually). Planning to build a combo ~50ton 4' press/shear/brake some day... but too many other projects at the moment.

[whateg0]

I can't weld, but I picked up some 5-minute epoxy the other day. I'm sure it will work just fine.
...
Their site says the radius of the bend is 110 degrees, which makes me wonder if they know what a radius is.

The forces on a press brake can be pretty high at times. Where they are welding pieces together, I don't know that I would trust glue to hold under a "heavy" bend. And a heavy bend doesn't necessarily mean thick metal. Even a piece of thin sheet bent to a sharp radius can produce pretty high forces. Of course, normally those forces should be vertical, but if the work is loaded unevenly, it can cause substantially more load on one end than the other.

110 degrees isn't a radius. 0.050" is a radius. 1/2" is a radius. 110 degrees is just that - degrees. So, it is how far the metal can be bent. In this case, a bit farther than a right angle. The bend radius is a function of the temper of the metal being bent, the thickness of the metal being bent, the nose of the bending punch, the die opening, and I've probably forgotten something.

As far as how useful it can be goes, that depends on your needs. If you are wanting to bend 3/8" thick material, as stated above, this is a poor choice. You'd be better off building something from some heavy channel, some round stock, and a piece of plate ground to an edge for that. If you get into bending covers for machines or boxes, then a press brake becomes a lot more useful.

Dave

[whateg0]

FWIW, I use Fusion 360 for CAD and in its sheetmetal workspace, it will locate bends for you. I haven't had good luck with consistency, though. I'm not saying it's the fault of F360, but it's an annoyance. Most times, I still bend some scrap as a sample to be sure I know where the bend will end up.

Dave

[SLK001]

To line up the bend, I just take a Sharpie and mark the bend line. Then, it is just as simple as making sure that the fingers are on the line. I also make sure that anything that I want to bend is in increments of the fingers width.