Slotting To Get Impossible Folds

Below points 1 & 2 are a typical switchboard X section of a internal wall and face. Normally parts 1 & 2 are stitch welded together and a typical length is 2000mm long. That is a lot of stitch welds + a lot of sanding the blisters caused by the welding that need to be smoothed out.

What I did for many years and still use today is X section number 3. Yes it is 1 piece, so no welding or sanding. I takes much less time. It is a impossible shape to bend so a slot (staggered slots along the length) is used. Most of the forming of other folds are done  prior to back bending at the slots. Bending at the slots is easily done by hand, then the last fold is bent (as per number 4) and then the slot which was bent by hand is straightened back by hand. The slots are set close enough to each other to allow easy bending. The finished component is stiffer than the original welding technique, and the slots are not seen by the customer as he /she see the face as numbered 3.

This is just an example. You can use technique quite a lot when you design this hand back bending into other parts. My rule of thumb is that there is always another way of doing things

Grooving Your Folds

At times you would like to have a fold in a specific place though it is impossible to fold it.
The solution is to groove it.
If you have access to a large flat bed plane, it makes it easy.
If you don't then you can do the following

Please wear your protective glasses when working with power tools

Example 1. Using a angle grinder with a thin cutting wheel, make a groove in your steel. You want to go about 2/3 of the thickness. Go slowly by doing many passes. The easiest way to know if you have grooved enough is by trying to bend it by hand. If it doesn't, do another pass until you can bend it up easy by hand. Example 1 can be used on material thicknesses up to 6mm thick.

Example 2. is similar to the above but the smooth edge of the fold is on the outside. The practical thickness is 2mm or less. Use a 3mm wide cutting disc in your angle grinder.

Example 3. is for materials up to 6mm thickness.
To get the perfect V is simply made by cutting a groove as per example 2 and then place a new grinding disk (not cutting disc) on the angle grinder and run it in the groove at 45 degrees.

Folding Small Parts The Easy Way

If you have to fold a lot of little parts
(width under 100mm), the best way to fold them is to have then nested using micro joints (0.5mm not cut)

As you can see the example part has 3 folds on it. Lets say we want a total of 6 parts, which is 18 folds.  If we join multiple parts together we can reduce this folding in this example to 8 folds.
Folding will be easier as well as it is easier to manage larger pieces.

This technique is a blessing when you have a 1000 parts you have to fold. Conventionally folding you make 3000 folds or by using micro joints it is now only 1200 folds.

Example
10 parts joined together with micro joints
or 100 pieces of 10 parts
2 folds per piece = 200 folds
+ additional fold on each part = 1000 folds
Totaling 1200 folds instead of 3000 folds

Breaking the micro joints are easy as the metal has folds on it so it doesn't deflect and just breaks the joints.

It is worth thinking out side the square!

Setting up a press brake to fold properly

98% of CNC press brakes have never been set properly when installed.

Specifically in relation to bend angles. 

"Do you need to put in a large correction to make your bends be the correct angle?" if so then the below directions will resolve this problem.

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WARNING. YOU WILL NEED ABOUT 3 HOURS THE FIRST TIME

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Before commencing you need to be able to adjust via the controller the following items.

1. Upper tool length or (punch length)

2. Die height

3. Die opening or (V width)

4. Radius on the edge of the V width.

Lets begin.

Choose a V die (example 16mm V). "Divide you V width by 8 and this gives you the optimum thickness for folding

Material 2mm (16mm V / 8 = 2mm)

Set your controller to bend an angle of 179 degrees "1 degree kink"

Do a bend. Is it correct?

If it folded to much, you need to increase the height of the V die or increase the length of the upper tool.

How much you may ask. ( 0.06mm = 1 degree approx on a 16mm V )

Obviously if it did not kink the metal you need to shorten the upper tool length.

Do a bend, and keep correcting the tool length until you get a 179 degree fold.

Now set your controller to do a bend of 90 degrees.

Do a bend. Is it correct?

If it folded to much, you need to decrease the V die size. use 0.3mm increments until you get a feel for it.

Obviously if it did not fold enough you need to make the V die wider.

Do a bend, and keep correcting the V die width until you get a 90 degree fold.

Now set your controller to do a bend of 135 degrees.

Do a bend. Is it correct? It should be within 1 degree.

To correct this you need to change the radius on the V die edge. A larger radius will bend more. This radius effects the middle range of folding though can change your 90 degree bend angle slightly.

The Ideal thickness for the above 16mm V die is 2mm (2x8=16) though 2.5mm material (2.5x6=15) is also acceptable as well as 1.5mm material (1.5x10=15)

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So what have you achieved. 

If you grab a piece of 2mm material, you can just set the any angle and bend knowing that you could be out of angle range by 1/2 a degree only whether you bending with the grain or against it. 

With these other thicknesses you will find a constant correction of 2 degrees one way or the other.

Now do another V die. You will do it in about 1/2 an hour, because you now know what does what