Accordian Folding - a quick how to

[Mick Maxen]

Assuming you have a bar with a mosaic pattern at the end, here are two ways to bring the pattern to the surface of a flat bar, ready to forge or grind into a blade.

The diagram below is a view of the side of the bar, ideally the bar should be square. If the bar is 30mm square, the distance at A should be about 10mm, a third of the width in from the edge. This distance also determines the thickness of the bar after it is forged flat, to a certain degree. The circles are holes that you drill right through the bar, from side to side. These can be about 6-8mm. The advantage of the holes is that they give you a guide to cut to and a rounded area at the bottom of the triangle. More on that later.

 

 

 

This diagram below, shows what the bar looks like after you have cut along the dotted lines. The cutting can be done with a bandsaw or a cutting disc in a grinder. The round area at the bottom of the triangles is to help stop any shearing force that you would get if they met at a point. Also you need to round of any corners for the same reason, as the first cut out shows.

 

 

Now the easy bit !. All the forging needs to be done at a welding heat. The way too do this is to work your way along the bar, by carefully working it open. This can be done under a power hammer with some tooling, just square or round pieces of bar welded onto handles. Or over the edge of the anvil, don't try and flatten each section, but work in stages. Open the bar a bit all the way along and the next time a bit more until it is a flat bar. Unfortunately if the bar starts to tear, most likely at the bottom of the Vs, you dont have much chance of welding it back up, as the layers are going in all directions.

The above way of cutting the bar is the easiest way from the forging aspect as you are half way there already, by cutting out the triangles, but the most wasteful as you are getting rid of about a third to a half of the material.

 

Another way to prepare the bar is shown below. This is the most economical way of using the steel, but the hardest to do, as the shear forces at the bottoms of the cut are greater. Round of all the edges as above and forge open in the same way. The best way to start to get this billet to open is to use chisels, down the cuts.

 

 

Here are a few examples. The first is the mosaic bar from a demo I did recently in Minnesota. The second is one of the triangles that we cut out of that bar, showing the pattern on the sides of the triangle. The width across the base is about 15mm. These are the areas that get exposed when you open the bar out.

The third photo shows some of the original square bar still attached, from a bar I made a few years ago, done the harder way but using all the bar.

The 4th photo is a closer look at the pattern.

 

 

 

 

 

 

Mick

[Niko Hynninen]

Mick!

 

That is AMAISING....

 

Pattern on that one...it simply start´s to move...

 

Thanks for showing.

 

Niko

[Ben Potter]

Beautiful work, Stunning patterns. Thanks for sharing.

[Garrett McCormack]

Gorgeous patterns! Excellent explanation, thanks!

[cwilliams]

Mick

Thats a incredible pattern, thanks for sharing. Might have to try that this winter.

Chris

[hankknickmeyer]

Mick,

Very good explanation.

I use a method similiar to your second example. I cut the verticals with a chop saw and round the top corners with a hand held disc grinder, then open the cuts to 90 degrees with a hand hammer on a sharp edge of the anvil. I finish from that stage on the power hammer. The bar is at welding heat and heavily fluxed during the opening and finishing operation. If the bar tears(always at the bottom of the cut where the welds are in tension) they can be rewelded pretty easily during the finishing. I think welding heat and heavy flux during the opening process might be the key to the the ease of rewelding, if the bar tears the flux flows into tear immediately and prevents oxidation.

Hank

[Mike Sheffield]

Cool moving pattern. Like Niko said it seems to keep growing at you. Very very sexy.

[Arthur]

Beautiful work!!! you can also save all those cut off triangles and weld them up in a can with powered metal...

[Beau Erwin]

Another method I've seen that results in no waste was explained by Dickie Robinson, he'd cut the slices off at a bit of an angle that way the edges would be angled as well, kind of a parallelogram when viewed form the side. He'd butt them against each other, then tack them in place. Forge weld everything together and then grind the welds off, you'd get the same effect minus the stretching you get when accordioning.