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Jared Smith




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PostPosted: Tue 30 Mar, 2010 1:42 pm    Post subject: flexibility of modern pattern welded swords?         Reply with quote

I am familiar with and am starting to make pattern welded knives, the modern way. I have only handled knives that were meant to be rigid, typically made of O-1, L6 "saw blade" family of steels, 1095, and 1080. (Have not yet handled a W-2 / 15N20 or 203E combination.)

What I am interested in is how forum owners of premium artisan (John Lundemo, Paul Binn, Patrick Barta) made pattern welded swords would characterize there reproduction, pattern-welded sword's flexibility compared to A-Trim, Albion, and other high quality reproductions?

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Dan Howard




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PostPosted: Tue 30 Mar, 2010 1:51 pm    Post subject:         Reply with quote

It all comes down to the skill of the craftsman and the quality of the raw materials. The Celtic region known as Noricum had good quality ore. Connolly reckons that he has personally seen a two-thousand year old pattern-welded sword dredged from Lake Neuchatel "bent almost double and then flex back" (Greece and Rome ar War , p.115). It is certainly possible to do the same thing with modern pattern-welding technology. The only difference is that it is easier to make such a sword from homogenous steel. If it is easier then more people can make them. If more people can make them then they cost less and more people can afford them.
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Jean Thibodeau




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PostPosted: Tue 30 Mar, 2010 11:14 pm    Post subject:         Reply with quote

Assuming good materials heat treat is going to make or break a sword ( Pun alert ) and I would also like to know how much bending and flexibility one can expect from a well made sword as too degree of bending and the number of repetitions one can expect without accumulating damage.

As long as one is talking of elastic bending and not plastic deformation one should be able to bend a sword without causing cumulative damage to the structure of the sword: Below a critical threshold one can get an almost infinite number of bending cycles.

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Hadrian Coffin
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PostPosted: Wed 31 Mar, 2010 12:15 am    Post subject:         Reply with quote

Hello,
I have a very nice pattern welded blade by Paul Binns. It was a custom piece made with bloomery iron (worked into wrought iron), forged in coal with a hand powered bellow, and ground with a stone wheel. The sword takes a set at about three-four degrees out of line. Iron can't be heat treated, anyone saying it can be is misinformed. The amount of iron in a pattern welded blade can result in the blade taking a set. However most of the time it can simply be bent back. Personally I believe Connolly was exaggerating a bit when he made that statement. Even modern heat treated spring steels have difficulty bending double and not taking a set. I have seen numerous broken pattern welded swords, many from simple over bending. In The National Museum of Ireland, Belfast there is a beautiful pattern welded sword, it was found by a farmer bent at almost a right angle... the farmer tried to bend it back over his knee and snapped it. I have examined this blade first hand, and have no reason to doubt this story. There are some pattern welded swords with great flexibility...but I find these to be the exception rather than the norm. Most of the original pattern welded swords I have examined will take a set after being bent four to five degrees out of line.
I also have examined a 01-L6 pattern welded sword by Michael Pikula, it was bent quite extremely without taking a set...I would compare its flexibility to that of an Albion.
Cheers,
Hadrian

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Ken Nelson




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PostPosted: Wed 31 Mar, 2010 6:46 am    Post subject:         Reply with quote

I would have to agree with most of what has already been said. A pattern welded blade that is properly welded and heat treated will perform similar to a blade made from a straight steel.

That being said, I also want people to remember that geometry has as much to do with flexibility (elactic deformation) as heat treat and steel selection. For example, if you were to make 2 blades from the same steel, one 10" long and 1/4" thick bowie and one 10" long 1/16 thick with a distal taper, and heat treat both to a 59 RC they will flex quite differently. The bowie would have to be clamped in a vise to flex it to the bending point(which may be very close to the point of failure) and it may only flex 25-30 degrees. the fillet knife, you could flex by laying the point against a cutting board, and pressing down. It will likely flex 90 degrees and return to true. Somewhere around 125-130 degrees you may get it to bend slightly and then break.

If you were to make a very thin sword, say 1/8" thick at the guard and 36" long, it may be easy to flex it nearly 180 degrees, but the weight of the tip may be enough to flex it a bit if it is held straight out.

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Martin Erben




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PostPosted: Wed 31 Mar, 2010 8:04 am    Post subject:         Reply with quote

I don't know if that'S exactly what you were looking for, but I've got a picture of a damascus Blade made by Markus Balbach from Germany. I've posted it around here several times, but here it is again:


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R D Moore




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PostPosted: Wed 31 Mar, 2010 8:05 am    Post subject:         Reply with quote

You Tube carries a short video of Albion destroying a viking style blade, one section in which they clamp the blade in a vise and bend it in each direction. The blade took a set so I think Hadrian was spot on.
http://www.youtube.com/watch?v=D2mDMS6-884&NR=1

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Jean Thibodeau




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PostPosted: Wed 31 Mar, 2010 9:40 am    Post subject:         Reply with quote

R D Moore wrote:
You Tube carries a short video of Albion destroying a viking style blade, one section in which they clamp the blade in a vise and bend it in each direction. The blade took a set so I think Hadrian was spot on.
http://www.youtube.com/watch?v=D2mDMS6-884&NR=1


But notice how extreme the bending it took before it took a set.

In use the sword wouldn't be bent past the point where it would get a set and normal use it should be able to take millions if not more cycles of moderate bending without failing: In an other Topic thread on this site it was mentioned that steel can be bent an infinite number of times as long as one doesn't produce plastic deformation.

Oh, with a very thick blade one can't bend the blade as much in degrees before the blade takes a set but at the same time bending it becomes very much more difficult.

With a very thin blade the tension on one side of the blade and the compression on the other side is much less than with a thick blade because the surface of a thick blade is very much farther than the centre of the blade so for an equal degree of bending the steel is stretched much more at the surface and reaches the elastic limit much more quickly.

In other words its all in the geometry of bending forces: If one had a theoretical zero thickness blade it would take no force to bend it and it could be rolled into a very small ball without any damage. In reverse a sword a foot thick could hardly be bent more than a few degrees without suffering from elastic deformation. ( Extreme examples just to clarify my point ).

All else being equal we are talking about optimally hardened blades of good materials, flaws in materials of a bad heat treat would weaken any sword to substandard performance.

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Dan Howard




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PostPosted: Wed 31 Mar, 2010 1:36 pm    Post subject:         Reply with quote

Jean is right. It is largely irrelevant whether it is pattern welded or homogenous. If it is thin enough, constructed properly, and appropriately heat treated then it will flex substantially without taking a set.
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Jared Smith




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PostPosted: Wed 31 Mar, 2010 2:24 pm    Post subject:         Reply with quote

Martin Erben wrote:
I don't know if that'S exactly what you were looking for, but I've got a picture of a damascus Blade made by Markus Balbach from Germany. I've posted it around here several times, but here it is again:


Thanks for the original post and this reminder Martin. That is really what I am interested in, as well as any others who have a modern material pattern welded sword that seems comparable to our "spring tempered" reproductions. I visited Markus Balbach's web site ( http://www.schmiede-balbach.de/seiten/damast.html ), but am not proficient enough at "guess reading" German to know what materials he uses. I would like to know what the materials in your example were, and also what sort of variations in hardness it has if it was tested. Possibly someone who can read Balbach's web site information can determine that very easily.

I initially posted because I am wondering how good the materials I am learning to use as a beginner (L6 "type" low nickle saw steel alloys plus 1075 through 1095) will be if I ever do attempt a pattern welded sword, and want to give it some sort of a reasonable balance of spring temper, edge hardness, etc.

I respect those who choose to replicate pattern welding with hand made bloomery iron, pack carburizing, manual hammering, and other traditional methods. For myself, I like replicas made of modern steel materials which are about as optimal as possible (mechanically speaking) due to the modern control of chemistry, and careful heat treat. Also, I don't have the time, money and willing assistants necessary to make all of the fabrication steps and equipment identical to the historical counterparts!

The heat treat issue is somewhat less simple with modern "exotic art style" pattern welded blades, made of modern materials, than it is for a comparable geometry blade made of just one of the same materials. The reason for this has a lot to do with the differences in speed at which the varying layers (usually nickle versus no nickel) optimal transformations (martensite, bainite, pearlite) occur during quench, tempering, etc. If one follows historical practices and places the "easier/better to heat treat" material in the cutting edge, a lot of the heat treat compromises can be avoided. However, that places a significant cosmetic design constraint on it, and eliminates edge slicing characteristics that I personally prize in modern pattern welded knives.

Absence of evidence is not necessarily evidence of absence!
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