Falling silk

C

Cliff Stamp

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It was discussed awhile ago about the possibility of a blade to cut a piece of dropped silk. I have done some work with this in the past few weeks with some success. It is not that difficult to cut the silk if you can move the knife. The edge has to be sharp, but it is not as difficult as some other cutting tests I have seen.

However if the knife has to remain still it is a different matter. Even with some very sharp blades ground at really acute angles (9-10 degrees per side), I had no success. These blades can cut freestanding hair above the skin, but can't do the job on the silk.

But, I am confident that you can, with the right steel (fine grain), and careful technique, get an edge about 4-5 times sharper than the above. You can also of course lower the edge angle, about 2-3 degrees per side is the limit on a knife and you need really thin steel to do that (1/16").

I will try again in a few weeks with a 52100 blade with the steel forged and heat treated by Ed Caffery. I be specific is the silk allowed to travel along the blade and be sliced in two pieces -or- is it supposed to be a clean push cut right at the point that the silk makes contact with the blade?


-Cliff
 
: But it seems that the silk slid down the curved Scimitar blade in the movie, but it's been several years since I have seen the movie.

I once made a curved, very thin blade from several files with different sizes both in length and thickness, heli-arced together using other files as a filler material, and had a nice thin sharp hollow ground blade.
I had it sharper than anything I had ever had before and it would nick a heavier nylon or rayon scarf dropped on it in several places, but not cut it in two.
I had yet to draw the temper on the blade and dropped it one day, shattering it into a hundred pieces!!!!:(
I was absolutely sick over that and never got back to trying another one.
And it was one pretty sword that I was really proud of!!!!:D
Wish I had it today.
 
Cliff, let me try an experiment of logic.
If you don't make silk cutter a user knife, thinner edge is better at least as far as 0.1mm from the edge. As you mentioned, fine-grain-ed material is neded, preferrably without carbon-iron crystaline! Simple iron, or other non-alloy materials that does not form crystaline will fit for the purpose better if you don't want durability for a silk cutter. Edge line is to curve to lesser the contact area between edge and silk, scimitar shape might be ideal.

I've never seen of heard of silk cutting with a blade set still except in "Bodyguard." Sometimes I heard a master swordsmith story. He picked up his sword he'd just forged, took it to a stream in neighbourhood. He plunged the sword into the waterflow, and stayed the sword inthe water. In a meanwhile several twigs came down along the flow onto the edge. If the sword cut every twigs in two, the master smith throwed it because of too much sharpness. If the sword twigs only when he wanted (but he never moved the sword), it is sent to his customer.

How do you think of the story? Well, I wished I'd lived near him to gather the swords he'd thrown away!
 
Cliff, see if you can rent a copy of the movie that I think was called "My Bodyguard" with Kevin Costner. (Help movie fans!) There's a scene in it where a scarf is tossed into the air and is split neatly into two pieces by a katana, I think. Weight of the silk and no blade movement as I recall.

Who knows? If you can duplicate the feat you may end up in movies.
 
I think the origin of the silk scarf story lies in the legendary meeting of Richard the Lionhearted and Saladin:
Richard set an iron mace between two sturdy chairs and then smashed it in two with his mighty broadsword. Saladin then tossed a silk scarf into the air, held his scimitar under it and deftly sliced it in two as it fell across his razor-sharp blade.
Click to expand...
 
Originally posted by Berkley
I think the origin of the silk scarf story lies in the legendary meeting of Richard the Lionhearted and Saladin:
Click to expand...

Berk,
That's the version I remember! The thing I remember best is Saladin's remark just before cutting the silk
" Your arm is strong, but is your sword sharp?"
Salidin cuts the silk and exits, leaving Richard sawing one of the pieces of silk back and forth on his sword with a puzzled expression on his face. They just don't make films like that anymore!

Patrick
 
there's an Ottoman sword on prominent display in the Topkapi Museum in Istanbul that's linked to such a story. I wonder if it was supposed to be Saladin's. All I remember about the story is that the sword's owner tossed a silk scarf into the air, drew his sword with a flourish, and split the silk with an upstroke.
 
By the way, the Saracen scimitars were not those extremely curved things you see in the movies either; they were only slightly curved or sometimes perfectly straight.

The Crusaders didn't use those ridiculously heavy things shown in the movies either; their swords weighed about 2 1/2 to 3 pounds and were well-balanced. Later two-handed swords were somewhat heavier but they came long after the First Crusade (and they were nothing like the two-handers in movies).
 
The old story is that this test could only be passed by wootz blades. Sometimes there is some truth behind the myth.
 
This has apparently been the subject of experimental study. Anyone have the reference:
J. D. Verhoeven, A. Pendray, W. E. Dauksch. Wootz vs. conventional steels: the silk scarf test // Blade, 1995, March, p. 60-63.
 
I think you are refering to the story of muramasa, whos a brillant but mentally unstable smith who enjoyed a sinister reputation whose sharp blades usually bring their owners to bloody ends. His blade was placed in a stream and it cuts thru every leave that touches his blade.Then another blade by the greatest of all swordsmith, masamune was place in the stream and all leaves avoided his blade. this is said to have reflected on Masamune's character ; which had in it a measure of nobilitty. He was recognised thru the history as being the finest of all jap smiths and rarely engraved his name on the tang although this practise was common with his sucessors and contemporaries. THus theres a common sayin... The Muramasa is terrible, the Masamune is humane. since the spirt of the smith is imparted into that of a blade.
 
Just my 2 cents ...

Is there anybody here who already tested their shaving blade or razor blade to cut a piece of silk toss to the air? I guess this test can be used as the base for comparison on the other blades test.
 
I believe my Bura tarwar, properly sharpened, could slice in half a silk scarf dropped across it. Without moving the blade.

On the other hand, we don't get hundred mile an hour winds coming thru here more than one to three times a year either, so it might be a while before the conditions were propitious.
 
WrongFriend :

If you don't make silk cutter a user knife
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I think this can't be the case, as it sort of defeats the purpose of it being the ultimate test of sharpness and cutting ability for a blade, as then as you noted the knife is fit for nothing else but cutting silk. What I would like to do is see if I can get a knife to do this, but still be able to actually functional as a normal use blade.

Simple iron, or other non-alloy materials that does not form crystaline will fit for the purpose better if you don't want durability for a silk cutter.
Click to expand...

The steels that I plan to try it with, are very fine grain, (0.5 micron) with a low alloy content. They are as fine as the finest abrasive I have (0.5 Micron, CrO). It is something to look into however. Another aspect that is relevant though is that the carbide structure of the alloy steels may actually help the cut.

Edge line is to curve to lesser the contact area between edge and silk, scimitar shape might be ideal.
Click to expand...

Yes, I was thinking of a Kris, as optimum, and note if you are going to allow the silk to slide along the blade, this is a slicing action and not a push cut so you don't necessarily want the finest finish, but a level of "tooth" that will enhance the slicing. The carbides in the alloy steels may therefore be of benefit.

-Cliff
 
Cliff, I'm searching some issues in "Knife" magazine about sharpness through my bookshelves. One is related to the narrowest width of edge, another is about finest plane that flies wood "tape" so thin that you can see through it. Give me some time to continue the discussion.

Now I see that you're aiming at how sharp a knife can be, instead how sharp an edge of any kind can be. A kriss blade seems interesting and promising. Maybe a tanto blade is also effective, but its sharpness on the second tip seems cheating as measure of "edge" sharpness.
 
Wrongfriend, yes, the problem with trying to measure sharpness by cutting something is that you are measuring cutting ability of which sharpness is a factor, but only one of many. You can compensate for this in various ways, but in general you have to be really careful when saying how sharp one blade is compared to another when all you could be really seeing is an increase in cutting ability which has nothing to do with the state of the actual edges, but could be do to the primary grinds, balance, or even issues with grip security and comfort.

In regards to just looking at the edge, Leonard Lee has spent considerable time doing just that. In his book on sharpening he shows several pictures of the edges of chisels at high magnification. He compares the results of using many abrasives and also includes shots of several razor blades as a comparison baseline. Several of the chisels he sharpened have more uniform edges (better polish) than the razor blades with less burr.

As for planes, most finish wood workers have a very high standard for sharpness as you need to be able to make clean cuts through the wood fibers and not bust them as that will give a very poor finish. As well, it takes some time to properly sharpen a blade, you might as well put the most durable edge on it when doing so, they will be shaving sharp and glide through the wood.


-Cliff
 
I think the silk is allowed to move long the stationary blade. I think in the Bodyguard the scarf is held unfolded. He moves it towards the blade and allows the scarf to drift out of his hands. So I suppose as any velocity remaining in the scarf is allowed as long as the scarf is released at more than 2', the scarf is relatively flat (not deformed by air motion), and it is not wetted. I am not sure about wetting the scarf the singer does appear to be over dressed for the climate, she may have prespired a lot.

Will
 
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