SAK's steel performance

When you do an experiment with one knife and get results that surprise you, you don't know if you've learned something you hadn't known about that particular knife or if you've learned something you hadn't known about knives. In this case Son of Triglav discovered that a knife can whittle through an axe handle once without being dulled to speak of ... but he didn't know that; he thought he had discovered that SAKs have amazing edge-holding....

That's what usually happens when you try something you've never done before, and we get frequent posts about amazing knives that can pierce aluminum cans, car hoods, steel drums ... I haven't seen a post about an amazing wonderful knife that can pierce a sheet of toilet paper -- and not even be dulled!!! -- but I expect one any day.... :)
 
No,not any knife. I've discovered that a 19 $ Victorinox SAK can whittle through pretty hard wood and stay virtually as sharp as before the task. The real question is: why should then I buy some hi-tech, tactical whatever folder which costs over 100 $ or even more (made of some super-mega amazing steel -which may go dull when cutting rubber plastic? http://www.canit.se/~griffon/knives/text/12c27vscpm440v.html. ) when lowly SAK can do the job? :eek:

Knives that can pierce through car hoods,steel drums ...wow hm that must be North American phenomenom or specialty. I honestly admit haven't heard for or seen such astonishing test tried elsewhere.
 
You're absolutely right -- it is useful to find out that even a low-buck knife can do things that some advertisers of high-buck knives brag about. I hate to think how many naive people have been so impressed by Cold Steel's advertising they've run out and spent a bunch of buck$ on a knife that can't do anything knives they already owned can do....

I've said it before but it's worth saying again -- everybody should take one or two cheap knives you don't mind risking and find out what they can do and what they can take. If you don't already have one it's worth buying a cheap knife just for abusive testing -- if only to see for yourself a lot of things you probably think only an idiot would try to do with a knife really aren't abusive at all.
 
We buy higher end knives because we want too. How much use do we really give them when we do buy them? Not a lot. We use our kitchen cutlery more. But its fun anyway and we tend to forget that for a little better advantage we are paying through the nose. Same story with cars which after all are there to get you from A to B.
Most of those soldiers and adventurerers, who's life might depend on their knife, carry very ordinary blades. Very few high end knives are really used. So what; but its nice that there is great stuff out there that really performs for not too much money.

SAK's are great. Opinel is another of my favourite inexpensive high performance knife manufacturers as is the Stanley knife.

Paper and cardboard contain wood pulp, water and resin; but also something like 20% chalk, silica, sand, clay, granite and all manner of stuff. Its the 20% that gives the colour and bulking out that is so abrasive. You can set an edge by wiping a blade across paper.

The SAK wood saw would have zipped through the handle ;)
 
Someone suggested the reason of the result was because of the thin grind but if I recall correct the Soldier model has a fatter blade than other SAK´s. It isn´t really ultra-thin.
I don´t exactly recall what steel they use but i think it isn´t just 420HC i think there are some amounts of cobalt or vanadium in the mix.
Anyway I think it would be fair to give credit to victorinox for getting the max out of the alloy.
BTW the Soldier is a nice piece.

/ Martin
 
The steel used by Victorinox has .52% C, 15% CR, .45%MN and .5% MO, as stated on there website (thanks to ISSTAIPEI who pointed this out in response to my post about SAK Steel). This is very close to 425M steel. Hardness of the mainblade is 56RC. I don't know if Wenger uses the same steel but it is probably similar.
 
This is an abstract from new Tecnical Informations from Victorinox site. It is from a document available from their site.

"Interesting facts about the original "Swiss Army Knife"

Technical details...

The exciting idea and the actual recipe for the success of VICTORINOX pocket knives lay in the multiple use of each spring: six
blades on only two springs made it possible to produce the Army Knife in such a light and elegant form.

A special blade steel is used for both cutting blades, made of stainless chromium and molybden-alloys. After hardening at
1,040 degrees and tempering at 160 degrees, the blades have a hardness of RC 56 (RC = Rockwell C, unit of hardness).

The wood saws, scissors and nailfiles have a hardness of RC 53, the screwdrivers, tinopeners and reamers RC 52, and the corkscrews and springs RC 49.

The metal saw and file is case-hardened and hard chrome-plated, so that even iron and steel can be sawn or filed.

Since 1951, the separating strips (plates) have been made of an aluminium alloy. As a consequence, the knives are lighter, which
makes carrying them in trouser pockets more comfortable. Previously,
plates used to be made of nickel silver.

The rivets and bushings are made of brass, the handles of Cellidor or Polyamid.

The spring presses onto the large blade with a force of approx. 12 kg, and, on the opposite side, onto the small blade with a force of around 8 kg. The total force of 20 kg presses backwards onto the corkscrew.
With 2 springs and 6 pressure points, this results in a total spring pressure of 70 kg.

This amount of pressure is required in order to let the blade snap shut, because the leverage ratio between axis and pressure
point, and between axis and fingernail grip, is approx. 1 : 20. In the case of the Swiss-Champ with its 8 springs or 24 pressure
points, the spring pressure therefore comes to a total of around 300 kg.

To resharpen the blades, VICTORINOX recommends using a honing stone, as the alloy from which the blades are manufactured is too hard for a honing steel.


... and clear VICTORINOX advantages
compared with imitations


The typical clicking noise which occurs when the blade is opened and engaged is an audible sign of the high spring pressure.

Even after years of intensive use, this spring pressure will remain the same.

The VICTORINOX tin-opener, which was patented in 1951, is unrivalled by any other pocket knife tin-opener when it comes to quality. It also has an additional small screwdriver for slotted and Phillips screws.

Only VICTORINOX knives have separating anodised aluminium strips adjoining the corkscrew, which provide a glass-hard, wear-resistant surface. This high-quality surface treatment trebles the cost of the
parts.

The punch, bore and sewing reamers have an optimal profile as a result of two further machining processes.

The rivets in the knife are reinforced by six additional metal bushings.

The open VICTORINOX screwdriver is under increased spring pressure when in the working position. Its facing edge is positioned behind the knife's axis at an angle of 89°. This prevents the screwdriver from
shutting when it is in use. It may also be used as an angled screwdriver. The bottle opener has been optimally designed to fit
the widest range of bottle tops.

The VICTORINOX wood saws were designed to be the maximum possible length.

All the teeth are very sharp and the metal saw and file remain sharp for longer thanks to their greater surface hardness.

The mini screwdriver incorporated in the corkscrew (e.g. for little screws in glasses) is a VICTORINOX patented design.

In a final quality check, 90 people ensure that only those pocket knives which are in perfect condition are sent for dispatch. Each
individual knife blade which leaves production undergoes a manual check to ensure a perfect finish. The VICTORINOX guarantee covers all material defects or manufacturing faults for an unlimited period.
Both the New York Museum of Modern Art and the State Museum for Applied Art in Munich have, on their own initiative, added a VICTORINOX Officer's Knife to their collections. "

Falcenberg
 
Son of Triglav :

And there was no splitting ,the knife,the egde had to pushed through whole lenght of a cut.
Click to expand...

By splitting I don't mean you start the cut and the shaving just cracks off. When you cut with the grain, or across it, the grains can split apart (and probably internally). This vastly reduces the force that the blade needs to exert to wedge the shaving up. To notice the difference it makes, cut right across the bottom of the handle perpendicular to the grain or simply cut straight down into the handle, unless you are extremely strong you won't make much of a cut at all. However on a slice through the grain you can easily get 1/4"+ penetration.

In regards to cardboard vs wood, yes wood generally takes a lot more force to be cut, and hardwoods can roll an edge readily. To get specific after about 30 max force cuts on hardwoods I can induce an edge roll that will lower push cutting sharpness to about 55-65 % of optimal on ATS-34 (60-61 RC), some steels do better some do worse, the type of wood also makes a difference. This will also eliminate the shaving ability. However a simple steeling will fix this. Cutting cardboard will actually wear metal off the edge.

In regards to the tomato, either the cutting board is very hard, the tomato was very dirty, or something was wrong with the initial edge on that knife.

-Cliff
 
Thank you for constructive replies and comments.They're appreciated.

Greenjacket, I have nothing against (buying) high end knives,as long they justify their too(?) high prices.But,in most "high end" knives cases, you pay for something what isn't worth that much money.

Cliff Stamp :

By splitting I don't mean you start the cut and the shaving just cracks off. When you cut with the grain, or across it, the grains can split apart (and probably internally).
Click to expand...
I understand now what you meant. Would the surface of wood be very smooth after such cut?
This vastly reduces the force that the blade needs to exert to wedge the shaving up. To notice the difference it makes, cut right across the bottom of the handle perpendicular to the grain or simply cut straight down into the handle, unless you are extremely strong you won't make much of a cut at all. However on a slice through the grain you can easily get 1/4"+ penetration.
Click to expand...
I agree. A slice along the grain require significantly less force.Although I have to repeat that those cuts I did (at the test) were more like push-cuts than slices.

In regards to the tomato, either the cutting board is very hard, the tomato was very dirty, or something was wrong with the initial edge on that knife.
Click to expand...
A dirty tomato !? haha how could I eat a dirty tomato (beside tomatos don't lay (grow) on the ground anyway) .There was probably something wrong with the edge.
Cliff, have you tested any Randall made knife? What do you think of their steel hardness,edge holding etc?
 
On the subject of the tomato problem.... I was under the
impression that Randalls are mostly of O-1 tool steel.
O-1 as well as many other carbon steels can be dulled by
contact with high acid foods.

I suspect this is the case with the tomato.


Thomas
 
Son of Triglav :

in most "high end" knives cases, you pay for something what isn't worth that much money.
Click to expand...

If you look at performance from a cost basis then the cheaper knives always dominate. It is possible to get better knives by spending more money, but the increase in performance will not be linear with the cost. Specifically I have knives that cut better than my SAK (Rucksack), hold an edge longer, are more durable, more comfortable to use and more secure in hand, but the gain is no where near the price ratio. Then again it is not like this is the case for any product.

Would the surface of wood be very smooth after such cut?
Click to expand...

It depends on the wood and the edge, ideally it should be. If the fibers are not being cut smoothly then the surface will be rough as the wood is being too heavily damaged. You can compensate for this by raising the edge polish, lowering the edge angle, or cutting at a skew or using a rolling/slicing motion (which in effect just lowers the functional edge angle).

Cliff, have you tested any Randall made knife?
Click to expand...

No, Randall is what I would consider a "name" knife. This is one where the price is dominated by reputation and not performance. I am not saying they are not "good" knives, but just that for the money and wait time, there are other places I would look for a knife. As well, looks play no part in my opinion of a knife, nor does history of use, etc., they are just tools .

Last time I checked they were using forged O1 and 440A, solid choices for work knives. I recall a moderate hardness, around ~55 RC or so, which would mean that they would indent more readily that a lot of high end cutlery which are around 59-61 RC, and as well suffer edge roll quicker. However they would likely have an advantage in ductility and impact toughness if the heat treatment was done well.

Thomas, yes a lot of kitchen work can cause edge degredation due to corrosion. However even on simple steels I have never seen anything happen quite that fast even on the more acidic fruits. The best way to determine what the problem is would be to resharpen the Randall, repeat the cutting and see if it happened again, be sure to use another knife as a baseline. Maybe the tomatoes are actually that abrasive, stranger things have happened.

-Cliff
 
The Randall stainless is 440B (they don't use 440C because they can't forge it). Lately they've been using some other stainless steels, but I don't think 440A is among them.
 
As you mentioned Cliff, the cutting board could be
suspect as well. My hunting companions and I had found
that when butchering deer, we were using cutting boards
we had sanded to allow a degree of ease in sanitation.
We found that edge degradation happened pretty quickly on these
boards.

This happened using pieces of plywood as well. We started
using a scraper to dress the cutting boards, and the knives
held their edges longer.

You're correct about the tomato issue Cliff, my observations
dealt with prolonged use of carbon steel with acid foods....
when I was a youngster, my folks canned lots of tomatos and the
knives (Old Hickory brand I believe) would dull rapidly from
nothing more than cutting tomatos, without cutting board
(in the hand) The tomatos were well cleaned for canning
purposes, so I assumed it was the acid dulling the knives.

Thomas
 
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