Cold Steel : Rajah III

Introduction and Specifications

The Rajah III is a continuation of a popular line from Cold Steel, the Rajah series :

The Rajah III is basically a scaled down, more pocket friendly, version of its big brother. Designed by Andrew Demko, it shares almost all the major features of the Rajah II including an AUS 8A stainless blade, Tri-Ad� lock, thumb plate opener, ambidextrous pocket clips, and a Grivory handle with steel liners for extra strength and rigidity.

The Rajah III�s handle offers a number of grip options due to its carefully sculptured shape and cross section and is particularly well suited to the reverse grip thanks to a unique thumb shelf built into the butt.

A few details on this one :

It is a large folder, even though it is the smallest in the Rajah series, and the size, weight and kukri style and Cold Steel build quality combine to often make a striking first impression :

wow what an impressive knife, first of all it is a large folder, well built, an extremely strong lock, steel liners, 6" blade, 14" full length, feels wonderful in the hand, the steel (AUS8-A) cuts like a razor out of the box,

The striking kukri design itself is often a point of attention and its dramatic design is rarely ignored :

Like the Kukri, the Spartan always presents its edge at an angle to the material being cut to produce a deep sheering effect. However, since its point is narrower and more acute than most Kukri blades, it stabs almost as well as it cuts. The Spartan also echoes the ancient Kopis in its handle. It's designed to help the hand resist the pull of centrifugal force and to retard forward momentum, when stabbing, or backward movement, when hammering or smashing with its pommel.

However it isn't obvious how a kukri's radical design scales down functionally to such a small knife.

Stock cutting

The Rajah III was bought used so no evaluation could be made of the as-boxed sharpness. However in regards to cutting ability, a little wood cutting showed a fairly obvious issue. The cutting ability was very low, it could barely make small curls even in moderate hardness wood. This was surprising as the edge angle is a fairly standard choice and should give decent performance when combined with the edge thickness and primary grind angle.

However, a quick check of the edge bevel in a little more detail showed the reason for the problem as the bevel is asymmetric. The left side of the bevel is close to 30 degrees and the right size much lower at approximately ten. As the left side was the side facing into the wood it was drastically reducing the performance. This heavy uneven bevel had to be addressed before the knife could be used significantly not only for means of cutting efficiency but also safety as it could cause skewing in cuts.

The edge was quickly reset to an 15 to 16 dps edge bevel with a simple benchstone. The edge was readily cut/ground. This steel is at about the limit of carbide level which can be ground with basic stones and doesn't respond that well to natural stones. It is significantly higher in carbide volume than tool steels like O1 and even A2, but is less than D2. With the edge angle lowered there was a significant increase in cutting ability.

A little specifics compared to the #1260 Mora making two inch points in one inch square pine. First with low force (10-20 lbs) :

Here the Mora cuts better which would be expected as low force cutting is mainly about the edge angle and the lower edge angle on the Mora produces larger shavings as shown to the right.

However with high force (50-70 lbs) :

deeper cuts are being made. The full flat blade grind of the Rajah III compensates as it thins out the blade behind the edge bevel and allows it to pull very close to the Mora.

Extended Use

Now kukris are not well known for their use in kitchens and this knife doesn't prove to be an exception to that. But for a lot of simple use it is perfectly practical :

Those kind of activities just require a decently sharp blade and the Rajah III easily handles the normal breakfast or lunch duties and it has the size/length to make a decent utility knife. Of course for that kind of use then the hyper strength of the tri-ad lock isn't necessary, and the kukri blade shape isn't an advantage, however they are not real negatives either.

Curiously enough the drastic curvature of the edge isn't really a significant factor and it does have a few things going for it over a typical kitchen knife :

And so compared to a standard semi-dull kitchen knife with angles typically between 20 and 25 dps, the Rajah III actually takes less force to initiate a cut and the lower angle also means the knife can be used to cut flatter to the potato which makes thinner peels easy. The tip is also quite robust but still easily can remove the eye or otherwise dig out spots of spade/blade cuts in harvesting.

However it has a common problem with a lot of larger folding knives which is that the wider blade forces the hand to be used in a very open grip to start the cuts and this leads to a fairly high rate of fatigue compared to a more more narrow paring knife. For a few potatos, no problem, but for a couple of dozen it is obvious that there are much better folder choices, something like the Spyderco Air for example is near ideal.

On onions, the Rajah III starts to show the limitations of the high blade thickness compared to the width. The blade grind is approximately three degrees per side while typical kitchen knives will be around 1.5 degrees per side. This very shallow angle provides high mechanical leverage which is one of the key reasons why high performance kitchen knives cut well.

Specific to onions, the simplest basic method to do a fine dice :

isn't practical because the horizontal cuts are not viable as the blade grind is too heavy which produces too much force on the cut and thus it is awkward/unsafe to hold the onion during the cutting. This of course just restricts it to a more coarse dice.

Now how much force is being talked about here, how much more effort does the Rajah take to make cuts? As a point of more specific comparison the Rajah was used / compared against a benchmark for kitchen cutlery :

The Herder has a very thin flat grind taken to such an extreme that the edge can literally flex over the thumbnail with very light force. This makes it fairly delicate in respect to rougher work, but foods in general are not that hard or difficult to cut. How much of a difference does this make, well doing a simple carrot slices takes :

There is no comparison, the Herder barely even moves a scale and the Rajah is just under 5 lbs. However while this means it is very inefficient compared to a kitchen knife, frankly the force is still so low it isn't really an issue from a practical perspective.

However moving on to thicker and larger vegetables :

then it moves from being inefficient to just awkward and impractical. The blade has the length necessary, but the cross section thickness is too high and can cause fracture. The radical curvature also causes the cutting to be forced to be made in a fairly clumsy manner as the common rocking/chop can not be used. It forces a repeated pattern of

where the knife has to be sliced through the vegetable similar to slicing a rope. Now of course this isn't a kitchen knife and there is a reason why utility/chef's knives don't have this geometry and blade curvature. But aside from light work, this is more of a fun knife for kitchen work than practical use.

However moving beyond kitchen work, the ability or use of the Rajah III becomes apparent when it is used for heavier work such as chopping light brush which leverages its :

It works very well chopping light scrub and brush and is much more capable than folders like the Spyderco Air which would work far better in the kitchen as a paring knife.

Now chopping and other dynamic work with a folder tends to produce the almost instant response of - "Use an axe!" but of course the type of chopping done with a folder isn't the size of wood used to build a log cabin, but more so to cut stakes, poles, limbs, and similar.

The Rajah III has the :

to allow chopping light brush vs just carving/slicing and this makes it far more capable than folders such as an Opinel which have a higher light cutting ability.

However there are obvious ergonomic issues :

These were all readily addressed with some coarse sandpaper to smooth out all the square corners which form high pressure points and lead to hot spots in hand.

Now of course the Rajah III isn't capable of replacing even a light machete. While chopping with this knife is more effective on small brush than slicing with an Opinel, there is a huge difference between the ability of this knife and even a small/light machete. Note the picture on the right which shows two small piles of wood :

The Rajah III has the ability to cut small wood for stakes, skewers, cordage, trim limbs for scrub cover and bedding, but struggles to cut larger wood which is necessary for shelter building :

As a bit more quantitative comparison, as a bit of math, as a first approximation, the following equation can be used to estimate the power that a knife can bring into a chop :

For the Rajah III :

A small machete :

Thus the machete can thus easily impact with five times the impact energy and thus can easily cut several times the size of the wood with ease that the Rajah III would struggle to cut.

After a lot of work with the approximately 15 dps edge with no concerns the Rajah III had the angle reset :

this was done with a TASK garden stone which is a very coarse silicon carbide stone :

This made a large increase in cutting ability and it enabled the knife to perform heavy stock removal readily. With the handle and clip sanded/chamfered the comfort was decent though full rounds would be a further increase in comfort/ergonomics.

As a point of amusement and possibly practicality in the extreme :

Now the Rajah III doesn't throw well not because of the balance because balance doesn't really effect how a knife throws, but it is very difficult to release because of the grip. It is best thrown no-rotation style which limits the distance to around 15 feet. It is also very short for a throwing knife which means it rotates quite fast and thus demands a high degree of precision in terms of counting rotations for accurate placement.

However it is one of the few folding knives that will have a manufacture make a video throwing them as a demonstration of the extreme lock strength/stability - albeit with significant warnings. The Rajah has been thrown a few dozen times at a distance of about 15 feet or less with no significant effect on the lock however it is likely to cause far more rapid wear than general even heavy cutting.

Grip

Ergonomics : at first glance the ergonomics of the Rajah III appear to be solid :

However it is one of those cases where pictures don't tell the whole story and there are details which become apparent in use very quickly.

These were addressed by sanding the inside of the scales to produce a basic chamfer and the clip was lightly stone washed to break all the hard corners.

Security : the Rajah III has many aspects/features which strongly enhance grip security :

The grip is also very large while allows a full grip even with large hands and is much wider than it is thick which prevents rotation. The only real concern are the sharp edges which need to be resolved as otherwise they will cause the grip to relax to prevent excess abrasion.

Versatility : the grip versatility is very high and there are only a few limitations. The handle is also well designed to be complementary to the other aspects of the design :

allows a significant amount of power to be generated in a swing and using an grip around the very end of the handle is possible due to the end hook / birds beak and that shifts the balance point far forward. As noted in the above this allows the Rajah III to be used to chop light brush far more effectively than cutting/slicing.

Now as noted in the above, initially the handle was abrasive due to sharp edges on the scales and the clip. Until this was resolved through sanding, that grip would be abrasive/uncomfortable without gloves.

The handle also works well in the stand :

looking to be obviously designed / intended as optimal for high power hammer style grips due to the :

However not all grips are comfortable/functional.

The two features which make the handle solid for hammer style grips :

tend to make the knife problematic for any grip which has the handle reversed in hand :

as they present two fairly abrupt points into the hand. Now there is no reason why the ends of those curves have to be so sharp. The could be more rounded and still be secure in a hammer grip. But to be very comfortable in reverse grip the inside space of the handle would have to be larger to keep them out of the hand. This obvious is dependent on hand size.

Clip :

Lock and Deployment

The Rajah III features Cold Steel's Tri-Ad Lock :

Undoubtedly, Cold Steel makes the safest, strongest folders on the planet. It's one of many qualities that separates Cold Steel from our competitors.

Our latest improvement is our patent-pending Tri-Ad lock. Andrew Demko is the originator of the Tri-Ad's novel locking mechanism. It's a successor to a patented lock design originally created by the very talented John PerMar.

Now if you look at the image on the right it might not seem like much of a difference from the classic lock back, however it is very different in one respect which is that it removes the mating surfaces from direct cutting load contacts.

The cornerstone of the Tri-Ad's� strength, among other subtle refinements, is the inclusion of a new "stop pin" which re-distributes the load of vertical positive and negative pressures on the lock.

The stop pin receives all positive pressure (pressure on the cutting edge) and transfers it into the handle frame and liners where it can be more effectively absorbed.

In short, in a regular lock back, the blade, when it comes under forces from impact can transfer these forces to the lock bar quite readily and cause the lock to disengage/fail. The rigid stop pin absorbs these forces and thus to disengage the lock the stop pin has to be sheared off or at least deformed/moved to the point the lock faces can separate.

The Tri-Ad lock, has demonstrated on video by Cold Steel showing the ability to take both heavy loads and impacts and it frequently gets praise for such :

... this is my first knife with the tri ad lock and i must say im impressed. its rock solid and i think the adjustable pivot screw may go unused for quite some time.

However this does come with a bit of a price it is just as frequently criticized because of the stiffness and issues with operation. At times this problem goes away with use as the parts wear and break in :

When I first began using it, the knife was a little hard to close at times but the more frequently I used it, the better it got. Now it opens and closes with no problem whatsoever.

However while the lock's strength and resistance to being unlocked by accident from vibrations/impacts are well demonstrated, even by Cold Steel doing throwing demonstrations, it does have, as noted in the video on the right of a common problem with all back locks. Due to the way that the hand grips the knife, it is possible to depress the lock unintentionally.

As with all issues of that type of accidental unlocking it is very dependent on the size/nature of the users grip. However it is one of the things which are easy to check and one of the standard of the folding knife lock checks advocated by Joe Talmadge (author of the rec.knives knife FAQ's).

Now to be pedantic, Joe's checks, based on recommendations from A. T. Barr were developed specifically for liner locks which are prone to having issues with insecurity as they are so critically dependent on interface geometry, however they do have application to all locks :

Open knife, then thumb the lock aside (blade is still open). Wiggle the knife back and forth. If the blade has *any* play at all, that's a bad sign. It might just be that the pivot is too loose, so tighten the pivot until there is no more side-to-side play, and then make sure the action is still acceptable. Sometimes a knifemaker will have a bad action, and then make it appear smoother by loosening the pivot too much.

On top of that, I do the "white knuckle" test, which many makers also fail. Making believe I'm under stress, I grab the knife in a very firm grip, letting the flesh of my fingers sink in and around the liner to whatever extent this happens. Now the question is: will small movements unlock the lock (if a small movement moves the lock AT ALL, assume it can unlock it)? If the lock is too loose or too high relative to the handle scales, a knife that passes the other tests might fail this. I made an expensive folder from a well-known maker fail this way. I sent it back to him and he fixed it to my satisfaction. That is why I like the AFCK-style handles that do not give easy access to the lock via a cut-out -- I'd rather it be a little harder to unlock than to unlock accidently under weird conditions.

Bob Kaspar recommended a torque test as well, which is a test many liner locks fail. You want to open the blade and then torque it while applying pressure against the spine. The lock should not fail simply because the blade is being torqued a bit. I do this test by sticking the blade through something hard, a few layers of strong cardboard or wood, and then torquing the blade while trying to shut it.

Interestingly enough there is a common solution to this issue which was developed by David Boye, the Boye detent.

Boye simply cuts a scallop out of the lock bar which puts the bar below the handle and thus reduces this possibility of an accidental contact and release in a tight grip. It is a very simple, but elegant solution.

Spyderco commonly uses this feature, and gives credit to Boye when doing so, Cold Steel doesn't. It is one of the few alterations to a knife which has no downsides as it doesn't effect ease of use of the lock and in fact increases comfort in use.

Steel - AUS-8

Nominal composition of AUS-8 :

AUS-8 is on the same tie-line as 440C which means it has the same carbon/chromium in solution so it has similar hardenability and obtainable corrosion resistance. However because it is used often on more inexpensive knives it tends to have a less than ideal hardening and it can cause issues with corrosion resistance as a result :

One afternoon on the farm, I cut some fresh peaches from a tree for my kids and the blade turned a bit. It had some dark spots on it in several places by that evening.

As for sharpening, AUS-8 is in general a fairly easy steel to grind compared to the high carbide steels commonly used in modern cutlery such as ATS-34, D2 and more extreme version such as M4, and 10V. However compared to steels such as AEB-L and tool steels such as O1 it is harder to grind. It is at the cusp of steels which in general are regarded as difficult and only really are likely to be an issue if just natural stones are used.

However this particular knife in AUS-8 has a significant problem which degrades ease of sharpening which is that the initial bevel is seriously uneven. One side of the edge is about thirty degrees and is almost three times the angle of the other side. This means that any jig system would struggle to match the edge bevel. Now of course this uneven bevel isn't intentional and serves no real purpose and so it was removed and the knife reground to an even 15 to 16 degrees per side.

The recurve tends to be problematic for some however the main thing to keep in mind is that it really is only an issue in the final micro-bevel where the stone/hone should be ideally perpendicular to the edge to minimize the burr. Otherwise just sharpen as normal and don't pay much attention to the fact there is even a recurve there in the initial shaping stage.

On an additional note, this knife has a sharpening choil/notch however the edge isn't ground all the way back to that point which makes it completely irrelevant.

This is one of the curious cases where someone in the manufacturing process clearly doesn't understand the design. That small notch at the base of the blade is there because without it then it can be difficult to sharpen the edge all the way back. If the edge is stopped in front of it then it makes that feature irrelevant and is nothing more than a point for material to catch.

Corrosion resistance, was curious. This knife has been used in the kitchen but rinsed and dried with a cloth and never left soaking in fruit acids or salt water and yet is still had obvious corrosion in multiple places. Essentially all of the tight spaces which are hard to reach with a cloth and tend to stay damp suffer obvious corrosion. AUS-8 is on the same tie line as 440C which means it has similar inherent corrosion resistance however in this case it obviously doesn't. This could be do to the heat treatment and as noted in the above a combination of lower austenization temperatures and/or a slower than ideal quench.

Overview

Issues :

Strengths :

Comments and references

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Most of the pictures in the above are in the PhotoBucket album.

Last updated :
Originally written: 30/01/2015
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