This knife was based on an existing design by Glen, the "Camp Knife", [ref]. After seeing the picture on the web which spoke of a base in functionality I visited Glen at this shop and spoke awhile about knives. I was impressed by his frank nature and his open and straightforward description of how he chose his steel, his methods for making the blade and heat treating as well as testing to insure the proper level of flexibility, durability, cutting ability as well as handling characteristics.
This knife was used to prototype several aspects of knife design. The blade was made longer and wider than the "Camp Knife", and a recurve was added. The handle was also heavily contoured and checkered for security in compromised grip conditions. The blade steel would be 5160, a standard for Glen for large blades. It would be selectively hardened; spring spine, hard edge, soft choil and tang. The spring in the spine gives stiffness and strength, the high hardness of the edge gives good impaction resistance with a high overall durability and solid edge holding, and the soft choil and tang dampens shock.
The finished blade from the side :
and from the top :
The overall fit and finish was high, smooth lines, no sharp transitions, including a fully rounded spine. The blade is fourteen inches long (10.6" sharpened) with a handle 5.6 inches in length with a quarter inch thick spine. The knife weighs 820 g (~1.8 lbs) and is quite blade heavy. The blade has a convex primary grind which extends to a secondary flat ground edge bevel from 0.05-0.06 inches thick and ground at 22-24 degrees per side. Here is a cross section of the knife, taken in the middle of the blade :
The relatively thick stock stock was chosen to allow the blade to have the necessary fluidity to work in thick and binding woods, as well as to give it the necessary stiffness for functional prying.
For some weed cutting, the custom was a bit too blade heavy. The cutting ability was fine, weeds and such just demand a high level of sharpness, but a slim and light machete would have been more efficient due to the lower fatigue rate. However such machetes can be problematic on harder woods, and wedge badly on thick woods. They are also limited in versatility due to a lack of a defined point and a low stiffness and strength.
For some wood chopping and carving, the performance was of the custom was solid. It handled splitting with ease, both inherently as well as with a mallet on some seasoned and knotty woods, all completed with no problems with edge damage. The blade was also stiff enough to allow significant prying even with the tip, easily able to dig through some 2x4's in a just over a couple of dozen stabs.
However the above work, while brief did suggest that the design could be further optimized in a couple of aspects; specifically the edge bevel was a bit too obtuse and the handle contours a bit too deep.
With use of a belt sander the edge on the brush blade blade was thinned out. The blade would be ground for about five to fifteen minutes, taking care to maintain the recurve and tip flow, and then the knife would be used to examine the cutting ability and durability of the new edge. As metal is removed there is always the concern that too much was taken away leaving the edge unable to take the strain of heavier work. The alteration of the edge was therefore a gradual one, with small changes made for each grinding session. As well all power grinding, lots f water was used to frequently cool the blade to eliminate the possibility of effecting the temper.
With each new edge profile use would start off light, first working with soft woods, bucking up some felled sticks and other thick wood cutting. Some live limbs would then be cut, precision swings working from base to tip of the trees working slowly to minimize stress on the blade. Next limbs would be cut in the opposite way, and the power generally increased until sweeping motions were used. The knife would also be used to split some wood with aid of a mallet, and finally taken into low light areas and used to clear dead and seasoned limbs off of trees were were very hard and tended to crack and split as much as be cleanly cut. With the blade after passing each of these trials with out hard it was ready for the next grinding session.
After several alterations the blade was finally modified into one smooth convex profile, no secondary edge bevel, the blade ground flat against the belt with just the small amount of slack providing the necessary curvature. The very edge was ground at about fifteen degrees per side, quickly tapering into an extensive shoulder of about 10-11 degrees. With the shaping completed, the edge was polished using waterstones and finished with CrO buffing compound. Taken out for more wood cutting the knife again had no problems maintaining a crisp and clean edge, free of dents or any other damage even after cutting small diameter seasoned wood.
The final blade specifics :
| Thickness | Width | Angle |
|---|---|---|
| inches | inches | degrees |
| 0.021 | 0.039 | 15.1 |
| 0.060 | 0.118 | |
| 0.122 | 0.276 | 11.1 |
| 0.195 | 0.591 | |
| 0.225 | 1.220 | |
| 0.155 | 1.496 | |
| 0.000 | 1.535 |
As the cutting ability grew while the edge thinned, the blade's handling characteristics also improved. The knife became more fluid in hand, more stable in heavy swings, and the impact shock steadily decreased and cuts became deeper and smoother.
It is critical to note that the level of geometry which is functional is dependent on the users skill, physical power and the type of material being cut. Once you know where you can go with one steel educated inferences can be made to other materials.
Getting specific, to a large degree denting is controlled by hardness, however chip resistance which is quite high with 5160 can vary widely from steel to steel.
The contours on the handle were designed as extremes for prototyping. In use, because the front of the handle was so narrow, the index finger would overlap the thumb and could be abrasive. It was not so much the thickness, but specifically the relative contrast to the middle of the grip, in short the contours were too extreme. Towards the rear of the grip a similar problem was noted.
The handle was thickened in the front and back using a base layer of a self-adhesive rubber tape from Lee Valley. Since it is self adhesive t is easy to remove, and it will give slightly and adds to shock absorption. However it is fragile, easy to cut or tear. An outer layer of "guard tape" was applied for extra durability. This is another self-adhesive tape sold by Lee Valley. It also adds to security as it is very abrasive.
With the grip filled out significantly all the handling problems disappeared and the overall functionality of the knife took a major step forward. The blade became more comfortable and secure in hand, fatigue was reduced which made cuts more precise and the overall performance of the knife increased as a whole.
After the above modifications, the knife was used extensively for brush work, mainly limbing, and the overall nature of many of the design aspects was filled out in regarding scope of use and overall functionality.
For a pure brush cutting blade, the stock thickness could be significantly lower, down to about 1/8", going below the blade loses so much rigidity that it starts to get problematic with any wood cutting. As an example, the Patrol Machete is more efficient cutting through small soft branches and other similar material. However this custom, was intended to be not completely focused on such work. The quarter inch thickness was necessary for the desired fluidity in thick woods, and level of strength and rigidity for leverage work up to and including the point, digging out pitch wood for example. The extra mass also allows for greater performance on seasoned woods, which can be problematic to cut with lighter blades due to excess vibration.
After using this blade and others of similar design for a lot of wood working, a couple of performance attributes stand out clearly. First, recurves are problematic on thick wood. Resistance to glancing and general stability isn't optimal, and getting cuts to align correctly can be troubling. A blade which has a convex curvature (the edge sweeps constantly upward towards the tip) like the Valiant Golok is more optimal for thick wood cutting. The power of the recurve however can be seen when cutting small diameter woods and other light vegetation. The concave curvature acts to lock in the material, preventing it from slipping up the edge and not being cut.
This is obvious when looking at wood and brush cutting tools in general. Thick wood cutting blades like axes have convex edge curvatures, while those which are used for small limb and brush clearing like bill-hooks are slightly concave, while others like sickles which cut mainly much softer vegetation are deeply concave. Using a sickle on thick wood is almost impossible it is so heavily optimized for cutting softer material. The curvature of bill-hooks and other similar blades is much less extreme and fairly close to flat (of which some are). These blade can be used for thick wood cutting, but will not be as smooth as those with a more optimal profile.
As for the Parrell custom brush knife, thick wood cutting was best performed with the tip, which has the optimal upswept or convex curvature. The middle of the blade which has the heavy recurve is used mainly for limbing and other chores. The recurve in the center also acts well to lock in wood and enhance control when using the blade as a draw knife for rough stock removal and more precision shaping. The rounded spine is strongly appreciated during such use as well.
The knife has a section in front of the handle which is wide enough to function as an extended three finger grip as it is not sharpened. However this extended choil does reduce some precision cutting ability. The unsharpened edge also fares as a safety guard, and because it isn't used for cutting can be much softer and thus better for damping shock. If this was to be used in a one-knife situation this region could benefit from having an edge formed as otherwise some tasks like wood whittling, for shaping as well as tinder, would be made significantly easier.
The knife is basically used in two main grips. One is forward around the relatively straight part of the handle which has the blade used in mainly short snappy cuts which are done fairly fast and used for cutting light vegetation and small woods. When more power is needed and less precision, the grip is shifted back to the full rear of the handle which allows for an inherently more powerful drive which is increased by the now more forward blade balance and increase in effective blade length, however some loss of precision does result.
In general this is a fairly task specific knife, it can be used for precision cutting but does not do it well mainly due to its size and weight. Some tasks like food preparation on a cutting board, are very awkward due to the recurve, and others like trying to peel potatoes are pretty much impossible due to the blade size and weight. However in regards to pure cutting ability, the knife performs very well due to the thin and acute edge profile and full primary grind.
As noted the the blade can handle even the hardest of wood working tasks without any visible damage. The edge retention was also found to be far in excess of production machetes and other brush knives which is due mainly to the much higher hardness of the custom blade. At the end of cutting sessions where both blades saw similar use, the machetes (of similar edge profile) would typically have visible edge denting and rolling and little fine cutting ability, yet the custom could still slice paper.
In general though, this knife doesn't go through more than a few sessions of wood cutting (a few hours each) before it is sharpened. The blade usually has not lost a significant amount of cutting ability at this time, but it is honed to prevent any microscopic damage from growing. Plus since the blade is fully convex with no secondary edge bevel, it takes some time to sharpen even with a light touch up is all that is needed as you need to grind the entire blade surface. As a side note, this keeps the blade flats free of any corrosion buildup.
Such sharpening sessions are usually performed with the use of a 4000 grit Japanese waterstone. The small hone, 1x4 inches, is worked over the blade with the knife held fixed. A smooth motion is used from the spine right down to the edge with the knife being honed in small sections, just the width of the stone. About a half a dozen passes of the hone are used per section. The blade is then flipped over and the process repeated. The hone is then used to make a couple of passes into the edge at a slightly higher angle to remove any burr and the entire process repeated once more. The knife is then cleaned, edge tested on paper, and then given a final honing on CrO loaded leather which will produce a fine shaving edge.
Because of the long blade, and the need to work the entire bevel, this process can take awhile, about fifteen minutes or so. With use of a belt sander, it would only be a minutes work. The process could also be speeded up significantly with the use of a very large strop, easily made out of fine sandpaper, or thick leather loaded with a fine SiC or diamond paste, and then finishes again on CrO loaded leather.
As an extreme example, the knife was on a couple of occasions struck against rock during some low clearing cuts. The edge damage was minimal with only slight impaction, no chipping or other fracture was induced.
The knife came with a thick and solid leather sheath. The scabbard has shown little wear from a couple of years of use.
In short I was very pleased with this knife. It was made exactly as designed and I learned a lot from its use. The performance of the steel was solid, showing the ability to take a relatively fine edge and had no difficulty, able to handle the hardest of wood working without problems.
You can comment on this review by dropping me an email : cliffstamp[REMOVE]@cutleryscience.com or by posting in the following thread on Bladeforums :
More information can be obtain at the website for Viking Metal Works.
| Last updated : | Tue Jun 3 14:31:50 NDT 2003 |
| Thu May 22 11:59:34 NDT 2003 |