Knives :
This review consists of :
Basic specifications :
A note on the edge, it is approximately a 10 dps bevel but as it is convex it tapers under 10 dps at the shoulder before blending into the primary grind and increases in curvature close to the very apex. The approximate angles are between 5 dps at the shoulder and 15 dps at the edge.
Some details on the sheath :
Extremely solid construction, significant weight yes and Kydex would be much lighter but leather tends to work better in extreme cold.
A little work by Mike with the blade on some 2x4, note :
A brief examination sure, but it shows an obviously decent combination of :
Initial impressions :
3/8" hemp :
As a general point of comparison, a 10 lbs cut on a 2" draw is a fairly high standard generally achieved by very fine edge knives so 50% of that on a heavy chopper is fairly solid performance indeed.
A typical session of about an hour on various scrap lumbers :
will typically produce very little effect on the edge, no significant wear, deformation, rolling or chipping. The grip has three distinct regions which allow chopping to be done with either a very slow and heavy chop in the forward grip and impacting just ahead of the center of mass, or a faster and more rotational chop right out in the main hump/curve.
The edge has a very nice balance between cutting ability and durability. The specific geometry :
This is a fairly thin grind but easily allows heavier work as noted on the right and cut wood which is :
As a fairly dramatic illustration of the difference between the grind of the Excalibur :
versus a common heavy machete grind :
can be seen in the video on the right. Note how the Excalibur has much higher penetration under lower force and easily is fluid enough for very efficient cutting. This is one of the ways that compound grinds can enhance performance, the other is that the strength to weight ratio is higher.
However while the Excalibur does a lot of things very well, there are benefits to other designs. For example the video at the right shows the Excalibur compared to a blade which has similar raw power but a dramatically different design as it is a heavy cleaver.
The cleaver has a very short blade and this makes it a lot easier to use in a few applications :
When working in actual ingrowth, not on a chopping horse, it might now always be practical to have the kind of swing clearance that the Excalibur demands and the shorter length of the cleaver allows more focused chops which can prevent or at least reduce damage from dirt/rock contacts.
Ergonomics and security are discussed in the videos on the right. In summary :
There are a few minor issues which do come up though which could be modified to further refine the knife :
Construction : as noted in the YT video on the right by the maker (Mike Gavac), the Excalibur has a partial tang. It runs the full length of the blade but it is not full tang in the sense it is the same thickness of the blade and width of the handle. The construction can be seen in detail in the video on the right (from the maker).
This partial tang construction is intentional to isolate the tang from the grip and provide a thermal break. The reason for this is to allow the tang to be enclosed and thus minimize metal contact and thus allow use without gloves in lower temperatures.
This style of handle uses inserts to fill in around the tang and thus there is a durability concern however extensive chopping and heavier impacts have not proven it to be a practical concern. To give greater confidence cold weather work will have to be undertaken in the winter.
The sheath was made by Bruce Rugg :
The sheath has been in use for years with no significant wear and the usual maintenance of periodic application of neatsfoot oil. The dangler allows the sheath to move freely so it doesn't tend to get hung up easily on contacts with brush and it keeps the blade secure and tight while moving around.
O1 is a low alloy tool steel with minimum alloy content to allow high hardenability and alloy oil quenching vs water. The use of oil, which is a slower quench, reduces risk of quench cracking and warping.
For the knife user, O1 is a very high carbon steel, more than enough carbon to allow full martensite hardness. It has enough carbon to provide an excess to form a well distributed array of fine carbides, mainly cementite as shown in the micrograph on the right.
It is a well respected steel for knives due to the combination of hardness, wear resistance and edge stability. The only two significant downsides are lack of corrosion resistance and impact toughness. However the latter is only really a concern in extreme work where mid-carbon steels would be preferred to be able to handle extreme impacts (rock, bone) or work in very cold temperatures.
In regards to corrosion resistance , the small amount of chromium does little to prevent corrosion. The image on the right shows the Excalibur after being exposed to :
With temperatures floating around 0 C for about two days. This is however just surface scale/rust which is trivial to remove without significant effort.
Less than a minutes work with a plastic pot scrubber removes all surface scale. The only lasting effects are :
There were only two small areas of the edge which were 0.1 mm deep and 1 mm wide that were effected by the corrosion.
Ease of sharpening is a high point of any low alloy steel, with a high hardness and consistent and fine micro-structure. Without a large array of alloy carbide :
As there are no alloy carbides and in general a fine distribution of
cementite even natural stones produces a fine shaving edge with trivial effort
even on a blade of this size. The only concern is due to the weight and
curvature that it may be of benefit to keep the blade still and work the edge
with a small stone.
Edge retention from a functional perspective, the edge retention is high enough that it basically isn't a factor. The knife will blunt by damage from accidental impacts long before the apex of the edge will slowly thicken from wear or mild deformation from wood impacts.
In a little detail, a short chopping session, consisting of enough wood to be equivalent to 100 2x4's will do little to the edge and it can easily slice light grasses with no issues. Doing actual work in the woods, that volume of work is difficult to near impossible to do without hitting dirt in the bark or similar on the surface of felled woods.
This raises the only real counter point to this steel which is that a lower carbon similar steel would still have functional hardness/abrasion resistance and prevent fracture in extremes and be easier to grind. From that perspective a steel such as H13, 4140, or Calmax would be preferred. However O1 is far superior to steels such as ATS-34 or D2.
The Excalibur is one of the highest performance large blades seen.
This one was customized with a particular tang configuration to enclose it to reduce thermal transfer and it has held up well with no issues.
Comments can be emailed to Excalibur Gavkoo
and/or the YouTube Playlist.
Most of the pictures in the above are in the PhotoBucket album.
| Last updated : | |
| Originally written: | 28/02/2013 |