Fallkniven U2


The review consists of:

Specifications

The U2 is a small lock back folder with a total length of 3.4" and weighing 42 grams. It has a laminate blade with a a core of Super Gold Powder Steel hardened to 62 HRC surrounded by VG-10. The blade is 0.095" thick, 2.5" long and 0.75" wide. The primary grind is full flat grind tapering to an acute edge 0.006-0.008" thick. The initial edge angle is high, hard to measure given the small width, but it isn't sharpened readily on the 20 degree Sharpmaker rods. The tip is has a slight distal taper, about 2 degrees, and is slightly convex. The grip is made from zytel with a smooth finish. The blade opens from either side with of a nail nick.

Stock work

The new in box sharpness was high, shaving smoothly, and push cutting newsprint, though scratcy. This performance was reflected push cutting light thread with the U2 taking 90 (10) g, though little aggression on a slice with 2.2 (6) centimeters of edge were required to cut 48lbs hemp under 500 grams of tension.

Push cutting 3/8" hemp required 24.0 (1.4) lbs. No aggression was seen on a slice, which is expected given the performance on the 48 lbs hemp. The relatively high force on the hemp shows the influence of edge angle as the U2 has a fairly obtuse edge angle in comparison to its thickness.

On hardwood dowel the U2 formed a one inch tip in 1.85 (25) cuts, extremely high performance due to the thin edge, and leverage advantage as the sharpened edge starts almost immediately infront of the handle which allowed efficient transfer of power from the shoulder with little wrist strain.

With a 50 lbs push the U2 sank 213 (11) pages into a phone book. Harder vertical stabs were not attempted due to security issues with the grip and possible lock release. Heavy wood digging was not performed as the tip is much to thin to take that use, far outside the scope of work of the knife.

kitchen

For paring the U2 does very well for a folding knife. Being very small and light with an efficient cutting profile, aside from the slightly obtuse edge, it also cuts well. Ideally it would be half as wide but it is much better in terms of control than knives like the Delica. In general it cuts well. On potatoes the U2 very nearly matched the performance of a a Japanese utility knife which made slices in about one lbs, while the U2 took a barely noticable increase to about 2 lbs. A similar small difference was seen when cutting up small onions. On stiffer vegetables the Japanese utility knife had a more significant advantage, on carrots it took 2-3 lbs with the U2 needed 7-9 lbs. The U2 is also problematic on larger vegetables simply due to the blade not being long enough to make full cuts, for similar reason it doesn't work well on most slices of thick breads, though can readily slice up a bagel.

In regards to corrosion, the steel handled even acidic vegetables like onions well. The U2 could slice up onions for stews/stir frys and resist corrosion while the rest of the food was being prepared (~10 minutes) without rinsing or drying. Fallkniven does offer task specific kitchen knives, the K1 and K2, and the PP Series .

brush work

The U2 is basically a small gentlemans folder and thus not suitable for hacking, chopping and splitting. For general wood work this knife would do well to be complemented by a larger blade such as the A2 Wilderness knife , or NL1 Thor or a quality folding saw such as the Zeta Pocket saw . The U2 does however make a surberb choice for carving and shaping woods, the thin edge allows the knife to bite in deeply deftly removing waste woods, and at the same time there is no problem in making thin slices to fuel a starting fire, as well as scraping shavings for the initial tinder. Care needs to be taken when shaping wood into bowls and spoons as the point is very slender, so do more cutting instead of prying, or use other techinques such as burning the hollows with coals. The U2 was used to carve a large spoon (about 2 tbls) out of a piece of pine. It took 45 minutes to carve out the hollow and then shape the spoon. While the shaping when very quickly as the blade cut very well, making the hollow was a a laborious process because the tip could not pry/break out large piece of wood, so the surface had to be scored and then crosshatched to allow the wood to be removed. It was still faster than using fire to burn out a hollow however.

Miscellaneous

In general the very thin and acute edge on the U2 makes it a very efficient cutting tool and the thin blade stock allows it to cut even thick materials well like 3/8"+ cardboard. The steel also proved to be highly corrosion resistant, no protectant was used and the blade suffered no signs of corrosion.

Edge retention

1/8" ridged cardboard : with the edge set at 20 degrees with the medium rods on the Sharpmaker, the U2 and large Voyager from Cold Steel in AUS-8 were used through three centimeters of edge with cuts made on a 45 degree angle. Both knives had bee reground to primary edge angles of 10 degrees per side. Sharpness was measured by slicing 48 lbs hemp under 200 grams of tension initially and 500 grams of tension after blunting. Details :

Edge retention of the U2 on cardboard, using a slice over three centemeters of blade. Sharpness was checked by slicing 48 lbs hemp, large Voyager used as reference. Edges had a 20 degree microbevel, medium Spyderco Rods
Model
length of edge required to cut hemp (cm*100)
Initial  7.1 m 16.5 m 29.8 m 55.8 m 95.1 m
U2 63 (4) 38 (  5) 50 (  5) 68 (9)   83 (14) 110 (22)
Voyager 70 (5) 75 (11) 93 (11) 95 (7) 118 (11) 170 (  8)

The U2 has better edge retention which would be expected as its a harder and higher alloy steel. It also cuts through the cardboard easier as its much slimmer with a thinner edge and thus will actually outcut the Voyager (how much force is required to cut the cardboard) even if slightly blunter.

3/8" thick hemp was cut with both knives slicing the rope using two inches of edge with the cuts unsupported (no cutting board). Both knives had primary edges of 10 degrees per side. Sharpness was measured by slicing 42 lbs cotton under 200 and 500 grams of tension. Four rounds were made for the U2, six with the Voyager, to produce the following results :

Edge retention of the U2 and Voyager on 3/8 inch hemp using a slice over five centemeters of blade. Sharpness was checked by slicing 48 lbs cotton. Edges had a 20 degree microbevel, medium Spyderco Rods.
# of cuts Model
U2 Voyager U2 Voyager
200 grams 500 grams
0 35 (  5) 41 (   2) 
8 75 (  5)105 (  6)  
24125 ( 8)224 (  16)  
56185 (19)468 (  39) 39 (  3)   67 (  5)
120345 (27)725 (  87) 57 (  4) 121 (11)
248425 (27)928 (108) 84 (11) 175 (36)

The U2 outcut the Voyager by about a factor of 3-4. The sharpness was also checked during the last three runs by cutting the 42 lbs cotton under a higher amount of tension to see that the increase in aggression held under a higher tension.

Cutting two inch strips off of 2x3.5" pine lumber, the U2 and Voyager were also compared. The edges were set by the fine rods on the Sharpmaker at 20 degrees. Sharpness was determined by push cutting light thread.

Edge retention of the U2 on pine using a slice over five centemeters of blade. Sharpness was checked by push cutting fine thread, large Voyager used as reference. Edges had a 20 degree microbevel, fine Spyderco Rods
Model
force to cut thread (grams)
Initial 150 cuts 450 cuts
U2 91 (5) 112 (10) 175 (15)
Voyager 92 (5) 144 (12) 215 (15)

The initial sharpness was again identical and the U2 had better edge retention but didn't have the same level of advatage as it did on the cardboard which is to be expected as wood carving is more dependent on edge deformation than abrasive wear. Note the primary blade geometries are very different on these blades which allows the U2 to cut much more wood under a given force.

Ease of Sharpening

With the primary grind tapering to such a thin edge, the ease of sharpening of the U2 is greatly increased over knives with much larger edge bevels even if the steel is inherently more easily machined. Specifically, the edge was lowered from the initial factory setting to about ten degrees using a 200 grit silicon carbide in less than a couple of minutes.

Handle

The Zytel handle has an ergonomic shape with no sharp corners except the inside of the handle slabs could be rounded. The only problem is that since it is so small that it fits inside the hand and thus on heavy extended cutting it can generate a high pressure point against the bottom of the pinky. This is an issue more with handle length than overall design.

Lock

The U2 is a standard lock back which engages securely, readily passing "spine whack" tests, both light and fast and moderately hard. White knuckling can cause the lock to be depressed but only in two specific grips. The first is thumb along the back of the handle right above the lock release - an obvious one. The second grip has the blade held point up, with the edge towards the palm. If the middle finger can make secure contact with the lock release, in a heavy grip it can be disengaged. Neither of the two grips are common working ones however and thus these are not likely to be actual functional problems.

Overall

This is a very nice small gentlemans folder with a blend of traditional vs modern characteristics. The initial edge was a little too obtuse however since it is so thin it regrinds very quickly.

Comments and references

Comments can be emailed to cliffstamp[REMOVE]@cutleryscience.com.

More information can be obtained at the page on the U2 at the Fallkniven website.Comments can be seen here :


Last updated : 08 : 03 : 2005
Originally written: Aug 17 : 2004
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