This is a custom utility knife made by Alvin Johnston, a shot :
It is made from O1 hardened to 63.5 HRC. The knife is 0.055" thick, 0.75" wide and 4.8" long. The edge is 0.012-0.014" thick, ground at 5.6 +/- 0.2 degrees. At 0.25" back from the edge the knife is 0.020" thick. There is a distal taper of 2" long forming the point.
According to the maker :
Heat at austenizing temperature for 5 minutes. I watch for the shadow in the unaustenized portion caused by the arrest point. Quench in 120øF quenching oil. Cool to -5øF for 1/2 hour. Temper at 212øF (boiling water) for 15 - 30 minutes. Cool to -5øF for 1/2 hour. Draw at 340øF for 1 hour.
The cold treatments + boiling water tempers are to maximize transformation to martensite. The tempering temperature was chosen to meet the peak torsional toughness which also gives a very high torsional strength.
With the new in box edge the utility knife cut ropes extremely well, it push cut 3/8" hemp with 11.0 (5) lbs with enough slicing aggression to reduce the force required down to 8.0 (5) lbs.
After the stock testing the blade was used in a variety of ways to get a feel for its scope of work, round out the stock testing profile and examine aspects of long term use. Before the EDC rotation of the knife begain the edge profile was adjusted down to the minimum of under 3 degrees per side by grinding the entire blade flat to a stone. Unless otherwise noted this was the angle with which the following cutting was performed.
The utility knife is a medium length kitchen knife designed mainly for slicing, it excells at cutting meats, the very thin blade and acute edge profile glides through with almost no resistance :
It also works very well as a paring knife, being narrow and with a very acute profile :
It doesn't have the dropped blade profile necessary for chopping style cutting on a cutting board but can handle the necessary tasks using a different grip and more of a draw/slice instead of a chop using a pinch grip :
and can be used on smaller vegetables easily :
and the thin cross section allows it to work very well on thick vegetables, easily slicing up turnips :
and easily cutting up fresh homemade breads :
While the edge on the utlity knife is very thin and acute, since the steel is very strong and the heat treatment maximizes the torsional toughness the blade can be used for meat work including fairly sloppy disjointing work on poultry :
Note the cuts through the bones :
It isn't actually necessary to make those cuts, the bones can just be cut through the joints, this was done just as a check on edge durabilty. During the chicken cutting the edge has a slight secondary bevel of about 5-6 degrees per side.
The only downside for kitchen work is that O1 will rust readily when left wet, especially if exposed to salts or acidic juices, rinse and dry the knife after use.
In terms of utility knives in general, there is another style, commonly used by the Japanese, the one on the bottom in the following picture :
This style is much more suited for chopping and dicing than the above O1 utility, it is the optimal design for such. However it loses a lot of versatility and is extremely awkward for peeling and similar chores for example. There are also other designs which fall inbetween those two types such as :
Which is from Spyderco and doesn't have as much blade drop as the Japanese knife but has more drop than the O1 utility and thus it won't dice/chop as effectively as the Japanese utility and won't peel as well as the O1 utility, but does better than either at the opposite.
Which knife is best depends on what else is available in the kitchen. A small paring knife and the Japanese utility or a small Chef's knife and the O1 utility make very effective combinations. The Spyderco is very nice to have as a one-knife solution to a large variety of work.
While not strictly designed to do so, the utility knife can be used for a large variety of bushcraft on all manner of vegetation.
Grasses and light brush are usually easily just pulled or ripped up by hand, however even a medium sized blade makes the process much faster and cleaner cuts are beneficial for braiding for cordage.
Cutting light grass and soft vegetation isn't very demanding, a cheap machete will do it all day long and it pretty much the optimal design. The only real requirement is that the edge be very sharp, to reduce the need for a draw.
When using a knife designed like this one, the critical concern is overgrowth, if a forceful cut brought the edge into a forceful contact with a rock hidden by the grass major damage would be induced on the knife.
There are a couple of ways to avoid this, simple foots sweeps before cutting, or the use of a stout pole.
The utility knife readily carves up wood, easily making both small shallow slices for fine tinder and making deep cuts to rough out stock and provide second stage tinder. The work doesn't need to be limited to soft woods either, it easily cuts up hardwood birch flooring :
With the sharpening brought down to the full primary grind, the edge turned slightly to the side during the cutting. The cutting was repeated with the edge at ~4.5 degrees per side and the damage was much reduced and limited to just a couple of patches on the edge where the cuts twisted a little [ref].
The paring knife work very well cutting ropes, cardboard and other materials, it has a very slim profile which gives it high cutting ability and since the blade is very short it has high control :
It is also capable of cutting much harder materials, and there isn't anything that it really won't be used to cut including old dirty carpet, and it easily takes apart an old boot :
In order to push the limits of the blade the knife was used to cut some thick plastics. It easily sliced up a bottle of dishwashing detergnt :
and then a 500 ml coke bottle, then a one litre :
However on a cut through the bottom of a 2 L bottle of coke the plastic twisted and the edge cracked. This removed a chip which was about 0.04" deep, note the edge was 0.005" thick (yes five thousands) at the point where it cracked. This is the only real weakness of the blade cutting wise, it can not take significant torques due to the very thin cross section so care must be taken to not twist the blade when it is in a fairly rigid media.
The knife is sharpened with use of the Sharpmaker to create a tiny microbevel with just a couple of passes per side. This however is not taking full advantage of the ability of the steel which is realized with a lower bevel angle. The knife was typically sharpened on a series of waterstones, often ending on a natural chinese waterstone + CrO loaded leather.
The ease of of sharpening is enhanced by the ability of the edge to resist damage when cutting due to the high strength and torsional toughness and thus even after challenging tasks very little work needs to be done to restore optimal sharpness. A further benefit to the above described heat treatment is that it provides a very fine grain and an edge which has little tendancy to form a burr.
Note however that the machinability of the steel is very low, the modification of reducing the edge from ~5 to ~2 degrees per side took quite some time even on a coarse SiC waterstone. It took about fifteen minutes and a lot of pressure. However once this modification was complete, keeping the knife sharp takes little time as noted.
The knife was used on a variety of materials both qualitatively and quantitatively to examine edge retention.
The O1 utility knife was compared to a small Sebenza in S30V. Three trials were ran cutting 1/8" ridged cardboard, on a slice through two centimeters of blade, edge retention was checked slicing light cord under set tension after a short interval (15 m) and a longer one (35 m).
As the Sebenza's steel is much softer, a micro bevel of 20 degrees per side was used, this is far more obtuse than necessary for the O1 blade, however the goal here was to reduce the effect of hardness and focus the comparion on the relative wear resistance of the two blades.
The first round had both edges recut to a primary edge angle of 3-5 degrees per side, with a light microbevel applied with the Sharpmaker medium and then finishing on the fine Spyderco rods. The micro bevel was barely visible, less than 0.05 mm wide when checked under magnification.
After the first short round the Sebenza was half as sharp as the O1 blade. Under mag and the entire microbevel had cracked off in certain sections. While the edge angle was high enough for strength, the underlying primary edge left it too thin and the steel just wasn't strong enough to keep it intact.
For the next run the micro-bevel was honed to a wider grind, 0.1 mm wide. After the short interval both blades were similar, however after the long interval the Sebenza was again well behind and again sections of the edge were just broke away, enough to be seen by eye.
This has a massive effect on resharpening obviously, the Sebenza doesn't respond to a smooth steel with the edge broken off, and it takes much more honing as you have to regrind the entire edge, about 10:1 in favor of the O1 blade.
For the final trial, the micro-bevel was increased to just over 0.15 mm wide. The O1 blade was also not optimally sharpened, only about 75% of optimal but the cutting was ran anyway as the main interest was on the integriety of the edge on the Sebenza.
Again both held well in the short interval and after the long interval the O1 was still ahead, less than 25 percent and again the Sebenza's edge had cracked in a few places, but less than before.
Of course if the cutting continued, the blades would move apart with the O1 increasing the performance gap as once an edge starts cracking the strain increases there and it continues cracking faster. Note again the O1 had a less than optimal edge, so with a proper sharpening it would have been ahead even more.
The O1 utility knife was used to cut used carpet alongside several other knives, custom and production, in general it did very well, in both cutting ability, edge retention and ease of sharpening : ref.
The grip is ideal for a small utility knife, comfortable in a variety of grips, not specific to any. As a general use grip it has limitations, mainly low security, but as noted this is mainly a kitchen utility knife, though the blade would work very well as a general utility knife with a more secure grip. The retention can be enhanced with grip tape, just be aware of the limitations of a knife with no guard.
Comments can be emailed using cliffstamp[REMOVE]@cutleryscience.com or by posting in the following thread on Bladeforums :
More information on the makers knives can be obtained at
Alvin's Knife Website. He can also
be found on rec.knives.
| Last updated : | 12 :01 : 2005 |
| Originally written: | 11 : 18 : 2005 |