Traditional Tanto by Running Dog knives


Specifications

This Traditional Tanto from Running Dog Knives was loaned for a review by Casey Butt. It is ground from 1/8" thick 15n20 stock. It is multipled tempered to 57-58 HRC . The knife has the American Tanto geometry and "The Running Dog Asymmetrical Grind", a primary chisel grind with a v-ground edge bevel. Here is a shot :

Running Dog traditional tanto

It did not come with the cord, that was added to check the functionality of using the blade as a neck knife. Using a loop pulled through the single eyelet and then over the sheath, the sheath stays flat and it is thin enough so that it does not print significantly.

The knife shows high attention to detail, every edge is rounded which increases ergonomics and overall durability. The cord-wrap is neat, inline and very tight. The overall geometry creates an efficient cutting profile with the edge being thin and ground at an acute angle and the primary grind high on thin stock.

The Concealex sheath is well finished with no loose bits or rough surfaces and holds the blade securely without being so tight that the draw is impaired. The sheath is also made in by a fold over pattern with smooth contours which has a higher durability than two piece designs with just a top contour.

Initial impressions

To get a rough estimate of its relative abilities, the Traditional Tanto was first compared to to a custom utility knife by Mel Sorg which was made from 3/32" thick D2, and has a full flat grind down to less than 0.02" behind the edge, with an acute bevel of less than 15 degrees.

The blades were used side by sides for a variety of light cutting work, including thick cardboard, dense vegetables, wood, cordage, meats, and fabrics. The Mel Sorg custom sets a high standard for cutting efficiency and the Traditional Tanto from Running Dog knives could cut along side the Mel Sorg custom and was not outclassed.

Some of the cutting performed was on very hard old wood which was so brittle that it tended to fracture when cut. After about 100 or so cuts there was some rolling on the edge of the Traditional Tanto however the edge on the D2 blade was still crisp as is it significantly harder. The drawback of the greater hardness is brittleness and low ductility. The edge on the Tanto was easily restored to 100% using a fine steel.

Throughout the work the handle was confortable and secure, no slippage even when working with a lightly compromised grip, light oil/soap + lots of sweat. Diamondwrap grips however can be abrasive to some, how much obviously depends on the individual.

In regards to corrosion, 15n20 will take a patina very rapidly if exposed to say fruit acids, this is so fast for example that when using the Tanto to slice sections off of an apple, the patina will form visibly in the few minutes it takes to eat the apple.

Compared to the Sub-Sniper

To get some quantitative information on the performance, the the Traditional Tanto was compared to the Sub-Sniper from Lynn Griffith.

cutting ability and edge retention

Both blades were sharpened on an x-coarse diamond DMT hone and finished with a couple of strokes on a 600 grit DMT diamond rod. They both have straight primary edges 5.0 cm long. The upper Tanto edge of the Running Dog knife was not used during any of the cutting so as to keep the work on an equal level. Here is shot of both blades :

Sub Sniper and Running Dog
Tanto

As a measure of sharpness, 1/4" poly rope was cut under 700 g of tension, recording the number of slices needed with fractional estimates made from divisions marked on the blades. Twelve cuts were made and the median taken used for a robust performance indicator. For the cutting stock, points were carved on pieces of scrap wood. The wood varied from about one half to two inches in thickness and from one to three inches in width. The wood had been outside for about a year, and in use for far longer than that. Most was pine but a few pieces were harder stock. Some was also covered in dirt which was wiped off but not washed clean.

Through the first cutting twenty pieces of wood were cut taking 120 and 110 cuts for the Traditional Tanto and the Sub-Sniper respectively. The second session saw 60 points took 410 and 405 slices, respectively. The last session went through 34 pieces of scrap taking 919 cuts for the Traditional Tanto and 927 for the Sub-Sniper. During the cutting grips was alternated to insure that the blades would wear on both sides of the bevel. Frequent rests were taken to eliminate fatigue.

Edge retention of the Running Dog Traditional Tanto and Sub-Sniper from Lynn Griffith while whittling woods
Model Edge angle Bevel width Slices of wood made
degrees inches Zero 110-120 515-530 1442-1449
Sub-Sniper 9-11 0.134 0.45 (4) 0.36 (4) 0.58 (3) 0.75 (3)
Tanto 11-13 0.045 0.40 (3) 0.70 (3) 0.70 (2) 0.90 (4)

It is clear that the Sub-Sniper has the better edge retention, as its performance on the poly is constantly ahead of the Traditional Tanto. This would be expected on light duty cutting as the steel in the Sub-Sniper is harder and more abrasion resistant. For interpretation, here is the above table in a simple plot. The circles are the Sub-Sniper and the plus signs the Traditional Tanto :

Edge retention plot

Note clearly that trying to put a single number on the performance is not trival as the blunting is not linear. At the end the blades are quite close in sharpness, just difference by about ten percent. However looking back at the history of the cutting, the Sub-Sniper shows a blunting at the end which was equal to the loss of aggression suffered quite early on with the Traditional Tanto. The biggest problem was that the sharpness was not measured frequently enough so it is hard to make some concrete numerical statements.

Of course that edge retention on slicing wood doesn't translate directly to edge retention on all materials. Wood isn't abrasive and the blunting here is mostly deformation and mainly influenced by hardness. Edge retention can also be influenced by wear resistance, corrosion resistance, impact toughness and ductility depending on what types of materials were being cut. In some of these aspects the 15n20 steel in the Traditional Tanto by Running Dog knives would have a large advantage as it is much tougher than the stainless ATS-34 steel in the Sub-Sniper.

UPDATE : this was one of the first extended edge retention comparisons performed which had multiple checks for sharpness. It clearly shows the nonlinear behavior and the complexity of comparing edge retention. More recent work with more frequent comparisons show that the onset of blunting follows a smooth exponential decrease.

Sharpening

After the wood cutting both blades were cutting at a significantly reduced rate, at about 50% of their freshly sharpened abilities. This blunting was also evident in the wood cutting as there was fraying of the wood fibers. The knives were cleaned and then stropped them on a canvas strop loaded with some non-abrasive wax strictly for alignment which was furthered with ten strokes per side on a smooth steel. The honing was finished with two passes per side on a 600 grit DMT rod. At each stage of the honing the sharpness was tested on the poly as in the above. The results :

Edge restoration via a strop, steel and a DMT rod
Model Initial Blunted Strop Steel DMT rod
Sub-Sniper 0.45 (4) 0.75 (3) 0.60 (4) 0.40 (2) 0.25 (2)
Tanto 0.40 (3) 0.90 (4) 0.45 (3) 0.35 (4) 0.30 (2)

In short both blades require just a couple of minutes of work to return to full sharpness with the Traditional Tanto responding stronger to the alignment work which would be expected as the steel is softer. At the end the blades are performing better than they were initially because the initial very coarse finish of the waterstone used to shape the bevels probably left them quite rough and created extra drag through the rope.

Cutting ability

The amount of slices that are required to point each stake can be used to determine a relative performance ranking of the two blades on push cutting wood (which is in general very indicative of how they cut solid materials). The following table lists the median performance of the cutting ability of the Running Dog Tanto as compared to the Sub-Sniper over the range of work described in the above :

Number of slices to point a small stake
Model Edge angle Bevel width First session Second session Third session
Sub-Sniper 9-11 0.134" 100 100 95 (3)
Tanto 11-13 0.045" 93 (3) 96 (4) 100

No significant difference. Though the Sub-Sniper's edge bevel is a more acute which enhances its cutting ability it is also thicker which acts to reduces it. Both blades have near identical flat primary bevels, ground at about 7-8 degrees. A histogram combining the results of all the 1500 cuts shows the performance ratio (Sub-Sniper to Traditional Tanto) is grouped strongly around 1 (median is 1.00 +/- 0.04), again showing that the two blades push cut through wood at identical levels.

Histogram of Running Tog Tanto
	vs Sub Sniper cutting performance

There had been significant modifications to the profile of the Sub-Sniper. The edge angle was lower which improved the cutting ability by 2:1 compared to its origional profile. For more details see : Review : Sub-Sniper.

Handle ergonomics and security

The cord-wrap grip is very tight and showed no sign of deformation under prolonged use. It is stable in hand and is not significantly effected by water or sweat. Cord wraps under heavy pressure do generate high pressure points in your hand when using them, so it may take awhile for you do adapt to the grip.

A concern with partial grips is that the end of the handle is inside the hand. On really heavy cuts there will be a lot of pressure applied to the contact point under the very end of the grip as this is what generates the counter torque necessary to push the blade through the material being cut. For a full length handle the contact pressure is much lower as the contact area is significantly greater.

Thus with partial grips it is easy to exert enough pressure on the contact point so as to damage the skin and create a blister. This is influenced by the shape and texture as well. When the Traditional Tanto was used alongside the Mel Sorg D2 blade on wood, after 200 cuts with each knife done rapidly at full force with little rest, a blister had formed right at the contact point of the end of the grip on the Traditional Tanto.

Problems such as this can be eliminated or at lest reduced in severity with use of frequent rests. During the wood whittling doing to it with the Sub-Sniper and Traditional Tanto no excess uncomfort was induced even during the the last session which was over 900 cuts due to the frequent breaks in the cutting.

Ease of carry

Worn mainly as a neck knife it worked well due to the low weight and relatively slim package. With really tight clothes, it will print too readily, at its thickest spot (where the sheath comes over the top of the grip) it is about 3/4" thick . The critical factor with most neck knives is how much grip ergonomics and stability are traded for a lower "print" during concealed neck carry.

Blade geometry aspects

The edge of the Sub-Sniper starts a lot closer to the position of your index finger than on the Running Dog Traditional Tanto when the blade is held in a hammer grip due to the more significant guard on the Traditional Tanto. This guard gives much greater grip security,and can easily do even very hard stab for example, even with a compromised grip, however there is a tradeoff in regards to cutting ability due to a decrease in leverage.

One other thing in regards to ergonomics, for a lot of precise draw cuts a grip which places the index finger hooked over the spine can be used with cut made by simply rolling the fingers down or torquing the wrist towards the inside of your elbow. This grip is used a lot for shaping wood for example, but a similar grip can be used for a lot of light cutting. When using this grip it is necessary not only to have a well rounded spine, but as well as strongly curved spine. The Sub-Sniper, with the full curved spine is much more comfortable to use in this manner than the Traditional Tanto with its flat spine.

As for general cutting ability, this blade already performs very well. The primary grind could be extended a little higher, but only by a small margin, and this would only effect performance slightly (a few percent) and even then only on really deep cuts (thick cardboard). The only major change would be to offer a thinner edge profile. The blade is ground to 0.02" behind the edge and this can be as low as 0.01" for a light utility knife (see blades by David Boye, Phil Wilson etc.).

A thinner edge will result in an edge which is narrower at a given angle and thus sharpen much faster and cut significantly better. It is critical however to note that with the edge this narrow and the blade so thin behind it, hard contact are much more likely to see damage extensive enough to effect the primary grind.

Comments and references

Comments can be sent to : cliffstamp[REMOVE]@cutleryscience.com or by posting in the following thread on Bladeforums :

Running Dog Knives was a partnership between Mike Murphy and Darrell Guthrie, to present knowledge they are no longer in business.


Last updated : 02 : 15 : 2006
Originally written : May 17 2001
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