SOG SEAL 2000

A shot of the SOG 2000 (top) and MPK from Mission knives :

Specifications

The SOG SEAL 2000 was basically donated by Eric Ridley for a review. It is made by stock removal from quarter inch thick 440A stainless steel, uniformly hardened to 56-58 RC. The blade is 1.25" wide and weighs 345 g. It has a sabre-flat primary grind ground at ten degrees per side. The tip has a distal taper of 2.8 degrees per side and the clip presents a slim profile. The edge ranges from 0.047" to 0.055" thick behind the bevel which is ground at 26 +/- 1 degrees. The serrations are chisel ground at about 20 degrees included.

Battle of the Navy Seals

The SOG SEAL 2000 is one of the many blades promoted as being used by the Navy Seals. Having another of such blades on hand, the MPK-Ti from Mission knives, a comparison of the two was made. The MPK-TI is also made from 1/4" stock but being Titanium is much lighter at only 250 g. The primary grind is full flat and only 3.5 +/- 0.3 degrees per side . The edge ranges from 0.030" to 0.032" thick behind the bevel which is ground at 20 +/- 1 degrees per side. The serrations are chisel ground at approximately 15 degrees included.

new in box sharpness

On the primary edge the SOG scores 275 +/- 34 g on thread, on 1/4" poly under a 1000 g load it can not make a cut, under a 1500 g load, a cut requires 1.62 +/- 0.09 centimeters of edge. The serrations on the SOG just bust the thread (650 - 750 g). On the primary edge the MPK-Ti cuts the thread with 200 +/- 14 g of force. It takes 2.15 +/- 0.27 centimeters of edge to make a cut on 1/4" poly under a 1000 g load. The serrations on the MPK-Ti cut the thread with 305 +/- 6 g .

The SOG SEAL only shaves smoothly near the tip. Examining the edge under magnification it is over buffed, the same problem as seen with the Recondo. Using just blade weight the primary edge just scores the poly after 50 passes back and forth. The serrations are very rough showing multiple 0.1-0.2 mm areas of damage under magnification, they look ground but not polished. They cut through the poly under blade weight only needing 10 passes.

On the MPK-Ti, the serrations are much less finished than the plain edge and under magnification irregularities are visible similar to what is seen on the SOG, however they are larger, from 0.2 to 0.3 mm deep. The serrations can't be pulled across the poly when it is under 1000 g of tension. If I attempt to pull the blade it just digs in and then violently rips the cord suddenly.

In short, NIB, the MPK-Ti is much sharper in both regards to push cutting and slicing. The primary edge is about 40% sharper than the SOG and the serrations more than double.

cutting ability on rope and wood

Push cutting on 3/8" hard poly using a hard rocking cut, the SOG SEAL takes 77 +/- 6 lbs of force and the MPK-TI only 51 +/- 3. Thus relative to the MPK-Ti, the performance of the SOG is only 65 +/- 3 %. This greater performance of the MPK is mainly due to both a higher primary grind a thinner and more acutely ground edge bevel, plus a more enhanced belly.

Whittling points on one inch hardwood dowel (basswood) with a one inch slice, the MPK took 34-38 slices, The SOG however took 72-84 slices, putting it at 47 +/- 5% of the performance of the MPK for similar reasons it was behind on the rope cutting. Around 45 lbs of force was used during the cutting.

Both blades had a leverage disadvantage while whittling because the cutting was done so far out on the blade. A choked up grip was not used as both had squarish upper guards which generate high pressure points. If the plain edges extended right back and the cutting was performed right in front of the handle, the MPK would be about ~24 lbs and the SOG ~46lbs .

Both edges were shaving sharp before the dowel cutting however would not even scrape shave after. Blunting was just due to rolling, a couple of passes on a steel and they would shave again.

chopping

Neither blade chops well as both are close to neutral balanced. With a two fingered grip around the edge of the handle in order to get some power, and a quick snap, the SOG SEAL has 85 +/- 9 % of the ability of the MPK-Ti. The MPK-Ti has a slight advantage, but not a horrible significant one. However, considering the MPK-TI is 260 g and the SOG 345, when the performance is normalized to weight, the SOG SEAL has 64 +/- 7% of the chopping ability of the MPK-Ti. This again shows the much more efficient cutting geometry of the MPK-Ti. This rank also reflects well the rope cutting performance which you would expect when the mass difference has been removed as they are then both just push cuts through semi-elastic material.

edge retention of the straight edge

On the primary edge, both blades were ran through cutting trials on 3/8" hemp rope . The cuts were slices over two inches of edge. Four trials were ran with each blade, including a fresh sharpening each time which ended with a 600 grit DMT rod. In short, after fourteen cuts of the rope both edges had degraded to the point where they would not slice paper. No significant difference in edge retention was noted. However due to the much higher cutting ability of the MPK you could still cut the rope far easier. Specifically MPK started needing 32-34 lbs and finished at 41-42 lbs. The SOG started at 41-42 lbs and at the end needed more than 50 lbs. Both sharpened with equal speed, the Ti blade tended however to gum up the hones. Details for the SOG SEAL :

cutting ability and edge retention of the serrations

The MPK-Ti's two inches of waved serrations started off only needing 16-18 lbs to cut through the 3/8" hemp. After 254 cuts the performance had only decreased to the point that the blade now took 18-21 lbs to cut through the hemp. Another 256 cuts were done on used and dirty 3/8" poly. This finally significant blunted the blade so it took 31-33 lbs to cut through the hemp. Checking the edge under magnification, only the tops of the serrations are worn and folded over. They protected the scalloped edges which do most of the cutting from grinding through the dirt left behind on the cutting block from the used poly. A few passes on a grooved steel and the serrations are back to cutting the hemp with 21-23 lbs.

The serration pattern of the SOG were poor on rope. The one and a half inches of serrations are pointier and more shallow. With over 55 lbs of force applied, not even one clean cut could be made through the 3/8" hemp. The rope had to be basically ripped apart. Cutting on a block, the points have to be driven deep into the wood to allow the scallops to contact the rope. On the MPK-Ti's serration pattern, the tops will actually do cutting. When the block was removed and the rope cut under tension, the MPK would outperform the SOG about four times to one in regards to the number of passes required under heavy force. The MPK would constantly cut through the poly requiring less than one inch of serrations while the SOG would require ~4 complete passes.

The serrations were then used on many types of fabric, old jackets, jeans, sweat shirts, as well as various belts and webbing. The MPK would constantly outperform the SOG many times to one. The only material that favored the SOG serrations was material that was weak that it would be readily torn apart. Cutting up some rubber tubing the SOG had an advantage over the MPK, about 25%. On wood, the SOG bites in a little deeper, but the MPK requires less force to be pushed through, neither had a significant advantage as a wood saw.

Note that there is a really large difference in the points of the serrations. Unlike the teeth in the serrations on the MPK-Ti, the SOG's are not fully ground by the pattern. The scallops intersect, they don't actually overlap like they do on the MPK-Ti. Thus the teeth on the SOG have very obtuse points ground at ~35-37 degrees.

In short, the cutting ability of the MPK-Ti serrations is more efficient than the SOG pattern by many times to one, and shows much greater edge retention.

primary edge durability

Both primary edges were durable enough to split 1-2 year old knotty seasoned pine and spruce. The force of the impacts was that large that the baton (a 2" piece of spruce) would be destroyed every few pieces of wood split.

serration durability

A dozen pieces of very knotty, 1-3" thick, and one to two year seasoned, Pine, Spruce and Fir stick were split into quarters. A two inch thick piece of Spruce, sixteen inches long was used as a mallet and the blades were hit with full force, which was enough to destroy the mallet at the end of the splitting. The SOG serrations were not visibly effected out side of a slight burr. Repeating the same work with the MPK-Ti induced visible deformations. Specifically there were seven places of visible damage, dents were from 1/4 to 1/3 a mm deep, except for one which was 1/2" deep. The deformations were 1-2 mm in length. A few passes on a grooved steel to reform the serrations and the MPK-Ti is back to 26-28 lbs on then 3/8" hemp on the cutting block. Even before the alignment, it was still out slicing the SOG. Thus even though the SOG resisted the damage better, since the cutting ability is so low, the MPK still out cut it.

As an extremely abusive task steel threaded tubing (two inches thick) was cut. Even with very high forces applied (more than 75 lbs), both knives could only score the tubing after a dozen passes, neither could cut through more than a few pieces of wire, the SOG doing better than the MPK. However while the SOG tips were just blunted, the MPK-TI serration pattern was completely worn flat. Trying out the blades on some 5/16" poly, the SOG now clearly had the advantage, taking only ~3 passes to cut through the poly, while the MPK, with little aggression remaining, required from 10-12. Fixing both patterns required a simple filing on the back to reform the teeth as well as some work with a 600 grit DMT rod in the scallops. Both blades would now cut the 5/16" poly in less than one slice. The MPK was more aggressive on the 3/8" hemp on the cutting board, it would cut through it requiring 41-43 lbs, the SOG needed 62-68 lbs.

point penetration and durability

On a vertical stab into a phone book, the SEAL was comfortable in the stab and penetrated well. The MPK had penetration close to the SOG but suffered from a too square upper guard. Without enough radius, the pressure was high and thus not comfortable, which reduced its penetration significantly. The MPK-TI achieved an average penetration of 656 +/- 27 pages, and the SOG SEAL SOG SEAL an average of 707 +/- 7 pages. Thus the SOG has a slight advantage. However this is simply due to its greater weight, if this is factored out, the performance is 71% of the ability of the MPK-Ti.

Holes were dug in in 2x4's large enough to fit the index and middle finger through. The board would be dug half way into, flipped over and the hole completed. The stabs would be hard getting 1/2"+ penetration, and the prying to the side at done with maximum force. Both the time it took to make the cuts as well as the number of stabs needed were used as measures of performance. Over an average of three runs the MPK-TI took 39 +/- 13 stabs through 4.1 +/- 1.6 minutes. An average of two runs had the SOG SEAL requiring 46 +/- 5 stabs through 3.8 +/- 0.7 minutes.

Through the digging, the MPK's point gave better leverage as the SOG's tended to pop out more because of its diamond-like cross section. After the trials both tips had suffered visible damage. The tip of the SOG suffered a bend of about five degrees running back 1.2 centimeters. In addition the very last mm of tip was bent over 45 degrees to the side. The MPK suffered a smaller bend, under three degrees running back about two centimeters. Both major bends were corrected with prying in the reverse direction. The large bend in the extreme of the SOG tip had to be filed off.

In regards to efficiency, there is no clear advantage. However as with other aspects of performance once the weight of the SOG is taken into account, the MPK-Ti is shown to be clearly ahead with a much more efficient profile. The MPK-Ti was also shown to be more durable.

corrosion resistance

After the hemp cutting the edge aggression was checked on the poly and it was about five centimeters near the base in front of the serrations but the rest of the blade needed eight centimeters. Basically the corrosion set inversely proportional to the distance from the tip which makes sense since that part was resting in the salt water solution directly. The dependence of the edge degradation on edge position was consistent with the visible rust evident on the blade. Near the tip the entire edge was covered in a light brown sort of fog. Moving back along the blade the rust was contained to just spotting. The majority of the spots were from 0.5 to one millimeter across, there were ~100 of them on the right side of the blade, only about 25 on the left. The blade had also corroded along the flats on the areas where the coating had been removed from previous cutting.

The MPK-Ti is unaffected by longer soaks in saltier environments.

handle ergonomics and security

The SOG grip is square and slippery where smooth and aggressive when checkered. Nothing great in the ergonomics or security department, however no real problems were noted with the above work. The MPK has a nice texture, not slippery but not abrasive, the grooves help as well. The shape is a huge improvement over the SOG. The only problems are the lack of a radius in a few key areas. Overall the grip on the MPK is more ergonomic and secure. The grip on the SOG is also limited in versatility due to the dual front guard.

handle durability

A wooden match was let burn out beneath both grips, with the flame just touching the handle material. The SOG grip smoked immediately, but didn't melt nor burn. Lots of blackening and a very aggressive dimpling pattern resulted, which interestingly enough feels very good in hand. With another lit match applied on the checkering part it suffered more damage of a similar type but still still didn't catch fire. When exposed to the lit match, the MPK's grip didn't smoke as much, nor did it melt nor catch fire. The handle also took a more aggressive texture and blackened. Grabbing the handle right after the flame burnt out was possible indicating a very low thermal conductivity, which you would expect the SOG grip was the same in that regard.

sheaths

The SOG SEAL 2000 sheath was Kydex, on par with other production Kydex sheaths. The MPK-Ti was an evaluation piece, no sheath came with it.

overview

For a quick visual overview of the two blades, the following table summarizes the work done. Superior is used when the performance advantage is less than two to one, vastly superior when the advantage is greater, and similar when the difference is so small it takes care to notice (less than 25%).

In short, the SOG has only one advantage over the MPK-Ti which is that the edge is significantly harder. This higher hardness give the steel more impaction resistance and thus it can resist denting much greater. Thus when both knives are whacked into hard objects, the MPK-Ti will take a dent to a greater depth.

Modifications

The main reason the cutting and chopping ability was so low on the SOG SEAL was the edge geometry and primary grind were too obtuse. A belt sander was used to blend the edge into the primary grind and the height of the primary grind raised slightly. The upper guard on the handle was also removed to aid in grip versatility. As the steel is easy to grind it was a quick modifictaion even though a lot of material had to be removed. A shot of the modified SOG SEAL 2000 along with two MPK's from Mission, one in Ti and another in A2 :

Specifics of the new profile :

With the new edge profile the cutting ability of the SOG SEAL 2000 increased dramatically. Now the blade only needed 46 +/- 1 lbs to cut the 3/8" hemp compared to 80 +/- 4 lbs with the stock profile. The wood whittling performance was increased even more to 6.5 +/- 0.5 slices to point a stake, compared to 77 cuts before. The performance in this areas was also enhanced by the greater grip versatility and the increase in leverage due to the serrations being removed so the cutting could be performed closer to the handle.

With the edge left at the belt finish (100 grit AO), the slicing ability of the SOG SEAL 2000 on hemp rope was dramatically increased as was the edge retention. Before the SOG started at 41-42 lbs and could only make about 14 cuts before the force exceed 50 lbs. With the new profile and aggressive edge finish the blade started out taking only 12 lbs to make a slice and after 510 cuts, needed about 20 lbs. Thus now, after making more than 500 cuts through the hemp, the blade is still cutting twice as well as it started with the initial profile.

The SOG Seal blade held up heavy chopping and wood splitting using a wooden mallet to cleave apart some knotty and seasoned woods with the new edge profile. However it would take damage more readily in contact with rocks, steel and other hard materials. However it did not fare well on an attempt to cut through a tension bar. An Estwing framing hammer was used as a mallet and the SOG cracked in half after just a couple of hits :

The MPK-Ti could not cut through the bar as the edge was too soft and just readily indented. However, the MPK-Ti did not suffer gross blade failure from the hammer hits, and more than a dozen were used.

Overall

The SOG is readily outclassed by the MPK-Ti, however the Mission knife is significantly more expensive and an argument could be made that a performance scaled by price would be favorable to the SOG. However Mission also makes the MPK in A2 which is significantly cheaper and has improved edge retention, significantly more chopping ability and a similar hardness as the SOG. The Fallkniven A1 is also a significantly superior knife.

Comments and references

Comments can be sent to : cliffstamp[REMOVE]@cutleryscience.com or posted to :

• SOG SEAL 2000