SureFire Delta


Knives :

This review consists of :

Introduction and Specifications

The Delta is a discontinued knife from SureFire. A basic description from Blade HQ :

Surefire Delta Folding Utility Knife (3.37" Stonewash Plain) EW-04

The Delta folding model is a rugged but lightweight combat/utility knife. Its superb fighting capability is maximized by its Crucible CPM-S30V blade steel, renowned for strength and edge retention, and by its brutally tough 1/8"-thick titanium frame halves with frame lock.

The frame incorporates a number of practical tools—screwdriver, wire cutter/crimper, parachute cord/seatbelt cutter, wrench, and self-seating wrench slot for smaller nuts, and also features a reversible pocket clip. Whether you're heading into battle or into work, you'll find the Delta folder an indispensable companion.

Specifications:

This one is the knife as described in the video on the right by Mike Gavac who has given one of the more detailed commentaries on the blade seen. A few comments from a brief web and YT scan :

This one was modified :

Note that the extensive regrinding which :

Will act to dramatically increase :

A very short overview, mainly initial impressions :

Stock cutting

Care needs to be taken below as what follows is NOT indicative of the performance (in general) of a stock Delta but what it could become with a little work.

With the edge off of a 600 grit DMT, on 3/8" hemp :

On carving wood compared to the #1260 Mora the Delta easily matched it in light cutting and out cut it 2:1 when heavy force was applied showing the power of a high grind which terminates in a very thin and acute edge.

Utility

While the Delta works ok over a broad range of materials :

It is a fairly heavy and large blade with a wide profile and thus can not match the ability of blades which are not so over built / tactical / heavy duty in general. If all a blade was to do is cut such materials there are much better blades which will cut with less force and more control.

Field

The Delta makes a fairly powerful cutter for snap chops with :

It easily has enough power to chop small soft woods when put under tension and severe 1-2" sticks in just 1-2 hits. This is also far easier than doing press cuts or slices. On harder woods then chopping becomes ineffective and it is more effective to cross notch but that that point it is moving beyond what is the sensible scope of work for this blade and a small saw of fixed blade is starting to become a more sensible choice.

The biggest issue is the lock because it will readily flatten/deform under impacts and thus care has to be taken in attempting heavier work for an extended period of time. The ideal solution is to make a small wedge, use it to hold the lock open and not engaged and then the blade can be used to chisel cut thicker wood without concern for damaging the lock face against the tang.

As noted in the utility section, it isn't a knife designed for light cutting and it was used to remove some sods for a walk-way. It was one of the nicer knives used for such work as it had :

However it had a rather serious problem in that it took damage far too readily. Now the point would seem to be obvious - this is cutting sods and thus there is contact with :

This is true, however as noted in the video on the right it isn't that the Delta was damaged it was that comparison after comparison, it would significantly get damaged more than the other knives. Yet another point showing a problem with the steel. The Delta was used along side multiple other knives including :

It would be expected that an S30V blade would be more easy to damage than some of these steels but it should not be less durable than VG-10 and especially not S125V which was actually retired by Crucible due to problems with durability (and difficulty of working).

Grip

Ergonomics : as a quick check on ergonomics the Delta was used to make 500 slices into pine with medium force (20 to 40 lbs). The ergonomics were very strong for a folder. There were some areas of improvement but they were of the nature of moving from very good to excellent :

The grip is also very versatile and equally capable in hammer, sabre, reverse and ice-pick grips. However as noted in the sod cutting, when the force is ramped up to 50-70 lbs the holes and cut outs in the handle do start showing signs of obvious issues with comfort.

Security : the security is very high due to :

The only downside is that the handle is quite smooth and thus there is not friction/abrasion based indexing so in hard stabs/thrusts there will be hard contact off of the front flipper.

Durability : the handle is made from slabs of titanium so aside from being easily scratched the durability is extremely high.

Sharpening

The initial sharpening was very quick, a little took quick as 50 pps on the fine side of a cheap stone reset the edge to a full apex. This very high ease of sharpening was due to the very thin edge due to the regrind by Mike Gavac (gavko). However while the knife easily sliced newsprint it was a little rough and didn't shave very well. This indicated a lightly problem with either excessive burr formation or fracture. Most likely fracture due to how fast the edge formed an apex.

A quick check under magnification verified the edge was fracturing which of course removed material very fast and also the fractures do not leave as sharp an edge as the scratches cut by the abrasive. However cheap stones often can cause these types of problems as they often can not cut the very high carbide steels well due to the inability of the abrasive to effectively cut the carbides directly.

Attempting to refine the edge on a 600 grit DMT stone :

Now this knife had been :

so the edge could just be suffering from weakening due to chemical of physical stress or it could be a problem in the thermal processing by the manufacturer or both.

The image on the right shows an attempt to thin out the primary using a fine stone (similar to a Norton India or 1000 grit waterstone). It was not overly practical due to the very low grindability of the S30V steel. Over one thousand passes per side was used in an attempt to plane down the bevels but all it did essentially was scratch up the knife due to the very high carbide volume of the steel.

This method is commonly argued by Murray Carter however he generally works on very low carbide steels which are often cladded with very soft steels which are very easy to grind. Modern high carbide steels will resist this well even with much more coarse stone and even then will take cycles of multiple thousands of passes to plane down the primary bevel.

However after a lot of sharpening (dozens of sharpening after use) and the edge starts showing improvement. The image at the right shows the edge off a 600 DMT (25 micron) stone :

While improved the steel is still not behaving as would be expected based on ideal behavior of S30V and it never improved significantly beyond this point.

Edge Retention

A first run on cardboard did not show promising performance :

Fine DMT
Sharpness 15% 10% 5%
cardboard cut (m)
21 (3) 0.7 (0.2) 4.3(1.1) 29 (9)

This low level of edge retention which is on par with Class I steels (inexpensive made in China kitchen knives) likely shows defects as it is not in general the expected performance of the steel which also shows some odd behavior in general.

The edge wore smooth rather rapidly it did not have a corresponding high grindability and this contradiction is one of the signs of a problem with the processing of the steel as it is hard to abrade but goes dull fast on abrasive material. This is often caused by micro-fracturing leading to premature wear.

Sure enough, note the image at the right which shows how the edge is still fracturing and it not being formed cleanly by a 600 grit (14 micron) DMT stone. This did not improve even after it was attempted three times to apply a secondary bevel and then grind that off into a true micro-bevel.

After extended use and multiple sharpness sessions (dozens) the edge retention on cardboard did improve however the progress was slow and even after all of this work it would not move out of a Class II type steel and was obviously and significantly inferior to other S30V blades. This is most likely due to a combination of the acid wash, over heating by SureFire and possibly less than ideal thermal processing in general.

Fine DMT
Runs Sharpness 15% 10% 5%
cardboard cut (m)
4 58+ 3(17) 1.5+0.2(0.2) 5.5+0.8(0.9) 40+ 8( 9)

Overview

Overview :

Comments and references

Comments can be emailed to cliffstamp[REMOVE]@gmail.com or by posting to the following thread :

and/or the SureFire Delta YT Playlist.

Most of the pictures in the above are in the PhotoBucket album.


Last updated : 15/10/2013
Originally written: 15/05/2013
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