DiamondBlade - Friction Forged D2 : Alpha 1

Introduction

DiamondBlade was the first knife manufacturer to adapt friction stir processing to knife manufacturing. 1 Now what is friction stir processing?

The basic concept of friction stir processing is remarkably simple. A rotating tool with pin and shoulder is inserted in the material to be joined, and traversed along the line of interest [...] . The heating is localized and generated by friction between the tool and the work piece, with additional adiabatic heating from metal deformation.

In short, it is localized forced heating of the steel, which is used to replace, by Diamondblade, the traditional heat treatment of the steel. Because of the conbined very high heat, short exposure time, local deforamtion and very fast cooling the steel has a very fine grain structure, a high proportion of alloy dissolved and a very high hardness in the formed martensite. In particular DiamondBlade claims to produce 2 :

The knife for the passaround is the Alpha 1, a few details :

A few interesting things about this Alpha 2 :

In particular, the edge has no slicing aggression at all (the full weight of the blade won't break the skin). In regards to the damage, there are two dents, one about a cm long the other a few mm, the damage is about 1/50 mm deep at maximum.

In addition to the Alpha 1, a Dozier K2 was sent out for a point of reference, also made from D2, just with a traditional hardening.

Results

From OldSpice :

I need to remove the heart, lungs, and important blood vessels from the thoracic cavity of a cat. I needed to cut through and remove a variety of tissue including the ribcage. The control was a standard disposable scalpel, #10.

Unfortunately the Alpha and Dozier performed poorly lacking the precision needed. Not only that but the thickness of their edge and blade required so much more pressure then the disposable scalpel it was possible to damage the specimen while trying to cut make cuts with either knife. The scalpel is more then capable of cutting through the ribcage and maintaining its sharpness. However the Alpha and Dozier required far to much force and would of damaged the organs chosen for preservation. The only tasks the Alpha and Dozier performed well at was scraping epithelial tissue away. While scalpels are often over used or dull a fresh one is still the better choice for precision cutting. [...]

I used both the Alpha and Dozier around the house to get a final feel for each knife. The Alpha has higher initial sharpness however its thick stock and obtuse edge really hurt its ability to cut through materials. I found myself preferring the Dozier over it as it seems to saw through most of the soft stuff you find at home just fine for quite a while. I really liked it for as a steak knife it seems to do really well there. I think D2 as prepared by Dozier would make a good kitchen knife for the average person.

The Alpha's small size is burdened by an extreme stock thickness and very thick edge. If that is necessary for the friction stirring to be applied it really makes me question if the technique is worth while for a knife.

I used a jig that holds holds a fishing line rated at +4lbs. The jig sits on a scale, push cut the line and record the maximum force. Before I started I made sure each knife could shave.Skinner- 70grams; Alpha- 110g; Dozier -170g.

I then sliced some 1/2 inch hemp rope along about 1" of the blade. I stopped when the knife started to become uncomfortable from the increasing force needed to make the cuts. The skinner made over 120 cuts, I got bored of counting; the Alpha made 75-80 cuts; the Dozier made 42 cuts.

After that I recorded the change in force needed to cut the fishing line. Skinner 280g; Alpha 311g; Dozier 470g. None of the knives could shave after the cutting.

Things I noticed. The Alpha can't cut flat to a board with a normal grip. I think it is close to impossible for most knives. Choking up on the Alpha like you would a chefs knife is painful. Using your index finger to guide cutting is pointless if you are trying to cut through anything tougher then meat. The Dozier was kinda of disappointing, having used one now I can scratch it off my list of knives to buy. The Alpha is very scalpel like. The Skinner produced less hotspots in hand. The Dozier functioned more like a saw then a knife. I was surprised that the Alpha worked better then the Dozier considering how much thicker behind the edge it is. The Skinner excelled at push cutting, it was had a less aggressive slice but didn't ever glide over the rope. The rope is pretty dirt even as packaged. Its a close approximation to the average material I cut on the farm.

From mccullen :

I was disappointed with the Alpha 1. It could be a good design for capping with a leaner grind and a handle that is less blocky.

The Dozier is a nice skinner and capping knife. I would extend the front finger choil / ricasso and soften the handle finger cutout on the backside.

I did not see any benefit with the friction forged D2. The shingle test did not show that the friction forged D2, D2 and S30V had any advantage over the other.

All the knives sharpened relatively easily and with about the same effort and time using my diamond stones.

From me2 :

There are some cosmetic issues I'd rather not see on a $350 knife, and the sheath is not what I'd like. The Dozier on the other hand is a real beauty. Easy to sharpen, stayed sharp through a couple of cardboard boxes, and only showed minor edge damage, just visible and just detectable with my thumbnail, after cutting up a bread wire tie into several pieces

I'm beginning detailed cardboard trials today for the FF, Dozier, and Delica for comparison.

Initial sharpening was done on a Norton 220 grit waterstone, followed by deburring and honing on the Spyderco Medium Sharpmaker triangles. The blades were destressed, given a couple of high angle passes ~45 deg., then given 15 pps, deburred again, and 5 pps. The edges then would catch arm hair above the skin and push cut the thread I use between 15 and 30 grams. The Dozier was a little more difficult to deburr, and the FF Alpha was a little sharper, but in reality there was huge overlap between the three, as I averaged 3 thread cuts to get the initial sharpness for each blade.

I remeasured the sharpness and found the Doz and Delica to be very close. The Alpha was behind. Averages were 23-28 grams for the Delica/Dozier, with 42 for the Alpha. I went with the cutting anyway, and the Alpha is behind the other 2, and the Delica seems ahead after 22 feet of cardboard cut by each. I'll post some numbers when done. I checked each edge at 40x and all look very similar, with a couple dents/dings in each and light reflecting from the side on all 3 in various spots.

I wasn't able to tell if the difference I saw in sharpness, particularly when compared to the Delica, was just a continuation from the initial sharpness difference (likely) or a difference in steel (unlikely). I have sharpened the Delica a lot with all the different methods I've used over the years. Not so with the Dozier and Alpha. [...] the bevel of the Alpha being so thick that I basically lost interest in really testing it to the limits. The Dozier was easily half as thick behind the edge.

Summary

In short, there was no significant observations of the Friction Forged D2 showing practical evidence of superior performance. There were however concerns about aesthetics considering the costs, and concerns about utility given the very small size of the knife. The very high edge thickness was also a consistent source of both puzzlement and at the limits, frustration.

Recap and Discussion

As a point of reference, Phil Wilson (knifemaker) compared a Friction Forged D2 blade and a PM D2 blade doing a stock comparison on cutting hemp rope. He found in multiple trials that the Friction Forged blade had about a 30% advanantage in terms of amount of rope to cut to dull the blade significantly. 1 . It may be simply that while this processing of D2 does make an inherently harder, strong and possibly even more wear resistant blade - the difference is fairly small compared to a standard (but quality) hardening and that in order to see it, very precise and controlled comparisons have to be made.

Forum threads :

References

1 : Patent by DiamondBlade

2 : White paper by DiamondBlade

3 : Phil Wilson, BF

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Written: 17/01/2015 Updated: Copyright (c) 2015 : Cliff Stamp