Byrd Finch vs some noname chinese knife

[Cliff Stamp]

I wanted to benchmark this knife, which is a no name, made in china, "stainless steel", linerlocking folder :

Ref :

http://www.bladeforums.com/forums/showthread.php?t=422935

A Byrd Finch was used as it is also a stainless steel knife made in china. This is a really small knife :

http://www.bladeforums.com/forums/showthread.php?t=422258

The first run was with the initial edge angles, no distinct microbevels and finished on 600 DMT. The cuts were made on a slice with 3 cm of edge through the ridges on 1/8" thick cardboard. which is just under the entire blade on the Finch. Kel_aa mentioned awhile ago that inverting the curves may be beneficial. I had reservations for a number of reasons however using the recently proposed intersection curves I think the problem with interpretation can be solved and I can deal with the numerical issues :

http://www.physics.mun.ca/~sstamp/knives/model.html

I also scaled the inverted curves which makes them veyr easy to interpret :

The graphs are scaled to the initial sharpness of the Finch and thus they show the percentage sharpness as a function of media cut. Plotted against the right hand side y-axis is the cutting advantage curve, which as noted previously is the additional amount of material the superior performance knife, in this case the Finch, can cut before reaching the same level of degredation as the inferior one . It also includes the results from the fit to the curve described previously :

y(x)=a*x^b+c

where c is the initial sharpness and a and b are the coefficients which control the rate of blunting. As this was a rough run just to get an idea of the performance the results are fairly noisy as they are a median of only four runs for each knife with 6 measurements of sharpness over a 3 cm section of blade at each point in each run. The Finch also had a reduced amount of points which is why the coefficients are not well determined.

However even with all of this is is apparent the Finch; (a) is initially sharper, (b) has a lower power coefficient, and (c) this combines to give it an advantage of about 150% for late stage blunting, so it is cutting about 2.5 times as much material. It should also be noted the no-name had the edge reground to remove the initial hollow ground edge. Out of the box the no-name could cut a few feet of cardboard before ripping.

At the end of the above cutting the no-name was having problems cutting newsprint and the Finch was still cutting it easily. The next comparison will reduce the no-name to the same angle and do a longer comparison which will also increase the precision and accuracy of the curves. Note that the cutting advantage curve is really uncertain because it is the intersection of the two fitted curves. I will be bounding it shortly with confidence intervals as soon as I figure out how to extract the relevant information (correlation coefficients) from the GNUplot fit command. In the meantime, I would caution that curve to basically be certain to one digit.

In short, the really cheap no-name knife will be significantly outcut by even the introductory level production knives however the advantage isn't likely as great as many might think/promote with some care to sharpen the edge well. On the next run I'll also likely include a VG-10 knife to serve as a high end abrasive cutting benchmark.

-Cliff

 

[kel_aa]

At the end of the above cutting the no-name was having problems cutting newsprint

I bow down to your sharpening skills and/or patience. That was about the starting performance on my Jaguar. So how would you characterize the feel of the Byrd steel?

 

[zpaulg]

I like these Byrds, must be said! Cheap to buy and seem good quality.

Value your opinions of same??? (Cliff)

 

[Cliff Stamp]

I like these Byrds, must be said! Cheap to buy and seem good quality.

Yes, I see them much the same.

That was about the starting performance on my Jaguar.

Initially this one was much the same until I reground the edge even, removed the hollow and got into decent steel. With the angle made more acute and more effort put into removing the burr, as noted in the Toolshed forum, the initial sharpness more than doubled. Which was surprising and I think may have just been either due to steel improvement or just a more natural sharpening angle.

I think I can double it once more because some of the edge gets very sharp so I just don't have the method down yet. I'll be cutting the angle back to 10 shortly which will make it easier because that is the angle I naturally sharpen so I hone that a lot easier than 15 and especially 20 which I almost never use aside from stock jig work.

So how would you characterize the feel of the Byrd steel?

The Byrd steel is similar to AUS-8A in terms of grinding, it is much easier than VG-10 for example but is more crisp. It is a nice introduction to relatively low carbide but yet fairly hard stainless steels. The steel is actually in the same class as AEB-L and the Byrd knives are actually harder than some makers/manufacturers are running AEB-L which is fairly surprising.

-Cliff

 

[ghost squire]

Very cool and useful graph!

 

[Cliff Stamp]

Thanks, I figured out how to bound the cutting advantage graph and will try filling in an area to illustrate. It is basically just as certain as the a values and these are difficult to determine well without a massive number of points because the graph is so monotonic. I may switch to a multi-plot approach to this as well to keep the graph from getting to cluttered.

-Cliff