Cutting Comparison Between All My Folders

[me2]

The title says it all. I used a scale to measure the force it takes to make a cut in cardboard, parallel to the corrugation grooves. All the cardboard came from the same box. I just used bathroom scale. The following folders were tested:

Spyderco Delica - carried and used a lot for the past 18 months. Roughly a 15 degree backbevel, 17 degree intermediate bevel, and a 20 degree micro bevel from the Sharpmaker.

Benchmade Griptillian HG 550 - backbeveled to roughly 15 degrees and sharpened on the Sharpmaker 20 degree slots. Only had this one about 2 months, so the wear and tear is at a minimum.

Benchmade 805 TSEK Partially Serrated - Factory edge from Benchmade after a blade replacement. Carried but not used much. I think cutting extra length from drinking straws for the kids and this test is the most use its seen. Only the plain edge section was tested

Byrd Cara Cara - Backbeveled as the others (~15 degrees), but with a polished edge off the leather belt on the 1x30 sander and no microbevel. Used and carried for a while now, though not as heavily sharpened as the Delica.

Gerber Drop Point Folder - Backbeveled at 15 as the others, no microbevel. The edge is as it came from the leather on the belt sander.

Parker Cutlery Large Trapper - An old knife my dad left me, sharpnened on the sander at ~15 degrees and finished on the leather.

Unknown China Slip Joint with Decorated Handle - ~15 degrees from the belt sander, finished with leather on the 1x30.

Buck Scoutlite - The whole blade was reground by me, and a final edge applied at 15 degrees with the sander and leather. Fresh after regrind it was 0.003" behind the edge, but has thickened up some since that first sharpening.

Cutting ability seems dependent on blade thickness, as the Trapper and Unknown actually cut the cardboard with less effort than anything else. These had thinner blades than the others too. I'd actually give the advantage to the Unknown, though they were very close. All the other folders were also very close. The Benchmades seemed to cut easier than the Spyderco or Gerber. The Cara Cara was behind the Delica and the Buck was in between the Benchmades and Spyderco. Below is a ranking from best to worst.

China Unknown
Parker Trapper
Griptillain HG
TSEK/Buck
Gerber Drop Point
Delica
Cara Cara

The China Unknown was a real surprise. I would have thought the Buck would do better. The BM's doing better than the Delica or Cara Cara was somewhat surprising, though the last time I did this test with a Benchmade in the lineup, it comes in second or first, and ahead of the Delica and Cara Cara.

[culpeper]

Very interesting! Good job!

[wildjim]

I sure would like to see some video ; )

[me2]

Sorry, no video capability. For pics of some of the knives, see my thread in the for sale forum. I want to do the M2 puukko I made, but havent gotten around to resharpening it after prying out some heavy staples. Yes, it chipped, but didnt break, and the slotted handle with no screws is still going, surpisingly.

The best cutters from above have full flat ground blades from 1/16" stock, about 1/2 to 5/8 inch wide. The rest were all in the 1/8" thick range with hollow ground or flat saber ground blades.

[Cliff.Stamp]

I just used bathroom scale.

There are so many myths and misconceptions about steels which would never have been conceived, nor propagated if the constant rope cutting used to promote steel/heat treatment was always done on a scale. That simple scale and a bit of though and care can reveal a lot of information about knife performance.

I just did some cutting with kurodrago's BushBuddy, I was just carving some soft woods. I expected the cutting ability to be very close to the Mora #1260 as the edge angles were identical 10-11 degrees per side. But they were not close at all, the BushBuddy needed a much higher angle to cut into the wood and much more force.

I took a simple block of beeswax, did a push cut into it with the Mora 5-6 lbs, then with the BushBuddy 7-8 lbs. About a 50% difference, I take out the Caliper and check the edge, sure enough the BushBuddy has a sweep to the final edge where it increases up to 15+ degrees, that must be the as-sold edge.



The China Unknown was a real surprise.

You will see the same thing if you do edge retention work as well, the thinner and more acute edge which has a higher quality sharpness will cut for much better for far longer. Now better steels will function at a lower cross section and take a higher finish, but in general there are few production or even custom knives which are sharpening to the capability of the steel anyway as they have to be left thick and obtuse to prevent damage from non-cutting.

In fact you can even take a piece of mild steel and sharpen it and it will out a lot of production knives on rope, cardboard, woods, etc. as mild steel will be stable at 12 degrees per side on such materials and most production knives are at edges of 20-30 degrees per side, edge thicknesses of 0.035-0.055" and the sharpness is mid to average at best.

Not only will the mild steel bar knife cut better to start but it will stay that way for a very long time. As a specific example I had to take 126 cuts through 3/8" for a knife made out of a tension bar to blunt enough to have the cutting ability be reduced to equal a freshly sharpened Sog Seal. Now of course a properly ground tool steel will mangle that in a comparison as they are stable at 3-5 degrees per side.

Serious sharpening :

http://www.youtube.com/watch?v=sCfl4stsagE

[me2]

There is a lot of misconceptions, as you said. I'm still mildly amused by people who promote a steel, and basically ignore geometry. The influence of geometry is what led to my flex testing of the very hard puukko. 10 flexes, 90 degrees, no set, no cracking.
the blade is about 0.058" thick. I'm kinda curious about how thick one can go and not snap the blade, but I don't have any way to harden and test different thicknesses. I suppose I could break out the engineering books and calculate it, but I could still be way off.

The part about the lower limit of tool steels has intrigued me since reading about Alvin's knives. I want to make some kitchen knives out of 0.03125" stock, and have it hardened up to around 63-65. I can get O1 in that thickness. Then just put on a 10ish degree convex edge off my belt sander. I have a knife with a similar geometry now, but the edge is at 17 degrees per side, and the unknown stainless is much softer. Spine thickness seems somewhat ignored in many cases, but when cutting through thick and relatively stiff fruit and such, it becomes important. My test is cutting through apples without cracking them. The puukko, at 12 deg/side and 0.058" thick, can't do it.

Many of those knives are gone now. I only have the Grip, Delica, M2 Puukko (w/o a handle), and the Cara Cara. By next week, the puukko will be a paring knife. I love it's blade profile, but have yet to put a permanent handle that I like on it.

[Cliff.Stamp]

I'm still mildly amused by people who promote a steel, and basically ignore geometry.

A lot of the people doing commentary are taking a cue from the makers who give some very misleading perspectives. As you noted in your edge retention comparison on the Cold Steel machetes, how impressive is it really to chop down a single tree and not have it blunt the knife, but yet how many people can you see on YouTube praising a knife, steel and especially heat treatment because the knife did not go blunt immediately in use.

I'm kinda curious about how thick one can go and not snap the blade, but I don't have any way to harden and test different thicknesses. I suppose I could break out the engineering books and calculate it, but I could still be way off.

The main source of stress is the difference in elongation between the outside diameter and inside diameter of the knife in the bend, this is directly proportional to thickness, the diameter is also of course proportional to the length of the knife, this is why machetes bend all over the place as they are both long and thin.


Spine thickness seems somewhat ignored in many cases, but when cutting through thick and relatively stiff fruit and such, it becomes important. My test is cutting through apples without cracking them. The puukko, at 12 deg/side and 0.058" thick, can't do it.

The thickness of the knife is only relevant if you are cutting that deep enough that the cutting medium actually "sees" that part of the knife and exerts a binding force on it. Meats, ropes, cardboard, wood, etc., common test mediums and common materials cut do not bind on a blade significantly past about 1/4" deep or so (unless it is really thick cardboard). But yeah, vegetables and fruits can do this the entire width of the blade hence you don't see a lot of very thick kitchen knives unless they have very wide blades and very high grinds.


By next week, the puukko will be a paring knife. I love it's blade profile, but have yet to put a permanent handle that I like on it.

I don't have much use for those types of grinds, but I have a very well used Mora #1260. I keep meaning to put a full flat grind on the thing, but each time I go to I remember it makes a very nice blade for cutting comparisons.

[me2]

I have a love hate relationship with puukkos. I love them for their simplicity, price, and ease of sharpening. Not quick, but easy. I suppose they work ok for bushcraft duty, but it just seems a full flat ground knife with the same edge angle would work just as well or better, and could be thicker for more strength/stiffness. Sharpening time would be less, but require some skill to hold the angle. But, getting all that metal out of the way and buying thicker stock takes more effort and money.

[Cliff.Stamp]

I have a love hate relationship with puukkos. I love them for their simplicity, price, and ease of sharpening. Not quick, but easy.

I have a number of them, the one I use more often is the #1260 which Ragnar no longer offers but is very similar to :

http://www.ragweedforge.com/1.jpg

Here is the #1260 and a pile of shavings, 7.5 mins, very light force :

http://i7.photobucket.com/albums/y269/CliffStamp/Condor/BushBuddy/DSC00209.jpg

This is the Bushbuddy, which has been reground twice before I received it, same amount of time and effort :

http://i7.photobucket.com/albums/y269/CliffStamp/Condor/BushBuddy/DSC00211.jpg

Removing the bark from both, the Mora stripped 120 g of wood to 40 from the BushBuddy, three times as much. This is what freaks people out when they first use a Mora, they compare it to something like a Cold Steel Recon Scout and are amazed at the cutting ability - and there is a fairly large one.

Then they make the mistake that this is due to the fact that it has a single grind which of course is not the case. The Condor's come with single grinds however the knives cut like tent pegs. The Mora's cut well as the edges are 10-11 degrees per side, that is all.

I have lots of knives which will out cut Mora's in the same way a Mora will out cut a Condor. That Mora I have in the above would seem like a very nice paring knife, slender blade, acute edge -until- you compare it to a paring knife I have by Alvin which has a full hollow grind, edge is sharpened at 3-5 degrees per side.

I suppose they work ok for bushcraft duty, but it just seems a full flat ground knife with the same edge angle would work just as well or better, and could be thicker for more strength/stiffness. Sharpening time would be less, but require some skill to hold the angle.

This is just physics, arguing against it would be like trying to claim gravity is repulsive, it is absurd.

However the problem is that the flat ground knives typically come with an edge between 0.035-0.065" thick and 20-30 degrees per side and are of 3/16-1/4" stock. Now take a typical Mora which is ground at 10-11 degrees per side from 1/16" stock there is no comparison at all, the Mora will out cut it several times to one. It is like comparing a knife to a screwdriver the performance is that uneven.

However if you compare as you said a full flat ground knife which tapers to an edge of 0.005"-0.015" thick (how much depends on your durability requirements) with a 10 degree primary edge and a 15 degree microbevel (properly set just 1-2 passes, resulting in a < 0.1 mm wide bevel) - well you have a completely different perspective.

Now you will find you have a knife which cuts just as well on shallow cuts, cuts much better on deep cuts, is more durable at the edge in scraping and hard cuts and sharpens many times faster and is lighter and is stronger (a wedge geometry has a much highest strength to weight ration than bar stock).

But, getting all that metal out of the way and buying thicker stock takes more effort and money.

Yes, you can't really expect that for $10 which is the starting point of the Mora's on that knife they are an excellent value, the problem is when you get foolish knives like this :

http://www.raymears.com/getimg.cfm?img=Woodlore_Knife2.jpg

This is 450 pounds stearling, for that price I think you can not complain about cost of a primary grind, tapered tang, etc. .