Testing S30V with more steels to follow

[sodak]

Here's your chance for some input. I'm going to be testing all of my S30V blades, in response to an older thread. After the S30V blades, I'll be running VG 10, ZDP 189, D2, and probably some others through the same tests. This will be a test of edge retention and probably stability as well. Anything that comes to light during the tests that is interesting will be investigated. Here's what I'm planning, I'm looking for comments, ideas, and anything that I might be forgetting.

1. Finishing all knives to a common, repeatable sharpness. For me, that means using my Edgepro. I will test both polished and rough edges (grit sizedly speaking). Polished means up to and including the standard 3000 grit tape. I'm still open on rough. Testing the edges will probably mean measuring phone book push cuts. I just got a bunch dropped off from the phone company, so last year's books will be the media. If this proves ineffective, then I'll probably try thread cutting.

2. Cutting at first will be using sisal rope purchased from Lowes. I'll try to purchase it all at once to hopefully minimize variation. I haven't yet decided on 3/8 v.s. 7/8, etc. The rope will be cut on the softest 2x4s I can find to minimize edge distortion.

3. For now, I'll measure the factory edge angle on my edgepro and record it. Maybe in the future I'll make all the knives the same angle, but we'll see.

I've got photobucket set up, and will try to have pictures when helpful to illustrate the process. The current plan will be to sharpen a knife, test cut, and measure. I plan on 3 runs rough, 3 runs smooth for each knife. I don't know how many test cuts will make for good dulling, I'm thinking of measuring every 20 cuts or so until completely dull. Every sharpening will be to remove weak metal, no steeling or any of that nonsense.

I would like to do some cardboard testing and carpet testing, but don't have reliable sources yet. I will probably add more metals to test, but this should keep me busy for several months.

Any comments or suggestions are welcome. If you would like to see a particular knife tested, then be prepared to send it to me. I'm not buying any more knives to satisfy anyone's curiosity. And for the record, I'm not testing INFI, unless it's at the end. When I've got calluses worked up. In case you're wondering about that comment, Jerry Busse cut around 1700 pieces of rope at a knife show with an INFI blade without dulling it. I'm quite sure that S30V will be at least an order of magnitude less. We'll see.

 

[hardheart]

great idea, unless any of the S30V blades are popular, then you're some ignorant poser who likes to do things with knives no reasonable person does just for attention and to besmirch the names of fine upstanding creators of beautiful pieces of art that must be adored, that are simultaneously capable of chopping through aircraft carriers and able to survive a ground zero detonation of a tac nuke. But keep in mind that no matter what the advertised toughness, you must never do more than sever loose threads from your slip with such valuable tools.

Anyway, I might still have a hunk of balsa wood I bought from the hobby shop years ago, if you'd like to use that instead of pine 2x4s. Will you be measuring rope cuts on a scale? Phil Wilson cut until it took >20lbs of force for his tests, IIRC. Might be a good thing. Also, I haven't seen it mentioned before, but do you plan on washing the rope first? The extra dirt trapped in the cheap stuff could add a lot of variation.

 

[sodak]

I'll make sure and hitch my slip up out of the way, good enough?

I think the pine will be soft enough, but I'll keep that in mind. 20lbs? Hmm... I have an extra scale laying around from last month when I had to replace my garage door spring. I could perhaps use that. I hadn't heard of washing the rope first. I'll try to see if I can find a spool wrapped in plastic first..

Thanks for the input!

 

[Cliff Stamp]

.... until it took >20lbs of force

This is much better than the pure subjective work done by Fowler and company, but it is still a very coarse measurement of sharpness due to the fact that you are actually measuring cutting ability and +/- 1 lbs means a LOT of cuts, i.e., easily hundreds depending on the geometry.

I plan on 3 runs rough, 3 runs smooth for each knife. I don't know how many test cuts will make for good dulling, I'm thinking of measuring every 20 cuts or so until completely dull.

Dulling is nonlinear so you are better off checking on a power law basis, measure every 2^n or similar.

-Cliff

 

[ehhh]

Are you also going to standardize the thickness behind the edges on the knives?
I could understand if you don't but it's an idea if you want to test the steel itself while trying to eliminate (not completely) the variation caused by geometry.

 

[sodak]

Cliff,
Good point about the dulling. I have a feeling I'll be doing more cuts than I originally planned.

ehhh,
I'll try it with the factory bevel first, but yeah, I'm expecting I'll have to standardize the thickness later.

 

[David E]

Cliff,

I'd like to see some lateral flexibility tests, especially with S30V.

Also, when you say "V-10" do you also include the Fallkniven laminate?

Thanks !

 

[gunmike1]

Your ideas sound good, Sodak. I'll have to think about some good tests, I know cardboard would be nice, but you will need a ton of it. I think a thread test would be ideal for the sharpness testing, but the yellow pages work great for me when I test sharpness after I sharpen. I'm not sure how they will translate when the knives start getting dull, as they require more sharpness than newsprint to pushcut in my experience (your material may vary). That would seem important as the whole point of S30V and the other high carbide steels would be they can still have a "working" (dull) edge that still cuts, even at a rather dull state. Finding a cutoff point to where you end the test seems like the trickiest part to me, maybe it would be when the performance levels off. I know when I first reprofiled my Jess Horn ZDP it went through a LOT of cardboard, and after initially being able to feel the dulling it seemed to reach a state where it just continued to cut without seeming to get any duller. I think Cliff has mentioned this is due to self sharpening from carbides tearing out, and after that experience and some others the concept makes sense to me, though I don't have the tools to look at the individual carbides, of course. I'm sure after doing a couple test runs you will be able to find a good cut off point.

Good luck with the test, I am watching it eagerly, and plan to steal some of your methods when I do some testing on Cliff's reprofiled U2 and Jess Horn, along with my Jess Horn and reprofiled Native. Luckily, I think my sister in law can get me tons of cardboard for free, but I'll have to pony up for the rope. Lots of work, but lots of fun, too!

Mike

 

[Cliff Stamp]

I know cardboard would be nice, but you will need a ton of it.

This depends on how far you go with blunting. If you check edge stability, or very high sharpness such as focused on by Landes, then you don't need much cardboard at all. You can decrease it further by just cutting very fast on a straight push. In comparison to slicing until you can't cut paper or similar, you need 10-100X more material.

-Cliff

 

[Dog of War]

This kind of work I find very useful, and am looking forward to your results, Sodak.

I also think you should consider a more sensitive test of sharpness such as newsprint or thread. Also examining edges under magnification, especially during the early stages of testing, could be very informative, microchipping tends to show up almost immediately.

For cardboard, beer case boxes might be a solution ... I was amazed how much cutting you could get from just one box when I did a round of testing a few months ago, since you only need to remove a 1/8"-1/4" strip. Perhaps they know you well enough at the local liquor store to help?

 

[Saunterer]

Sodak,

This is shot in the dark, but where are you located? I'll have plenty of carpet within the next month; replacing my whole house. If you are close, I'll have plenty to give away.

I cut through about 75 feet of carpet and padding (hitting concrete also) last night with my VG-10 blade. Went from shaving sharp to dull... 30 minutes later had it spooky sharp again

 

[Phil Wilson]

Sodak, a couple of things:
try to get rope without the plastic tracer in it. Depending on what orientation the tracer is when you cut it can give different results.

mark off a length of each blade so you are cutting with a known length each time.

a blade with a belly, cuts better with less force than a flatter edge in my experience so the closer the geometry of the test blades the better.

The scale is important, yes I pound force can make a difference but you will find you hand gets educated and you can tell when the blade is taking more force to cut without even looking at the scale. You then check the scale to see where you are. Not a precise operation as Cliff mentioned but you will be surprised how sensitive your hand is.

Good luck this is just a few of the variables, there are many more as you will discover.. Phil

 

[db]

For the slicing part of the rope test if you want to prevent using a cutting board you, could tie one end to something and hold the rope taut to slice it. If you think the amount of tension is also important instead of tying it off you could tie a weight to the end and then slice off from the other end.

 

[gunmike1]

This depends on how far you go with blunting. If you check edge stability, or very high sharpness such as focused on by Landes, then you don't need much cardboard at all. You can decrease it further by just cutting very fast on a straight push. In comparison to slicing until you can't cut paper or similar, you need 10-100X more material.

-Cliff

That makes sense, just use the same small section of each blade and pushcut until it won't pushcut or slice newsprint or copier paper or whatever type of test you consider the end point. Do you then rehone, or do you test other sections of the blade (presumably still sharp and unused) to save time and effort? I can see the upside of saving time by using different section of the same blade, but possibly getting less consistency by using different sections of the steel and the different curves of the different sections of the blade which may influence the edge retention. Of course the variation from the material may be a larger effect than the different sections of the blade anyway, I'm just trying to brainstorm here.

 

[Phil Wilson]

Sodak, welcome to the world of edge holding testing. I think cutting rope can tell you a lot about how a blade will actually act in use in the field. The problems are that there are so many variables to deal with. Some you can control and some you can’t so the upshot of the whole thing is that you can detect larger differences between blades (15% or more) smaller differences get lost in the experimental accuracurcy of the whole process. The key is to hold as many variables constant as you can and then be able to tell when the blade is dull. I like Cliff’s method of cutting string under tension with a known force. That takes most of the feel factor out of it. My method is that I can feel when the force starts to get higher for the same cut. I keep an eye on the scale and limit the force to 20 lbs as close as I can. My back up is to feel the blade. If you run your thumb along the length (gently of course) you can easily feel the smooth spots. They will occur where you have been applying the most force. If the blade is dulling by abrasion then all this will happen gradually and if you feel the blade every 4 or 5 strokes then you can monitor the dulling. Here are some things I have learned and a little more detail on the technique I use. Remember I am not an expert except on what works for me. You will develop your own process but maybe this will help to get started.

The cutting stroke should be a combination of a slice and down force. Pure down force shears the rope and dulling only occurs in one spot. You can push cut (shear) rope for a long time, it acts like a metal shear in a sheet metal shop and that only tells you how it dulls that way. Real life dulling is more of a slice cut.

A longer blade makes a better test knife. ( 6 inches cutting length is idea). You can’t slice very well with a short blade. The dulling will average out over the whole length and happen slower. It is therefore easier to monitor.

My cutting tests have shown me that sharpening, blade thickness and hardness can make as much difference as steel grade. You can sharpen to cut rope. A shaving edge you will find won’t cut very well. You need some tooth to cut rope or skin a deer or fillet a fish. If you don’t compare apples and apples then all the testing doesn’t tell you much except your wrist will get very sore.

The sharpening has to be as close to possible on each blade.
The geometry has to be identical
Handles make a difference. If the handle hurts your hand then it can influence how you cut. The slice to push ratio for example.
Heat treat and blade hardness should be known. One pt hardness can make a very big difference on some steels.
Use the same rope batch, need to buy a lot of it. By the way rope can vary from foot to foot depending on how much dirt is in it and the density of the fibers. How do you measure that? If you try to wash it then you are washing a lot of rope. You will soon get tired of that. To average out the dirt factor you need to cut a lot of rope.
A 5/8 inch dia rope seems ideal. Thinner and you are cutting more board underneath that rope. Get larger dia stranded rope and take out one strand.
The best technique is to work with two knives of different steels. Cut a few strokes with one and the alternate to the other. The difference will be more apparent than if you do them one at a time.

Have a sharp knife on hand and cut with it once in a while to calibrate your self on how a sharp knife cuts compared to the test knife.
Ask a friend to duplicate the tests and see if they get the same results.
Try to stay impartial. If you think from the beginning that BG 42 will out last S30V for example then maybe in you subconscious you will make it come out that way.

Go past the 20 lbs to 30 to check the edge for rolling or breaking. 20lbs is a lot of force in the real world and if the blade takes more then that, maybe the edge could be thinner.

I think cutting rope can tell you a lot about how a particular blade will perform in the field. Field testing in real life should be done in conjunction with experimental testing. After a while the true character of the knife will come out. One more thing, it helps to wrap your wrist with an Ace bandage. I sometimes takes hundreds of cuts to dull a good blade. Phil

 

[sodak]

Saunterer, I'm in the Denver area, so too far, and I don't have room to store a lot of carpet, but thank you very much for the offer.

Thanks for the comments and suggestions everyone, especially Phil! I'll be checking and pricing rope this week. Something tells me that I'll be using a lot. I've done a little rope cutting in the past, but nothing approaching this scale. One thing I will be doing will be to keep very detailed records, so that if something is out of the ordinary, or not a good test, then I'll hopefully be able to drill down to the problem fairly quickly.

The first knives that I'll be testing are a Buck 110 and Vanguard in S30V. I also have a Vanguard in 420HC, and I have 110's in both 420 HC and BG 42 from the custom shop. So I'll hopefully be able to use some of Phil's suggestions in comparing them, and will definitely be marking with a sharpie the section of blade. After these, I also have a Spyderco Native (Walmart) and Manix in S30V, and a Sebenza.

Consistency is important, and the more I think about it, the more that I think that using a coarse finish on the edgepro is the way to go. That will be the quickest and easiest way for me to duplicate sharpness. I'll forget about high polish, maybe later as a trial run, but the question will be, what finish to leave on the edge? I have the typical waterstones from Ben, 180, 220, 320, 600. I might have the 120's, I'll have to go check. Would 220's be too fine? Or would 180 finished with green CrO on leather (stropping) be the way to go?

Thanks again for the suggestions, I'll be printing this one off and keeping it in the garage next to the rope!

 

[Cliff Stamp]

Do you then rehone, or do you test other sections of the blade (presumably still sharp and unused) to save time and effort?

You have to do multiple honing trials to average over sharpening anyway. I use the unworn sections mainly as reference points for more qualitative tests like shaving and do better describe non-measurement paper cutting.

Consistency is important, and the more I think about it, the more that I think that using a coarse finish on the edgepro is the way to go.

For slicing, coarse edges take a lot of material to test because the edge retention is really high. You also want to cut unsupported material (no cutting board) or else you are going to get a more complicated blunting pattern because of the additional nonlinear influence of the cutting board.

If you are also actually serious about getting unbiased results then you should take a few steps to make sure you are not introducing a systematic deviation for one blade over the other. The easiest way to do this is to have a friend do an unknown number of cuts and then you continue and only when you stop with all the numbers recorded do they tell you how many cuts they did. There are a few minor problems with this, but the upside/benefits are extreme.

The cutting stroke should be a combination of a slice and down force.

Ideally you should separate these (push/slice) because they test different attributes. D2 is a great slicing steel, but poor for push cutting. I agree rope cutting, or anything for that matter will allow you to judge the performance of the blade in a meaningful way as long as you put some thought into doing it in a sensible and meaningful way.

-Cliff