Blade Testing

Deweyknives

Deweyknives

Joined
Nov 29, 2006
Messages
1,097
Mace and I had a short discussion about edge testing. I usually make test pieces untill I'm satisfied with my HT process,then recreate that process [as close as I can] for that steel. Once I have the knife handled, I do some cutting and testing. After doing autobody work for 30 years,I think my hands are pretty 'smart' and can feel blade quality,hardness and consistancy while I work the edge. After tempering I start a secondary edge angle with a file to create a referance line, clean up decarb, and to 'feel' the hardness and evenness of the edge from plunge to tip. Mace, on the other hand, tests each knife after HT and temper, before going on. I understand [and appreciate] the logic of this routine also.

When you make an 'average' blade from your 'usual' steel, when, how, and how extensive do you test EACH blade?? Keep in mind, I'm talking about steel that you use on a regular basis and already have a feel for. Just curious!!:)
 
After the last temper cycle,I first check the hardness just under the front edge of where the grips will be. (Rockwell hardness tester makes this fairly easy) I then sharpen and slice paper to check for edge smoothness and sharpness. I then chop hard maple cross grain from tip to ricasso several times to check for edge geometry and harness. I then go back to the paper to check for flat spots. If it passes this, I finish the knife. If not I re-heat treat.

Jim Arbuckle
 
For me it is all about geometry, (it is for most others as well, whether they know it or not). Messing with the actual blades and their qualities only tends to be a distraction when determining the quality of heat treat and the internal condition of the steel, and by the time you have it sharpened it is a little too late to worry about those things anyhow, except for the next one you make. Each blade is Rockwell tested until I have walked it in to the desired hardness for the application. Control samples are measured for impact strength and the fractured ends are examined for grain condition and characteristics of fracture before mounting, grinding and polishing for microscopic examination.

Now that I know what my forging and heat treatments have done inside and out, all that is left is to determine what the final shaping and polishing has done for the performance. Occasionally I chop seasoned barn beams to see how the edge geometry works and how a new handle configuration feels. Most people are so focused on the blade that they never pay attention to how that handle is going to feel after long use, or how it will affect the cut. I have found that clearing a fence row of saplings and brush is great for this on larger knives. For smaller blades loan them to friends to dress out a deer (hog, cow, bear, rhino, etc... any larger game) and watch how they use them and how they stand up to that use (not everybody handles a knife exactly like you).

Folks don't like to hear it but many of the most common "tests" have little use in my shop as they tell me little or nothing about what I want to know. I honestly don't care how much an edge flexed over a brass rod as this only suggests something about the heat treatment when it is too late and then says very little compared to what it indicates about the edge thickness, and I already know how thick the edge is since I ground the dang thing. I am more interested in other strengths so for years at many of my demos I have shown my brass rod test, which consists of impacting the edge on various angles with a 1/2" brass rod, taking good bites of the softer metal and looking close for any damage to the edge.

Cutting various materials by hand can be so subjective that it is almost useless as a standardized test for me. Hair shaving is a minimal standard as it really doesn't take much and if I can't at least do this I am not bothering with other tests. Depending on how you sharpen it you can have a blade that will shave like crazy (a fine polished wedge) but not cut other things well (which need some toothiness) or vice versa. I find cutting cigarette paper to be a pretty good standard of sharpness that is better than shaving, there are ranges of efficiency in shaving with everybody seeing it differently (I have seen some who were happy pulling more hair out than actually cutting it), with cigarette paper it either cuts or it don't.

Sometimes I will put the edge under the microscope to see what its condition and configuration is and how the steel took that edge, and reexamine it later to see the exact mechanisms of edge wear. I don't bother with it much anymore, but a very good test for folks heat treating in a forge or other open flames is to drop the blade point first from five or six feet into concrete or steel plate, if there is any damage to the tip, you are overheating it. Due to the specialized and subjective nature of it, I don't bother with any of the popular modes of rope cutting.
 
I cut cigarette papers as well, sometimes. (I can't afford to waste all my papers, though. :rolleyes: )I also use the brass rod method, and try to put the knife through its paces a bit, for its intended purpose. This Christmas, a co-worker wants to buy 3 skinners from me, so I'll make a prototype skinner and give it to a guy I know who cleans a great deal of deer every season, to test out. I made a grafting knife for my horticulture professor, so I went and cut a lot of 3/8" oak cuttings with it. My testing methods won't tell me anything until the knife is completed, but at least that tells me if I need to remake the knife. Some equipment to test my knives is definitely on my wish list, though.
 
I can just imagine overhearing this conversation at a show someday:

"Ya know, Joker 1.25's are a decent test for an everyday working edge, but if you really want to see how good your edge is, ya gotta use ZigZags, and not the glue edge."

"Did you hear that BS Joe is passing around? He tells everyone he's cutting papers, but what he's not saying is that he's using Easy Widers! Hell, anyone can cut a Easy Wider, they're like printer paper."

"Jeesh, Widers. And did you see what he's getting for his knives? Tsk, tsk."

:D
 
AcridSaint said:
Mike, you know that Top papers are the easiest, don't lie to everyone.
Click to expand...

I thought Tops were for testing wear resistance and edge retention? :confused: "Man, I made 72 cuts through Tops and it would still shave hair!" :)
 
It's only good for testing wear resistance when it has "hemp rope" rolled in it, sorry. Looks like you've fallen victim to another knifemaking myth.:o
 
Ahhh! That hemp was for knife testing?? My bad. Oh, well, the knife cut through the pan of brownies ok so everything's groovy anyway, man!

Thanks for the clarification!:thumbup:
 
Does anyone think some of us take testing too seriously? i see if mine flex, shave, chop, cut and hold an edge well. i feel my hands also "smart" and i feel when the steel is too soft or too hard. i think it just an experience thing, i know my steel, and i have never had a knife break or dull too quickly except for one, and i was knowingly abusing it. i just smoke the cigarettes:D :rolleyes: Just my thoughts...
 
Fitzo, the really funny thing about it is that there are indeed different cutting qualities between papers. Zig Zag is easier to cut than Top and cutting them lenghtwise is much easier than across the paper (the glue side doesn't count). Now I would really like to point out that I only know these brands from this use, this is the only reason I have ever bought papers in my life. I must admit that buying them is still one of the most embarassing things for me, I would rather point out the exotic condoms I want to a cashier than rolling papers, and always feel the need to explain what I do for a living and what they will be used for. They, of course, never really care.:rolleyes:

Not that I would have any problem with a person rolling their own cigarettes, just I only do tabacco wrapped in other fine tobacco leaves, not paper.
 
I smoked roll-your-own Tops for a long time, found them to taste decent and be much cheaper than buying a pack. At the time, you could buy enough tops for 2 or 3 packs worth of cigs for 99 cents at a gas station and cigarette packs were almost 3 bucks at a discount store... Of course, that was before I moved out to tobacco country. Bugler bacca sucks, by the by.

Quit smoking 5 years ago, so my experience is probably outdated anyways.

Back to your regularly scheduled thread.
 
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