I just finished my first knife about a week ago. I'm currently doing some edge holding testing on cardboard, using a BM Ares in 154CM as a standard. The blade on the home made knife is O1 by Starret. After sharpening I pressed it against the edge of an old Buck Scoutlite and it notched the Buck w/o any noticable effect on the O1. The Scoutlite was Buck's old 425 Modified. I didnt test the hardness of the home made, but I quenched and tempered another piece and it was 56-57 Rc. I'm up to 360 cuts on the Ares and it still shaves hair. Both were sharpened on the Sharpmaker to the brown flats. Here's where my questions start. The O1 would cut free hair held between my fingers off the brown stones, but the 154CM would not. Both would shave hair from my arm. Any idea why the difference? I dont really have any data or other info, I'm just happy my first attempt seems to have worked out the way I wanted. Geometry on the home made is full flat grind on 1/8" x 1" stock, about 3.75" blade length. It was 4", but after tempering, it warped and I broke the tip off trying to straighten it. The edge thickness before sharpening was ~1/32", maybe less, I dont have anything accurate enough to go below that. Any other common materials that I could use to test sharpness? I may be able to get some rope from the shop, but they use it and are pretty stingy. I've also thrown the O1 knife (and the Ares, but thats a different story) and only had a few scratches, no damage. Its very light, probably 3-4 ounces, but I dont have a scale to measure low enough. My bathroom scale measures to 1/10 lb, but doesnt show any change. Its a clip point, and was designed as a hunting knife. The fit into the handle could be better, but it works, and there's a small gap at the spine into the handle, 0.01" or so.
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Finished My First Knife
- Thread starter me2
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Any pictures? Sorry I can't answere your sharpening question.
Cliff Stamp
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me2 said:The O1 would cut free hair held between my fingers off the brown stones, but the 154CM would not. Both would shave hair from my arm. Any idea why the difference?
Arm shaving is pretty low in terms of optimal performance, depending on the coarseness of your hair and exactly how you are doing it, it could be as low as 25% of optimal. It is a decent starting point, but you can go much further especially with properly hardened and ground tool steels.
Are the blades the exact same in terms of edge angle? If the O1 is more acute it will cut better at the same edge finish or sharpness. If they are at the same angle then you could be seeing the benefit of finer grain of the O1, but likely it could be as simple as a less optimal edge on the 154CM due to burring or similar.
Any other common materials that I could use to test sharpness?
Used carpet works well on the extreme edge and it will quickly show large differences in knives even without any great effort to be quantitative. Rope is nice but expensive. Your best option is to use something local to you, what you have available, ask friends as well to keep materials, people drop off used carpet for me all the time for example. You can also just EDC both and rotate in use and keep track of the sharpening frequencies. Over a decent period of time the variances will all smooth out and the averages will stabilize and give a solid indicator of performance.
-Cliff
Sorry, no pics yet. I'll try to take some w/ the digital camera at work. Handle is cherry wood, with a mahogany guard, coated w/ linseed oil.
Cliff,
The angles are the same, although the BM gets thicker faster. Both are 20 degree microbevels from the Sharpmaker after sharpening on an 800x waterstone at 17 degrees. I used Jeff Clark's method for deburring during sharpening at the beginning of the brown flat stage. The test blade is a fixed blade, so I wont be carrying it, sadly. I can only carry a folder at work.
Cliff,
The angles are the same, although the BM gets thicker faster. Both are 20 degree microbevels from the Sharpmaker after sharpening on an 800x waterstone at 17 degrees. I used Jeff Clark's method for deburring during sharpening at the beginning of the brown flat stage. The test blade is a fixed blade, so I wont be carrying it, sadly. I can only carry a folder at work.
Cliff Stamp
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Some of the stainless can be hard to machine so it might be a case of not enough work as well, though in the end a number of people have noted that when comparing to the extreme for sharpness, differences can be seen in steels, Jeff for one, it may be just a carbide/grain issue, but that is a pretty high angle and you tend to only see such issues when they are low.
Anyway as a general note it is nice to see an actual performance comparison to a reference, most times makers will only show the work with their blade with noting to serve as a benchmark so it is very difficult to know if anything special was in fact achieved or could the same performance simply be duplicated or even exceeded with a regular decent production knife.
-Cliff
Anyway as a general note it is nice to see an actual performance comparison to a reference, most times makers will only show the work with their blade with noting to serve as a benchmark so it is very difficult to know if anything special was in fact achieved or could the same performance simply be duplicated or even exceeded with a regular decent production knife.
-Cliff
Just wanted to post a quick update. The edge passed the brass rod test w/ no detectable damage by sliding it across a fingernail. I used a safety rod from the Sharpmaker, and checked for deflection in the kitchen light. The blade deflected with relatively little pressure, no where near the 40 lbs discussed in the chapter on knife testing in Wayne Goddards book. Of course the rod was much smaller diameter, so the pressure was possibly as high. He uses a 1/4" brass rod, the Sharpmaker rod is about 1/8". A couple of kitchen knives also passed the test. Maybe I'm doing it wrong. I used an angle similar to the 20 degree microbevel from the Sharpmaker, and stopped when I saw the deflection. The deflection returned and I tried again on different locations, which also returned after the pressure was removed. Anyway, I hope to finish the edge holding tomorrow.
Cliff, the Ares is my EDC now, so there may have been some wear that I didnt remove when sharpening. I suppose I should have gone back to the 800x stone and then to the Sharpmaker. Anyway, I've carried it for about a month now and have a good idea what can be expected. This was the knife I batoned through some 22 gauge roof deck with the back of a broken hatchet head. That took a couple chunks out of the blade maybe a little wider than the sharpened bevel. Its been 2 years and the blade was replaced by BM, so maybe it didnt exceed the bevel, but was deep enough that it needed replaceing. Anyway, everyone feel free to comment on the brass rod test, as I'm not sure exactly what it proves, or when to stop. It seems if you push hard enough, any blade would chip or deform. I did the tin can test for a while, stabbing into a soup can lid and twisting to see if it did any damage. It did on every knife I tried, so I stopped.
Cliff, the Ares is my EDC now, so there may have been some wear that I didnt remove when sharpening. I suppose I should have gone back to the 800x stone and then to the Sharpmaker. Anyway, I've carried it for about a month now and have a good idea what can be expected. This was the knife I batoned through some 22 gauge roof deck with the back of a broken hatchet head. That took a couple chunks out of the blade maybe a little wider than the sharpened bevel. Its been 2 years and the blade was replaced by BM, so maybe it didnt exceed the bevel, but was deep enough that it needed replaceing. Anyway, everyone feel free to comment on the brass rod test, as I'm not sure exactly what it proves, or when to stop. It seems if you push hard enough, any blade would chip or deform. I did the tin can test for a while, stabbing into a soup can lid and twisting to see if it did any damage. It did on every knife I tried, so I stopped.
Cliff Stamp
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me2 said:I suppose I should have gone back to the 800x stone and then to the Sharpmaker.
To be really sure you need to clean the edge back beyond the blunted region to remove any stressed metal, after I clean back to fresh I usually go around 50-100 more passes on the coarse hone to preset the edge before doing any comparisons, this of course wears blades *fast* so isn't advisible for actual EDC class sharpening.
[brass rod]
... as I'm not sure exactly what it proves
Nothing, it is an unspecified bend test.
It seems if you push hard enough, any blade would chip or deform.
Pretty much, all steels have an elastic and plastic region, the edge angle and thickness are also of critical influence on the result. I have taken blades and by altering the angle of sharpening made it fail the test both ways as well as pass it. You may be able to use this to show if an edge was hardened or was tempered, but anything else is unlikely.
I did the tin can test for a while, stabbing into a soup can lid and twisting to see if it did any damage. It did on every knife I tried, so I stopped.
That is pretty hard to do without any damage, you would need a decently obtuse edge angle , 15+ degrees, I like to cut them with control as a fairly far test of rough work.
-Cliff
Cliff Stamp
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There have been many, many people think highly of it, I don't see it as any use because it is too uncertain, it is the same as "put a knife in a vice and bend it, if it breaks it is too brittle, if it bends it is too soft". Well how far it bends it important and some knives work better if they actually "fail" either way than if they passed. It depends on what the knife is intended to do.
-Cliff
-Cliff