Tree topping? How sharp CAN it be?

S

sja2249

Joined
Feb 11, 2006
Messages
174
I don't normally worry about putting a scalpel edge on all my knives, but I decided to test my skills on a pair of Opinels.

The only problem is that once I reach a certain point, I no longer have a good benchmark for whether I'm improving or not.
I've gotten both blades sharp enough that waving them near my beard will slice off the ones that stick out further than the
rest... And I can whittle the beard hairs with no trouble.

I can get similar results waving the knife over my hair or over my arm... picking off random taller hairs. I cannot, however, whittle head or arm hairs. They seem to be too flexible and just bend away from the blade. Does that mean I have a little further to go to perfect my skills, or is that normal? Both knives push cut through newspaper with almost no resistance. How do I tell when I've gotten them "sharp enough"?

LOL I'm probably doing this all wrong as far as some of you are concerned... I freehand hone the blades on DMT Fine and Extra Fine bench stones, then move to an ultra fine ceramic, then strop on newspaper treated with a little Flitz metal polish.

Anyway, thanks for any tips, tricks, or advice any of you can provide.

Sam
 
Probably the most direct way to see what an edge can do, is to use a guided system of some sort. Might be an EdgePro, Wicked Edge, Lansky, Aligner, etc. Consistent angle control is what really sharp edges are all about. Even if you still otherwise prefer to freehand sharpen, an angle-guided edge can set a 'benchmark' for finding out what the steel is capable of, and also for finding out if your own skill set is up to par (proper use of pressure, fully apexing the edge are the other critically-important factors, besides controlling angle).

I literally never knew how sharp an edge could get, until I produced my first good one from a guided system. That gave me a 'target' to shoot for, in all my other sharpening endeavors.

Shaving/tree-topping/whittling hair has a whole lot of variables in itself. Different people's hair will behave differently, and hair from different areas of the body can be easier or more difficult to cut cleanly (leg hair is often easier than arm hair). Moisture/humidity makes a big difference too.

Edited to add:
Edge durability is important. A lot of times, a wire edge on a blade can shave, tree-top or whittle hair. But it will collapse under more challenging cutting tasks, even in paper. So, simply testing on hair alone might not prove much about the real quality of the edge.
 
Last edited:
For straight razors cutting a free hanging hair is a common benchmark, but as pointed out many variables still exist in that. I take my edges to 12K grit then to news print and plain leather. Thefinishing on 6K and 12K is done edge trailing and, of course, without proper exectution in previous steps you will get less than perfect results in the final steps.

Also, in general, the lower the Vanadium content the finer the edge can be.


-Xander
 
Hmm... Cutting a free hanging hair... I guess that's my next benchmark.

Part of the point of this exercise is to see just how well I can do freehand...

I rarely bother taking my edges to this level of sharpness...

Thanks! :)

Sam
 
I think you're next step is going to be looking at the edge under magnification.
 
i have the same problem i can whittle leg hairs. the blade just does not catch head hairs. i think it is alot in the steel's capability of getting sharp. the only knife i got to head hair whittling is my kershaw zing . tree topping a free hanging hair.
 
I'll have to take a look with my pocket microscope...

Mine will slice through hairs poking up off my head... but if I hold one in my fingers, it just bends away from the edge. Arm hairs and beard hairs just pop...

If popping a free hanging hair is possible, then I'll get there. :)

Not bad for a pair of Opinel #8's. One is stainless and the other is carbon.

Sam
 
I don't know if anyone else really cares, but I figured I would continue documenting my progress.

I've learned that my pocket microscope is not the ideal instrument for examining a knife edge. The 30x magnification seems like enough, but I don't have enough hands to see the edge at the angles I'm interested in... and I have a tendency to blind myself with the polished edge...

On the other hand, I'm happy to report partial success with the carbon steel blade. I can pop and/or split curls off of a hair from my head... But I need to hold it so that relatively little is sticking out between my finger and thumb ( about half an inch ) in order to do so... and it's a LOT easier to do that from the root end than the other end. I still can't pop a 3 inch long hair by holding it at the root end, but SOMETIMES I can pop it by holding it from the other end and cutting near the root end.

I'll start on the stainless blade next... and then try to get both blades to pop a free hanging hair.. so far, I'm very happy with my results.

Thanks for any and all advice/suggestions.

Sam
 
I read on the Spyderco subforum a story from Sal about how they got in a prototype of one of the kitchen knives from Japan and it came with a piece or rice paper and a note.

The not said, fold the rice paper in half, place it on the blade at the tang and blow it down the length of the knife. Just blowing it down the knife cut it in half.

Now that is sharp!
 
peeintheshower said:
so just for my own knowlege, carbon steel will get sharper then stainless, correct?
Click to expand...

I've read that in some places... I can't say that my experience matches that. I've also heard that it's easier to sharpen a carbon steel blade than a stainless blade. I can't say that I notice any obvious difference between the two Opinels. One is stainless, the other is carbon. Thus far, they seem to be equally sharp and took equal amounts of effort to get them that sharp. From what I've read, both steels are relatively soft. Perhaps it makes more difference when the steels are harder?

I'd love to hear other opinions, especially if someone has experience with matching Opinels or some other equivalent.

Thanks!

Sam
 
Scurvy092 said:
I read on the Spyderco subforum a story from Sal about how they got in a prototype of one of the kitchen knives from Japan and it came with a piece or rice paper and a note.

The not said, fold the rice paper in half, place it on the blade at the tang and blow it down the length of the knife. Just blowing it down the knife cut it in half.

Now that is sharp!
Click to expand...

That sounds pretty amazing. I'm certain I'm nowhere near THAT point, yet!

Sam
 
peeintheshower said:
so just for my own knowlege, carbon steel will get sharper then stainless, correct?
Click to expand...

I think it's safe (and more accurate) to say 'carbon steel is usually much easier to make very sharp'. Some modern stainless is very fine-grained, and can get extremely sharp. Whether any particular steel gets sharper than another, is more determined (in the end) by the person sharpening it, and the appropriate selection of abrasives to do the job.

Some of the 'super steels' rich in vanadium carbides are a lot more challenging to make as sharp, due to the larger average size of the carbides, and their extreme resistance to abrasion (sharpening). Simple carbon steels don't have those big, hard carbides, so they sharpen up much easier, with simpler abrasives.

Those two Opinels mentioned earlier are perfect examples. The stainless one is Sandvik 12c27Mod, and is very fine-grained. I have one each of the stainless and carbon No. 08s, and the stainless can get extremely sharp. It just takes a little more work and time. No vanadium carbides in it, but the chromium carbides make it more abrasion-resistant.
 
12C27N, 13C26N, 14C28N are all steels developed for razor blades and will take a very fine edge at an acute angle. Carbide size and grain refinement plays a major role in how fine an edge a steel can take (and support). Something to note here as well, very fine/sharp edges ar very easily damaged by our normal methods of checking, thumb nail, paper cutting, shaving dry hair, etc. Straight razors typically use 15*-17* edges, (30*-34* inclusive) which is much finer than most edc or even fine detail knives.

I would work edge trailing on a 6K and 8K stone/film/natural then move to 12k film or natural with a slurry, then strop on 0.3um pasted balsa for 30-50 laps then plain newsprint and plain leather. Edge should be highly polished by now.

Be sure to test on different parts of the edge too, this degree of sharpness is difficult to get, but will likely happen somewhere on your edge.


-Xander
 
Scurvy092 said:
I read on the Spyderco subforum a story from Sal about how they got in a prototype of one of the kitchen knives from Japan and it came with a piece or rice paper and a note.

The not said, fold the rice paper in half, place it on the blade at the tang and blow it down the length of the knife. Just blowing it down the knife cut it in half.

Now that is sharp!
Click to expand...

Not to doubt Sal, but I've been living in Japan for the past 25 years, spend a LOT of time with the various knife makers and sword sharpeners in Seki City and in Sakai in Osaka city, and I have NEVER seen anything like this. It reminds me of the story about King Richard and Saladin during the Crusades where Richard is bragging that his sword will cut a log in half with one blow and Saladin responds by dropping a silk cloth onto his scimitar and just the weight of the falling cloth cuts the silk in half.

We can all agree that a Gillette double-edged razor blade is pretty darn sharp, right? Thin, strong enough to last several shaves, and easily whittles hair. Try taking a roll-your-own cigarette paper and lay it over the Gillette and give it a blow. There are several brands that are rice paper. Trust... but verify.


Stitchawl
 
fast14riot said:
(...) Straight razors typically use 15*-17* edges, (30*-34* inclusive) which is much finer than most edc or even fine detail knives. (...)
-Xander
Click to expand...

Xander, aren't straight razors typically about half that? I seem to recall that many have inclusive angles somewhere around ~17° inclusive (8.5°/side). Most of my knives are sharpened to around 30° inclusive (15°/side), or sometimes even less.
 
Straight razors are usually put flat on the stone. Which means that the only thing creating an angle is the spine of the blade.

There's NO WAY I'd ever shave with a 30 degree angle razor.
 
:o oops, yes your right! It was a long day at work and I hadn't eaten dinner yet! Yes, angles are 15-17 degrees inclusive!

( I have had my coffee this morning!)

-Xander
 
sja2249, i had a customer tell me that he was treetopping hairs with a knife i sharpened (done on 80 grit abrasive). i have a vid of a knife i made cutting free hanging newspaper. http://www.youtube.com/watch?v=I7iDE2EBzBw

i made a knife for a friend here in town and i decided to show him what i call a "novelty edge". i pulled out a moustache hair and proceded to whittle it as if it were a toothpick down to where i was holding it. after that i removed that edge and put on my normal shaving sharp edge.
 
You must log in or register to reply here.
Back
Top