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Sharpening on a rock?
- Thread starter m
- Start date
This is an image from one of our military survival schools in Peru. Here the students learn to use rocks and concrete to sharpen their machetes before going into the jungle. To answer your other question...with a soft stone that will readily breakdown and a little water you can get a shaving edge on a machete. The secret to this process is to have a flexible blade with a long flat grind. Personally I would rather use a good flat rock for machete sharpening than just about anything else....except for a belt sander.
If you need more info then do a search on Tactical Knives magazine website for a back issue in which I covered primitve sharpening techniques in a sharpening column...can't remember the issue it was in.
Jeff
------------------
Randall's Adventure & Training
jeff@jungletraining.com
Jeff
------------------
Randall's Adventure & Training
jeff@jungletraining.com
Cliff Stamp
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- Oct 5, 1998
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Natural sharpening stones are just shaped rocks and they work very well on all except the highest alloy steels as on those they are not hard enough to cut the carbides. You can use just about anything to get a decent edge on a knife. I have sharpened even high alloy stainless steels (VG-10) on a pick. That is mainly aligning though.
Getting the edge to approach shaving sharp is another matter as the rock or whatever needs to be very even as otherwise you will tear up the edge. You can flatten a rock fairly quickly using fine sand as a lapping compound which also serves as a rough abrasive to load a makeshift strop.
-Cliff
Getting the edge to approach shaving sharp is another matter as the rock or whatever needs to be very even as otherwise you will tear up the edge. You can flatten a rock fairly quickly using fine sand as a lapping compound which also serves as a rough abrasive to load a makeshift strop.
-Cliff
Cliff,
What steels do you mean when you say high alloy? I would think the shape (grind) and the hardness would effect how well a knife sharpens on "found" stones as well. I would like some specifics on what knives are good or bad to sharpen this way if you or anyone else has the time and inclination.As usual thanks for all the info.
msauta,
Thanks for the information.Unfortunately I don't think I have that one and I can't get it to come up on their site.
[This message has been edited by m (edited 06-29-2001).]
What steels do you mean when you say high alloy? I would think the shape (grind) and the hardness would effect how well a knife sharpens on "found" stones as well. I would like some specifics on what knives are good or bad to sharpen this way if you or anyone else has the time and inclination.As usual thanks for all the info.
msauta,
Thanks for the information.Unfortunately I don't think I have that one and I can't get it to come up on their site.
[This message has been edited by m (edited 06-29-2001).]
You can read the article here: http://www.jungletraining.com/primitiv.htm
As far as what sharpens the best, the thinner the edge grind and the more flexible the blade, the better it works on improvised stones.
Primitive flat diamond hones made by EZE LAP that are sometimes stumbled upon in remote areas seem to work about as good as anything.
Jeff
------------------
Randall's Adventure & Training
jeff@jungletraining.com
As far as what sharpens the best, the thinner the edge grind and the more flexible the blade, the better it works on improvised stones.
Primitive flat diamond hones made by EZE LAP that are sometimes stumbled upon in remote areas seem to work about as good as anything.
Jeff
------------------
Randall's Adventure & Training
jeff@jungletraining.com
Cliff Stamp
BANNED
- Joined
- Oct 5, 1998
- Messages
- 17,562
M :
Stainless mainly, I have not tried grinding any of the other alloy blades as rough hones and such as the edges on them are too refined and they would suffer an extreme performance loss if honed in such a manner. I might look at this in more detail as I restore old used blades.
Hardness is not as critical as alloy content. 1095 for example grinds very easily as compared to 440C even if the 1095 is much harder. Of course given the same steel, as the RC is dropped it will be easier to grind away, but also it will tend to suffer more impaction damage and thus require more work in the first place.
As for grinds, well I would not want to try and freehand a convex grind on a rock but that is just because I find that difficult on any flat hone. Any flat grinds should be ok. In regards to angle and such, that doesn't effect sharpening except by influencing how much damage the edge takes and thus how much work needs to be done.
Of course if you have not done a lot of freehand sharpening then you may find it difficult to sharpen on a rock if the angle is different than what you naturally tend to use, but you would have the same difficulty when using a benchstone.
And that is all flat rocks are, they are just the lowest quality benchhones you can get. Even the quarry rocks that are so poor that any decent Japanese craftsmen is likely to throw them away in disgust rather than shape a waterstone out of them , will be far better than any rock you are likely to find.
As well, based on my experience, the amount of work that it would take to reduce a quality blade down to such a level that you could improve it on a flat rock is well beyond a trip. You are talking an extended stay, or doing something in the short term that is very damaging to the blade, like digging in rocky soil or leaving it exposed to a very harsh enviroment, like salt water for long periods of time.
For long term stays I would investigate means of sharpening like using very fine silt combined with a rock that you have lapped flat. It is the eveness of the abrasive that is of primary importance. Even a small flaw in a hone can tear up an edge and leave large scores which not only reduce the performance but weaken the edge.
Can honing on flat rocks be done? Well yes, but I see it as akin to practicing cutting with a lawnmower blade as compared to a decent machete / bowie / whatever. You will get the job done, but it is far more difficult than with a decent tool.
The same skills that you would use on a decent hone (stroke control, cleaning when required, lapping to flatten and remove damage) are identical that you would use on a flat rock so just practice those. If you can freehand well on a quality hone, a flat stone will pose no problem, and just give a lower quality edge in a much longer period of time.
-Cliff
Stainless mainly, I have not tried grinding any of the other alloy blades as rough hones and such as the edges on them are too refined and they would suffer an extreme performance loss if honed in such a manner. I might look at this in more detail as I restore old used blades.
Hardness is not as critical as alloy content. 1095 for example grinds very easily as compared to 440C even if the 1095 is much harder. Of course given the same steel, as the RC is dropped it will be easier to grind away, but also it will tend to suffer more impaction damage and thus require more work in the first place.
As for grinds, well I would not want to try and freehand a convex grind on a rock but that is just because I find that difficult on any flat hone. Any flat grinds should be ok. In regards to angle and such, that doesn't effect sharpening except by influencing how much damage the edge takes and thus how much work needs to be done.
Of course if you have not done a lot of freehand sharpening then you may find it difficult to sharpen on a rock if the angle is different than what you naturally tend to use, but you would have the same difficulty when using a benchstone.
And that is all flat rocks are, they are just the lowest quality benchhones you can get. Even the quarry rocks that are so poor that any decent Japanese craftsmen is likely to throw them away in disgust rather than shape a waterstone out of them , will be far better than any rock you are likely to find.
As well, based on my experience, the amount of work that it would take to reduce a quality blade down to such a level that you could improve it on a flat rock is well beyond a trip. You are talking an extended stay, or doing something in the short term that is very damaging to the blade, like digging in rocky soil or leaving it exposed to a very harsh enviroment, like salt water for long periods of time.
For long term stays I would investigate means of sharpening like using very fine silt combined with a rock that you have lapped flat. It is the eveness of the abrasive that is of primary importance. Even a small flaw in a hone can tear up an edge and leave large scores which not only reduce the performance but weaken the edge.
Can honing on flat rocks be done? Well yes, but I see it as akin to practicing cutting with a lawnmower blade as compared to a decent machete / bowie / whatever. You will get the job done, but it is far more difficult than with a decent tool.
The same skills that you would use on a decent hone (stroke control, cleaning when required, lapping to flatten and remove damage) are identical that you would use on a flat rock so just practice those. If you can freehand well on a quality hone, a flat stone will pose no problem, and just give a lower quality edge in a much longer period of time.
-Cliff
- Joined
- Apr 27, 1999
- Messages
- 6,117
Rather than look for a flat rock I would look for a flattish or cylindrical water worn (aka river rock).
The only problem with river stones where I live is they are usually quartz which is way too hard to sufficiently break down and cut steel.