Cliff Stamp
BANNED
- Joined
- Oct 5, 1998
- Messages
- 17,562
Specifications :
This is a drop-point knife with about six inches of sharpened edge and a very long choil, about two inches. The blade weighs 310 g and is forged from O-1 steel and came with a satin finish. The edge is hardened to 57 HRC. The handle is Rose wood and is shaped with finger grooves. The guard is steel and the butt is bronze. It came with a very robust leather sheath.
Blade profile :
The knife is about 1 1/8" wide with a full convex grind. It came with a secondary bevel which was decently acute which I blended back into the primary edge bevel. This was done simply because I can freehand sharpen that grind easier with benchstones than knives with secondary bevels. After the grinding the profile was as follows :
0.010 x 0.020"
0.024 x 0.063
0.050 x 0.116
0.071 x 0.177
0.098 x 0.290
0.123 x 0.435
0.160 x 0.683
0.188 x 0.935
0.186 x 1.106
Thus the knife edge is formed by a bevel of under thirty degrees included and this sweeps back strongly and is under 20 degrees included by the time you reach the thickness of the secondary edge bevel on most knives. This should offer a high degree of smooth cutting ability, with of course a corrosponding decrease in edge durability.
Choil :
As noted the knife has a very large choil. The major problem with this design is that it puts the start of the sharpened edge far infront of your grip. This creates a torque disadvantage which means that your wrist strain will be high for heavy cutting. In this case it is about a 66% increase for me . It is dependent on the size of your hand, the wider your hand the smaller the decrease in torque, about 55-75% would cover most adults. So given that this is a fairly significant decrease in cutting performance why put in the choil aside from aesthetic reasons? The argument could be made that you can simply use the choil as part of the grip to remove the leverage disadvantage, but there are ergonomic issues with even the most comfortable choils, so there has to be other reasons.
The large choil gives you several of the advantages of a much longer blade while at the same time retaining the precision of a smaller one, though with some sacrifice to ergonomics. This blade acts for example in chopping as if had an eight inch blade in regards to power, it also has the same reach . It would therefore significantly out chop the same knife without the choil. The point could be made though that this would all be possible if the extra two inches of choil were simply two extra inches of handle, as well the extra handle length would be much more comfortable as a grip than a choil. This is true, the only advantage that comes from having the extra length in the choil rather than an extended handle is that the choil allows directly deeper cuts.
Guard :
At first glance I thought that the guard curvature was off as it goes out straight and then slants up, this would tend to promote ramping and thus lower security, however working with the knife in a choked up position, this geometry fits very well inbetween the fingers. The guard does prevent a number of reverse grips because it is so thin at the point , about a mm, it digs readily into the palm, it is very difficult to use for paring type cutting for example. A thicker guard would be more comfortable, but might split the fingers too much to make choked up grips functional. If you removed the guard more grips would be functional, but of course you would lose grip security.
Cutting ability and handle issues :
I was mainly carving cedar, not because of any particular property of the wood, but simply because I had some baseboard left over that was going to be burnt. Comparing this knife against a Camp Tramp from Swamp Rat knife works, both were similar in ease of heavy roughing. This wood is so soft you can ream off large chips quite easily, so it isn't the best wood for such comparisions, but I had it on hand and it did allow me to get a feel for the handle which was my main reason for doing all the whittling. Later on I used some more dense wood and the forged custom did not have the extent of the performance increase I expected given its thinner profile. The the more narrow choil induces another torque disadvantage as the spine isn't fully supported by my hand and thus the blade gets pushed back on an angle into the start of the cut. On the much wider Camp Tramp I can position my thumb a little in front of my index finger and push directly into the cut.
As for the handle, as noted in the above, because the edge is so far infront of the grip you are at a leverage disadvantage. I did some comparison cuts to have a look at this to see if I could estimate the difference, but what tended to happen was that I would just push harder on the cuts where the leverage was worse. In any case you can really feel a huge difference in the strain on your wrist. If I control the cuts so that the cut ratio comes out from what I would expect given a simple torque comparison, my wrist feels about the same effort wise. You can compare it more directly by just doing heavy full power cuts both ways at maximum force, this does as noted though do a number of your wrist. I'll probably check this later on.
I thought at first that since the choil is so thick, almost a half an inch of steel, and decently rounded it would be fairly comfortable, and in fact it is much more ergonomic than trying to use the Camp Tramp in the same manner. However it doesn't take more than a few cuts for a problem to become evident very quickly. The guard is very thin and the edges squarish and thus they generate high pressure contact points quickly. I can use it for longer than the Camp Tramp, but both would have me wanting a glove quickly. However the fix for this was simple, I just used a dremel and rounded the edges on the guard. It is still a little abrasive as it is thin, but not so much that I would find it a problem. With this fix it is now much more comfortable than the Camp Tramp in a choked up position.
Does the more acute grind profile show any cutting advanatges? Well much of the cutting was strongly influenced by grip issues which tended to mask the difference in edge geometry so I took that out by doing some simple chopping. I just put the baseboard and held it across my knee and did some light chopping with both knives. It was readily obvious that the forged custom could get the same penetration as the Camp Tramp under much less impact which you would expect given the more acute profile. However this will not actually carry over to a direct advantage in chopping because the heavier Camp Tramp can generate more power in the swing which will act to increase its penetration directly. I'll comment more on that later when I get some chopping comparisons done.
Edge retention, durability and sharpening :
How did the edges hold up? Well normally carving wood doesn't do anything to tempered steel as normal grades of wood are not that abrasive, however this wood was painted, many layers in fact, and the paint was breaking apart around contacts with the edge during fairly fast and heavy cuts which does make it a lot more demanding than on clean wood. The Camp Tramp and custom were both lightly blunted, both could not shave but both could slice photocopy paper stright down. The Camp Tramp was stropped 20 passes per side on CrO loaded leather and was again shaving sharp. The custom was hit with 30 passes per side and not greatly effected mainly because the contact pressure is very low on the custom due to the full grind, this is the advantage of having a secondary edge bevel it greatly speeds up sharpening. I used a 4o00 grit waterstone to reset the bevel on the custom, this only took about a minute or so as it was not as noted heavily blunted. I then gave it a light 10 passes on CrO and then another 10 on plain leather, it was now back to full performance and could for example push straight into the paper.
I should note that the custom did have some areas of edge damage about a tenth of a mm deep. This doesn't mean however that the steel is inherently less durable, the edge angle is slightly more acute for one, but also the wood was used could have contained grit as it was lying on the basement floor for a few days.
Overview :
With the current profile it should prove a very solid cutting tool for the majority of utility woor and be a very nice wood working blade. I am looking forward to getting some more use out of it, hopefully this weekend I will be able to do some light chopping and limbing with it. The finger grooves might be a problem as they are a bit too far apart for my hand. I would estimate for them to be dead on you would want about 3.25-3.5" between the center of the knuckle of your index finger and pinky. I'll put up a few shots shortly.
Ref :
http://members.attcanada.ca/~armjan/Index.html
-Cliff
This is a drop-point knife with about six inches of sharpened edge and a very long choil, about two inches. The blade weighs 310 g and is forged from O-1 steel and came with a satin finish. The edge is hardened to 57 HRC. The handle is Rose wood and is shaped with finger grooves. The guard is steel and the butt is bronze. It came with a very robust leather sheath.
Blade profile :
The knife is about 1 1/8" wide with a full convex grind. It came with a secondary bevel which was decently acute which I blended back into the primary edge bevel. This was done simply because I can freehand sharpen that grind easier with benchstones than knives with secondary bevels. After the grinding the profile was as follows :
0.010 x 0.020"
0.024 x 0.063
0.050 x 0.116
0.071 x 0.177
0.098 x 0.290
0.123 x 0.435
0.160 x 0.683
0.188 x 0.935
0.186 x 1.106
Thus the knife edge is formed by a bevel of under thirty degrees included and this sweeps back strongly and is under 20 degrees included by the time you reach the thickness of the secondary edge bevel on most knives. This should offer a high degree of smooth cutting ability, with of course a corrosponding decrease in edge durability.
Choil :
As noted the knife has a very large choil. The major problem with this design is that it puts the start of the sharpened edge far infront of your grip. This creates a torque disadvantage which means that your wrist strain will be high for heavy cutting. In this case it is about a 66% increase for me . It is dependent on the size of your hand, the wider your hand the smaller the decrease in torque, about 55-75% would cover most adults. So given that this is a fairly significant decrease in cutting performance why put in the choil aside from aesthetic reasons? The argument could be made that you can simply use the choil as part of the grip to remove the leverage disadvantage, but there are ergonomic issues with even the most comfortable choils, so there has to be other reasons.
The large choil gives you several of the advantages of a much longer blade while at the same time retaining the precision of a smaller one, though with some sacrifice to ergonomics. This blade acts for example in chopping as if had an eight inch blade in regards to power, it also has the same reach . It would therefore significantly out chop the same knife without the choil. The point could be made though that this would all be possible if the extra two inches of choil were simply two extra inches of handle, as well the extra handle length would be much more comfortable as a grip than a choil. This is true, the only advantage that comes from having the extra length in the choil rather than an extended handle is that the choil allows directly deeper cuts.
Guard :
At first glance I thought that the guard curvature was off as it goes out straight and then slants up, this would tend to promote ramping and thus lower security, however working with the knife in a choked up position, this geometry fits very well inbetween the fingers. The guard does prevent a number of reverse grips because it is so thin at the point , about a mm, it digs readily into the palm, it is very difficult to use for paring type cutting for example. A thicker guard would be more comfortable, but might split the fingers too much to make choked up grips functional. If you removed the guard more grips would be functional, but of course you would lose grip security.
Cutting ability and handle issues :
I was mainly carving cedar, not because of any particular property of the wood, but simply because I had some baseboard left over that was going to be burnt. Comparing this knife against a Camp Tramp from Swamp Rat knife works, both were similar in ease of heavy roughing. This wood is so soft you can ream off large chips quite easily, so it isn't the best wood for such comparisions, but I had it on hand and it did allow me to get a feel for the handle which was my main reason for doing all the whittling. Later on I used some more dense wood and the forged custom did not have the extent of the performance increase I expected given its thinner profile. The the more narrow choil induces another torque disadvantage as the spine isn't fully supported by my hand and thus the blade gets pushed back on an angle into the start of the cut. On the much wider Camp Tramp I can position my thumb a little in front of my index finger and push directly into the cut.
As for the handle, as noted in the above, because the edge is so far infront of the grip you are at a leverage disadvantage. I did some comparison cuts to have a look at this to see if I could estimate the difference, but what tended to happen was that I would just push harder on the cuts where the leverage was worse. In any case you can really feel a huge difference in the strain on your wrist. If I control the cuts so that the cut ratio comes out from what I would expect given a simple torque comparison, my wrist feels about the same effort wise. You can compare it more directly by just doing heavy full power cuts both ways at maximum force, this does as noted though do a number of your wrist. I'll probably check this later on.
I thought at first that since the choil is so thick, almost a half an inch of steel, and decently rounded it would be fairly comfortable, and in fact it is much more ergonomic than trying to use the Camp Tramp in the same manner. However it doesn't take more than a few cuts for a problem to become evident very quickly. The guard is very thin and the edges squarish and thus they generate high pressure contact points quickly. I can use it for longer than the Camp Tramp, but both would have me wanting a glove quickly. However the fix for this was simple, I just used a dremel and rounded the edges on the guard. It is still a little abrasive as it is thin, but not so much that I would find it a problem. With this fix it is now much more comfortable than the Camp Tramp in a choked up position.
Does the more acute grind profile show any cutting advanatges? Well much of the cutting was strongly influenced by grip issues which tended to mask the difference in edge geometry so I took that out by doing some simple chopping. I just put the baseboard and held it across my knee and did some light chopping with both knives. It was readily obvious that the forged custom could get the same penetration as the Camp Tramp under much less impact which you would expect given the more acute profile. However this will not actually carry over to a direct advantage in chopping because the heavier Camp Tramp can generate more power in the swing which will act to increase its penetration directly. I'll comment more on that later when I get some chopping comparisons done.
Edge retention, durability and sharpening :
How did the edges hold up? Well normally carving wood doesn't do anything to tempered steel as normal grades of wood are not that abrasive, however this wood was painted, many layers in fact, and the paint was breaking apart around contacts with the edge during fairly fast and heavy cuts which does make it a lot more demanding than on clean wood. The Camp Tramp and custom were both lightly blunted, both could not shave but both could slice photocopy paper stright down. The Camp Tramp was stropped 20 passes per side on CrO loaded leather and was again shaving sharp. The custom was hit with 30 passes per side and not greatly effected mainly because the contact pressure is very low on the custom due to the full grind, this is the advantage of having a secondary edge bevel it greatly speeds up sharpening. I used a 4o00 grit waterstone to reset the bevel on the custom, this only took about a minute or so as it was not as noted heavily blunted. I then gave it a light 10 passes on CrO and then another 10 on plain leather, it was now back to full performance and could for example push straight into the paper.
I should note that the custom did have some areas of edge damage about a tenth of a mm deep. This doesn't mean however that the steel is inherently less durable, the edge angle is slightly more acute for one, but also the wood was used could have contained grit as it was lying on the basement floor for a few days.
Overview :
With the current profile it should prove a very solid cutting tool for the majority of utility woor and be a very nice wood working blade. I am looking forward to getting some more use out of it, hopefully this weekend I will be able to do some light chopping and limbing with it. The finger grooves might be a problem as they are a bit too far apart for my hand. I would estimate for them to be dead on you would want about 3.25-3.5" between the center of the knuckle of your index finger and pinky. I'll put up a few shots shortly.
Ref :
http://members.attcanada.ca/~armjan/Index.html
-Cliff