Cliff Stamp
BANNED
- Joined
- Oct 5, 1998
- Messages
- 17,562
Some work with a modified Livesay RTAK
This is Chad Engelhardt's RTAK made by Newt Livesay and designed by Jeff Randall. It is an extended version with a 14" blade, the norm is a ten inches. The steel is 1095 with a differential temper. I think the edge is 58-60 RC, the spine significantly softer. The blade shows signs of significant use, but has held up very well. The coating for one has just taken on a polished look, much better than a lot of what I have seen.
Design :
The handle is quite large, which is nice, as it means it is usable even on the rare occasions that I want to use a thick work glove. However it has quite a big swell which makes for an uncomfortable grip as I normally hold a knife high up on the handle. Different people have different hands and hold blades in different ways so this obviously isn't a universal opinion. The handle is also too slick for my preferences, as well as too thin and I would prefer more of an edge hook to drive off of, as well as to enhance security in general.
In regards to general design, the steel thickness, type and primary grind are all very sound choices. However I would not want a clip point. While it does offer some advantages, it makes a decent beater for rough work (roots), I would prefer a more inline point for reasons of balance (minor) and strength and stiffness (major). This does give up point penetration ability of course.
The edge was about 80 thousands thick behind the bevel which is ground at ~18 or so degrees. I made some measurements but promptly lost them, so that is from memory. I would radically slim down the edge, to at least half would be a start. This would still have it at more than twice the thickness of the Patrol Machete (near the front). About 0.030" is what I would expect my functional limit of durability to be for such work, but maybe I will be surprised by the replacement for the Patrol Machete.
NIB work :
I gave it a light sharpening and used it for limbing and general light brush work on woody vegetation . It took some time to develop a decent grip on the handle, I ended up working with index and fore finger in front on the swell, but it placed too much pressure on my index finger. This is further hampered by the grip being too smooth and thus I was having to hold tighter than normal, which compounds the problem of the rather thin cross section. My grip would relax to relieve the pressure and then the blade would slip to far forward. As noted, a more significant end hook would be nice both to prevent the blade from coming out of my hand as well as something to drive off of, the latter would only be practical with the swell removed.
The blade fares at about 65-70% of the raw chopping ability GB Wildlife Hatchet when bucking small wood (number of hits). This was only a few sections cut, but it was readily obvious that the performance was significantly lower. It was also significantly behind the Trmontina bolo on limbing ability. Some stock cutting on hardwood dowels showed the main cause. The hatchet could point one in about 15 slices, whereas the RTAK took ~37. This difference doesn't carry directly over into chopping performance, as chopping also depends on issues such as mass, balance, and of course the primary grind. The dowel slicing just shows the influence of the edge geometry, most importantly the angle and secondly the thickness.
Modifications and further work :
I adjusted the edge on the RTAK using a belt sander. I didn't change the angle of the very edge, just swept the shoulder back to 10-12 degrees per side. The edge then goes on very close to flat until it hits about 0.025" thick at which point it sweeps down to a very robust ~18 degrees per side. This is still over built for me personally, but I want to take the changes a bit at a time so I can see how much gain is made each time, plus it means that there is little risk of significant edge failure. The blade was then sharpened using a 1000 and then 4000 grit waterstone, and then finished with stropping on CrO loaded leather. It takes a fine polish easily which you would exact, as well it was very ease to grind. 1095 has a very high machinability and a fine grain.
This alteration to the edge profile made a huge impact on the cutting ability, roughing out hardwood dowels for example jumped from ~37 slices to ~15, now at the same level of the GB Wildlife hatchet. The next session of limbing showed a drastic performance jump. It now cut much closer to the Tramontina bolo, and doesn't bind, and is much stiffer. I took the Tramontina along, but unlike the first session I never used it extensively as the RTAK was enough.
The Tramontina has a similar edge profile except the shoulder is lower by a couple of degrees, and the very edge sweep is about 13-15 degrees so its more acute in both ways than the RTAK. However the RTAK actually has a primary grind which evens the score somewhat and means that it can stand a slightly more obtuse edge profile at the same level of cutting ability, and be more functional over all because of the stiffness. The RTAK has a high grade of steel and heat treat so in fact should be able to withstand a lower edge profile anyway.
After the limbing session (~500 chops), the RTAK still actually shaved roughly in places, and overall was still easily able to cut light grasses, no visible damage except for a couple of preexisting rough spots near the tip which I never removed when I sharpened it. I intend to use it with this profile for awhile until I take it down again so it will match the edge profile on the Tramontina, eventually it will be under it.
The handle of the RTAK took a major jump in comfort once the edge profile was changed to raise the cutting ability, it is still not practical for me though as the swell is too much, though the size I like. I am going to reduce the swell somewhat, a little at a time as it obviously can't be put back on once it is taken off.
I did have a problem with the RCM from Livesay, which is a similar knife :
http://www.physics.mun.ca/~sstamp/knives/RCM.html
which had edge ripple induced while on hardwood limbing on standing trees, done for prep for felling usually, as those limbs are sharp and hard enough to readily tear skin so you want them out of the way. They also make excellent kindling as well though as they are dry and small so they burn readily. In any case, I have been doing a fair amount of this with the RTAK with no problems, and nor do I expect any given the edge thickness. I don't think I could get this to ripple if I tried by beating the knife sideways into limbs. My wrist would probably give out from the vibration before the steel would bend.
Further work :
I have been using it with no problems lately as the main light brush knife and it is working very well. I still want to do some direct comparisons against the Tramontina on limbing, bucking and felling before I take the RTAK down again. I also figured out a workable grip, just index finger in the cutout, which seems obvious now. My natural instinct is to grip up further on the blade, but this way is more comfortable. I'll use it a while like this before removing some of the swell. There are still security problems due to the lack of texture and end hook. I will be interesting to see how both compare to the Jungle knife as it takes a significantly different approach to a solution of the same problem.
Overall :
The only real drawback of the RTAK's design over the Tramontina (stamped flat stock vs primary grind) for this type of work is that the thicker spine on the RTAK means that it doesn't make as good a limb hammer (or sod cutter etc.) on the dried branches, as the Tramontina can actually cut somewhat with the spine due to the higher pressure and the hump. However this doesn't compete with the stiffer RTAK and the potential for greater cutting ability once the edge profile is again modified. Primary grinds are a huge potential advantage. Plus the thicker and rounder spine of the RTAK make it a more friendly draw knife and splitter. I can break up dried small scrap by lightly chopping into it with the RTAK and just hitting the spine with my palm, that isn't comfortable with the Tramontina. The sheath is very well done for Kydex, though I don't actually wear it because it gets in the way. It does make a nice support for a writing pad.
Here is a link to some more detailed commentary on the Tramontina Bolo for reference :
http://www.bladeforums.com/forums/showthread.php?s=&threadid=198896
The blades will be used on lighter vegetation once it thaws around here.
-Cliff
This is Chad Engelhardt's RTAK made by Newt Livesay and designed by Jeff Randall. It is an extended version with a 14" blade, the norm is a ten inches. The steel is 1095 with a differential temper. I think the edge is 58-60 RC, the spine significantly softer. The blade shows signs of significant use, but has held up very well. The coating for one has just taken on a polished look, much better than a lot of what I have seen.
Design :
The handle is quite large, which is nice, as it means it is usable even on the rare occasions that I want to use a thick work glove. However it has quite a big swell which makes for an uncomfortable grip as I normally hold a knife high up on the handle. Different people have different hands and hold blades in different ways so this obviously isn't a universal opinion. The handle is also too slick for my preferences, as well as too thin and I would prefer more of an edge hook to drive off of, as well as to enhance security in general.
In regards to general design, the steel thickness, type and primary grind are all very sound choices. However I would not want a clip point. While it does offer some advantages, it makes a decent beater for rough work (roots), I would prefer a more inline point for reasons of balance (minor) and strength and stiffness (major). This does give up point penetration ability of course.
The edge was about 80 thousands thick behind the bevel which is ground at ~18 or so degrees. I made some measurements but promptly lost them, so that is from memory. I would radically slim down the edge, to at least half would be a start. This would still have it at more than twice the thickness of the Patrol Machete (near the front). About 0.030" is what I would expect my functional limit of durability to be for such work, but maybe I will be surprised by the replacement for the Patrol Machete.
NIB work :
I gave it a light sharpening and used it for limbing and general light brush work on woody vegetation . It took some time to develop a decent grip on the handle, I ended up working with index and fore finger in front on the swell, but it placed too much pressure on my index finger. This is further hampered by the grip being too smooth and thus I was having to hold tighter than normal, which compounds the problem of the rather thin cross section. My grip would relax to relieve the pressure and then the blade would slip to far forward. As noted, a more significant end hook would be nice both to prevent the blade from coming out of my hand as well as something to drive off of, the latter would only be practical with the swell removed.
The blade fares at about 65-70% of the raw chopping ability GB Wildlife Hatchet when bucking small wood (number of hits). This was only a few sections cut, but it was readily obvious that the performance was significantly lower. It was also significantly behind the Trmontina bolo on limbing ability. Some stock cutting on hardwood dowels showed the main cause. The hatchet could point one in about 15 slices, whereas the RTAK took ~37. This difference doesn't carry directly over into chopping performance, as chopping also depends on issues such as mass, balance, and of course the primary grind. The dowel slicing just shows the influence of the edge geometry, most importantly the angle and secondly the thickness.
Modifications and further work :
I adjusted the edge on the RTAK using a belt sander. I didn't change the angle of the very edge, just swept the shoulder back to 10-12 degrees per side. The edge then goes on very close to flat until it hits about 0.025" thick at which point it sweeps down to a very robust ~18 degrees per side. This is still over built for me personally, but I want to take the changes a bit at a time so I can see how much gain is made each time, plus it means that there is little risk of significant edge failure. The blade was then sharpened using a 1000 and then 4000 grit waterstone, and then finished with stropping on CrO loaded leather. It takes a fine polish easily which you would exact, as well it was very ease to grind. 1095 has a very high machinability and a fine grain.
This alteration to the edge profile made a huge impact on the cutting ability, roughing out hardwood dowels for example jumped from ~37 slices to ~15, now at the same level of the GB Wildlife hatchet. The next session of limbing showed a drastic performance jump. It now cut much closer to the Tramontina bolo, and doesn't bind, and is much stiffer. I took the Tramontina along, but unlike the first session I never used it extensively as the RTAK was enough.
The Tramontina has a similar edge profile except the shoulder is lower by a couple of degrees, and the very edge sweep is about 13-15 degrees so its more acute in both ways than the RTAK. However the RTAK actually has a primary grind which evens the score somewhat and means that it can stand a slightly more obtuse edge profile at the same level of cutting ability, and be more functional over all because of the stiffness. The RTAK has a high grade of steel and heat treat so in fact should be able to withstand a lower edge profile anyway.
After the limbing session (~500 chops), the RTAK still actually shaved roughly in places, and overall was still easily able to cut light grasses, no visible damage except for a couple of preexisting rough spots near the tip which I never removed when I sharpened it. I intend to use it with this profile for awhile until I take it down again so it will match the edge profile on the Tramontina, eventually it will be under it.
The handle of the RTAK took a major jump in comfort once the edge profile was changed to raise the cutting ability, it is still not practical for me though as the swell is too much, though the size I like. I am going to reduce the swell somewhat, a little at a time as it obviously can't be put back on once it is taken off.
I did have a problem with the RCM from Livesay, which is a similar knife :
http://www.physics.mun.ca/~sstamp/knives/RCM.html
which had edge ripple induced while on hardwood limbing on standing trees, done for prep for felling usually, as those limbs are sharp and hard enough to readily tear skin so you want them out of the way. They also make excellent kindling as well though as they are dry and small so they burn readily. In any case, I have been doing a fair amount of this with the RTAK with no problems, and nor do I expect any given the edge thickness. I don't think I could get this to ripple if I tried by beating the knife sideways into limbs. My wrist would probably give out from the vibration before the steel would bend.
Further work :
I have been using it with no problems lately as the main light brush knife and it is working very well. I still want to do some direct comparisons against the Tramontina on limbing, bucking and felling before I take the RTAK down again. I also figured out a workable grip, just index finger in the cutout, which seems obvious now. My natural instinct is to grip up further on the blade, but this way is more comfortable. I'll use it a while like this before removing some of the swell. There are still security problems due to the lack of texture and end hook. I will be interesting to see how both compare to the Jungle knife as it takes a significantly different approach to a solution of the same problem.
Overall :
The only real drawback of the RTAK's design over the Tramontina (stamped flat stock vs primary grind) for this type of work is that the thicker spine on the RTAK means that it doesn't make as good a limb hammer (or sod cutter etc.) on the dried branches, as the Tramontina can actually cut somewhat with the spine due to the higher pressure and the hump. However this doesn't compete with the stiffer RTAK and the potential for greater cutting ability once the edge profile is again modified. Primary grinds are a huge potential advantage. Plus the thicker and rounder spine of the RTAK make it a more friendly draw knife and splitter. I can break up dried small scrap by lightly chopping into it with the RTAK and just hitting the spine with my palm, that isn't comfortable with the Tramontina. The sheath is very well done for Kydex, though I don't actually wear it because it gets in the way. It does make a nice support for a writing pad.
Here is a link to some more detailed commentary on the Tramontina Bolo for reference :
http://www.bladeforums.com/forums/showthread.php?s=&threadid=198896
The blades will be used on lighter vegetation once it thaws around here.
-Cliff
