Cliff Stamp
BANNED
- Joined
- Oct 5, 1998
- Messages
- 17,562
This axe has a 2 lbs head with 3.5 inch face and a 25 inch handle. It is a traditional limbing axe, with enough reach to allow a clean sweep of a felled tree and enough heft to allow good power without generating excessive fatigue. Like all the Gransfors Bruks axes, this one is hand forged and has not been excessively polished or painted to "clean up" the forging. It is made of Swedish steel, most likely something like L6, and hardened to around 57 RC, just at the point where it can be filed.
Concerning balance, as Jimbo noted awhile ago this is just about perfect. It is center head balanced, which means if suspended upside down the head will true right to the center of the handle. The center of mass of the axe is also right below the head, perfect for the traditional two handed swing. The axe goes weightless as your power hand slips up the handle and as you sweep back down the center of balance rushes out and you can thus generate a large amount of power without always having to swing such a head heavy axe.
The handle has perfect vertical grain and is shaped to allow comfort even under very heavy hits. There is one small fault in the wood however. About midpoint up the handle there is a very small knot, about 1 mm in diameter, about 5 mm in from the edge of the handle. Not something that I would let pass if I was picking out the axe, will see how it goes in use. It is a small knot, and surrounded by strong wood. I don't foresee major problems. It would be more serious if it was just under the head.
The edge, like all Bruks axes comes nice and thin, with a high polish. However this one has a spot that is slightly marred. It is dented in and strongly reflects light. It looks like the edge was scraped off of a piece of hardened metal right after sharpening. Using a smooth steel I aligned the edge in that area (about 1.5 cm long) with about 20 light passes per side. Once I was finished you could just barely see light reflecting off of the edge.
Doing a simple check on push cutting sharpness, cutting light thread, I was surprised by how sharp the axe was near the toe of the bit. It would cut the thread repeatedly with just the barest hit of pressure, needing about 30 g of force to make a cut, this is at the same level of a razor blade. For reference, a well finished "shaving sharp" production knife will take about 100 g or so to cut the thread. However near the heel of the bit, the Bruks axe was not nearly as sharp taking about 175 g to make a cut, this is "hair scraping sharp". The damaged area after I steeled it needed about ~300 g. As a check of slicing sharpness I cut 1/4 inch poly under a 1000 g load. The edge took from 0.5 cm to 1.8 cm to cut through the poly. Thus parts of the edge were very sharp, as sharp or sharper as any production or custom knives, while other parts were significantly behind.
Moving beyond simple sharpness, I used the heel of the axe to do a rocking push cut through 3/8 inch poly. The axe cut through the rope with ease, biting it very strongly it was able to make complete cuts with 36 +/- 4 lbs of force. For comparison, this is the same cutting ability of the large drop point Twistmaster from Cold Steel. If this seems surprising, you have to consider that even though the cross section of the axe head is quite large, the actual edge profile is very thin and acute. Specifically here is the actual geometry :
http://www.physics.mun.ca/~sstamp/images/gb_forest_edge.gif
This is to scale, the crosses are the points that I measured. The edge starts off with a bevel of around 16 degrees per side but very quickly sweeps back to under ten degrees and finally hits a relief of about 6 degrees right before the start of the hollow part of the head profile. Note this is significantly more acute than most modern knives and thus the axe will easily out cut them on shallow penetration work.
I look forward to trying this axe out in felling some small work and cleaning it up. I may even be able to get out this weekend. Note, some work on a strop, 10 passes per side on CrO loaded leather, solved the problem with the marred portion of the edge.
-Cliff
Concerning balance, as Jimbo noted awhile ago this is just about perfect. It is center head balanced, which means if suspended upside down the head will true right to the center of the handle. The center of mass of the axe is also right below the head, perfect for the traditional two handed swing. The axe goes weightless as your power hand slips up the handle and as you sweep back down the center of balance rushes out and you can thus generate a large amount of power without always having to swing such a head heavy axe.
The handle has perfect vertical grain and is shaped to allow comfort even under very heavy hits. There is one small fault in the wood however. About midpoint up the handle there is a very small knot, about 1 mm in diameter, about 5 mm in from the edge of the handle. Not something that I would let pass if I was picking out the axe, will see how it goes in use. It is a small knot, and surrounded by strong wood. I don't foresee major problems. It would be more serious if it was just under the head.
The edge, like all Bruks axes comes nice and thin, with a high polish. However this one has a spot that is slightly marred. It is dented in and strongly reflects light. It looks like the edge was scraped off of a piece of hardened metal right after sharpening. Using a smooth steel I aligned the edge in that area (about 1.5 cm long) with about 20 light passes per side. Once I was finished you could just barely see light reflecting off of the edge.
Doing a simple check on push cutting sharpness, cutting light thread, I was surprised by how sharp the axe was near the toe of the bit. It would cut the thread repeatedly with just the barest hit of pressure, needing about 30 g of force to make a cut, this is at the same level of a razor blade. For reference, a well finished "shaving sharp" production knife will take about 100 g or so to cut the thread. However near the heel of the bit, the Bruks axe was not nearly as sharp taking about 175 g to make a cut, this is "hair scraping sharp". The damaged area after I steeled it needed about ~300 g. As a check of slicing sharpness I cut 1/4 inch poly under a 1000 g load. The edge took from 0.5 cm to 1.8 cm to cut through the poly. Thus parts of the edge were very sharp, as sharp or sharper as any production or custom knives, while other parts were significantly behind.
Moving beyond simple sharpness, I used the heel of the axe to do a rocking push cut through 3/8 inch poly. The axe cut through the rope with ease, biting it very strongly it was able to make complete cuts with 36 +/- 4 lbs of force. For comparison, this is the same cutting ability of the large drop point Twistmaster from Cold Steel. If this seems surprising, you have to consider that even though the cross section of the axe head is quite large, the actual edge profile is very thin and acute. Specifically here is the actual geometry :
http://www.physics.mun.ca/~sstamp/images/gb_forest_edge.gif
This is to scale, the crosses are the points that I measured. The edge starts off with a bevel of around 16 degrees per side but very quickly sweeps back to under ten degrees and finally hits a relief of about 6 degrees right before the start of the hollow part of the head profile. Note this is significantly more acute than most modern knives and thus the axe will easily out cut them on shallow penetration work.
I look forward to trying this axe out in felling some small work and cleaning it up. I may even be able to get out this weekend. Note, some work on a strop, 10 passes per side on CrO loaded leather, solved the problem with the marred portion of the edge.
-Cliff
