Cliff Stamp
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- Oct 5, 1998
- Messages
- 17,562
I recently did some work comparing a Heafner bowie (D2) vs a Ratweiler (SR101) on a variety of materials that you generally would not want to cut. Both blades were freehand sharpened to 16/18 degrees per side and raised to a fine polish by a natural chinese waterstone and would easily push cut newsprint and shave smoothly with no draw.
I started off with some 1/2" dirty poly rope which had been on the ground since last year and only recently came out of the snow and ice. Each knife made a dozen chop cuts with no effort and sent the pieces of rope flying. They easily sliced sections off of a cardboard box in the section of blade that had cut the dirty rope, little change to the cutting ability.
I then chopped up a steel handle off a mop, hollow tube, I assume mild steel. They easily chop cut through six sections each. The Heafner indented a little, about 0.2 mm deep and about 1.5 mm in length in one spot. They then chopped up a bone from a beef roast, whacked it into pieces. No visisble damage to the Ratweiler. They both easily still cut some slices off the cardboard box, they were not shaving sharp any more.
http://i7.photobucket.com/albums/y269/CliffStamp/Heafner Bowie/hb_rat_broom.jpg
I then chopped through the reinforcement bar that ran across the roof of a SUV which I chopped out awhile ago with the Heafner bowie. This is where things were interesting. The Heafner bowie is a lot more powerful on the swing as it is heavier (660 vs 540 grams) and carries more weight ahead of the grip where the Ratweiler is in comparison very light in what Possum coined dynamic balance.
Now since the Heafner impacts the bar with much more energy (I intend to measure this later on as well as the dynamic balance specifically) it might seem that it would take more stress and the comparison unfair towards it, but this isn't the case. It has the ability to cut right through the bar in 1-2 chops maximum, and after three sections cut the edge was barely effected :
http://i7.photobucket.com/albums/y269/CliffStamp/Heafner Bowie/hb_edge.jpg
In comparison the Ratweiler needed about 4-8 chops to cut through the bar and there was massive twisting when it failed to cut through due to lack of power on the swing and all the energy went into snapping around the edge as it would be in the metal at the end of the swing, and a result after three sections cut the edge looked like this :
http://i7.photobucket.com/albums/y269/CliffStamp/swamp rat/ratweiler/ratweiler_edge.jpg
For perspective :
http://i7.photobucket.com/albums/y269/CliffStamp/swamp rat/ratweiler/ratweiler_bar.jpg
Now some might point out, well yeah, there were way more impacts with the Ratweiler, but that wasn't the reason. After an equal number of impacts, which was three sections with the Heafner and one with the Ratweiler, the difference was obvious. Because the Heafner had much more power on the swing it was just taking compressional forces and the Ratweiler torsional, and steels are way weaker torsionally than they are compressionally.
http://i7.photobucket.com/albums/y269/CliffStamp/Heafner Bowie/hb_rat_crossbar.jpg
I am going to see if I can't get another piece of bar and rerun this just to check of course, but I have seen similar behavior lots of times when cutting metals. If you have to cut hard objects you have to get through them, if you only get part way then you have to go really light because otherwise if you get snaps across the edge then it leads to trouble.
Of course both knives could be chisel cut with a baton to remove the difference balances as a factor. I intend to check this as well assuming I can get the materials. This was more just to note how the nature of the knife can effect durability readily and that increasing chopping power can actually raise edge durability which is kind of unexpected at first thought.
-Cliff
I started off with some 1/2" dirty poly rope which had been on the ground since last year and only recently came out of the snow and ice. Each knife made a dozen chop cuts with no effort and sent the pieces of rope flying. They easily sliced sections off of a cardboard box in the section of blade that had cut the dirty rope, little change to the cutting ability.
I then chopped up a steel handle off a mop, hollow tube, I assume mild steel. They easily chop cut through six sections each. The Heafner indented a little, about 0.2 mm deep and about 1.5 mm in length in one spot. They then chopped up a bone from a beef roast, whacked it into pieces. No visisble damage to the Ratweiler. They both easily still cut some slices off the cardboard box, they were not shaving sharp any more.
http://i7.photobucket.com/albums/y269/CliffStamp/Heafner Bowie/hb_rat_broom.jpg
I then chopped through the reinforcement bar that ran across the roof of a SUV which I chopped out awhile ago with the Heafner bowie. This is where things were interesting. The Heafner bowie is a lot more powerful on the swing as it is heavier (660 vs 540 grams) and carries more weight ahead of the grip where the Ratweiler is in comparison very light in what Possum coined dynamic balance.
Now since the Heafner impacts the bar with much more energy (I intend to measure this later on as well as the dynamic balance specifically) it might seem that it would take more stress and the comparison unfair towards it, but this isn't the case. It has the ability to cut right through the bar in 1-2 chops maximum, and after three sections cut the edge was barely effected :
http://i7.photobucket.com/albums/y269/CliffStamp/Heafner Bowie/hb_edge.jpg
In comparison the Ratweiler needed about 4-8 chops to cut through the bar and there was massive twisting when it failed to cut through due to lack of power on the swing and all the energy went into snapping around the edge as it would be in the metal at the end of the swing, and a result after three sections cut the edge looked like this :
http://i7.photobucket.com/albums/y269/CliffStamp/swamp rat/ratweiler/ratweiler_edge.jpg
For perspective :
http://i7.photobucket.com/albums/y269/CliffStamp/swamp rat/ratweiler/ratweiler_bar.jpg
Now some might point out, well yeah, there were way more impacts with the Ratweiler, but that wasn't the reason. After an equal number of impacts, which was three sections with the Heafner and one with the Ratweiler, the difference was obvious. Because the Heafner had much more power on the swing it was just taking compressional forces and the Ratweiler torsional, and steels are way weaker torsionally than they are compressionally.
http://i7.photobucket.com/albums/y269/CliffStamp/Heafner Bowie/hb_rat_crossbar.jpg
I am going to see if I can't get another piece of bar and rerun this just to check of course, but I have seen similar behavior lots of times when cutting metals. If you have to cut hard objects you have to get through them, if you only get part way then you have to go really light because otherwise if you get snaps across the edge then it leads to trouble.
Of course both knives could be chisel cut with a baton to remove the difference balances as a factor. I intend to check this as well assuming I can get the materials. This was more just to note how the nature of the knife can effect durability readily and that increasing chopping power can actually raise edge durability which is kind of unexpected at first thought.
-Cliff
