The Double L Hoofknife story Trials and tribulations of trying to make the worlds best Hoof knife.
Sunday, March 07, 2004
Break it and then go fix it. The Double L Hoofknife story.
Version 3
Some times when we set out on a new venture, we have little or no idea just where it will eventually lead us and this is exactly what happened here at the Double L, a subsidiary of Bronk’s Knifeworks. Just to bring you up to speed, we designed the Double L Hoof Knife so that the blades can be changed in order to keep down the cost and bring up the quality of the knife to better achieve high performance. We make our living here making knives good enough to make your living. We wanted a knife that would perform well in the field and remain economical to use. In order to do this we decided to make the handle from durable aluminum and cover it with attractive wood Micarta scales for comfort and the replacement blades can be easily installed by removing a pair of Chicago screws. The blades are made from high carbon spring steel (1095) and heat treated so that the edge is very hard so that it will stay sharp longer. The Back of the blade is left much like a spring and can flex without breaking. This is referred to as differential hardening and is akin to how the Samurai swords were made. Much research and testing preceded the launch of the Double L Hoofknife and the performance of the knives exceeded our expectations. All the feedback came back as positive and everyone who used the knife liked it. Then it happened. The phone rang and I was talking to a farrier who had not just one but two broken blades. I was stunned and asked him to ship me the blades for testing but the initial testing indicated that they were indeed right on track. However when the remnant was placed under a strain it snapped much too easily. What could be wrong here, I asked. Then it hit me. I had been working on a research project regarding grain boundary embrittlement of alloy steels in regard to steels such as E52100 and O 1 tool steel. These are steels that I have considered using for some new projects in the future and they require special handling as far as heat treating is concerned. This is the irony, 1095 (the steel used in the “Double L Hoof Knife”) is regarded as non alloy (10XX) steel and should, by its very nature, not have these same characteristics and problems as the high carbon chrome steels. However fate sometimes does not bend to our beckon and call and reaches out to us with new lessons to be learned. I dug out the spec sheets of some the shipments of 1095 that I had received over the past couple of years and yes indeed, there was a trace amount of chromium in some of these batches of steel. It should be noted here that the steel mills do not control the individual batches to the nth degree and often trace alloying elements are introduced into the batch from the various sources such as scrape piles of used steel. This will lead to some considerable differences in the steels behavior and response to heat treating, giving that a small change in the steel chemistry will profoundly affect the steels characteristics. Chromium is added to many steels to aid in the hardening process. This is a good thing as a rule and can simplify one of the difficulties of hardening steels if added in sufficient quantity, but it does require some adjustment to the process because it consequently will also affect the carbon migration. While not enough chromium is present to make the hardening noticeably easier with the 1095 steel, it did appear to have a significant affect. Now here is the real problem. I thought and I knew that the time and temperature curve required to disperse the carbon uniformly through out the steel. 10XX steels usually only require a short amount of time to do the job at elevated temperatures, but testing has demonstrated that trace amounts of chromium can require a much longer soak time at elevated temperatures to get the carbon into full solution and uniformly dispersed from fully annealed steel. I also knew that during the annealing process, the carbon will gradually pool up in small globules, hence spheroidized steel. The chromium will bloke the carbon and can greatly slow down the migration upon reheating, preventing it from getting uniformly dispersed, but at what percentage? With higher percent carbon steels, if the carbon is not allowed enough time to become dispersed and go into complete solution, the carbon can form on the grain boundaries as carbides which are very brittle leaving an undesirable grain boundary configuration and brittle blade. Testing has shown that a minimum of 20 minutes are required for complete saturation with some steels. Grain boundary embrittlement has been considered a problem of hypereutectoid or high carbon steels such as 52100 or O1, and I surmised that the mid range steels can be adversely affected by heat treating annealed steels as well. 5160 may not be affected by grain boundary problems, but I would also think that having the carbon uniformly dispersed would be a good thing with any steel and would lend to a more abrasive resistant edge as well as being stronger.
During the process of running these tests, I submitted samples of the 1095 to a metallurgist for further analysis and after careful revue of what I had done and looking at polished and etched samples under high amplification, Dr. John Verhoeven determined that something indeed was happening to the steel but the carbon was probably not the culprit in this case. Instead Dr. Verhoeven has suggested that the real culprit or culprits may be sulfur and or phosphorus.
John suggests that during the annealing process the sulfur and phosphorus will disassociate itself from the iron and remain dissolved in the cooling austenite until the austenite gradually transforms to pearlite and disappears. At this point, the sulfur and phosphorus would be deposited on the grain boundaries as a concentrate. Given that the strength of steel is duly credited to the strength of the material forming the grain boundary and binding the grains together, these two elements would leave a weakened grain structure as they have little strength in themselves.
Upon reheating considerable time, as the tests have indicated, is needed to disperse the impurities into complete solution. With a quicker cooling, such as in normalizing or hardening, the sulfur and phosphorus will remain dispersed throughout the iron and in this scattered condition will have little effect on the grain boundary or the strength of the steel.Although this will add a significant amount of time to heat treat blades, it is the only viable solution to achieving truly stunning performance from a blade and has become standard operating procedures here at the shop. I have destroyed many of the blades in testing and am confident that even though the “Double L Hoofknife” blades are very hard on the cutting edge they are also very resistant to breakage. Achieving a truly great hoof knife has been a long and arduous task. It has drawn on the experience of the makers 28 plus years in the knife making field, has required help in the form of analytical testing, much field testing and last but not least the valuable feedback from our farrier friends and customers who use our knives to make their living. We have had to replace very few blades and we will continue to do so if any one does have a blade break providing they send it back for analysis. And as always we consider problems here as opportunities to improve what we consider the worlds finest hoof knives. Contact bronks@bronksknifeworks.com Lyle Brunckhorst Bronk’s Knifeworks 23706 7th Ave. SE Suite B Bothell, WA 98021 425 402-3484 The Double L Hoof Knife is distributed exclusively by Delta Horseshoe Co. 4000 Alvis Court, Rocklin, CA 95677, 1 800 931-7181
Version 3
Some times when we set out on a new venture, we have little or no idea just where it will eventually lead us and this is exactly what happened here at the Double L, a subsidiary of Bronk’s Knifeworks. Just to bring you up to speed, we designed the Double L Hoof Knife so that the blades can be changed in order to keep down the cost and bring up the quality of the knife to better achieve high performance. We make our living here making knives good enough to make your living. We wanted a knife that would perform well in the field and remain economical to use. In order to do this we decided to make the handle from durable aluminum and cover it with attractive wood Micarta scales for comfort and the replacement blades can be easily installed by removing a pair of Chicago screws. The blades are made from high carbon spring steel (1095) and heat treated so that the edge is very hard so that it will stay sharp longer. The Back of the blade is left much like a spring and can flex without breaking. This is referred to as differential hardening and is akin to how the Samurai swords were made. Much research and testing preceded the launch of the Double L Hoofknife and the performance of the knives exceeded our expectations. All the feedback came back as positive and everyone who used the knife liked it. Then it happened. The phone rang and I was talking to a farrier who had not just one but two broken blades. I was stunned and asked him to ship me the blades for testing but the initial testing indicated that they were indeed right on track. However when the remnant was placed under a strain it snapped much too easily. What could be wrong here, I asked. Then it hit me. I had been working on a research project regarding grain boundary embrittlement of alloy steels in regard to steels such as E52100 and O 1 tool steel. These are steels that I have considered using for some new projects in the future and they require special handling as far as heat treating is concerned. This is the irony, 1095 (the steel used in the “Double L Hoof Knife”) is regarded as non alloy (10XX) steel and should, by its very nature, not have these same characteristics and problems as the high carbon chrome steels. However fate sometimes does not bend to our beckon and call and reaches out to us with new lessons to be learned. I dug out the spec sheets of some the shipments of 1095 that I had received over the past couple of years and yes indeed, there was a trace amount of chromium in some of these batches of steel. It should be noted here that the steel mills do not control the individual batches to the nth degree and often trace alloying elements are introduced into the batch from the various sources such as scrape piles of used steel. This will lead to some considerable differences in the steels behavior and response to heat treating, giving that a small change in the steel chemistry will profoundly affect the steels characteristics. Chromium is added to many steels to aid in the hardening process. This is a good thing as a rule and can simplify one of the difficulties of hardening steels if added in sufficient quantity, but it does require some adjustment to the process because it consequently will also affect the carbon migration. While not enough chromium is present to make the hardening noticeably easier with the 1095 steel, it did appear to have a significant affect. Now here is the real problem. I thought and I knew that the time and temperature curve required to disperse the carbon uniformly through out the steel. 10XX steels usually only require a short amount of time to do the job at elevated temperatures, but testing has demonstrated that trace amounts of chromium can require a much longer soak time at elevated temperatures to get the carbon into full solution and uniformly dispersed from fully annealed steel. I also knew that during the annealing process, the carbon will gradually pool up in small globules, hence spheroidized steel. The chromium will bloke the carbon and can greatly slow down the migration upon reheating, preventing it from getting uniformly dispersed, but at what percentage? With higher percent carbon steels, if the carbon is not allowed enough time to become dispersed and go into complete solution, the carbon can form on the grain boundaries as carbides which are very brittle leaving an undesirable grain boundary configuration and brittle blade. Testing has shown that a minimum of 20 minutes are required for complete saturation with some steels. Grain boundary embrittlement has been considered a problem of hypereutectoid or high carbon steels such as 52100 or O1, and I surmised that the mid range steels can be adversely affected by heat treating annealed steels as well. 5160 may not be affected by grain boundary problems, but I would also think that having the carbon uniformly dispersed would be a good thing with any steel and would lend to a more abrasive resistant edge as well as being stronger.
During the process of running these tests, I submitted samples of the 1095 to a metallurgist for further analysis and after careful revue of what I had done and looking at polished and etched samples under high amplification, Dr. John Verhoeven determined that something indeed was happening to the steel but the carbon was probably not the culprit in this case. Instead Dr. Verhoeven has suggested that the real culprit or culprits may be sulfur and or phosphorus.
John suggests that during the annealing process the sulfur and phosphorus will disassociate itself from the iron and remain dissolved in the cooling austenite until the austenite gradually transforms to pearlite and disappears. At this point, the sulfur and phosphorus would be deposited on the grain boundaries as a concentrate. Given that the strength of steel is duly credited to the strength of the material forming the grain boundary and binding the grains together, these two elements would leave a weakened grain structure as they have little strength in themselves.
Upon reheating considerable time, as the tests have indicated, is needed to disperse the impurities into complete solution. With a quicker cooling, such as in normalizing or hardening, the sulfur and phosphorus will remain dispersed throughout the iron and in this scattered condition will have little effect on the grain boundary or the strength of the steel.Although this will add a significant amount of time to heat treat blades, it is the only viable solution to achieving truly stunning performance from a blade and has become standard operating procedures here at the shop. I have destroyed many of the blades in testing and am confident that even though the “Double L Hoofknife” blades are very hard on the cutting edge they are also very resistant to breakage. Achieving a truly great hoof knife has been a long and arduous task. It has drawn on the experience of the makers 28 plus years in the knife making field, has required help in the form of analytical testing, much field testing and last but not least the valuable feedback from our farrier friends and customers who use our knives to make their living. We have had to replace very few blades and we will continue to do so if any one does have a blade break providing they send it back for analysis. And as always we consider problems here as opportunities to improve what we consider the worlds finest hoof knives. Contact bronks@bronksknifeworks.com Lyle Brunckhorst Bronk’s Knifeworks 23706 7th Ave. SE Suite B Bothell, WA 98021 425 402-3484 The Double L Hoof Knife is distributed exclusively by Delta Horseshoe Co. 4000 Alvis Court, Rocklin, CA 95677, 1 800 931-7181
Break it and then go fix it.
The Double L Hoofknife story.
Some times when we set out on a new venture, we have little or no idea just where it will eventually lead us and this is exactly what happened here at the Double L, a subsidiary of Bronk’s Knifeworks. Just to bring you up to speed, we designed the Double L Hoof Knife so that the blades can be changed in order to keep down the cost and bring up the quality of the knife to better achieve high performance. We make our living here making knives good enough to make your living.
We wanted a knife that would perform well in the field and remain economical to use. In order to do this we decided to make the handle from durable aluminum and cover it with attractive wood Micarta scales for comfort and the replacement blades can be easily installed by removing a pair of Chicago screws. The blades are made from high carbon spring steel (1095) and heat treated so that the edge is very hard so that it will stay sharp longer. The Back of the blade is left much like a spring and can flex without breaking. This is referred to as differential hardening and is akin to how the Samurai swords were made.
Much research and testing preceded the launch of the Double L Hoofknife and the performance of the knives exceeded our expectations. All the feedback came back as positive and everyone who used the knife liked it. Then it happened. The phone rang and I was talking to a farrier who had not just one but two broken blades. I was stunned and asked him to ship me the blades for testing but the initial testing indicated that they were indeed right on track. However when the remnant was placed under a strain it snapped much too easily. What could be wrong here, I asked. Then it hit me.
Luckily I had been working on a research project regarding grain boundary embrittlement of alloy steels in regard to steels such as E52100 and O 1 tool steel. These are steels that I have considered using for some new projects in the future and they require special handling as far as heat treating is concerned.
This is the irony, 1095 (the steel used in the “Double L Hoof Knife”) is regarded as non alloy (10XX) steel and should, by its very nature, not have these same characteristics and problems as the high carbon chrome steels. However fate sometimes does not bend to our beckon and call and reaches out to us with new lessons to be learned.
I dug out the spec sheets of some the shipments of 1095 that I had received over the past couple of years and yes indeed, there was a trace amount of chromium in some of these batches of steel. It should be noted here that the steel mills do not control the individual batches to the nth degree and often trace alloying elements are introduced into the batch from the various sources such as scrape piles of used steel. This will lead to some considerable differences in the steels behavior and response to heat treating, giving that a small change in the steel chemistry will profoundly affect the steels characteristics.
Chromium is added to many steels to aid in the hardening process. This is a good thing as a rule and can simplify one of the difficulties of hardening steels if added in sufficient quantity, but it does require some adjustment to the process because it consequently will also affect the carbon migration. While not enough chromium is present to make the hardening noticeably easier with the 1095 steel, it did prove out in a full days worth of testing to significantly affect the processes of achieving the optimum desired result required to produce a first class hoof knife.
A first class hoof knife is one where the edge will last due to its hardness and yet the blade will be strong enough to withstand the rigors of use.
The problem is the time and temperature curve required to disperse the carbon uniformly through out the steel. 10XX steels usually only require a short amount of time to do the job at elevated temperatures but testing has demonstrated that trace amounts of chromium can require a much longer soak time at elevated temperatures to get the carbon into full solution and uniformly dispersed from fully annealed steel.
During the annealing process, the carbon can gradually pool up in small globules, hence spheroidized steel. The chromium will bloke the carbon and greatly slow down the migration upon reheating, preventing it from getting uniformly dispersed.
If the carbon is not allowed enough time to become dispersed and go into complete solution, the carbon will form on the grain boundaries as carbides which are very brittle leaving an undesirable grain boundary configuration and brittle blade. Testing has shown that a minimum of 20 minutes are required for this particular job using this steel.
Grain boundary embrittlement has been considered a problem of hypereutectoid or high carbon steels such as 52100 or O1, but I would guess that the mid range steels will be adversely affected by heat treating annealed steels as well. 5160 may not be affected by grain boundary problems, but I would also think that having the carbon uniformly dispersed would be a good thing with any steel and would lend to a more abrasive resistant edge as well as being stronger.
Although this will add a significant amount of time to heat treat blades, it is the only viable solution to achieving truly stunning performance from a blade and has become standard operating procedures here at the shop. I have destroyed many of the blades in testing and am confident that even though the “Double L Hoofknife” blades are very hard on the cutting edge they are also very resistant to breakage.
Achieving a truly great hoof knife has been a long and arduous task. It has drawn on the experience of the makers 27 plus years in the knife making field, has required much analytical testing, much field testing and last but not least the valuable feedback from our farrier friends and customers who use our knives to make their living.
We have had to replace very few blades and we will continue to do so if any one does have a blade break providing they send it back for analysis. And as always we consider problems here as opportunities to improve what we consider the worlds finest hoof knives.
Contact me
bronksknifeworks.com
Lyle Brunckhorst
Bronk’s Knifeworks
23706 7th Ave. SE
Suite B
Bothell, WA 98021
425 402-3484
The Double L Hoof Knife is distributed exclusively by
Delta Horseshoe Co.
4000 Alvis Court,
Rocklin, CA 95677,
1 800 931-7181.
The Double L Hoofknife story.
Some times when we set out on a new venture, we have little or no idea just where it will eventually lead us and this is exactly what happened here at the Double L, a subsidiary of Bronk’s Knifeworks. Just to bring you up to speed, we designed the Double L Hoof Knife so that the blades can be changed in order to keep down the cost and bring up the quality of the knife to better achieve high performance. We make our living here making knives good enough to make your living.
We wanted a knife that would perform well in the field and remain economical to use. In order to do this we decided to make the handle from durable aluminum and cover it with attractive wood Micarta scales for comfort and the replacement blades can be easily installed by removing a pair of Chicago screws. The blades are made from high carbon spring steel (1095) and heat treated so that the edge is very hard so that it will stay sharp longer. The Back of the blade is left much like a spring and can flex without breaking. This is referred to as differential hardening and is akin to how the Samurai swords were made.
Much research and testing preceded the launch of the Double L Hoofknife and the performance of the knives exceeded our expectations. All the feedback came back as positive and everyone who used the knife liked it. Then it happened. The phone rang and I was talking to a farrier who had not just one but two broken blades. I was stunned and asked him to ship me the blades for testing but the initial testing indicated that they were indeed right on track. However when the remnant was placed under a strain it snapped much too easily. What could be wrong here, I asked. Then it hit me.
Luckily I had been working on a research project regarding grain boundary embrittlement of alloy steels in regard to steels such as E52100 and O 1 tool steel. These are steels that I have considered using for some new projects in the future and they require special handling as far as heat treating is concerned.
This is the irony, 1095 (the steel used in the “Double L Hoof Knife”) is regarded as non alloy (10XX) steel and should, by its very nature, not have these same characteristics and problems as the high carbon chrome steels. However fate sometimes does not bend to our beckon and call and reaches out to us with new lessons to be learned.
I dug out the spec sheets of some the shipments of 1095 that I had received over the past couple of years and yes indeed, there was a trace amount of chromium in some of these batches of steel. It should be noted here that the steel mills do not control the individual batches to the nth degree and often trace alloying elements are introduced into the batch from the various sources such as scrape piles of used steel. This will lead to some considerable differences in the steels behavior and response to heat treating, giving that a small change in the steel chemistry will profoundly affect the steels characteristics.
Chromium is added to many steels to aid in the hardening process. This is a good thing as a rule and can simplify one of the difficulties of hardening steels if added in sufficient quantity, but it does require some adjustment to the process because it consequently will also affect the carbon migration. While not enough chromium is present to make the hardening noticeably easier with the 1095 steel, it did prove out in a full days worth of testing to significantly affect the processes of achieving the optimum desired result required to produce a first class hoof knife.
A first class hoof knife is one where the edge will last due to its hardness and yet the blade will be strong enough to withstand the rigors of use.
The problem is the time and temperature curve required to disperse the carbon uniformly through out the steel. 10XX steels usually only require a short amount of time to do the job at elevated temperatures but testing has demonstrated that trace amounts of chromium can require a much longer soak time at elevated temperatures to get the carbon into full solution and uniformly dispersed from fully annealed steel.
During the annealing process, the carbon can gradually pool up in small globules, hence spheroidized steel. The chromium will bloke the carbon and greatly slow down the migration upon reheating, preventing it from getting uniformly dispersed.
If the carbon is not allowed enough time to become dispersed and go into complete solution, the carbon will form on the grain boundaries as carbides which are very brittle leaving an undesirable grain boundary configuration and brittle blade. Testing has shown that a minimum of 20 minutes are required for this particular job using this steel.
Grain boundary embrittlement has been considered a problem of hypereutectoid or high carbon steels such as 52100 or O1, but I would guess that the mid range steels will be adversely affected by heat treating annealed steels as well. 5160 may not be affected by grain boundary problems, but I would also think that having the carbon uniformly dispersed would be a good thing with any steel and would lend to a more abrasive resistant edge as well as being stronger.
Although this will add a significant amount of time to heat treat blades, it is the only viable solution to achieving truly stunning performance from a blade and has become standard operating procedures here at the shop. I have destroyed many of the blades in testing and am confident that even though the “Double L Hoofknife” blades are very hard on the cutting edge they are also very resistant to breakage.
Achieving a truly great hoof knife has been a long and arduous task. It has drawn on the experience of the makers 27 plus years in the knife making field, has required much analytical testing, much field testing and last but not least the valuable feedback from our farrier friends and customers who use our knives to make their living.
We have had to replace very few blades and we will continue to do so if any one does have a blade break providing they send it back for analysis. And as always we consider problems here as opportunities to improve what we consider the worlds finest hoof knives.
Contact me
bronksknifeworks.com
Lyle Brunckhorst
Bronk’s Knifeworks
23706 7th Ave. SE
Suite B
Bothell, WA 98021
425 402-3484
The Double L Hoof Knife is distributed exclusively by
Delta Horseshoe Co.
4000 Alvis Court,
Rocklin, CA 95677,
1 800 931-7181.
