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- 660
Glad to hear. Its a great book.
-
The BladeForums.com 2024 Traditional Knife is ready to order! See this thread for details: https://www.bladeforums.com/threads/bladeforums-2024-traditional-knife.2003187/
Price is$300$250 ea (shipped within CONUS). If you live outside the US, I will contact you after your order for extra shipping charges.
Order here: https://www.bladeforums.com/help/2024-traditional/ - Order as many as you like, we have plenty.
How To Slipjoint tutorials and advice
- Thread starter Stang Bladeworks
- Start date
- Joined
- Feb 19, 2018
- Messages
- 660
SIDE NOTE:
I want to post this in case anyone starts using my CAD files before I can finish the tutorial. My templates do not have any relief cut for the spring. I left this out because spring tension is a preference. I use 3/32" cpm 154 and I find that it is necessary to cut a bit of a relief. I will cover this in detail later. It sounds like some people may get a head start so I just want to clear this up. Also take note of the 2 different springs detailed in my post titled GET PDF FILE HERE TO PRINT TEMPLATES. If you plan to follow the tutorial ignore this post. Sorry for the confusion I just want to make sure that my info is still useful to those who will be starting asap.
I want to post this in case anyone starts using my CAD files before I can finish the tutorial. My templates do not have any relief cut for the spring. I left this out because spring tension is a preference. I use 3/32" cpm 154 and I find that it is necessary to cut a bit of a relief. I will cover this in detail later. It sounds like some people may get a head start so I just want to clear this up. Also take note of the 2 different springs detailed in my post titled GET PDF FILE HERE TO PRINT TEMPLATES. If you plan to follow the tutorial ignore this post. Sorry for the confusion I just want to make sure that my info is still useful to those who will be starting asap.
- Joined
- Feb 19, 2018
- Messages
- 660
TUTORIAL POST #3
I want to get this out of the way today as well. After this one I will begin the actual tutorial. I plan to cover the materials used in building the knife. Again I will call upon others to provide their input here. These materials will be for building the design in the CAD file. This is a shadow pattern slipjoint. There are no bolsters or liners. I really want to try this soon but I haven't yet so I cant speak to it. As I learn more about this I will supplement this topic. The books do a great job at explaining this. I also know there are members here who can do them great.
first up is steel. I use cpm 154 in 3/32" thickness. My tutorial will be based on this steel. I have the heat treat recipes for both the blade and spring. Much credit goes to USA knifemaker for their heat treat video. If you plan to use this steel as well watch this.
I will share my heat treating in detail during that part of the tutorial. If anyone needs it sooner let me know. If you plan to use another steel please leave your heat treat info for the blade and spring so others can learn from it. Note: you can make the blade of your steel of choice and still use a cpm154 spring. I am not sure about other steels, I have seen a lot of people use cpm154 as a spring material so I followed suit.
Next up is pins. 3/32" brass pins. They are cheap when purchased by the foot. You can also use stainless steel but I find it less forgiving. If your holes are slightly off the brass will play a little nicer. I use stainless pin stock for temporary assembly (details later in tutorial). Bottom line pin stock is cheap, get lots. Get multiple types, maybe you will like one better than another.
Now for the fun part... handle material. Because this is a shadow pattern the handle material will be the only support for the spring mechanism. Choose a suitably strong material. I recommend G10, micarta or carbon fiber. These are all strong light and easy to work with. Avoid natural materials (bone, antler etc.) at least for the shadow pattern. I love them but they will frustrate you with a shadow pattern build. Also avoid acrylic and resin wood for the same reasons. Keep in mind you will be drilling 3 holes in each scale. If these holes are not perfect the handle is garbage so don't start with something that you aren't willing to lose. If you make knives like me you are likely no stranger to throwing stuff away. My design is laid out to allow you to get both scales from one standard size handle slab. So, if you order a set of scales you can get 2 knives out of it, or one mulligan...
here is a link to some micarta https://usaknifemaker.com/canvas-natural-canvas-micarta-3-16-knife-handle-material.html
By the way. I use 3/16" for this build. if you use a different steel stock thickness you will need to adjust accordingly. Keep in mind that your overall dimension after shaping will be slightly smaller than (scale thickness x 2) + steel thickness. I suggest measuring some of your slipjoints to see what you like.
That's basically it for this build. One nice thing about slipjoints is their simplicity, especially shadow patterns like this. FYI USA knifemaker has black and natural canvas micarta scales for super cheap. This is what I started making these with. I do think G10 is slightly easier to work with but hard to beat that price.
I want to get this out of the way today as well. After this one I will begin the actual tutorial. I plan to cover the materials used in building the knife. Again I will call upon others to provide their input here. These materials will be for building the design in the CAD file. This is a shadow pattern slipjoint. There are no bolsters or liners. I really want to try this soon but I haven't yet so I cant speak to it. As I learn more about this I will supplement this topic. The books do a great job at explaining this. I also know there are members here who can do them great.
first up is steel. I use cpm 154 in 3/32" thickness. My tutorial will be based on this steel. I have the heat treat recipes for both the blade and spring. Much credit goes to USA knifemaker for their heat treat video. If you plan to use this steel as well watch this.
Next up is pins. 3/32" brass pins. They are cheap when purchased by the foot. You can also use stainless steel but I find it less forgiving. If your holes are slightly off the brass will play a little nicer. I use stainless pin stock for temporary assembly (details later in tutorial). Bottom line pin stock is cheap, get lots. Get multiple types, maybe you will like one better than another.
Now for the fun part... handle material. Because this is a shadow pattern the handle material will be the only support for the spring mechanism. Choose a suitably strong material. I recommend G10, micarta or carbon fiber. These are all strong light and easy to work with. Avoid natural materials (bone, antler etc.) at least for the shadow pattern. I love them but they will frustrate you with a shadow pattern build. Also avoid acrylic and resin wood for the same reasons. Keep in mind you will be drilling 3 holes in each scale. If these holes are not perfect the handle is garbage so don't start with something that you aren't willing to lose. If you make knives like me you are likely no stranger to throwing stuff away. My design is laid out to allow you to get both scales from one standard size handle slab. So, if you order a set of scales you can get 2 knives out of it, or one mulligan...
here is a link to some micarta https://usaknifemaker.com/canvas-natural-canvas-micarta-3-16-knife-handle-material.html
By the way. I use 3/16" for this build. if you use a different steel stock thickness you will need to adjust accordingly. Keep in mind that your overall dimension after shaping will be slightly smaller than (scale thickness x 2) + steel thickness. I suggest measuring some of your slipjoints to see what you like.
That's basically it for this build. One nice thing about slipjoints is their simplicity, especially shadow patterns like this. FYI USA knifemaker has black and natural canvas micarta scales for super cheap. This is what I started making these with. I do think G10 is slightly easier to work with but hard to beat that price.
Last edited:
Kevin Wilkins
Knifemaker / Craftsman / Service Provider
- Joined
- Oct 7, 1998
- Messages
- 1,486
Thanks for this very informative thread, the Robinson book is also available as an eBook on Amazon.
DWG is a proprietary file format owned by Autodesk, who makes Autocad.
- Joined
- Feb 19, 2018
- Messages
- 660
TUTORIAL POST #4.1
This post will cover everything involved in getting the blade and spring ready to heat treat.
First off I want to explain how I set my spring tension. If we are not clear on this the rest of this tutorial will be unnecessarily confusing. I have 2 versions of the spring in my cad file. one version represents how the spring will look when installed in the knife in its final form. this is how I set my open, close and half stop positions. If you were to cut out that spring and install it in the knife it would put no downward force on the blade tang. There would be no tension, just two pieces of metal against one another. Your blade will not be secure in any position and the knife is not functional. The other spring (blue spring on the cad file) extends into the blade tang. If you can picture this piece being installed in the knife it would be applying a downward pressure on the tang in all 3 positions. When properly heat treated this is what provides your spring tension.
The back half of both versions of the spring are identical and overlap each other. I hope this is clear. If anyone is at all confused on this let me know. the rest of the build is dependant on this being done correct. All of the resources I have recommended have accomplished this in different ways. This is something I came up with and if one of the other ways makes more sense to you then feel free to deviate. Just make sure you understand how it will affect the build later on. I like this way because it gives me a repeatable process. My tension has been set at 1/16" (meaning my spring extends into the tang 1/16") as per Don Robinsons book. I just accomplished it a different way. This method also allows me to accurately lay out all my holes in advance.
(note: if your stock is not precision ground surface grind prior to affixing template to ensure your holes are perpendicular to the steel.)
The next step is affix your template to the steel. I have been using 3/32" cpm154 and I find it works well. This is what I will base my tutorial on. If anyone uses something different please let us know how it goes. I find it helpful to measure up your steel in bar form then translate that into the cad file. I then lay out my pieces on the virtual steel. This allows me to minimize waste. In the cad file provided this has been done on a 1.5" piece of bar stock. Feel free to modify as required to suite your needs. I then glue the template onto the actual steel with spray adhesive(I use gorilla brand but I'm sure any brand will do just as well). Once complete your steel should look something like this.
Make sure your template is flat on the steel (no creases or bubbles), use a flat object to squeegee out excess glue if needed.
Next up, drill holes. This step is pretty easy but if anything is off you will have problems later. I like to drill the holes prior to cutting anything out. This was recommended by AR Customs knives in his video and I think it is a great tip. Much easier to work with one larger piece. Use an optical center punch to mark each hole.
The punch is pretty easy to use. Line up the crosshairs with the template. drop in the punch and tap with a hammer. for a better explanation watch this.
Drill both holes in the spring with a 3/32" drill bit, Drill the pivot hole on the Blade with a #41 bit. This bit is slightly larger and will allow for a free pivot after peening. Its only oversized by a couple thousandths so there is no noticeable lash. This tip is also from Don Robinson. Use a 123 block to ensure your bit is square to the table of your drill press. Even if your stock is perfect it doesn't matter if your drill press is out of square. Sometimes a cheap drill press can be slightly off just from adjusting the height of the table. Check for square after you have adjusted your table.
This post will cover everything involved in getting the blade and spring ready to heat treat.
First off I want to explain how I set my spring tension. If we are not clear on this the rest of this tutorial will be unnecessarily confusing. I have 2 versions of the spring in my cad file. one version represents how the spring will look when installed in the knife in its final form. this is how I set my open, close and half stop positions. If you were to cut out that spring and install it in the knife it would put no downward force on the blade tang. There would be no tension, just two pieces of metal against one another. Your blade will not be secure in any position and the knife is not functional. The other spring (blue spring on the cad file) extends into the blade tang. If you can picture this piece being installed in the knife it would be applying a downward pressure on the tang in all 3 positions. When properly heat treated this is what provides your spring tension.
The back half of both versions of the spring are identical and overlap each other. I hope this is clear. If anyone is at all confused on this let me know. the rest of the build is dependant on this being done correct. All of the resources I have recommended have accomplished this in different ways. This is something I came up with and if one of the other ways makes more sense to you then feel free to deviate. Just make sure you understand how it will affect the build later on. I like this way because it gives me a repeatable process. My tension has been set at 1/16" (meaning my spring extends into the tang 1/16") as per Don Robinsons book. I just accomplished it a different way. This method also allows me to accurately lay out all my holes in advance.
(note: if your stock is not precision ground surface grind prior to affixing template to ensure your holes are perpendicular to the steel.)
The next step is affix your template to the steel. I have been using 3/32" cpm154 and I find it works well. This is what I will base my tutorial on. If anyone uses something different please let us know how it goes. I find it helpful to measure up your steel in bar form then translate that into the cad file. I then lay out my pieces on the virtual steel. This allows me to minimize waste. In the cad file provided this has been done on a 1.5" piece of bar stock. Feel free to modify as required to suite your needs. I then glue the template onto the actual steel with spray adhesive(I use gorilla brand but I'm sure any brand will do just as well). Once complete your steel should look something like this.
Make sure your template is flat on the steel (no creases or bubbles), use a flat object to squeegee out excess glue if needed.
Next up, drill holes. This step is pretty easy but if anything is off you will have problems later. I like to drill the holes prior to cutting anything out. This was recommended by AR Customs knives in his video and I think it is a great tip. Much easier to work with one larger piece. Use an optical center punch to mark each hole.
The punch is pretty easy to use. Line up the crosshairs with the template. drop in the punch and tap with a hammer. for a better explanation watch this.
Drill both holes in the spring with a 3/32" drill bit, Drill the pivot hole on the Blade with a #41 bit. This bit is slightly larger and will allow for a free pivot after peening. Its only oversized by a couple thousandths so there is no noticeable lash. This tip is also from Don Robinson. Use a 123 block to ensure your bit is square to the table of your drill press. Even if your stock is perfect it doesn't matter if your drill press is out of square. Sometimes a cheap drill press can be slightly off just from adjusting the height of the table. Check for square after you have adjusted your table.
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- Feb 19, 2018
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- 660
TUTORIAL POST 4.2
Now that you holes are drilled you should be sitting here.
Now its time to cut out the pieces using your method of choice. I use a bandsaw. WHATEVER YOU DO, DO NOT CUT TO THE LINE. LEAVE YOURSELF ROOM ON ALL SIDES OF THE TEMPLATES. this step doesn't really require a lot of advice. Its probably the least fun part of the entire process.
That should land you here.
Notice that there is room to work around the template for the next step. Do not notice my ugly jagged bandsaw cuts...
The next step is to grind the parts closer to final size. I will do this as a separate post.
Now that you holes are drilled you should be sitting here.
Now its time to cut out the pieces using your method of choice. I use a bandsaw. WHATEVER YOU DO, DO NOT CUT TO THE LINE. LEAVE YOURSELF ROOM ON ALL SIDES OF THE TEMPLATES. this step doesn't really require a lot of advice. Its probably the least fun part of the entire process.
That should land you here.
Notice that there is room to work around the template for the next step. Do not notice my ugly jagged bandsaw cuts...
The next step is to grind the parts closer to final size. I will do this as a separate post.
Last edited:
- Joined
- Feb 19, 2018
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- 660
TUTORIAL POST 4.3
When shaping the pieces it is important to leave material in a few areas. certain dimensions are not finalized until after the heat treat. I will do my best to show these areas and explain why its important to leave some meat on the bone there.
The first area to leave some space is on the top of the spring.
If you grind this flush to the line, when the spring tension is applied you will have a dip right around the center hole. This this will be set perfectly flush after the knife is assembled during the final fit up. It does not need to be pretty at this time.
area number two is the front of the spring. if you grind this to the line you run the risk of not being able to set the blade how you want. As you remove material the blade tip will sit higher and higher in the open position. Better to leave it long and fine tune it later. when you first assemble the knife expect the blade to be canted down in the open position. This is normal. It will be corrected later. You can always shorten the spring but you cant make it any longer. So far I have thrown away 2 knives as a result of this. Be smarter than me.
All other parts of the spring can be ground to final dimension. Be careful not to overshoot any lines.
Onto the blade
It is important to leave some material at the kick and the half stop. in order to set the closed position and half stop properly you will need some material to work with later. It is ok to cut in the radius at both positions but do not grind to the line on either position where the actual contact points are.
It is perfectly fine to leave the surfaces flat and grind the radius in later. (this is what I normally do) Now you can grind all other parts of the blade to the final dimension. At this point I use a small triangular file to cut in the sharpening notch. There is a little more filing to be done on the blade. You need to file in a small gap between the bottom of the spring and the top of the blade in front of the pivot.
This does 2 things. It provides a small space for pocket lint and debris as well as helps with a secure open position. You only want spring tension being applied to the portion of the tang behind the pivot. this forces the blade up and allows the back of the blade to contact the front face of the spring. if the blade is contacting the bottom of the spring in front of the pivot it can create blade play or rocking in the open position. Its best to have 2 defined points of contact to avoid this. this is also the reason for having the radius at the half stop and closed positions. you may have noticed a slight relief cut into the bottom of the face of the spring. This can be ignored for now.
Now surface grind the blade and spring as a pair. They must be the exact same thickness. Then your pretty much ready to heat treat.
I have posted a fair amount today so I will leave this for a bit before I go into heat treating. please provide feedback or suggestions so this guide can be as complete as possible. If anyone has questions let me know.
When shaping the pieces it is important to leave material in a few areas. certain dimensions are not finalized until after the heat treat. I will do my best to show these areas and explain why its important to leave some meat on the bone there.
The first area to leave some space is on the top of the spring.
If you grind this flush to the line, when the spring tension is applied you will have a dip right around the center hole. This this will be set perfectly flush after the knife is assembled during the final fit up. It does not need to be pretty at this time.
area number two is the front of the spring. if you grind this to the line you run the risk of not being able to set the blade how you want. As you remove material the blade tip will sit higher and higher in the open position. Better to leave it long and fine tune it later. when you first assemble the knife expect the blade to be canted down in the open position. This is normal. It will be corrected later. You can always shorten the spring but you cant make it any longer. So far I have thrown away 2 knives as a result of this. Be smarter than me.
All other parts of the spring can be ground to final dimension. Be careful not to overshoot any lines.
Onto the blade
It is important to leave some material at the kick and the half stop. in order to set the closed position and half stop properly you will need some material to work with later. It is ok to cut in the radius at both positions but do not grind to the line on either position where the actual contact points are.
It is perfectly fine to leave the surfaces flat and grind the radius in later. (this is what I normally do) Now you can grind all other parts of the blade to the final dimension. At this point I use a small triangular file to cut in the sharpening notch. There is a little more filing to be done on the blade. You need to file in a small gap between the bottom of the spring and the top of the blade in front of the pivot.
This does 2 things. It provides a small space for pocket lint and debris as well as helps with a secure open position. You only want spring tension being applied to the portion of the tang behind the pivot. this forces the blade up and allows the back of the blade to contact the front face of the spring. if the blade is contacting the bottom of the spring in front of the pivot it can create blade play or rocking in the open position. Its best to have 2 defined points of contact to avoid this. this is also the reason for having the radius at the half stop and closed positions. you may have noticed a slight relief cut into the bottom of the face of the spring. This can be ignored for now.
Now surface grind the blade and spring as a pair. They must be the exact same thickness. Then your pretty much ready to heat treat.
I have posted a fair amount today so I will leave this for a bit before I go into heat treating. please provide feedback or suggestions so this guide can be as complete as possible. If anyone has questions let me know.
Attachments
Last edited:
Interesting history on the dwg file format. From https://en.wikipedia.org/wiki/.dwg website:
"In June, 2011 the USPTO issued a final refusal[42] to register DWG as a trademark owned by Autodesk. They were quoted as saying:[43]
DWG is merely descriptive of applicant's goods under Section 2(e)(1) of the Trademark Act for two reasons: (1) DWG is a recognized abbreviation for “drawing," and (2) .dwg is a file format used for computer-aided design (CAD) drawings made both with applicant's CAD software and others' CAD software.
Autodesk appealed the decision. The USPTO affirmed in 2013 their refusal to recognise DWG as a trademark.[44] Despite this, Autodesk websites still claimed DWG as a trademark after the decision.[45]
In late 2014 Autodesk again lost, this time at the United States District Court for the Eastern District of Virginia. The judge dismissed all their arguments.[46]"
- Joined
- Feb 19, 2018
- Messages
- 660
Thanks. It is my intention to have a pdf of the tutorial. I want to include advice from others as well so there are multiple ways to tackle each step. Ideally i will edit it a bit and add some better pics. I would like it to be book quality. Then ill find a way to make it accessible to everyone. Hopefully a few people can build along with this. That way i can see if this is actually helping anyone. Im excited to see your smaller blade. You can scale the entire knife without changing anything. Just upsize the holes back to 3/32. Good luck. Remember to post pics.
I work in the CAD industry and did not know that. Protecting formats is a big deal, even for old formats that lack monikers and relationship type data. I dont really get it, that secrecy, and technology advances, is why there are 100s of formats and dozens of versions of some formats. We have a huge team devoted to translating between formats. It is a pita really.
Looking forward to more from the tutorial. I will reserve questions/comments until the end.
- Joined
- Feb 19, 2018
- Messages
- 660
TUTORIAL POST #5
This post will cover the heat treating of both the blade and spring. The information is for cpm154, if you are using a different steel you will need different heat treat specs.
The first step is to clean both the blade and spring. I use rubbing alcohol. This removes any contaminants that could affect heat treat. Even finger prints can have a negative affect. Once cleaned I recommend using surgical gloves to handle the parts. Next you will need to place both the blade and spring into a foil envelope. I buy the foil in bulk and make my own envelopes to size. You can also buy premade ones. Regardless of what you choose make sure your foil is rated to at least 2000 degrees f. Apparently there is some foil that can only handle 1500 f. Avoid this kind. If you are making your own envelope double up on your seams to help keep everything air tight. you can put multiple pieces in one envelope but don't stack anything. It is very important that all pieces lay flat so they can be properly quenched later on. You should have something like this.
I have multiple blades and springs in each one of these. Yours will be much smaller if you just make one knife.
Now place the envelope in your kiln at room temp. The first step is to heat treat both the pieces the same. Below is my heat treat recipe for cpm154.
place envelope in kiln at room temp
ramp as fast as possible to 1440f
hold at 1440f for 11 minutes
ramp as fast as possible to 1950f
hold at 1950 for 25 minutes
Now put on some long welding gloves and remove the envelope with a set of pliers (don't use your favorite pliers for this). immediately close the kiln door. Leaving the door open at high temps can cause stress on the coils due to the extreme temp difference between the kiln and the ambient air. Now quench the entire envelope between two plates of aluminum (1 inch thick). I have fastened my plates onto a woodworkers vise as shown in the above picture. I got this idea from Jeremy at homestead knives. It works great for doing this alone. You don't need a ton of force just press down firmly on the top plate. While you are doing this blast in compressed air from all sides. Having a vise also makes this easier. Continue applying pressure and blasting air in for 45ish seconds. At this point remove the envelope while wearing gloves (its still about 200f) and use tin snips to cut the foil open. Your envelope will be burnt looking and will have sealed itself around the steel parts (like a vacuum sealed steak). At this point both pieces will be 60HRC, verify with a hardness tester if you have one. If any air got in you may have some discoloration. This is not a huge deal but will affect hardness readings until it is ground off later.
I only have 1 kiln so I fire up my kydex toaster oven and let it get to 400f. I then place both the blade and spring inside and start a timer. The spring must be tempered at a much higher temp than the blade. This will result in a softer material with spring property. I set my kiln to 1175f and wait for it to cool down with the door closed (about 1 hour) By placing both pieces in the toaster oven at 400f you immediately start tempering them. This prevents cracks that can result from the steel being in such a volatile state. Its always best to temper asap after the quench. 400f is the actual tempering temp for the blade. This will not be the final temp for the spring but it wont do it any harm to throw it in while you wait.
Once the kiln reaches 1175f remove the spring from the toaster oven and place it in the kiln. it will sit like this for 2 hours. After 2 hours remove it and let it cool to room temp then place in the kiln at 1175f for another 2 hours.
The blade will go through the same steps, just at 400f. It will finish up before the spring because there was no delay in its tempering process. If you are impatient you can likely remove the spring from the kiln when the blade has completed its second 2 hour cycle.
Once both pieces are done tempering surface grind them together again to remove any scale and to ensure they are at the exact same thickness and perfectly flat for final assembly. During the heat treat process it is possible for slight irregularities to develop. This will correct them. At this time hardness test the blade (expect 59HRC) and the spring (expect 47HRC). If you don't have a hardness tester just cross your fingers.
My process does not involve cryo treatment as I don't have the means to do it at this time. If you wish to cryo you will need to adjust accordingly. If anyone has any opinions or advice on cryo I'm all ears.
From my research the spring is functional from 42 to 49 HRCish. The softer it is the less springy and the harder it is the more snap it will have. A harder spring is also more likely to fail. I haven't played with this at all. Mine have come out at 47 and I'm happy with the results so far.
It is beneficial to practice all the heat treating steps in advance to avoid any confusion during the actual process. Its fairly time sensitive. Once the steel is removed from the kiln you want to quench it within 20 seconds or so. Have the air compressor ready and be sure its at full pressure.
If you don't have a kiln just mail your parts out to a heat treat company, sit back and relax
As always feedback is welcome. I am no expert, this is just what has been working for me so far.
This post will cover the heat treating of both the blade and spring. The information is for cpm154, if you are using a different steel you will need different heat treat specs.
The first step is to clean both the blade and spring. I use rubbing alcohol. This removes any contaminants that could affect heat treat. Even finger prints can have a negative affect. Once cleaned I recommend using surgical gloves to handle the parts. Next you will need to place both the blade and spring into a foil envelope. I buy the foil in bulk and make my own envelopes to size. You can also buy premade ones. Regardless of what you choose make sure your foil is rated to at least 2000 degrees f. Apparently there is some foil that can only handle 1500 f. Avoid this kind. If you are making your own envelope double up on your seams to help keep everything air tight. you can put multiple pieces in one envelope but don't stack anything. It is very important that all pieces lay flat so they can be properly quenched later on. You should have something like this.
I have multiple blades and springs in each one of these. Yours will be much smaller if you just make one knife.
Now place the envelope in your kiln at room temp. The first step is to heat treat both the pieces the same. Below is my heat treat recipe for cpm154.
place envelope in kiln at room temp
ramp as fast as possible to 1440f
hold at 1440f for 11 minutes
ramp as fast as possible to 1950f
hold at 1950 for 25 minutes
Now put on some long welding gloves and remove the envelope with a set of pliers (don't use your favorite pliers for this). immediately close the kiln door. Leaving the door open at high temps can cause stress on the coils due to the extreme temp difference between the kiln and the ambient air. Now quench the entire envelope between two plates of aluminum (1 inch thick). I have fastened my plates onto a woodworkers vise as shown in the above picture. I got this idea from Jeremy at homestead knives. It works great for doing this alone. You don't need a ton of force just press down firmly on the top plate. While you are doing this blast in compressed air from all sides. Having a vise also makes this easier. Continue applying pressure and blasting air in for 45ish seconds. At this point remove the envelope while wearing gloves (its still about 200f) and use tin snips to cut the foil open. Your envelope will be burnt looking and will have sealed itself around the steel parts (like a vacuum sealed steak). At this point both pieces will be 60HRC, verify with a hardness tester if you have one. If any air got in you may have some discoloration. This is not a huge deal but will affect hardness readings until it is ground off later.
I only have 1 kiln so I fire up my kydex toaster oven and let it get to 400f. I then place both the blade and spring inside and start a timer. The spring must be tempered at a much higher temp than the blade. This will result in a softer material with spring property. I set my kiln to 1175f and wait for it to cool down with the door closed (about 1 hour) By placing both pieces in the toaster oven at 400f you immediately start tempering them. This prevents cracks that can result from the steel being in such a volatile state. Its always best to temper asap after the quench. 400f is the actual tempering temp for the blade. This will not be the final temp for the spring but it wont do it any harm to throw it in while you wait.
Once the kiln reaches 1175f remove the spring from the toaster oven and place it in the kiln. it will sit like this for 2 hours. After 2 hours remove it and let it cool to room temp then place in the kiln at 1175f for another 2 hours.
The blade will go through the same steps, just at 400f. It will finish up before the spring because there was no delay in its tempering process. If you are impatient you can likely remove the spring from the kiln when the blade has completed its second 2 hour cycle.
Once both pieces are done tempering surface grind them together again to remove any scale and to ensure they are at the exact same thickness and perfectly flat for final assembly. During the heat treat process it is possible for slight irregularities to develop. This will correct them. At this time hardness test the blade (expect 59HRC) and the spring (expect 47HRC). If you don't have a hardness tester just cross your fingers.
My process does not involve cryo treatment as I don't have the means to do it at this time. If you wish to cryo you will need to adjust accordingly. If anyone has any opinions or advice on cryo I'm all ears.
From my research the spring is functional from 42 to 49 HRCish. The softer it is the less springy and the harder it is the more snap it will have. A harder spring is also more likely to fail. I haven't played with this at all. Mine have come out at 47 and I'm happy with the results so far.
It is beneficial to practice all the heat treating steps in advance to avoid any confusion during the actual process. Its fairly time sensitive. Once the steel is removed from the kiln you want to quench it within 20 seconds or so. Have the air compressor ready and be sure its at full pressure.
If you don't have a kiln just mail your parts out to a heat treat company, sit back and relax
As always feedback is welcome. I am no expert, this is just what has been working for me so far.
- Joined
- May 4, 2011
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- 65
Derek, thanks for putting together this tutorial. I'm excited to see it progress.
- Joined
- Feb 19, 2018
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- 660
Thanks for reading. Ill be adding more soon.
- Joined
- Feb 19, 2018
- Messages
- 660
Excellent thread sir!
Thanks
- Joined
- Feb 19, 2018
- Messages
- 660
Quick update
I am currently building a slipjoint for a customer. I am taking lots of pictures for the tutorial. I will be continuing this thread shortly. I want to make sure i have lots of pics to help show what im trying to convey. Up until this point i have been using old pics. Thanks everyone for your patience.
I am currently building a slipjoint for a customer. I am taking lots of pictures for the tutorial. I will be continuing this thread shortly. I want to make sure i have lots of pics to help show what im trying to convey. Up until this point i have been using old pics. Thanks everyone for your patience.
