Introduction: Bowie Knife From Leaf Spring
I've tried my hand at making a couple of knives before with the steel bought from a knife making supply place. I've always wanted to try making one out of a leaf spring and I've had a set of leaf springs setting around in the back yard from my 1939 Ford pickup. Memorial day weekend was coming up so I decided to give it a try.
Step 1: Materials and Tools Needed
Materials for the knife
1 leaf spring - cost - free
1 piece of cocobolo wood for the handles - $5
1 piece of 1/4 aluminum plate for the hand guard - free, laying around the garage
a couple of pieces of aluminum wire about .110 thick - free, laying around the garage
JB weld epoxy - $4
The desire to see this project through to the end and create something new from 'junk' - priceless
A lot of the tools here you could use an alternative/work around. I used a torch to heat, straighten, heat treat the leaf spring. I could of (and it would of been easier) to make a mini forge - there are a couple of them described as other instructables.
Welding torch, Anvil, Misc hammers, a GOOD hacksaw, a couple of different files, a craftsman belt sander, hand held angle grinder, clamps, buffing wheel (harbor freight) & my trusty DeWalt angle grinder.
Step 2: Getting Some Usable Material Out of the Leaf Spring
Leaf springs are made out of some amazing stuff. The steel is made to flex, millions of times without breaking but without taking the heat treatment out of it you really can't do anything with it other than what it was made for.
Since I didn't have a forge what I did is heat up 1/2 of the spring in sections until it was red hot, hoping that would take the heat treatment out of it.
Once I did that I heated it up again and with some help straightened it out until it was flat. between the torch, anvil and a hammer I was able to get it straight enough to use.
Then I cut it in half, cleaned it up some with the belt sander and it was hopefully ready to use.
Step 3: The Design
I came across a picture of an early Bowie knife on the web. It had what's called a 'coffin handle' on it. I guess the shape of the handle and the rivets make it look like an old time coffin. The design was simple enough that I could have a chance of success with it.
So with that, I tried resizing a picture of the design to full size then basically free-handing the design on the steel.
From the pictures you can see that there is a groove in the leaf spring, I'm planning on grinding that out but want to wait until the design it cut out so that I can minimize the amount of material I have to remove.
Step 4: Cutting the Pattern Out of the Material
Now the hard work starts.
This steel is hard enough a jig saws blades don't really work and I don't have a band saw so I had to go old school on it. As you can see from the pictures, I would drill a 1/8 hole about every 1/2 inch around the pattern. Then I would hack saw through the material between the holes. For some of the longer runs, I would just go to town on it with my trusty DeWalt angle grinder (Everyone should own one of these).
After a couple of hours of continuous drilling/hack sawing/angle grinding/belt sanding I had the pattern of the knife.
Once that was done I started trying to remove material to get rid of the groove in the steel that was in the original leaf spring. This turned out to be a major pain in the butt to do. It actually took longer to do this than it did to cut the pattern out.
Step 5: Grinding the Blade
Ok apologies here for the pictures that were after the fact. I was so focused on this I completely forgot to take pictures during. Also, I used two belt sanders, one Craftsman 3" belt sander for the big work and another with a 1" wide belt.
So I've tried in the past to grind the blade profile 'free hand' and it was a disaster. So I put together the most basic of jigs. I cut a piece of 2x4 a about 9 degrees and I made it long enough so I could C clamp the blade to it.
I also filed a 1/2 round where the blade will meet the cross guard/handle. - Why well because my belt sander's edge isn't a perfect 90 degrees between the belts edge and the side of the belt sander. This will prevent me from having a clean vertical end where the blade profile ends. The 1/2 round lets me get a cleaner, more vertical grind. (This isn't the best explication, I hope the picture helps)
So even with my 2x4 'jig' I always have to make sure that I'm pressing the blade against the belt sander parallel to the belt.
For the clip point I originally tried to do it using the wheel of the belt sander. One side looked great, the other side looked crappy. I finally had to finish them off with a 1/2 round file.
I had a lot of issues here. My blade wasn't completely flat and the slight curve meant that the blade profile looks slightly different on one side and the other. Also when I was removing material to get ride of the groove in the leaf spring one side of the blade wasn't parallel to the other.
Step 6: Drilling the Holes for the Handle, and Final Grinding
So once the blade profile was ground. I changed belts to a finer grit and as best I could tried to clean up the blade. I want to avoid doing this after hardening because it will take more work because the material is harder.
I also drilled the holes for the handle. The blue on the blad is layout die (Dykem)
Step 7: Heat Treating & Annealing the Blade
So books are written about how to do this. I went with a basic approach that has worked well in the past.
Ok - dangerous part here. Take all the proper precautions necessary to not burn yourself or others or set the house on fire.
A quart of motor oil - any brand or weight
A container to put the oil in that the part of the blade you are heat treating can be completely submerged - don't use a plastic container!!
A heat source - my welding torch
something to hold the blade with - vice grips
A fire extinguisher, gloves, eye protection, don't do this alone. Don't do this in the house or garage.
So the oil should be warmed before you plunge the knife blade in it. I heated up a old hammer head I had to glowing red and put it into the container with oil. It did the trick!
So heat the blade (you don't need to do the handle) to a dull red color - the blade will become non-magnetic when it gets to that color. If you are using a torch like I do, be careful not to over heat the tip of the blade. It's easy to forget and you can melt the tip of the knife off if you aren't careful. Heat the blade evenly, take your time. If you are doing this for the first time and not sure - try heating up a piece of scrap steel first to practice.
Once the blade is dull red, quench it into the oil. Plunge it in and out, continue to do that 10-15 times then put the blade into the oil for a while. There will be fire and smoke here. Just an FYI.
So somehow the first time I did this, the blade curved, so I had to re-do it. Heated it up again, somehow bent the blade back straight and did the quench again.
So now you need to anneal the blade. Very important because the steel is very brittle.
I wire wheeled the blade to get the oil residue off
So you have to heat the blade up to 400 degrees and let it set at that temperature for 10-20 minutes then cool - do this twice.
If you have an old toaster oven - great, do it outside. I didn't, so I cleaned the oil residue off of the blade, turned on the kitchen oven to 400, put the blade in for about 20 minutes, removed it, let it set at room temperature until cool and repeated. Try to do this when the wife/mom/SO isn't around because they tend to flip out when they see you doing this :-) And if you didn't clean the oil off the blade good enough the whole house will smell - no bueno.
When you are done - depending on the type of steel it will be a 'straw' color. I liked the look so I decided to leave the blade that way.
Step 8: Handles, Cross Guard, Sand, Polish & Final Sharpening
The original blade I based mine on had Rosewood handles. So I made a trip to my local exotic wood store (Hopefully everyone has one of these establishments close by) to pick up some materials for the handle. Instead of rosewood I found some cocobolo that looked pretty awesome so I decided to go with it.
I decided to go with aluminum for the cross guard and rivets because I had that material laying around. Not knowing how well the aluminum wire would flatten I made a quick sample handle to test it out. Turns out with a minor counter sink in the handle and having the aluminum rods at a specific length then flatten out ok.
The cross guard was cut with a hacksaw from a 1/4 aluminum plate I had hanging around. After cutting I squared it up with the belt sander. I drilled the countersinks and riveted the cross guard in place.
For the handles I sawed up the wood to a little thicker than 1/4 inch, belt sanded it flat, traced the pattern on the wood and belt sanded/sawed it up so it was a close fit but not that close. I wanted to finish that with a file & sandpaper.
Then I drilled the holes in the rough cut handle for the rivets one side at a time.
When that was done I mixed up some epoxy and glued the handles on, making sure the rivets holes lined up.
I clamped the handled to the blade with every clamp I had.
With the handles glued on I belt sanded the handles flat to match the cross guard. Then I drilled the counter sink holes and got ready to rivet the aluminum wire in. Thankfully they all turned out acceptable. I used a hammer and a flattened center punch to do this,taking care not to hit the wood handles. Then I belt sanded the handles and cross guard again with a finer grit belt.
Now I wanted to bevel the handle, I used a 1/2 rat tail file and sand paper to do this. To round the cross guard I used a flat file and carefully rounded it.
Polishing the cross guard
I should of did this before I put the handle on. Now since the handles were on I had to tape up the wood so that the polishing wheel wouldn't ruin them. I also COVERED the blade with cardboard. If you have ever used a polishing wheel before you know how easy it can grab a hold of what your polishing and toss it across the garage. You don't want this happening with a 8 inch pointed piece of steel. I took extreme care here to carefully polish the aluminum. As I mentioned in the previous step, I like the straw color of the blade from annealing so I decided to go with it.
I did the final sharpen on the 1" sander with a special emery belt that is used for sharpening knives. It took an edge really well and now its ready to use!
Step 9: Lessons Learned
A lot of these apply to any project, some, for some reason I have to keep learning some of them over and over.
1. Make sure the the blade material is flat. Mine had a slight curve to it that cause a lot of issues with grinding the blade profile.
2. Jigs - If you can make a jig for something - especially for grinding the blade profile - take the time to make it. It will take away time from making your project and you may just use it once, but it may also avoid having to throw out the project and start again. There are a lot of example jigs for holding blades on the web.
3. Blade design - Unless you really don't care, just don't free-hand some one off design and go cutting and grinding, you might not end up with something that looks particularly appealing. Take the time to get something traced on the steel that you like and take the time to get it cut out.
4. Handle making. I'm glad i made a practice handle. I had problems in that when i drilled the holes in the handle the wood was splintering when it came out the other side. By turning up the drill RPM, getting a new sharp drill prevented this. I also was able to practice riveting on a throw away handle and not the real one.
5. Tools. I hear people say they don't have the tools for a particular project over and over and never try anything. Your have to grow your tool collection. Don't get bummed out if you have to buy one or two tools to do a project. Once you purchase it you've added to your collection and will have it to use for years to come. Also, a good place to look for tools is at estate and garage sales. I've purchased some of my best tools from estate sales for just a couple of bucks. Check the internet or local papers.
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