Introduction: Rasp and Pepper Tree Knife

Picture of Rasp and Pepper Tree Knife

My grandfather is a vet, and when he found out I got into blacksmithing a while ago, he sent me a handful of farrier rasps to play around with. Naturally, my first inclination was to make knives out of them, but I did not have anything good to make the handles with. However, that changed a few months ago when my dad cut down a pepper tree at his place. Pepper trees are my favorite type of trees, so I salvaged as much of the wood as I could get, and several pieces were just the right shape to use for handles.

Now, I have a good set of pack knives I can bring on hunting and camping trips that are good for cutting and slicing small things, but also pack the weight needed to hack apart tree branches and firewood.

Step 1: Tools and Materials

Picture of Tools and Materials

All you need for this project is a large rasp and a tree branch. Ideally, you want to find a branch that is about the same diameter as the rasp you are using so the edge of the blade is flush with the handle. Fortunately, this is the perfect size for a nice, comfortable handle.

As for other tools and materials, you will need

-Grinder (with a cutting disk and a flap disk)

-Drill

-Forge and anvil

-Oil and pan (vegetable oil will work)

-Epoxy

-Polycrylic

-Propane torch

-Whetstone

-Basic safety equipment (gloves, glasses, etc.)

Step 2: Shaping the Rasp

Picture of Shaping the Rasp

Cut a wedge off of the end of the rasp to give it a forward cutting surface. I found that a 45 degree cut gives it a very nice and somewhat aggressive look. Then, heat the entire rasp in a forge and flatten all of the little burrs. This will help prevent them from catching on absolutely everything you try to cut.

As for the edge that will become the blade, use the flap disk to create the bevel that will later be sharpened with a whetstone. The flap disk is much less aggressive than a grinding disk, but goes much faster than filing by hand. A belt grinder would be perfect for this, but an angle grinder and a flap disk are the next best thing.

For this knife, I went with about a 30 degree bevel and shaped both sides evenly.

When creating the bevel, there are two important things to consider:

1) Be gentle and patient with the bevel. Move the grinder back and forth along the blade so you do not overheat particular sections. Also, do not try to fully sharpen the knife with the flap disk at this point; that is a job for the whetstone later. Instead, sharpen it just enough to define the bevel.

2) Do you want a serrated blade? Many times, rasps have rough sides, and if you are careful, you can translate this to a serrated edge on your knife as shown in the last picture for this step.

Step 3: The Handle

Picture of The Handle

Time to get the handle prepared. First, drill a hole in the center of the handle that is the same diameter as the thickness of the rasp. Using a small file or by carefully wiggling the drill bit, widen the hole towards the edge of the handle, but keep it in line with the placement of the blade. The hole should be just large enough to start sliding the tang in.

Now for the fun part. Using a propane torch, heat up the tang to a very faint cherry red glow and push the tang into the handle. This will burn away the wood and give the handle a closer fit. The tang will cool off fairly quickly, so set it aside, shake the ash out of the handle, and repeat the process until you are happy with the fit. It is important to avoid getting the tang much hotter since it will burn away too much wood. I experimented with heating the tang up to a bright orange in my forge, but when I tried pushing it into the handle, the handle just caught on fire and burned in more of a circular pattern.

Once you are happy with the way the blade and handle fit together, set the handle aside for now.

Step 4: Heat Treating and Sharpening

Picture of Heat Treating and Sharpening

The process of heat treating metals is a complex process and there is much discussion on properly heat treating blades and catering the process to specific metals. However, most of that is beyond the scope intended for this project. I wanted to keep the build short and simple, so I went with a basic oil quench for hardening the blade. This gives it a sleek, black finish while hardening it enough to keep a decent edge for a while. If you want to go more in depth on hardening and tempering the blade, this would be the time to do so.

Once you are done, you can sharpen the blade. I chose to do this by hand using a whetstone.

Step 5: Getting a Handle on the Project

Picture of Getting a Handle on the Project

Epoxy the sharpened blade to the handle, making sure you are placing the blade in the right direction. I used some of the small two-part, 5 minute epoxy for this. The mount has held up on my first knife for several months of decent usage so far, and it appears to still be in excellent condition. Once the epoxy is dry, give the handle a light sanding to take away the rough edges and put on two or three coats of polycrylic. Once that is dry you are done!

Step 6: Enjoy!

Picture of Enjoy!

Enjoy your new knife, and be careful with it!

Comments

Ultra-Indigo (author)2015-06-29

good ibble. at first I thought you were going for a two in one tool, knife and wood rasp. it looks kinda neat.

I'm going to go for the 2 in one idea, it would be very useful out and about.

Jtoa3 (author)2015-08-12

i am currently making a knife from a file, but i figured that files and rasps are similar enough that i could ask this question. since i am working with a nicholson file, but did not anneal it, do i need to heat treat and temper it? i am capable of working with it un-annealed, but I don't have access to a high end forge, and I hate to ask my friend to borrow his low end one.

Lethrwolf (author)2015-07-28

very nice... next time put some small cuts in the tang before putting into the epoxy... this will keep the handle from coming off by giving something for the epoxy to grab.

also it was said to make sure the wood has 'cured'... this will also make sure it does not split later... never seal wet wood... for anyone that does not know.. hope you get many years of use out of it. i have made many different types of knives and machetes from all kinds of things like leaf springs, files, re-bar... lots of fun.

epotter307 (author)2015-07-15

I love it. So apocalyptic looking. It looks like a movie prop. Voting!

macgyver603 (author)epotter3072015-07-16

Thanks!

tdenney16 (author)2015-07-05

How do you avoid the over heating?

macgyver603 (author)tdenney162015-07-05

You have to move the angle grinder back and forth as you are grinding the bevel. The friction from using the flap disk without moving the grinder will cause the metal to heat up rather quickly in a single spot, so moving the angle grinder back and forth give the metal more of a chance to cool. The metal will still heat up, though, so if it gets to hot, just back off for a sec and let it cool back down.

Ninzerbean (author)2015-07-05

This is great - but I have a question - did putting the rasp into the forge make the raspy parts get smooth? You say to put the rasp into the forge and flatten all the parts - how do you flatten them exactly or does the heat of the forge do that for you?

macgyver603 (author)Ninzerbean2015-07-05

I used a hammer and anvil to flatted the prongs out.

Ninzerbean (author)macgyver6032015-07-05

Oh. Ok, thank you.

Norode (author)Ninzerbean2015-07-05

No, dude. Putting it in the forge anneals it, then he probably used the flap-disk on the grinder to take off the rasp "teeth".

Ninzerbean (author)Norode2015-07-05

Gotcha, the annealing makes it soft enough to do, hence the oil quenching later. Thank you.

bigpig (author)2015-07-05

It would make a great weapon. So unsanitary and impossible to clean that it infects anyone you might stab. LOL!

ElmarsM (author)2015-07-05

It's looking awesome, however you shouldn't use raw wood, it has to be dried for at the very least a year before it can be used!

silvertank (author)2015-07-05

Excellent idea! Rasps are incredibly hard and make a good hacking blade. You can also use the rasp to pull fibers from the wood as a fire starter. Well done!

I was going to use spring steel (from old lawn mower blades), but I think a rasp is better starter for a camping knife.

jackowens (author)2015-06-29

Very nice!

strumbot (author)2015-06-29

Very nice, very simple. I have done something similar with old files. I'm working on a smaller piece using some scrap pattern welded steel I acquired.

macgyver603 (author)strumbot2015-06-29

Thanks. You should post some pictures when you are done with it.

About This Instructable

30,099views

395favorites

License:

Bio: I enjoy working on all sorts of projects. Whether it is creating something with my forge or building the biggest thing I can think of ... More »
More by macgyver603:How to Stream Video, Pictures, and Data From 90,000ftThe Perfect Hard Boiled EggRasp and Pepper Tree Knife
Add instructable to: