Forging is fun. Steel needs to be hot forged but iron can be cold forged, needing only to be annealed when hammering has hardened it.
Common nails are made of iron, (or of mild steel in this case you must anneal them when you feel they are getting harder to hammer) ; any nail, around 3 inches long, can be turned into a small knife. Old bent nails cost nothing so you can try and make different shapes at no cost. Annealing means bringing the steel to a red-heath temperature and letting it air-cool.

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Picture of WHAT YOU NEED
You need a hammer, a lump of steel for an anvil (a sledge hammer head will do), a stump, a flame, a couple of pliers, and a file.

Step 2: Bend the nail

Picture of Bend the nail
1) The blade has to be thinner on the cutting edge and thicker on the back, but the edge that gets thinner becomes longer because the squeezed metal must find space anywayand your blade would bend upwards.
 To prevent it you first slightly bend the blade then hammer the inside of the curve.

2) Blow after blow you will see the blade straightening. The point of the nail gets the right shape by itself if you hammer it evenly.
3) The stake you’re hammering on had better be a bit rounded since you have to “pinch” the edge of the blade.

Step 3: Round off the head

Picture of Round off the head
4) Now you can round off the head of the nail, hammering it on edge. As the diameter of the head diminishes, a protruding edge develops on both sides of the head.

5) Tuck in this edge bending it down.

Step 4: The shank

Picture of The shank
6) Now you flatten the part of the nail between the head and the blade to make the shank. Try and keep the nail's head out of the stake.

7) After flattening it, the shank is hardened: to soften it you must bring it to red heath with a flame and let it air-cool.

8) Now you hold the shank with two pliers and twist it.

9) Some hammer blows on the twist will straighten it. Now you have a small handle with a good grip.

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This is really cool. I am going to make one as soon as possible.

Thantos2000 made it!2 months ago
this was a success thanks a bunch
Qwertyfish4 months ago
Could these be sharpened? As I am looking to make a letter opener out of one but the one I made is not very sharp. Can these be sharpened and if they can how?
pennabilli (author)  Qwertyfish4 months ago
just use a coarse file, an irregular edge cuts (really breaks, tears) better the paper and does not slip.
You will find that a longer blade is more functional than the ones I posted,
Qwertyfish5 months ago
Do you have to anneal the nail before hammering because when i hammer mine it doesn't seem to shape. This could be the surface or the nail itself. Any suggestions?
pennabilli (author)  Qwertyfish5 months ago

usually the iron nails are already annealed. Maybe you are using steeel
nails, they must be hot worked, annealing the will only admit a few
blows before hardening again

I made one today I couldn't be happier with it it is great
pargo9 months ago
I just made mine its pretty cool its not very sharp though but keep up the good work
Venemot11 months ago

I call this bad boy the HARBINGERRRR

Ozzynny11 months ago

Hi, I have some very old iron nails, but having some trouble forging/hammering them. They split and splinter - despite being annealed and cooled. Any tips??

codongolev3 years ago
made a couple of itty bitty nail knives (well, I guess one's a sword). here they are!

I really like your nail knives! They look kind of cute :P haha..

Maybe they are the next best tactical knife in the market. They can easily be hidden and they are extremely dangerous.

HTWTUSA11 months ago

My new favorite knife a carpenter, I have 1000's of these just waiting to be made...gonna start this weekend. Seriously, most unique knife platform I've ever seen.

southbaysue3 years ago
Wow! Incredible. The metal just becomes beautiful! I wonder do you do any hands-on lessons? You are a true artisan - I bet your hands could tell a thousand stories...
pennabilli (author)  southbaysue3 years ago
Ahem... in fact teaching metalworking classes is what I prefer to do.
But I live in Pennabilli, a village in Italy.
happy Easter!
so what you're saying is that I need to plan a trip to Italy....any nice places to stay in Pennabilli?

I, too, am interested in the answer to that...

pennabilli (author)  bryan31413 years ago
Yeah, nice and inexpensive, either a small hotel or a B&B.
And Pennabilli ( is worth a visit, if you are in Italy I mean.
muddog151 year ago
Use rail road tie nails.
These are fun for practice, but they are dreadful as knives. I am writing a few instructables on forging for very little cash. My goal is to make a full shop for 20$ total. If you want advice on forging for beginners, or resources for steel and tools, message me.
P.S. old files are great for small knives and broken leaf springs are great for big knives and swords
How did that 20$ shop go? Do you have an instructable for it?
this is amazing. being a metal worker myself, this really gave me some new ideas. i build bigger swords but am very fascinated by this idea. great job and keep up the good work.

gabe yoo1 year ago
You could make a drill bit out of the handle design
pennabilli (author)  gabe yoo1 year ago
in fact i did, not with a nail which is made of iron, but from a jeweler's burr (+ or - same diameter as a nail).
If I haven't done it yet, (must check- bad memory) I will post an instructable on a drill bit making soon.
W8L42B93 years ago
very good i also did a project like this...i used a nail to make a scalpel...i need to sharpen it so i can use it to cape animal i was working on a sword..a little harder then i thought but it is comeing alone very well...all i am useing for this project is a hand held torch, regular hammer...25 pound dumbell that i hammer against...heavy leather gloves and a aluminum coffe pot to cool it down ....and last and the best creativity...
Sledgehammer heads work better as anvils, the weight will chip. I would suggest building a real forge. (you can build one for 5$) and wear safety glasses aswell. I don't wear gloves, or an apron and I'm using pliers as tongs. Burns are solve able in a week or so, but get burning metal in your eye and you are in trouble. You can get a whole setup for around 20$ if you really hunt for supplies, and 50$ if you're not willing to wait. And that includes an anvil. If you are truly interested, message me.
mritz2 years ago
you can also use these as pretty good arrow heads
chipf mritz2 years ago
I made arrow heads out of finishing nails for my survival kit. They are light wieght. But still puncture 1/4 in plywood.
soldeir 9 mritz2 years ago
good idea!!!! my "homemade" arrows kinda suck...this will improve them :D
soldeir 92 years ago
Freggin amazing!!!!! 5*!! i might post a pic of one i make :D
I don't have a propane torch, but I do have unlimited access to a bunsen burner. Would that get hot enough to work?
pennabilli (author)  handful of dust3 years ago
Probably it won't suffice. Yu need a hissing flame, not a soft one. A portable propane torch like the one you see in my tutorial, costs from 20 to 30 $, and is very useful also in other occasions.
lae523 years ago
Try using an old rail road spike. Lots of steel and will make a knife that can actually hand held and usable. Rail spikes are usually pretty decent steel as well.

jnass lae523 years ago
Yes and no Dave... for knives you want to look for the spikes marked "HC" or HCX" on the heads... these are a higher carbon content (about .4%-.6%) and are hardenable. Normal spikes are simply mild steel and as such aren't hardenable by conventional means, so will not hold much of an edge.

I am a professional blacksmith and have much experience with RR spike knives...
lae52 jnass3 years ago
Thanks for the info. I wasn't aware of the markings. Are they literally on the head or are they on the side by the head?

jnass lae523 years ago
Usually right on the head Dave, though it can be kinda tough to find when they get rusty... a wire wheel helps clean them up so you can see it sometimes.
conway106 jnass3 years ago
Try putting the HC spikes in a bath of white vinegar. It will take the rust off of the spike-all of it. The spike will look brand new!. Leave it covered by the vinegar for 2
or 3 days. Any longer and the spike will start pitting. Good luck! Mike
Those RR spikes also make great war-hammer heads in a pinch. I've got a knife design I would like to make with one. I made one on a larger scale with stainless steel I would like to reduce in size from 2 ft length down to a spike length.
sstock1 lae523 years ago
Rail spikes are mild steel and cannot be hardened to produce a good cutting tool. Mild steel is also weaker. Better, use an old car coil or leaf spring or a lawn mower blade. Heat it red hot and quench it in oil or water, then polish it so you can watch the temperature indicating colors run as you reheat it to temper it to the hardness desired- straw for metal cutting and bronze to purple for wood cutting. Blue indicates it's annealed and soft again.
shortone3 years ago

Put you in my gift guide for guys! Just thought I'd let you know :)
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