Introduction: Cast a Celtic Bronze Sword (Beautiful, Authentic Leaf-Shaped Ewart Park)--Easier and Cheaper Than You Think!
Have you ever wanted to paint yourself blue and run through the heather? Brandish a big bronze sword and shout imprecations at pesky Roman legionaries? Of course you have--And now you can!
This instructable will detail the process of making a beautiful bronze leaf-shaped Ewart Park through gathering materials, making a blank,creating a mold, melting the metal, and pouring the sword. There are several files included that will make the blank easier for you to make, as well as links to outside sources for instruction not quite in the scope of this instructable and for purchasing hard-to-find resources. (eg. constructing a cheap metal-melting forge, buying delft clay/oil sand)
Access to basic woodworking tools and the ability to use them is assumed, but pretty much everything else involved can be made or figured out.
Please keep in mind that working with molten metal CAN BE DANGEROUS if proper caution is not exercised. Wear rugged, closed-toed shoes, preferably heavy boots. Buy welding gloves. Get a face mask. Always use proper tools. Basically, if it seems dangerous, don't do it. (I'm not responsible if you hurt yourself, but I'd be very sorry if you did. So don't.)
If you have the chance to TAKE A CLASS in metal casting, whether that be from your local community college or another party, I definitely suggest that you take it! You'll learn a lot--more than I could hope to tell you in an instructable--and it's incredibly helpful to go into this with qualified supervision. That being said, I don't believe a class is absolutely required, so long as you realize the seriousness of working with LIQUID FIRE, do some research, and act accordingly--ONLY WORK WITHIN YOUR COMFORT ZONE.
Also, it would be FANTASTIC if you could vote for this instructable in the two contests it's entered in! Just click contests in the top right of the screen and hit *vote*--Thank you so much for your support! It helps a ton!
Now, to the first section: Materials!
Step 1: Materials
Quick list of all the things you'll need:
--draw knife, hand saw, belt sander, (Table saw is helpful)
--tape, a printer, paper
--welding gloves like these http://www.harborfreight.com/welding-gloves-39664....
--heavy, protective boots (So you don't, ya know, pour molten bronze on your foot)
--welding apron http://www.harborfreight.com/split-leather-welding...
--long pants, long sleeves
--a forge (Yeah, I know this one sounds like a doozy. We'll get there.)
--Some form of tongs that will allow you to reach into the forge and pull out and pour the crucible of molten metal without spilling it or burning yourself (Tongs from old fireplace sets often work well, just make sure they're sturdy)
--copper and tin (or some bronze, if you want to be fancy about it)
--casting sand (We'll get to this, too.)
--casting flask (We'll get to this, too, too.)
--pine boards, one to be carved into the blank, possibly more if you don't want to buy a casting flask
Step 2: Sword Phase 1: Paper Cut
Attached are scans of my drawing of the Ewart Park. They are as accurate, clean, and symmetrical as I could make them, and they *should* be to the correct scale if simply printed onto printer paper.
That being said, if anyone has trouble with this, please let me know in the comments and I will post the full measurements!
So, print them off and put them on each other so as to make the full sword. Use a ruler along the handy dandy center line and line up the horizontal lines (holding it up to a light helps with this), and tape the papers together all the way along the seams.
The result should look something like the attached image.
Now cut it out!
Congratulations! You now have a very limp...some might say flaccid...2-dimensional sword!
Step 3: Sword Phase 2: Wooden You Believe It?
Get a board--I use cherry, but pine should work--and tape your paper to it. The board should be about 6" wide, 1/2" thick, and 4' long. Trace the outline of the paper onto the board.
IF you have a tablesaw: raise your blade up to a little less than half the width of the board. Move the wall over so that, when the board is placed on the wall with the width vertical, the blade is about 1/8" left of center. Angle the blade about 15 degrees toward the wall. Cut, flip, and repeat. For the other side, do basically the same thing but set the blade 1/8" right of center and angle it 15 degrees right. The idea here is to create the rough shape of the blade so you don't have to do as much carving later on. DO NOT cut the outside pieces with the drawing on them all the way off. Simply lower your blade as needed to leave enough wood that they won't break off.
NOW, you need to cut the traced sword out. Do this with whatever saw you feel comfortable using. I used a small hand saw. Leave yourself some space around the line: It's WAY easier to cut more off in a later stage than to add it.
You're almost done: now, you need to get the thickness right. I recommend using a draw knife and later an upside-down belt sander to shave down the sides. This is something that you can do to your own aesthetic, but here's some stuff to keep in mind:
--The area from the base to the "shoulders," where the drawing flares out to two points about 6" up, needs to be completely flat. This will have wood riveted on both sides to serve as the handle.
--the thickest point of the blade is right above the shoulders and is 10mm thick. From there, it slopes slowly down to the tip of the blade. The point of greatest width on the blade is 5mm thick.
--the two sides should meet in the middle of what was the piece of wood. If you need to mark the midpoint of the depth of the board before you start, then definitely do it.
--There should be a heavy ridge in the middle of the blade at the base which tapers and softens up to the widest point of the blade, past which the ridge is gone
--Think of the belt sander as a whetstone that you're using to "sharpen" the blade. Angle the blade and run it along the belt sander, keeping it moving. This will help you keep an even slope along the whole of the blade
Congratulations again! You are holding a piece of history! (Wooden history, but we'll get to the bronze in a second. Be proud!)
Step 4: Acquiring a Furnace, AKA Firey Fire Thing
If you have a furnace, feel free to skip this. If you DON'T, here are a few options to get yourself set up:
Mini Metal Foundry (This may need to be scaled up.)
Propane jets--will make your forge run cheaply, heat up faster, have less slag, whiten your teeth, and generally make your forge better.
In addition, you will need a crucible and some kind of tongs to pick it up with (I recommend getting these from an old fireplace set, so long as they're sturdy). As far as the crucible is concerned, STEEL CRUCIBLES WILL NOT WORK. Steel crucibles melt through when bronze or brass is put in them, due to interaction with the lattice structure of the steel. You will need a GRAPHITE CRUCIBLE like this one: https://www.amazon.com/Foundry-Graphite-Crucibles-...
Or this one, which will hold more metal (Which might be necessary depending on the size of your blank) but can't be guaranteed to fit in the mini foundry: https://www.amazon.com/Foundry-Graphite-Crucibles-...
Step 5: Make Some Special Sand
There are three options for casting sand:
- Greensand: This is a great, cheap option for high quality results. Make it yourself! http://foundry101.com/archive.htm
- Petrobond: if you don't want to make greensand, buy some professionally mulled Petrobond for fantastic results! http://shop.petrobondforsale.com/Mulled-Petrobond_...
- Clay-y, sandy dirt: That's right, if you happen to live in a clay-dirt area, just go out, dig up some dirt, sift it as finely as possible, add some play sand and a *little* water so that it barely clumps together when you squeeze it in your hand. Treat it like greensand. This will usually give perfectly acceptable results.
Step 6: Making Flasks and Making Casts (Hey That Kind of Rhymed!)
Flasks are what you put around the sand when your molding it. You can make them or buy them:
Buying them (I've never used these guys before, so make sure they have something that will fit your sword in it): http://www.hinesflask.com/
But scaled up to fit the dimensions of your sword.
This page explains well how to use your flasks and cast in greensand (or any of the other materials). Read it and do it! You are going to end up setting your cast vertically so your pouring into the hilt and down toward the point, so set the blank up close to one side and use a peg or something to fill the space between the blank and the side. This is where you're going to be pouring the bronze in.
From this point, I will assume that you have a satisfactory mold made.
Step 7: Acquire and Alloy Copper and Tin
What you need to know:
Copper: You can get it at any scrap yard. It's fairly reasonably priced, but look up the prices online before you go. If they mark it up a few cents on the pound, that's fine. If they mark it up several dollars...that's not. Grab about 5 pounds.
Tin: You can get this at thrift shops. What you're looking for is pewter--it looks a lot like aluminum, but it has a lower melting temperature, which you can use to test it when you get it home. Take a camera or smartphone, take pictures of the possible objects/their serial numbers if they exist, and look them up on the internet. Most things will be on ebay and tell you what material they're made of. You might have a few misses, but this is MUCH cheaper than trying to buy the stuff online.
If you can't get to these, simply go online and buy some bronze. It'll be more expensive, but it'll save you time and is cheaper than buying copper and tin online and alloying it.
If you DID buy copper and tin, you want to alloy these in your crucible. The ratio is, by weight, [EDIT: I had the wrong percentages the first time.] 88% copper and 12% tin.
There are two methods you can use to alloy the metals. The first is to simply put the tin in the bottom of the crucible, pile the copper on top, and heat it to liquid. This is generally easier to do, but having the tin liquid for too long makes it absorb gasses from the air, which has the possibility of causing structural problems. The second option is to heat up the copper first and drop in the tin later, which causes less gasses to dissolve but can lead to insufficient alloying. You may need to push the copper down with some sort of rod as this progresses--the copper doesn't necessarily have to reach its melting point to alloy with the easy-to-melt tin.
Step 8: Pour the Darn Thing
So you've gotten this far! Soon we will have our sword.
Set your mold up as specified earlier. Melt at least 1kg of bronze in your crucible, heating it well PAST the melting point so as to let it flow in the mold. Using your tongs, pick up the crucible, lift it to the opening in the mold, and pour the molten metal in. It will hiss and bubble--this is normal.
Step away and let it cool for an hour.
Knock the mold apart, keeping in mind that everything in it is still going to be very, very hot, and gaze on your new sword!
Step 9: Plier Off the Extraneous Metal and Polish It Up
Exactly as the title suggests. Take a pair of pliers and carefully work any pieces of metal that stick out up and down until the metal fatigues and it snaps off. Then, use files, sandpaper, steel wool, and eventually an oiled cloth to polish it to a shine that pleases you! This may end up taking a full day of work, but you'll be impressed by the results if you're patient.
That concludes this instructable! If this receives any interest, I'll be happy to make another on making/riveting the handle, hardening and sharpening the blade, creating your own custom furnace like the one pictured in here, and anything else you guys would like!
NOTE: Several of the pictures in this instructable are from Neil Burridge, a masterful bronze caster and historical weapon expert. He's who got me interested in bronze casting in the first place, and I owe him a huge debt for his inspiring work. Check out his website here, and maybe buy something! http://www.bronze-age-swords.com/index.htm
Have a fantastic day!