How to cast pewter into simple Hardboard/MDF moulds. This is a method for simple shaped objects with no undercuts. Its my first instructable so go easy on me!
Small sheet of hardboard, any off cuts will do.
A fretsaw (hand or powered)
Leadfree pewter, which you can buy online.
Blowtorch, or small camping stove.
A clip for the hairslide or a piece of dowel about pencil sized.
Solder and soldering iron or pencil torch.
Polishing wheel or dremmel.
Step 2: Making the Hardboard Mould
Here I make a hairslide using 4mm thick hardboard for the mould. The hairslide is about 9x3 cm so as you can see from the photo the board for the mould is a bit bigger. First thing to do is cut three boards to roughly the same size and then using a fret saw cut the oval out of the first board, give the edges a bit of a sand to smooth out any rough bits. It helps to make a tester in card to see if you like the shape.
Place the first board onto the next board and draw around the oval shape, next draw the waves within this oval shape onto the board, cut the waves out with the fretsaw and lightly sandpaper. Thin down the waves with sandpaper so that they are about 2mm thick, use wood glue to attach the wave shapes to a piece of board as in the photo. So what you have is a three part mould, an oval shape that drops over the wave shape and then a flat back. Cut a v shape in the top of the oval as in the photo and file a groove in the back board with a round file, this is for pouring pewter into when the mould is put together. Make sure the smooth side of the Hardboard face each other not the rough side.
Step 3: Put Mould Together
So now you have the three pieces for the mould, you need to clamp them together with clamps or soft wire, with the pouring slot at the top. Use wood blocks or bricks to hold the mould upright and stable. See the photo. Make sure there are no gaps between the boards that pewter could run out from.
So we are ready for the casting.
Step 4: Casting
Before melting the pewter make sure you wear saftey glasses and leather gloves, pewter melts at a low temp. but still gives a nasty burn. Cast in a well ventilated area on a flame proof surface with a fire extinguisher handy, make sure the mould is dry, as moisture will make the pewter spit back. Take your time and keep the work area uncluttered so spilled metal doesnt start a fire.( as you can see in the photo I dont practice what I preach !)
I use a blowlamp to melt leadfree pewter in an old tarnished spoon (low tech) the pewter doesnt stick to the spoon and it pours small amounts well. You can melt using a small camping stove which should melt the pewter in less than a minute.
When the Pewter is liquid, pour slowly into the slot in the top of the mould, be ready for metal that will run out from the top when its full and also trapped air can cause hot metal to blow back. (wear the goggles and gloves, and or a face mask.)
Step 5: Let Cool & Open the Mould
After about 15 minutes it should be cool enough to take the mould apart and see what youve got. If cool enough remove the casting from the mould, it might stick a bit, but a bit of careful levering with a screwdriver should sort it out. There will be a sprue of pewter at the top from where you poured in, this can be cut off with a hacksaw. If it looks good clean off rough marks with files and your ready for polishing. If things didnt go well you might have to change the mould slightly, on the plus side you can just melt down the casting and try again, so no metal is lost.
I use a polishing mop in a drill stand and start with coarse paiste and work through to fine, then I give a final polish with silver polish (brasso) You can use a dremmel type tool with a polishing head or wet & dry paper working to a fine grit and then go to silver polish.
Step 6: Solder on the Clip
This hairslide uses a clip that solders to the back, it could be riveted on using copper rivets or two holes could be drilled for a dowel to be passed through. The pewter bends easily to form the shape of the slide.
To solder the clip I use leadfree solder on the back of the clip and then I place the front of the hairslide onto a damp sponge or rag.
I then place the clip on the back of the hairslide and sweat solder the clip in place, the damp rag stops the heat from soldering burning through to the front.
Give everything another clean up and your done. This method of casting pewter can be used for lots of simple designs with no undercuts. Once you get more undercuts you need to cast into silicone moulds. The Hardboard should last for quite a few castings and hold up well to the heat, but it will burn if you catch it with the torch.
Safety first, make sure to wear gloves and goggles and be aware that pewter will burn, please dont send me pics of horrible burns or a hole where your house used to be! If your not sure of something stop and have a read up on it and then start again. Its my first go at an instructable so go easy on me, Im happy to answer questions and alter the make where needed. Have fun.
crazyg made it!