One of my big bugbears in jewellery making was wire ingots.
As if heating this big bar of pig iron up to temperature and then using a cigarette butt an stopper wasn't bad enough, trying to get the ingot out was often problematic.
Especially with white gold, which often has a tendency to 'solder' onto the iron.
I have been using the method described below for about 15 years and I personally think its a vast improvement over the commercially available casting ingots.
Here is a link to the first one I made.
I make it out of normal mild steel that is available at hardware stores.
The base is 200 mm long and 40 mm wide and 4 mm thick.
The rest is 8 mm square bar.
And 100 mm length of 5 mm rod that the lock pins are made of.
After the steel is cut to the right length, I mark five divisions and drill through it with a 3.2 mm drill.
This is because I am using a 4 mm tap and 3.2 mm is the correct size for the pilot hole.
Once the square bar is drilled, I clamp it into position and use it as a guide and drill right through the base plate.
Then the holes in the base plate are expanded to 4.2 mm and also counter sunk at the bottom.
At the back, counter sunk steel screws.
Then I tap all the holes in the square bar with a 4 mm tap.
View from the bottom showing the counter sunk holes and the 4 mm screws.
The base must be lie flat, otherwise it will wobble, which is not good for casting.
I trim the screws off and then file and sand them flush.
Now the end corner is added in the same way.
And then also cut off flush and sanded down.
Then I made two lock pins.
They hold the guide bar in place.
A simpler design is to solder a 5 mm piece of rod to the metal of your choice.
I soldered 1 mm round steel disks I had lying around.
Make it longer than needed and trim it off at the bottom once the lock pin is in place.
Casting anything smaller than 5 mm square is not efficient because it becomes to finicky to pour and you spend more time fixing a bad cast than working.
When the 5 mm stop is used, the lock pegs only fit in the second and fourth holes.
The first and third lock holes are for the 8 mm variable stop.
Here the wire ingot is set up to have 30 grams of silver cast in the 8 mm size.
I made a mark where 30 grams of silver is and I use that as a basic guide.
So if I cast 60 grams, then it is twice the distance from the end.
15 grams, half.
Because I cast a known weight into a fixed cavity, it means the mould always casts complete ingots.
So how it works is that when you choose say the 5 mm size, then you put the stop where you want and you hold the guide against the stop and flush against the end.
Holes two and four then align and the lock pins fit in and lock the guide in place.
Then it's ready for casting.
When the lock pins are removed the guide is loosened and the ingot is also then loose and can easily be picked up and quenched.
Here 30 grams of silver has been cast.
This is a proto type and so I have just done silver, hence the 30 gram mark.
Gold would be a different mark in terms of distance.
The left side of the guide is cut at an angle so I can see what side is up.
The bottom of the ingots as they come out.
There are more tutorials at http://meevis.com/jewelry-making-class-list.htm