Tips for Using the ClayMill Extruder:
If you haven’t taken the ClayMill extruder from PMC Connection out of the box yet, or if you have but were afraid to use it, here are a few pointers that may make it easier for you to get started.
This extruder is quite different from the popular small one. First, It has a black ball at the end of the handle to prevent the handle from sliding off.
It’s important to know that this ball screws in reverse (to the right). The reason is, that if it screwed to the left, it would come loose and fall off during the extrusion. So if it seems hard to turn, it is because you are turning it in the wrong direction.
Second, the piston is not attached to the screw. If you scroll the handle all the way to the right, the piston will come out of the barrel.
This makes it easy to clean both the piston and the inside of the barrel.
To put the piston back in the barrel, scroll the handle to the left to make room for it, and place it inside with the circular indentation facing the barrel, and the flat side facing out. Once it’s in, keep scrolling the handle to the left to make room for the clay. Since the piston is not attached to the screw, it will not go in. Simply push it inside with your fingers until it reaches the end of the screw. Repeat this if you need to make more room for clay.
Third, the tube adapter is a disc with 7 holes. It is used with another die, with the thicker rubber washer sandwiched between them (the thinner rubber washer that cones with the kit is a replacement for the washer that is wrapped around the piston). Because of the size of this extruder, it does not necessarily require a pin or a hole corer to create a tube. For example, if you fit the rubber washer between the tube adapter and a disc with a square hole, a square tube with a square hole will be extruded.
Likewise, if you use a disc with a triangular hole, a triangular tube with a triangular hole will be extruded. This is what makes it possible to make the earrings below:
Hopefully, more dies with other shapes will be coming soon.
The center hole allows you to attach different sizes of pins or hole corers. The holes will always be round. The type of corers that can be used are shown on p. 116-117 of my book Metal Clay Practice.
The rubber washer that comes with the kit is less than 2″ in diameter. This may cause clay to be trapped between the washer and the walls of the barrel. You can get a larger 5 mm washer at the hardware store for about 50 cents.
When using the extruder with more than one type of metal clay to achieve a color pattern, the steel circle should always be 1 card thick, or it will not be able to sinter. If the mix involves bronze, it means that the piece has to be fired at mid-fire schedule, lower than what is required for steel. Only minimal amounts of steel will be able to sinter at this lower temperature. I often watch students while they work and notice that their steel circle is too thick. “But I rolled it with one card!” is usually the answer. Then I take the roller and roll the circle again, pressing harder. Here is the result:
Some of us, including me, don’t have enough strength to turn the handle all the way without leaving some clay inside the barrel. I find it much easier to operate the extruder when it is held in a vise.
My suggestion is to first practice the different options with a single type of clay. That way you will not be losing any clay. Anything can be retrieved or recycled.
You will notice that when you use the tube adapter, some clay will be trapped inside the rubber washer. The same happens with the smaller extruder, but with the ClayMill the amount is much bigger. When using a single type of clay, this is not a problem; just return it to your storage. When using more than one type of clay, this trapped clay is still usable. One option is described on p. 119 of the book Metal Clay Practice. Another option will be suggested in part II of this posting, which is a project for a Cat’s Eye Ladder.