Metal Spinning How to Part One -- Lever and Fulcrum
How does the metal spinner work?
Most information on metal spinning explains the tools and the lathe rather than how to use them. This discussion is going to focus on the metal spinner rather than the tools and machinery. Not much has been written on how to metal spin, first because it is difficult and secondly because metal spinners were members of Guilds that protected their trade and methods. In Europe many Guild member were restricted as to where they could move. The Guilds didn’t want their trade secrets to be revealed or cross pollinated with metal spinners in other towns, cities, state and/or countries.
I will restrict our discussion to hand metal spinners. Hand metal spinners are those who secure the mechanical advantage afforded them by the use of a lever and fulcrum. More precisely the metal spinning tool and the fulcrum pin. The invention of the lever most likely predated the invent of the wheel, however it was the ancient Greek mathematician Archimedes, 287 BC -- 212 BC, that explained the principle of the lever. The metal spinner uses the tools and fulcrum pin because of the mechanical advantage.
The way in which the metal spinner uses the tool and fulcrum pin makes it possible to do work the could not otherwise be done or at least be done very long. The metal spinner uses their body rather than their arms and hands. In general their left arm remains straight and their right hand is used to make small clockwise/counter clockwise adjustments to the spinning tool. No particular mechanical advantage is being attained the arms. It is the body that employs and exploits the principles of the lever.
Now let’s discuss the position of the body. The metal spinner stands in front of the lathe with their left foot pointing towards the lathe, perpendicular to the axis of the lathe. The right foot is pointed to the right at about 45°, towards the tailstock of the lathe. The feet are apart to provide for a stable footing. As I explained earlier it's the body that move rather than the arms in metal spinning. The movement is in the direction of the right foot that is pointed towards the tail stock at about 45°. During this movement to the right the metal spinner moves up on his or her toes. The movement is up and to the right towards the tailstock.
You could think of the left hand as being held in place as if someone had taken a roll of duct tape and in multiple passes had taped the hand in place on the tool rest with the metal spinning tool up against the fulcrum pin. One big ball of tape stopping the tool from moving in any direction, left or right.
Your left hand will hold everything in place and also keep the metal spinning tool from moving in and out during the spinning operation. Now that you have the idea, forget the duct tape, that was just to make the point, because the tape would restrict the left hand from doing the second activity which is moving the fulcrum pin from hole to hole in the tool rest during the metal spinning. By moving the fulcrum pin back and forth in the tool rest you can secure both a static and mechanical advantage relative to your work piece (what you are spinning).
Most people think that the metal spinning tool is held in the right hand, but that is not the case. The metal spinning tools are held in position by the left hand and the right armpit of the metal spinner.
The right hand also has two basic jobs, the first is to keep the metal spinning tool from falling out of the metal spinner’s right armpit and secondly to rotate the tool to the appropriate surfaces of the spinning tool. The right hand rotates the tool and holds that position during the metal spinning process.
Now you know where to stand, and what to do with your hands and feet, you should now have a basic understand of how the metal spinner uses the static and mechanical advantage provided by the tool, tool rest and fulcrum pin. You should practice positioning your hands and feet while holding the metal spinning tool. Move back and forth, don’t forget to move up on your toes as you move towards the right and tail stock. Think about the roll of duct tape and imagine how it would hold everything in place. I know it is a little like learning to fly an airplane by using a chair and broom handle, but this is fundamental to acquiring the metal spinning skills, have some fun, and prevent injuries from fatigue that will result from working too hard rather than using the lever and fulcrum.
I am not ready to write the definitive book on metal spinning, but rather I prefer to blog a series of posts that explain the metal spinning process from the metal spinners prospective. In future posts I will focus on how to set up the lathe and workpiece relative to metal spinning and efforts to secure the maximum static and mechanical advantage from positioning yourself and the tools correctly.