Metal spinning is an old, hard-learned and spectacular craft. The basic idea rely on the transformation of a round sheet (a blanc), into a symmetric object. Metal spinning performs just that, in contrast to more wellknown works by the lathe.
The lathe is more of a sturdy wooden type. At the lathes shaft will a form (mandrel) be located. A mandrel can in its simplest form just follow the inner contour of the desired shape, but can also only support a smaller part, or be
dividable. To fix the blanc against the mandrel, will a support (follower) be used. This and the blanc will then be hold in place by the force from the tailstock.
The basic spinning tool clamps by the spinner between the main body, and right arm. This had therfore a long wooden handle. As support for the tool will a steelpin in the toolrest be used. This has a row of holes, so the pin can be moved on, when work proceed. With rhytmic, smooth strokes, will then a circular blanc transform into a bowl, chalice, et cetera. You may though had to spin in several steps, or use more then one part, to perform a complete item.
The following comes from afTRYCK, which you can download HERE. There are only parts visible here, without any real links between them.
A further step on the line of development, were reached when we came to the pole-lathe. This had a wooden-pole located eather in the cealing, or on a separate stand. From this pole were a cord finding its way downwards, looping over the shaft/pulley, ending at a foot-operating pedal. By pressing this where the pole forced to bow, and a (waddeling) motion was born.
Illustrations showing pole-lathes exist at least from the 14th century. But the type must be older than that. In Sweden is such a thing called a Svegsvarv. Svarv is the same as a lathe, and sveg is from the German word sweig (branch,limb). The art of metal spinning has most likely been executed on pole-lathes. There are still people that build this kind of lathes.
Rolling mills are known since the 1500-s, mainly used in mint works, or at jewellers. From mid 1800-s came then the modern, industrial rolling of sheets. The advantage of more even quality, and faster production, were features that must have been significant.
In a couple of trades has sheets been casted more directly. Example on such are the 4-8 sided pewterflasks that become popular in the 17th century, and that still were produced into the 1800-s. These were made of casted sheets, and soldered thogether. Roofs covered with lead-sheets can still be found on some churches. Such sheets were made by using a sort of sledge, that was hollow, and also provided with a narrow opening in the bottom. The sledge was filled with liqued metal, and then in a even phase runned over the underlying surface. Similar technique has been used by people that manufacures organ pipes.
This craft is an old, hard-learned and spectacular one. The basic idea rely on the transformation of a round sheet (a blanc), into a most often symmetrical object. Metal spinning performs just that, in contrast to more wellknown works by the lathe.
In the picture can you see a spinner holding his tool, and som steps from a blanc to a cylinder.
When a blanc (the work-piece) are clamped between the mandrel, and the follower, will it almost for sure be of-centre. This is corrected by loosing somewhat on the tailstocks wheel, an then with a tool pushing the blanc into a centered position. This tool can be a piece of hard wood, a steelrod, or something similar.
The work-piece has in most cases to be lubricated. This to reduce the friction that occures between the tool, and the blanc. A good lubricator should be so stiff that it not splashing around. A smaller amount are often better then the opposite. It shall also be easy to remove afterwards.
Folding a rim are often a good idea. You had though, to be steady on the hand. it's not that easy to perform, when the rim gives more or less resistance. If things starts to go wrong, can it be quite difficult to correct it. This depending on the problem of reaching the backside of the rim. The illustration shows a rim that have been workt to hard at one point, and therefore partly sunkt.
In worst cases, can the result be more of a roller coaster. Then it's time to surrender.
The metal spinning lathe, can be described as more of a sturdy wooden- lathe, then an ordinary metal (capstan) one. Special features are the robust tailstock, and the toolrest with holes (for a supporting steelpin).
The picture shows a lathe with:
1- Headstock/Transmission housing
2- Mandrel(form you spin on)
3- Follower(Holdes the blanc between the mandrel and the tailstock)
A good feature for a tailstock are stability. Many tailstocks included with woodlathes are to short, and weak. If a tailstock for spinning purpose, can`t stand the pressure, will you get serious problems with centering the blanc. It
can also quickly be out of control and become airborne.
Most of the tailstocks buildt for spinning has a quick relese lever. A such as in the picture can be lifted somewhat, and then slided back-and-forth. Finer adjustments are made with the wheel in the right end.
As extra support at heavier work, can a belt be used around your waist. To have any use of such shall you lean on it with your bodywight. Some amount of bodymass, are not missplaced here. Some like to be tamed by a belt, some don`t. I think it's basically a question of habit.
The best support comes from the little pin in the toolrest. Without this, had spinning, probably never been invented.
Here is two objects that have been spun twice, to get there final shape. The concave one has at first, been a cylinder. In the second spin, has then all the surface been workt. On other hand, the bellied one, has almost got its final shape in the first job. Only the concave neck, has been spun once more.