Short documentary – favourite tool of a tap maker

Bastian Asmus
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A conical reamer for the tap maker

In Nuremberg the tap makers belonged to the redsmiths. This article is about a simple question of how the conical opening of a late medieval tap was dressed. Although you can do this completely manually, as I have shown in the short documentary, it is highly unlikely that it was actually done this way by the Nuremberg Red smiths or tap makers. Grinding the stop cocks into the tap takes several hours, even if the casts had a good fit to  begin with. Of course, it is not the spent labour time that has caused me to investigate the grinding of the stop cocks in more detail, it was rather the pictorial evidence that I found in Weigels book of trades and in the Nürnberger Hausbücher of the Zwölfbrüderstiftung.

Tap maker Hans Zeuller

Redsmith and tap maker Hans Zeuller

Redsmith Hans Zeuller with conus reamer. Source: Wikimedia Commons

The tool with which Hans Zeuller uses is clearly visible inside of the tap We can assume that it is a kind of conical reamer; i. e. a tool used in a scraping rather than a cutting fashion. Metals are very dense and can hardly be cut by hand. Although this is the oldest illustration, the tool is essentially the same as the one shown in the most recent figure by Christoph Weigel (see there). The colour of the depiction is interesting: it doesn’t seem to be made from non-ferrous metals, nor steel or iron, as the colouring of the vice, saws, hammers and files suggests. But what material is it made of?
The picture contains countless other exciting details, such as the fire extinguishers or the cupping heads. A new article on this will hopefully soon be published.

Tap maker Georg Wehe

Tap maker Georg Wehe

Tap maker  Georg Wehe, † 1625, uses also a tool to dress the inner surface of the taps conus. Source: Wikimedia Commons

In this picture we also see a conical reamer, but this one seems to be made of non-ferrous metal. Unfortunately, the working end is also completely concealed in the tap, so that here too it is not possible to clarify what the tap maker’s tool looked like. It is also interesting to note that this must have been solely a tap maker. Any other cast cast products are missing. Does this picture reflect the extreme specialisation of Nuremberg craftsmen in the 17th century?

The tap maker by Christoph Weigel

The Tap maker by Christop Weigel, 1698.

The tap maker by Christoph Weigel (1698). Two conical reamers are visible, one in the background and one in the hand of the left tap maker. These are reminiscent of Hans Zeuller’s tool (see above). Source: Deutsche Fotothek Library via Wikimedia Commons.

In the late 17th century, tap valves are apparently still reworked according to the same principle. However, it seems that the tool here also functions as a tool for model making of the wooden models. Furthermore, it seems that the stop cocks are made up of two parts. In the foreground you can see a trough in which the stop cocks handles seem to lie, however without a cone. The handles show holes that indicate later joining by riveting. But this is a different story and shall not be deepened here.

Reconstruction of the conical reamer

As is so often the case in archaeology, only the analogy conclusion and the range of the technically possible remains to be done in order to make a reconstruction. The following assumptions were made:

  • it is a cutting or even more likely scraping tool, not a grinding
  • there is only one cutting edge in the tool to get a cleaner cut
  • the corpus is made of the same alloy as the taps -> could be made by the craftsman himself
  • the cutting edge is made of carbon steel -> another material would not work
  • there may be different tools, see figures

Before the reconstruction, a prototype was first produced with modern tools in order to test the ideas and incorporate these findings into the reconstruction. Afterwards, the tool was cast in the lost wax process and a steel blade was inserted. The blade is fixed with small metal wedges in a groove in the tool.

The tool functions perfectly and the inner cone of the taps can now be perfectly machined, so that there is no need for hours of grinding – that’s what I call innovation!

Applied Archaeometallurgy

My past contributions have always been about the tap makers and taps. Even now I still have not reached the end of the story. The great thing about applied archaeometallurgy is that it is still possible to go deeper yet in order to understand a production process; and only in this way it can be done: observation – research – hypothesis – practical testing – analysis of the experiment. Well, this is all known as a epistemological approach and as such typical of the humanities. It is really important to me, however, that the applied or practical work is only just beginning with the examination of the hypothesis. Only the results and a subsequent synthesis of the results will help us in the archaeology of (crafts) processes.

 


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