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The famous Thuringian Stone Honing Machine
Some of you may have asked how the old hollow razor grinders honed their straights. The bigger razor companies produced hundreds of razors a day and also a single grinder could finish up to a dozen or even more if he used a hollow grinding machine or was very experienced and skillfull to do this by hand. So how did these grinders or companies hone their razors after they have been grinded. By Hand? Hundreds a day?
No!
I can only speak for the hollow grinders in Germany and don’t know, if there had been similar developments in other countries in the 19th or 20th century.
The first time I heard about this machine was, when I visited an old hollow grinder - while I was searching for thuringian whetstones maybe 5 or 6 years ago. Instead of benchstones he gave me two disks with a diameter of 9.5 inch and a thickness of nearly 1’’, that were visibly made of thuringian waterwhetstone.
When I asked – what have these disks been for? … he answered that they belonged to an old machine for honing razors, that, unfortunately, he had disposed several years before.
He also gave me some coarser man made disks of the same diameter
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Than he explained the principle of the machine. The disks were mounted on two different shafts that moved in reverse directions, the disks oriented horizontally like plates. On the bottom of each shaft the coarse artificial disk for setting the bevel on a razor was mounted and above maybe with a distance of 10-15 cm the thuringian disks for finishing the straights. The razor was laid down flat on the turning disk for a few seconds, then moved slowly backwards until only the front part of the razor was on the disk and then switched by a turn off the reel to the other plate, to hone the other side of the razor. Having done this a few times, the razor could be honed to perfect endfinishing in a few minutes.
Well you may imagine that I was fascinated by this machine and I strongly wanted to figure out, how this machine looked like and how it was operated. The machine is also described in the famous german textbook “The straight razor”, which was published in 1939, describing the so-called Hamburg way of hollow grinding. But there is no figure or picture of the machine in the book.
I looked for old advertisements, photographs and so one, but didn’t find anything concerning this machine. My investigations brought a first result when I found the original patent of this machine. The first patent was registered in 1908 by Carl Friedrich Ern, the famous Solingen razor grinder and developer of the double hollow grinding machine called “Hexe” (witch) that revolutionized the razor manufacturing in the early 20th century.
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In this first patent two disks were arranged on top of each other, the first one driven by a hollow shaft in one direction, the second one above driven by a full shaft the moves in the hollow shaft in opposite direction. So by this solution the disc are both of the same material and quality and the razors had to be moved from the lower disk to the upper disk.
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On a later stage, the solution with two shafts side by side and equipped each with two disks was established. The following scheme shows the principle:
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The machine was build by the Solingen company Louis Perlmann, a company which was a main supplier for equipment to the hollow grinders, but also produced their own razors, brand names “Louper”, “Flamme” and “Golf”.
The grinders I spoke to, also explained me that there had been machines with three discs on each shaft, below a coarse artificial stone for bevel-setting, followed by a blue thuringian for the progression and on top a yellow-green thuringian for endfinshing.
Here are the three different disks. The blue one is an Escher (JGES) labelled disc and is produced at the last site of the Escher& Son company in Theuern.
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Each of the discs made of thuringian whetstone have a weight of 2 – 2.5 kg!
It must have been a very difficult and hard work to cut these disks from the raw material in ancient times, without electrical machines. I have found a lot of broken pieces from discs at the old production sites.
… to be continued…