Although the head was moved up and down the column by a simple, quick-action lever-operated rack-and-pinion mechanism, once a coarse setting had been achieved it could then be accurately adjusted into its final position by a very fine feed worm-and-wheel mechanism engaged by a metal-to-metal conical clutch (horizontal axis handwheel); one revolution of the knurled-edge, micrometer-engraved fine-feed handwheel (vertical axis) moved the head assembly through just 1 mm. 

After some work Christian Späth in Germany has discovered a way of reproducing the original Hommel mottled yellow-and-black "craquellee" finish. For 1 square metre a 3 litre pack is required. In 2004 the price was €105 plus shipping. Contact: mail@spaeth-schwarz.de