A machine to undertake powered filing might seem, at first rather an oddity but in a toolroom where precisely crafted one-off parts have to be made, such a machine allows a skilled man to turn out jobs not only faster but also without sacrificing anything in the way of accuracy. Filing and sawing machines (sometimes referred to as die filers) were made by several manufactures but amongst the better known was the German-made Thiel "Produro", the makers claiming that both models offered, the 111 and larger 115 could cut any steel and even tackle, when fitted with diamond-embedded files or using diamond lapping or polishing pastes, hardened steels and tungsten carbide.
A neatly designed and very compact unit with dust-proof enclosures, the Produro had an infinitely variable-speed drive (though a patented gearing system) that allowed both the stroke length and stroke rate to be altered while running.
Instead of a table that moved up and down, the Thiel's was fixed in the vertical plane (though inclinable in all directions) with the mechanism for clamping and moving the files and blades adjustable. Extra equipment allowed the Produro to be set up for copy filing, a thankless task often delegated to an apprentice - though made easier by the provision (as part of the standard equipment) of an enlarging lens, light unit and a chip blower.
Intended for smaller work in shops dealing with horological, instrument, jewellery and similar work, the Model 111 had a stroke that could be varied between 1 and 2.125" (25 to 60 mm) and the rate set from 80 to 380 per minute. The 8.875" (225 mm) square table could be tilted through 10° in four directions and, with the machines throat of 5.125" (130 mm) as the limiting factor,  could mount work up to 10.25" (260 mm) wide. The machine was approximately 17" (430 mm) wide, 26" (660 mm) front to back and weighed 375 lbs (170 kg).
Ideal for larger jobs - almost certainly the biggest that would be sensible to tackle on this class of machine tool - the Produro 115 had a stroke that could be varied between 1.75" and 5" (40 to 120 mm) and the rate set from 60 to 300 per minute. The 17" x 16.5" (440 x 420 mm) table could be tilted through 15° in four directions and, with the machines throat of 9.5" (240 mm) as the limiting factor,  could mount work up to 19" (480 mm) wide. The machine weighed a substantial 1080 lbs (485 kg).