Koch Grinding Machine. Grinding and polishing.
The Koch 4004 is a design that is as simple as it is brilliant. A grinding and polishing machine for the gouges and chisels of sculptors and woodturners.
The grinding stone on the machine is a self-cooling ceramic disc containing aluminum oxide. Any type of steel can be sharpened with it. The grinding disc makes the steel much less hot than the “normal” white disc on your grinding machine. The machine is a so called slow runner, 1400 RPM. The motor is a 300 W single-phase motor with a shaft that runs to the left and right of the motor. The windings are on this shaft and the pressure is absorbed by large ball bearings.
The burr that occurs during grinding can be removed with the felt discs. Both felt discs are made of special felt and differ in hardness. They are enriched with aluminum oxide. Soft felt discs for quick material removal and hard felt discs for even polishing. (The yellow disc is for round profiles and the green for straight ones, for example chisels.)
Koch Grinding paste
The included Koch grinding paste is grit 2500. There is also a polishing paste grit 3500. This grinding paste also has self-cooling properties, making it possible to quickly sharpen tools made of tool steel without overheating them. The rods mounted in front of the machine are polished and 12 mm thick. This means that any attachment from, for example, the Tormek can also be used on this grinding machine. The most useful of these is undoubtedly the SVD 186R.
A CBN wheel is also available for this machine. The advantage of a CBN wheel is that the diameter does not decrease. The levers therefore no longer need to be adjusted. There is also a Koch 4004 machine with a CBN wheel available.
The special thing about this machine is that you can move from the stone to the felt disc while your chisel remains in the grinding jig. It’s super fast and the result is amazing. I wouldn’t believe that you can “polish” away grinding marks of 80 grit with 2500 polishing paste. But it is true, and it happens with unprecedented speed and ease! The guide rods can be infinitely adjusted and secured with a handle.
1 Ceramic disc (150x30mm, Grit 80)
Felt disc 120x20mm (Can also be ordered later)
Felt disc 150x30mm (Can also be ordered later)
1 Kg Koch polishing paste green, grit 2500 (Can also be ordered afterwards)
handles for adjusting the guide rods
plexiglass protective cover
In the video below, the Koch HT 4004 is compared with the Sorby Pro Edge, the bench grinder with CBN wheel and the Tormek T8.