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Merkur Industrial Machine Tool Series: Model No. 305 - Arched Eccentric Press

Hi folks, Doc here, with another model in my Merkur Industrial Machine Tool Series. Along with the Upright Iron Planer that you can also see here in the Model Gallery, this model appears in the Merkur "Nejstarsi" manual, which features a number of designs modelled after machine tools of the 1920s and 1930s (you can download a copy of the manual from the link on my G-Files page in the How-To section). I'll present six of these models in the series, this being the second: an arched eccentric press.

As the illustration from the manual shows (see image at left), this is another great design. Like the other models in the series, this model could be built with the Merkur No. 7 Set of the period. I built the model using a modern No. 8 Set, plus a few extra parts. Once again, my goal was to duplicate the model in the manual as closely as possible. As it turned out, the only change I had to make involved how I bolted together the No. 2026 curved strips that form the arch at the top of the machine. Finally, I added a motor to automate the finished model. My final result is shown in the photos below.

As the images on this page show, the bulk of the machine is a tall, slender frame with two legs and an arched top. This frame has two identical front and back halves spaced about ½" apart that are joined together with trunnions and 3-hole strips. Between the two legs of the frame is mounted a stationary rectangular platform that forms the bottom portion of the press. Near the upper ends of the frame legs is an assembly consisting of a pair of axles and large pulleys that pass through the 3-hole strips and upper trunnions joining the front and back halves of the frame. A No. 2047 119-tooth gear is mounted on the outside send of the right shaft. The pulleys are connected by a third short axle that passes through opposing holes along the outer edge of the pulleys. The upper portion of the press is suspended from this connecting axle (see photos below). When the pulleys rotate, the upper portion of the press moves up and down as a result of the "eccentric" motion of the shaft from which it hangs.

A long horizontal shaft is mounted high up on the back of the machine behind the "eccentric" pulleys and shafts. A No. 1046 17-tooth gear mounted on one end of this shaft meshes with the 119-tooth gear. A large 85mm drive pulley is mounted on the other end of the shaft; between the gear and the pulley are a series of smaller pulleys that function as flywheels, and can also be used to drive other machines (see photos below). Actually, the original design calls for a second 85mm pulley to be bolted to the first, but I didn't have an extra one, so my version only uses one.

Although the original design did not incorporate a motor, this model, like the upright iron planer, is a perfect candidate for automation. I used the same process as I did with the planer, bolting another No. 1036 flanged plate to the rear of the model base, and mounting the motor to it using a pair of motor brackets. With the motor shaft pushed forward to engage the low gearing and a No. 1040 small pulley mounted on the end of the shaft, I connected the motor pulley to the large drive pulley above it using a large rubber o-ring. The final model is a terrific display piece that runs smoothly and looks great - I'll post video of it in action soon.