The mechanics

In order for stepper motors to be used in a reasonable price range, a gearbox was needed. Here the group had to build a suitable gearbox itself. All calculations as well as the construction were worked out independently (with a little help). The gear itself consists of a skeleton to which the toothed and belt wheels are attached. A pulley with 31 teeth is attached to the stepper motors. From this wheel, a belt goes to a pulley with 101 teeth. This is bolted to the third pulley, which has 30 teeth. The third rim wheel is connected to the 4th pulley, which has 70 teeth, again via a belt. The fourth pulley is bolted to a hardened steel gear which has 20 teeth. This gear is toothed with another gear, which is made of plastic and has 90 teeth. The plastic gear is bolted directly to the revolver. On each belt (two per gearbox) a spout device is attached. This consists of an adjustable axle with two small bearings, which press against the belt. The gear ratio is 34,209,677 and the efficiency calculated by us is 0.875520. The straps are minimally elastic and ensure that there is very little clearance between the stepper motor and the turret movement. This gives us minimal acceleration and deceleration curves for each individual step of the engine (the engine makes up to 12,000 steps per second). Thus, the gears do not wear out that fast.

Pressing the dispensers and panning the glass was another challenge. Originally an electric motor and a worm gear had been planned for dispensing the ingredients. This proved to be ineffective. Instead, servomotors are now being used to push the arms up against the bar doser. The glass used to be moved back and forth by a stepper motor. For a more precise control, we now also use a servomotor here. So that the glass does not fall over during the movement, the servomotor makes many small steps.