ModelPlan 138




John Ince's

Two New Meccanographs Incorporating the Schmidt Coupling

Our ModelPlan features two new designs for Meccanographs, designed & described by John Ince.

They were inspired by a desire to demonstrate the Schmidt coupling in use. The Schmidt coupling has been discussed on "Spanner" in recent years and was evidently invented for use in offset printing machinery. Its function is to transmit a steady rotational motion from an input shaft to a parallel but non-aligned output shaft the position of which may change continually.

John's first aim was to show how the Schmidt coupling worked with an actual moving output shaft. Once this function was achieved then it was a simple matter to add a pen holder, and pen arm cam to put the device to practical use. Once a mechanism is devised to both rotate a designing table, and move it to and fro, it is evident that a pattern may be drawn even when the pen is fixed in one position. By adding pen movement the pattern becomes more complicated.

The Schmidt Meccanograph Mark 1 is the simpler of the two. Its instructions cover the Frame, Designing Table Support Cage, Backlash Control, Schmidt Coupling, Pen Cam Support Structure, Pen Cam Drive, Pen Cam, Designing Table Transverse Motion, Fulcrum Adjustment, Primary Drive, Pen Arm, Designing Table, and Operation of the Meccanograph.

The Schmidt Meccanograph Mark 2 incorporates three gearboxes which allow the cam speeds and the table rotation speeds to be varied. Its instructions cover the Frame, Primary hand Drive, Cam Drive Layshaft, Cam Drive Gearbox, Pen Cams, Table Drive Layshaft, Table Rotation Gear Change, Designing Table Support Cage, Transverse Motion Cam, Transverse Motion Table Link, Pen Support Arm, Pen Arm Support, Pen Arm Drive Strips, and Operation of the Meccanograph.

With the instructions are five colour and fourteen black and white illustrations and a Parts List for each Meccanograph.