Flesher: Technical Support

System 3 Service Bulletin 007:

System 3 Printwheel Drive Sheave Positioning

The drive sheave on the System3 Z-axis is a dual-flange unit. The flanges control proper tracking of the belt around the large sheave and through the spindle stiffener bars.

The drive sheave must be positioned the proper distance from the back of the spindle plate to insure that the pulley flange does not rub the back of the spindle plate or the belt rub the inside of the two stiffener bars the belt must pass through.

If the belt is allowed to drag, you will experience vertical title baseline problems, character spacing errors in horizontal titles, and/or incorrect characters. You may even loose printwheel heat, if the drag is sufficient to stall the motor in 'idle' mode. (The controller turns off the heat if the motor stops rotating to prevent hot-spots on the wheel.)

Proper position of the drive sheave on the motor shaft is with the front flange of the sheave 0.010 inch (0.254mm) from the spindle plate. To set this distance, loosen the two set-screws and place a piece of 0.010" shim stock on the spindle plate. Push the drive sheave against it. Tighten the set screws. Note: If .010 shim stock is not available, a single thickness of “F-Grade” buckram can be used. It is typically .012 - .014 thick.