Point actuators
The first thing to do was examine the mechanism Geoff had made after our last meeting (see last post), and it was wonderful.
Convinced it was the way to go, Stephen and Geoff set about converting the other 8 units to the new design. This entailed taking everything off, drilling a new hole for each switch (they pivoted around one of the existing holes), assemble switches and resolder wires. We also took the opportunity of replacing the plastic spacers for the servo mounts for wider, wooden spacers that were more stable. Laurence prepared the rectangular plastic sections for the tie-bar units and the plastic tube reinforcement for the actuator wire.
After lunch, another tie-bar unit was fabricated and, together with one of the motor units, fitted in place of an existing point motor. However, it wasn't easy to fit and adjust the two units and the connecting wire, which would require some serious thought to overcome satisfactorily. We could also see that due to the size of the new unit, the adjacent motors would be difficult to fit and could require additional cranks and fittings - not what we wanted for reliable operation. Spirits deflated, we decided to review the situation at the next meeting.
Driving home, Stephen started to consider reverting to the original direct-wire design, but using the excellent large-sweep servo action. Over a cuppa, the idea turned into a sketch, which was sent to Geoff, who immediately saw the potential and started to investigate. The following day, he had a working mechanism - mk 3 (or is it mk4?).
Stephen's design didn't work, as elements clashed or moved excessively, but Geoff's solution with an off-centre tie-bar horn/wire not only created a solid, easy to build unit, but was also much more flexible to fit.
 |
| The unit being tested. |
 |
| The unit installed on the layout. |
We are back in business!
