Assembling the Turntable Drive

In my last post, I detailed the assembly of the Kitwood Hill 65 foot turntable pit.  The next step was to mount the bridge turning plate on the upper side of the pit floor, and the gearbox and motor below.  The turning plate is a pre-assembled unit that uses two gears back to back, screwed onto 3.7 mm laser board with two machine screws.  A circular PCB board is held to the plate with doubled sided tape.  The PCB board is scored to allow two gold plated sprung plungers to route power to the bridge track as the bridge rotates.  Here is a picture of the bridge turning plate.

On the underside of the pit floor laser ply boards are assembled into the walls of the gear box.  The primary axle is inserted from the top side and two 60T gears are pressed back to back on the axle  Simon Cox has found that two large gears are needed to prevent slippage.

The idler gear is made up of a pinion gear and a large 60T gear.  It is inserted so that the pinion gear engages with the large gears on the primary axle.

Here is a view of the assembled gear train so far.  The two wires on the left are the power leads to the gold plated sprung plungers that make contact with the PC board on the turning plate, routing power to the track.

The final step is to insert the motor.  The motor is tiny -- about a half an inch long -- with an elaborate gear drive on one end.  In spite of its small size, the motor has plenty of power to turn the turntable bridge.

The motor is affixed to the motor plate with two machine screws.  In attaching the motor, one of the tiny 3 mm screws flew off into hyperspace, where it remains to this day.  I emailed Simon Cox and received an answer almost immediately.  He said he would send another set of screws at no cost.  I was impressed with the service and support provided by this small British manufacturer.  Kudos to Kitwood Hill Models!

Once the motor is secured to the plate, a small pinion gear is pushed onto the motor shaft.  This gear engages with the large idler gear, driving the turntable bridge plate.

The motor plate is secured to the sides of the gear box with small 3 mm machine screws.  Take note that the tabs that join the gear box to the motor plate are not symmetrical.  Be careful to follow the pictures in the instructions.  The parts must be assembled as per the instruction sheet or you will find yourself trying to unglue wooden tabs and slots without breaking anything .... a likely scenario, I can vouch for!

With the bridge plate, motor and gear train in place, it was time to test the mechanism to see if it all worked as promised.  The motor is low voltage (3 vdc) and the kit comes with a battery holder for two AA size batteries.  I powered up the motor, and with very little noise, the bridge plate began to turn slowly.  It worked!

With the completion of the pit and turntable drive, the next installment in this series will turn to construction of the turntable bridge, wiring the track, and inserting the model onto my roundhouse module.