Author Topic: Turntable power (for the garden)  (Read 1040 times)

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Offline John Candy

Turntable power (for the garden)
« on: February 28, 2016, 10:01:12 AM »
Turntable power (for the garden)

The only major track component remaining to be completed is the turntable and the radiating tracks.
The turntable pit has been sitting empty for a couple of years now (precision cut by Filcris into the recycled plastic base) awaiting a decision on the method of construction.

I have purchased a 6 inch square (U.S. made) galvanized Turntable bearing (runs on ball bearings) which, I hope, with sufficient greasing will stand up to the weather, at least for a few years before requiring replacement. I have several 7.25inch gauge wagon bearings (donated by Mark P) whichare just about right for the out-rigger wheels to run around the perimeter rail.

The decision to be made is whether a manual/mechanical "Meccano" style lash-up or a motor-powered arrangement would be better ... and where to get the necessary bits.

"Finger power" is not an option for me.

So, what kind of motor and gearing arrangement would be needed to :-
a) provide sufficient power to rotate via the central spindle mounting.
b) resist the weather.

Regards,
John.
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline cabbage

Re: Turntable power (for the garden)
« Reply #1 on: February 28, 2016, 03:00:30 PM »
John,

You are not going to be able to rotate that amount of mass easily with a central force. You easiest option is to motorise the wheels on the perimeter rail and use the leverage of the radius to spin the turntable. The Muffet MOD1 gears are easily weather proof. As to the power requirements a few items of data required please. Mass to be rotated and radius. As to having a weather proof electric motor -these may be a "fit as required" device.

regards

ralph

Offline John Candy

Re: Turntable power (for the garden)
« Reply #2 on: February 28, 2016, 09:51:59 PM »

Ralph,

The heaviest and longest locos that I would expect to fit on the table would be a Pacific, such as Kingscale Britannia or B.L. A3 (however much they may weigh in at).

I had expected that it would be difficult to drive the table from the spindle, unless using a very large cog on the spindle (perhaps 9 ins. diameter) and driven by a large, slow-revving, motor, with a further step-down gear interposed.

Would a chain (or toothed belt) drive to the centre spindle be a practical proposition?
Attaching the motors to the revolving deck would introduce two complexities(although it may prove to be the only way).
Firstly, power/control cables (or some kind of dirt/wet -proof pick-up contact system) would be required to connect to the revolving bridge component.
Secondly, the difficulty of fitting/concealing from view the motors and gearing beneath the extremities of the bridge deck.

Another thought I have had while typing this is possibility of the entire base of the pit revolving (the bridge being rigidly attached to the pit base) being driven by a largish motor and friction drive acting on the circumference of the pit base (which is perfectly circular and of 20mm thick recycled plastic board).

Regards,
John.
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline cabbage

Re: Turntable power (for the garden)
« Reply #3 on: February 29, 2016, 07:04:03 AM »
Technobots sell MOD1 rack in small strips that it should be possible to line the inner ring of the pit with. This couples to a simple gearbox would engage the rack and spin the unit. It would not be very high and sit underneath the decking of the turntable. Only the ants and spiders would see it...

Always try to keep things simple!

regards

ralph

Offline John Candy

Re: Turntable power (for the garden)
« Reply #4 on: February 29, 2016, 07:17:40 PM »
Thank you Ralph.

I will investigate the rack components.

Regards,
John.
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.