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Reply to "turntables which type and kind do you members think are the best for atlas track n big engines?"

 I wanted a turntable to take to modular layout shows that was large enough for the articulated engines that club members were running.   The turntable module had to be light to be lifted solo into my van for transport to shows,  thin to allow additional modules and gear to be piled on in the van, durable to withstand handling, and simple to setup the morning of a show (less than an hour).  The turntables demonstrated at York didn't satisfy those criteria.

With my previous experience cutting circles (AKA "router on a stick") in plywood while building Dobsonian telescopes, a turntable was just another circle cutting exercise, so I broke out the router. The turntable is 34.5" (Big Boy size) in a 4ft x 4ft module frame.  The module sides frames are 1x4s with Luan plywood decking, selectively reinforced with a double layer.  The assembled weight is at the limit of what I can manage.  Construction uses a Dobsonian-inspired Formica + Teflon bearing.  The floor of the turntable well (half the bearing) rotates (yes, its not prototypical unless you consider the B&O roundhouse turntable, but works well for this module).  Appearance is tinplate with an Erector set operator's house, no fragile handrails, etc.  

I motorized the turntable using a friction drive gear motor but discovered that large locomotive weights caused slipping (this IS prototypical) of the drive system.   I considered a stepper motor, gear drive, and indexing but a solution that would eliminate slipping added unacceptable weight.  I also found that casual operators at shows needed practice to control the motor for precise positioning.  So, the motor was removed and the KISS principle now works.  Operators can use the ever-reliable Armstrong motor and optical alignment techniques for rotating the bridge to the desired track.

Slip rings on the turntable bearing for bridge track power were considered but the initial solution (a quick hack) of extra length wires that could twist and untwist has lasted nearly two decades unchanged.

Wiring toggle switches to 16 tracks was a PITA.

If you are have woodworking skills (especially with a router), building a manual turntable for Big Boys is straight forward.  Making it light and portable is an additional challenge.  Wiring is always tedious.  You can do this for $100 in materials and your labor.  Scale appearance and detailing are up to you.  The difference between a DIY manual drive solution and the $$$$ turntables shown at York are in the reliable motorization and indexing systems the vendors offer, plus the nice scale details.  Having a turntable in your layout is a real plus.  At our modular shows, turntable operations always draw a crowd of spectators and, with the slow speed operation of today's locomotives, running locos in out of storage tracks is fun.  You really need one on your layout - DIY or buy one - you won't be disappointed.

John

OGR Publishing, Inc., 1310 Eastside Centre Ct, Suite 6, Mountain Home, AR 72653
330-757-3020

www.ogaugerr.com
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