AlbertTheFrog Posted October 23, 2016 Share Posted October 23, 2016 I need to build a couple of (cheap, not pretty!) powered turntables for an inglenook project. The actual build should be easy enough but I need to find a way to stop accurately at each road. I have a couple of ideas, but if anyone can point me at any on-line sources I'd rather not reinvent the wheel. The turntable will be about 16" (40cm) in diameter and there will be four stop positions. I tried a Google search but lots of the hits were about commercial products and then there was the one with live 110v mains ... Link to post Share on other sites More sharing options...
amdaley Posted October 23, 2016 Share Posted October 23, 2016 I need to build a couple of (cheap, not pretty!) powered turntables for an inglenook project. The actual build should be easy enough but I need to find a way to stop accurately at each road. I have a couple of ideas, but if anyone can point me at any on-line sources I'd rather not reinvent the wheel. The turntable will be about 16" (40cm) in diameter and there will be four stop positions. I tried a Google search but lots of the hits were about commercial products and then there was the one with live 110v mains ... You could try here. http://www.locomotech.com/ Tony. Link to post Share on other sites More sharing options...
DCB Posted October 24, 2016 Share Posted October 24, 2016 Why re invent the wheel? Nothing wrong with good old wooden spokes and an iron hoop, Indexing is always a problem, I saw them have about three attempts to get the Minehead turntable lined up last time I was there.... Link to post Share on other sites More sharing options...
RAF96 Posted October 25, 2016 Share Posted October 25, 2016 Being a tightwad I have tried every diy turntable method under the sun and none of them were any good - says a lot for my skill-set. I have tried those TV turntables with a bit of ply on top, I have converted a Dapol TT kit to something like a functioning unit, I have hand crafted them from metal extrusions and wooden parts, I have motorised them and hand positioned them and it all boils down to alignment of the rails being the critical factor both radial and horizontally. The only bit I ever got right was the polarity swapping along with led indication of same. The best one I made was a small hand positioned wagon TT made from a CD and case, which worked great. Summary - if you want a decent loco sized one to work properly then be prepared to shell out a good sized wad of cash for a well engineered one. It will pay in the long run. Link to post Share on other sites More sharing options...
RMweb Gold Joseph_Pestell Posted October 25, 2016 RMweb Gold Share Posted October 25, 2016 I am sure that MERG must have something. But since you are off-scene, it can be quite simple if you don't mind the turntable always going round the same way and stopping at every road (meaning that you may have to press the button several times). There are some quite cheap US HO turntables of that sort of length so it may not be worth building them yourself. Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted October 25, 2016 Share Posted October 25, 2016 ...I need to find a way to stop accurately at each road... My 'thought experiment' low tech solution is a high reduction ratio drive with plenty of backlash which cuts out in rough alignment, the bridge secured by an actuator driving a conical plug into a matching socket for a low wear horizontal and vertical alignment lock. Link to post Share on other sites More sharing options...
DCB Posted October 26, 2016 Share Posted October 26, 2016 Bachmann do a great H0 table for about £140, scale 55 foot in 00. Most RTR tables turn much too slowly. The table should stop near the right exit and then wriggle back and forth until the indexing mech drops in. Still working on my powered table, works on a lower level with a 50 mm pivot and Dapol deck. Scheduled for completion in 2050 Link to post Share on other sites More sharing options...
Gordon H Posted October 26, 2016 Share Posted October 26, 2016 I am sure that MERG must have something. Yes, there was a demo turntable on the MERG stand at the Peterborough show, driven by a stepper motor and controlled using a PCB which is available from the Kitlocker. Link to post Share on other sites More sharing options...
RMweb Gold Huw Griffiths Posted October 26, 2016 RMweb Gold Share Posted October 26, 2016 I am sure that MERG must have something. Yes, there was a demo turntable on the MERG stand at the Peterborough show, driven by a stepper motor and controlled using a PCB which is available from the Kitlocker. I'm not familiar with this circuit - but I can't help wondering if it might work with a DIY traverser. Link to post Share on other sites More sharing options...
Gordon H Posted October 27, 2016 Share Posted October 27, 2016 I'm not familiar with this circuit - but I can't help wondering if it might work with a DIY traverser. I don't know that much about its detailed operation, but in principle it could easily work a traverser. For turntable operation I believe it has the ability to take the shortest route between positions around the table - of course this would need to be disabled for a traverser where there can only be one. For my own traverser, built quite a number of years ago now, I used my own hardware design, adapting another project that was current at the time. Link to post Share on other sites More sharing options...
RAF96 Posted November 4, 2016 Share Posted November 4, 2016 My DIY TT was based on a Dapol kit for the pretty bits, but I used a 1/4" stereo jack plug and socket as the pivot and power transfer method. I used a stereo jack as I wanted polarity indicators (red/green LEDs) on the TT deck to tell me if my DPDT deck power switch was set to the correct polarity and the extra connection filled that need. The wiring diagram for it is in my gallery so easily found without copying it here. Rotation was a Heath Robinson motor/gearbox driving a friction wheel controlled by a sprung loaded ( to Off) reversing switch.so totally rubbish but it worked as proof of concept, since binned in favour of the same TT power arrangement positioned mandraulically. Link to post Share on other sites More sharing options...
AlbertTheFrog Posted November 14, 2016 Author Share Posted November 14, 2016 Thanks everybody. I'd have come back sooner but wife life got in the way! Albert Link to post Share on other sites More sharing options...
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