burgundy Posted March 9, 2018 Share Posted March 9, 2018 I have bought a 16" transfer turntable to use as a rotating fiddle yard for a small layout that I am currently working on. I should like to install two tracks which should be adequate to hold two trains (one on each track), made up of a loco and two vehicles. Can anyone suggest, please, how I calculate the alignment of the two roads? At the centre point, they will be parallel with the minimum of clearance, but then diverge so that they meet the edge of the turntable to be perpendicular to the edge at that point. How do I work out the necessary radius? Is there an elegant piece of geometry that would enable me to calculate it - or is it back to the more traditional "fiddle to fit"? Any ideas gratefully received. Best wishes Eric Link to post Share on other sites More sharing options...
Gordon A Posted March 9, 2018 Share Posted March 9, 2018 Two outward facing curves the ends of which line up with the tracks on the non rotating part of the unit without any kinks. It is a bit of suck and see. Make sure there is a gap between the adjacent tracks at the centre point so passing stock does not come into contact. You may get a third straight road in the middle depending how long you want the roads to be. Gordon A Link to post Share on other sites More sharing options...
DCB Posted March 10, 2018 Share Posted March 10, 2018 (edited) Having drawn it in Anyrail and Faststone Image Viewer I am not at all sure it can be done. 16" sounds much too short for two parallel tracks in H0 gauge accessed by a single track. I have made a number of turntables, all of them successful and you really don't want a curve leading to the turntable edge if you can avoid it. remember you have eight rails to line up to better than plus or minus half a mill in two planes as the deck revolves. My doodles show either an excessively close track spacing or excessively sharp curves at the turntable ends. With more than one track the shorter the deck the greater angle the tracks need to turn through and the less length available for the curve. Edited June 10, 2018 by DavidCBroad Link to post Share on other sites More sharing options...
Orion Posted March 10, 2018 Share Posted March 10, 2018 (edited) Here's a quick drawing in Templot Not quite as elegant as you requested, but easier to draw quickly. Just print it out to scale. Dimensions in mm Edited March 10, 2018 by Orion Link to post Share on other sites More sharing options...
Orion Posted March 10, 2018 Share Posted March 10, 2018 ..and a more elegant version Link to post Share on other sites More sharing options...
burgundy Posted March 10, 2018 Author Share Posted March 10, 2018 ..and a more elegant version FEW2.jpg Orion Thank you Out of interest, what radius does this work out as? Best wishes Eric Link to post Share on other sites More sharing options...
Orion Posted March 10, 2018 Share Posted March 10, 2018 Orion Thank you Out of interest, what radius does this work out as? Best wishes Eric 31.1 inches. I used the standard NMRA HO settings for the distance between track centres. Link to post Share on other sites More sharing options...
burgundy Posted March 10, 2018 Author Share Posted March 10, 2018 31.1 inches. I used the standard NMRA HO settings for the distance between track centres. Thank you - much appreciated. I had had the suspicion that it was going to come out a lot sharper than that. Best wishes Eric Link to post Share on other sites More sharing options...
Orion Posted March 10, 2018 Share Posted March 10, 2018 I see from your layout posts that you are modelling broad gauge. Would you like me to adjust the gauge to 17.5mm on my plan? (it is 16.5mm gauge at the moment) Link to post Share on other sites More sharing options...
burgundy Posted March 10, 2018 Author Share Posted March 10, 2018 I see from your layout posts that you are modelling broad gauge. Would you like me to adjust the gauge to 17.5mm on my plan? (it is 16.5mm gauge at the moment) That would be very kind - although the extra mm should not make a huge difference! Best wishes Eric Link to post Share on other sites More sharing options...
Orion Posted March 10, 2018 Share Posted March 10, 2018 No problem. Link to post Share on other sites More sharing options...
Sturminster_Newton Posted June 8, 2018 Share Posted June 8, 2018 Thank you for this little diversion. The basic principles will work for my planned O-gauge 'micro'. I am looking to build a three track 'transfer table' fiddle yard, and was wondering how the track alignment is worked out. Now I know once the transfer table is produced, I'll be able to work out my final layout for the sidings. Wiring may be a little complex as I want to add isolating sections as well as the main feed to the 'run off' aligned track. I'm looking to standard analogue control. Link to post Share on other sites More sharing options...
duncan Posted June 8, 2018 Share Posted June 8, 2018 I had a 3ft 3 x track turntable on my O gauge micro, found it best to do it by eye. Link to post Share on other sites More sharing options...
DCB Posted June 10, 2018 Share Posted June 10, 2018 Thank you for this little diversion. The basic principles will work for my planned O-gauge 'micro'. I am looking to build a three track 'transfer table' fiddle yard, and was wondering how the track alignment is worked out. Now I know once the transfer table is produced, I'll be able to work out my final layout for the sidings. Wiring may be a little complex as I want to add isolating sections as well as the main feed to the 'run off' aligned track. I'm looking to standard analogue control. The best way to sort the alignment is by eye. draw the centre lines for the approach tracks, make up your locking device to hold the tracks in alignment and then lay the main approach track. Lay the first end of the first turntable track and with the table locked in position align the turntable track with the approach track only adjusting the one on the turntable. Mark this as no 1 or Master. Revolve the table 180 and align the other end, Having the turntable rails in at least a couple of sections joined with fish plates makes alignment as in in out easier. Next fit the run off siding to align with the No 1 end of the turntable, revolve 180. If it is in alignment good, if not your're stuffed as vertical mis aligment has to be altered by adjusting the deck/ pivot not in relation to the approach track board not by fiddling with tracks. You need +/- Half a millimeter for anything like decent running. Once the first turntable track is working and aligned with approach and run off tracks lay the second turntable track approach track what ever but dont touch the No 1 end track alignment or the approach track or you will get in a complete muddle. Regularly check No 1 end and the approach road align during works and test it with a derailment prone loco at every stage. If you get it right. Locking, approach to No 1 alignment, add the rest, then it may like mine need minimal maintenance for 25 plus years. If it works like a Hornby RTR turntable you will probably be continually re railing stock until you rip it out in frustration and use cassettes Link to post Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now