Controlling Interests #10 – more on turning tables, Fisherton Sarum’s turntable is replaced

Wear and tear occurs on anything mechanical over time and model railways are no exception, especially when subjected to the rigors (and occasionally operator error) of exhibiting for hours on end at shows. One of the focal points on Fisherton Sarum is of course the turntable which during an exhibition seems to be pretty much constantly on the go especially when younger viewing eyes are present.

My T14 is turned on the turntable at Fisherton Sarum

I have posted before about the turntable on Fisherton Sarum in my Controlling Interests #2 post here., but as a quick recap the turntable comprises of a Peco LK-55 kit where I have utilised the well and deck, whilst adding scratch built sides to represent the turntable installed at Salisbury; and it is controlled by  MERG turntable control kit which drives via a stepper motor and gearbox.
During the last couple of shows I attended with Fisherton Sarum I noticed that the operation of the turntable was getting less and less reliable mainly due to issues of the plastic drive shaft mounting hub on the underside of the table deck starting to disintegrate and wear to the  track power feed split contact ring.  I therefore decided to hopefully remedy the issues by removing the deck and trying to replace the drive shaft mount and also effect a repair on the power feed ring. However having examined the removed turntable and due to the lack of the original plastic now remaining at the mounting point it proved difficult to align my replacement metal bush accurately, both vertically and centrally, to give reliable running.

The original scratch built side sides have been grafted onto the new deck

I have now therefore obtained a replacement turntable kit and built a brand new replacement deck (if anyone wants the kits well components that I now have surplus to requirements let me know, free to a good home…) and carefully added the scratch built sides from the original deck to the new one.

The replacement split ring pick up bush in the middle of the well

I have also replaced the now worn power feed split ring in the turntable well as the plungers on the underside of the deck over time had worn a groove and then starting to catch on the edge of the copper split rings.
In order to make future maintenance easier and allowing easy removal of the deck, if required, I have also now incorporated new direct coupling with grub screws. I carefully drilled on a pillar drill to ensure vertical alignment, the bush in the underside of the deck to suit a 4mm OD silver steel rod to match the output shaft of the gearbox and the coupling,  as the Peco LK-55  kit is designed to be interference fit  for a standard Meccano imperial Standard Wire gauge 8 shaft.
I had tried as an experiment a  Ruland Aluminium Flexible Beam Coupling, from RS Components to link the drive shafts of the deck and gearbox, but although these are designed specifically for use with stepper motor drive systems where no back lash is a requirement a certain amount of juddering occurred as they flexed, so I have gone back to a fixed brass coupling but one with two opposing grub screws at each end to ensure a good grip on the shafts (which as per good practice have a slight flat filed on them to ensure the grub screw can grip properly.

The replacement turntable has been fitted and tested on Fisherton Sarum and means that the layout is all ready for its next outing at the Hampton Court MRS, Tolworth Showtrain, on 11th / 12th November at the Tolworth Recreation Centre, Fullers Way North, Tolworth, Surrey, KT6 7LQ

7 thoughts on “Controlling Interests #10 – more on turning tables, Fisherton Sarum’s turntable is replaced

  1. Well, that blew my illusions out of the water. Having looked at the various photographs of Fisherton Sarum I was convinced you had working 4mm crew operating the turntable….


    (PS very informative!)

  2. Thanks for this Graham. Turntables are an impressive and important part of a layout but often troublesome.
    I went down the Danish route and am very happy with it. The Heljan product is reliable and although I run my layout DCC the turntable is analogue with a juicer to sort out polarity. Another option.

  3. I was told it was bad practice to use 2 grub screws at 180° to each other. When racing RC cars years ago if you used 2 grub screws as you have after a while of use one would always be loose.

    1. Hi Alec there are certainly two schools of thought probably more so if the rotational speeds are greater with the lower speed in this case it should be ok

  4. 34090 looks so much better if fitted with the correct Air Force Blue nameplates she ran with in service. Not sure if red nameplates were ever fitted. I’ve never seen a photo with them in red, only in blue, and wonder where the idea she was a West Country and therefore was to have red plates came from. I know of course some Battle of Britains had red plates in later BR days, but not in malachite.

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