As part of the layout control changes currently being made to Fisherton Sarum (more of which later) involves the turntable I thought it was about time I posted about the turntable itself. The turntable at Salisbury was originally a 65’ foot heavy over girder type. In 1958 this was replaced by a larger diameter under girder type. An unusual feature of Salisbury shed was the the access to the stores building unloading platform was via a shunt across the turntable and I have replicated this feature on Fisherton Sarum and it often raises a comment at exhibitions.
On Fisherton Sarum I wanted to represent the original style of over girder table installed at Salisbury. I used a Peco kit for the well and the deck, modifying the deck by scratch building the heavy over girder sides and a the addition of the turner’s platform.
Thick plasticard and Plastistrut sections was used for the girder sides along with an overlay embossed with a punch to represent the rivets along the top of the sides. A small outbuilding was provided to act as a mess room for the turners employed at the shed, on Fisherton Sarum this is a modified Wills kit.
Ironically the Peco kit unmodified matches the later style at Salisbury.
Since I first built Fisherton Sarum the turntable was powered via a Frixinghall motor and gearbox that did not have any form of automatic indexing. This meant that the rotational speed of the table was not easy to control and track alignment had to be done by eye (sometimes easier than others) via a switch. This is in the process of being changed to stepper motor and gearbox controlled via a Model Electronic Railway Group (MERG) turntable controller kit, kindly built by Mark Riddoch, more of this in a future post.
Hi Graham
I have been looking at using a stepper motor to drive/align a turntable but have not got very far. There are demos on Utube but there does not seem to be a kit of parts that I know will work together. I have looked on model robotic sites but they seem to use servos. It’s relatively easy to get stepper motors even using ones from old printers etc. There are very cheap controllers on Ebay but knowing if they will work together is another matter. The programming of the number of steps required for each function has been the hardest part to find a kit of parts for. I was surprised that Maplin or Rapid did not do a kit of parts for all of this. I looked on the MERG site and found nothing there and have just checked again and still there is nothing about stepper motor controllers, are you trying out a prototype? My turntable at the moment uses a micro switch to stop in the correct position. I have used the largest nylon spur gear I could find so as to avoid slop in the positioning of the deck. The gear was a spare part from a model helicopter and is about 120mm diameter and is driven by a worm gear I made on the lathe. Please keep me informed of your progress.
All the best
Alec
Hi Alec
Thanks for the comment. I do not at the moment know if the MERG controller that Mark has built for me is an early version or not, I think it might just be that the website has not yet been update, although I think you need to be a member of MERG to access everything. I will find out some more details for you and it will be the subject of a future post.
Alec
I have just checked the http://www.merg.org.uk/kits.php site and the Turntable controller PCB (part number 979) and the 18F2420 PIC – Blank Programmable Microcontroller as used in Stepper Motor Turntable Controller (part Number 761) are listed.
Graham
I did find those two items after I had contacted you. It says they are used in the Stepper Motor Turntable Controller. But I could not find the Stepper Motor Turntable Controller kit in the list. Is it a kit or just documentation I wonder?