Motorising a "00 Peco" Turntable


Introduction
The following should hopefully be of help to anyone who wants to motorise the 00 gauge Peco turntable and get the best performance out of it. The turntable itself is a very nice model and straight forward to build but I found it was not just a case of bolting a motorising kit underneath to make it work well. There is a little bit of work needed to get the best out of it and this is described below.
The Turntable kit
Full and easy to follow instructions are supplied with the kit itself and assembly should present no problems for the average modeller. However if you are intending to motorise the unit for use on your model then Don't fit the locking ring that is glued to the underneath and retains the bridge in place, as this will prevent you removing the bridge easily in the future and there is a modification that you will need to do so that the unit has as little play as possible.
Also when you cut the circular hole in your baseboard for the unit then make sure it is an easy fit and drops nicely into place If it has to be forced in you will find that it distorts the turntable body enough to give you some tight spots as you rotate the bridge.
Preparing for fitting the motor.
On the one that I built I found that the bridge did not run on all 4 wheels while being rotated and this was due to the fact that the turntable well was not dished enough to allow all the wheels to make contact with the ring of track in the base of the well. In addition the height of the rails was a little high and sagged as a heavy loco was run onto the bridge.
I fitted 3 pieces of wood underneath the table so that the tuntable well could be pulled slightly down to allow the bridge to run on all 4 wheels.
Use small wood screws to achieve the pulling down countersunk into the table floor. You can then adjust these to give just enough downward pull without distorting the whole table. Once you have this set correctly the screws can be hidden with a little weathering.
When you have the bridge rotating freely with slight downward hand pressure to overcome the contact springs then you are ready to continue to the next stage of the preparation.
You will find now that when you hold the bridge down then the centre shaft (where the locking collar would have fitted) extends out from the underneath of the table well.
Mark how much this sticks out and with a fine saw remove a little more than that amount from the shaft so that it is just recessed inside the collar of the table well.
The underside of the completed unit showing the 3 pieces of wood that are used to draw the centre of the turntable well down to allow the 4 wheels on the bridge unit to run properly on the ring of track.
Use small wood screws countersunk into the table floor to adjust the amount of pulling down so that you don't over do it and distort the whole table well.
Also seen here is the additional bearing to keep the worm gear tight against the large gear. (see text below)
Visible under one of the wooden strips is the decoder used on my unit to enable it to run on DCC.
Preparing the Motor / Gearbox
The following is based on using the kit available from Frizinghall Models
The kit comes supplied with 4 gear wheels in the gearbox and this gives you far too much reduction in table speed unless you have it running at full tilt which is very noisy and not good for the motor or gearbox. As mentioned in the notes that come with the kit, remove 2 of the gears and replace with one of the plastic spacers supplied. Before fitting the worm gear which is a force fit on the long output shaft you need to find from your junk box a washer and a collar about 8mm long or enough washers / nuts to make up this length and put these on the shaft so that the worm can be pushed up tight against them. Collar against the worm and at least 1 washer between the collar and gearbox. You may need to slide the shaft through the gearbox so that there is some of it extending out beyond the worm gear. This extension is needed later to help remove any play. Before finally pushing the worm up tightly to the collar and gearbox apply some grease under the washer against the gearbox so that it is well lubricated.
A close up of the washer and collar needed to remove the play on the output shaft of the motor / gearbox unit.
As mentioned above if you don't have a suitable collar available then a number of washers or nuts could be used instead.
Preparing the turntable bridge
Push the supplied shaft into the collar of the bridge until it is firmly home (I superglued it as well so that it will not move in the future). Fit the bridge into the well and with the whole unit upside down rest the motor and gearbox unit on the underside of the well. Time now for more washers. Place sufficient washers on the end of the bridge shaft so that the large supplied gear is at the correct position to mate up with the worm gear. Make sure that the washer nearest the table well is of sufficient diameter so that it will not go into the collar of the well.
The underside of the turntable bridge showing:-

1. The contact studs that feed power to the track.

2. The shortened boss that no longer protrudes through the base of the well.

3. The meccano shaft pressed and glued in place.

4. My collection of washers and a nut to make the large gear line up with the worm once the bridge is held down into position on the ring of rail at the base of the well.
Note the large washer nearest the boss so that the stack of washers etc. cannot enter the hole in the collar.

5. Plenty of grease so that it all runs easily when secured with the large gear.
Fitting the Gearbox
Now it's time to put it all together. With the whole unit still inverted hold the gearbox so that the worm is a snug fit with the large gear then mark and drill two holes to secure it in position using the supplied nuts and bolts. You should also countersink these on the well floor so that they well disappear when you colour / weather the inside of the well. At this stage I also filled the whole of the gearbox with grease to prevent wear and help with smooth quite running.
Once the Gearbox is bolted in place you can fit the large gear with the washers and tighten the grub screw to keep it in position. Again plenty of grease on the washers and on the bridge collar.
The unit should now work and can be tested by applying power to the motor using a train controller. However you may find like I did that there is still excessive play and it is not too easy to make the tracks stay lined up with the approach rails.
I then added another piece made up from some old Meccano parts to hold the worm firmly against the large gear. If you don't have any old bits of Meccano handy then you could easily fabricate something from steel or aluminium sheet that will do the job.
The additional bearing made up in my case from soldered Meccano strips to hold the worm on the output shaft firmly against the large gear.
If you don't have any odd bits of Meccano to hand then a similar thing could be fabricated from sheet metal or a strip of angle section.
Even with the bracket fitted above I was still finding some play in the system and finally tracked this down to a few thousands of an inch caused by the flexing of the gearbox plastic end face. When this is magnified by the distance from the centre of the table to the edge of the bridge it adds up to a full rail width.
This was overcome by fitting the two additional collars shown below. These are made from the brass parts of a large cable connector removed from its plastic cover (chocolate block). Again plenty of washers and grease between the connectors and the bearing strip.

addidional bushes
The additional collars fitted to remove the last of the play in the table. These are made from the brass inner parts of a large (Chocolate Block) cable connector and if you get the correct size they are a good fit on the gearbox output shaft.
Note the use of several washers between the collars and the bearing strip.

Quieter running
If you find that even with plenty of grease in the gearbox you can't get a reasonably quite running from the unit then here is a trick that may help. I have found that the following has worked on 2 occasions in the past.
First run the unit at a mid speed and well packed with grease in each direction for about 15 minutes. If there is no sign of it starting to bed in and run quieter then remove the large C shaped staple that holds the front of the gearbox in place and remove the front complete with the output shaft and worm gear. Next remove all the individual gears and lay them out on a piece of kitchen roll in the order of removal.
Then replace the gears in reverse order. Ie the first one you took out now goes back in nearest to the motor drive gear and the last one you took out which was the one next to the motor now becomes the one that drives the output shaft.
Replace the gearbox front and the large C shaped staple to hold it in and try running again. I have used this trick on 2 different gearboxes and in both cases it worked wonders resulting in a remarkable reduction in noise from the unit.

DCC
The layout that my turntable is fitted to (Livsey Lane) is operated by DCC so I decided that the turntable should also be driven using that system. This was very simply achieved by fitting a "Bachmann" decoder chip to the underneath of the table well and feeding the motor via this so that forward is clockwise and reverse is anticlockwise. I have programmed the chip as Loco 69 (anyway round) and set up the top speed so that it gives the correct rate of rotation for the table. I have also set the acceleration and deceleration rates to zero so that it is easy to stop it when the tracks are lined up.
Click for video
A video just under 3 minutes in duration showing a WD loco arriving on the table from the yard and then the table being moved to allow the loco to drive off onto the coaling and water siding.
This is followed by another sequence from the other side and closer in showing a 9F leaving the shed and the table moving it to the departure road.
Note that as the tracks get to near alignment it is possible to slow the table down to a mere crawl so that perect alignment can be made by eye.

John Essex Heywood Model Railway Group

This page updated 7th January 2012