DIY engine turntable

Has anyone made their own manual turntable?  I'm looking for some DIY plans to do so.  It seems like such a simple product idea yet there are no inexpensive off the shelf options. 

Thanks

George Bailey: You know what the three most exciting sounds in the world are? Anchor chains, plane motors, and train whistles!

It's a Wonderful Life, 1946

 

Check out my Lionel and MTH auto trains

http://gwpreisch.wordpress.com/

Original Post
Garrett76 posted:

Has anyone made their own manual turntable?  I'm looking for some DIY plans to do so.  It seems like such a simple product idea yet there are no inexpensive off the shelf options. 

Thanks

That's because the whole concept of a PROPERLY model railroad turntable is NOT "inexpensive", especially if you want it work properly. The old Bowser turntable kits sure LOOK nice, however their operation, i.e. smoothness for a large one, is not so good.

The old saying "You get what you pay for." surely applies to O Scale turntables!

Hot Water posted:
Garrett76 posted:

Has anyone made their own manual turntable?  I'm looking for some DIY plans to do so.  It seems like such a simple product idea yet there are no inexpensive off the shelf options. 

Thanks

That's because the whole concept of a PROPERLY model railroad turntable is NOT "inexpensive", especially if you want it work properly. The old Bowser turntable kits sure LOOK nice, however their operation, i.e. smoothness for a large one, is not so good.

The old saying "You get what you pay for." surely applies to O Scale turntables!

I have to admit that I have never built a turntable, but I have done a number of similar mechanisms, and I don't agree that it has to be expensive to work well. With modern stepper motors and an Arduino, I think an automatic one might be easier than a manual version. The Maker movement has caused a lot of useful stuff to become accessible. 

--pete

 

 

My heart is warm with the friends I make, 

And better friends I'll not be knowing;

Yet there isn't a train I wouldn't take,

No matter where it's going.

                        Edna St. Vincent Millay

 

A manual turntable is relatively easy to construct. Get your router out and fashion an extension to the base ("router on a stick") to cut large circles in plywood.  Pay attention to keeping the pivot point in the pit centered on the rim of the pit when assembling.

The automation of the turntable with indexing is an interesting challenge - Arduino, steppers, motors, fine positioning, locking in position, etc. makes a nice project.  Remember that scale locos have scale weights that impose loads on the motors that stall rotation.  (I have observed that stalling the drive mechanism IS prototypical.)

The manual turntable uses the ever reliable arm-strong motor and Mk. I eyeball for positioning, and, for my DIY turntable used in modular shows, works very well with virtually no training needed for the operators.

The wiring of the bridge track implies a slip ring or an overhead wire.  My quick hack of letting a twisted wire pair hang underneath has survived a couple of decades with o need to re-engineer the solution.  Adding a motor (and the temptation for continuous rotation) would require slip rings or an overhead power feed.

Wiring storage tracks and a switch panel is tedious. and if I repeat the process, I may go with an LCS BPC.

I recommend you build a manual turntable first.

Here you go, a scratch made, inexpensive working turntable with pit from my post linked below.  It works via a hand crank and clothes dryer belt and has been working for over 40 years and cost me $10 !

https://ogrforum.ogaugerr.com/...ra-027-layout?page=1

I hopes this helps and at least encourages you to build your own.

Choo Choo Charlie

Post 9   6-25-2016

Turntable Construction

The center piece of the layout is the scratch built, inexpensive turntable and roundhouse.  Designing and building the turntable was the most fun part of the whole train layout and well worth the time and effort as it provides much operation interest and fun.   The Turntable was built during the initial layout construction in 1977 in Kingston Jamaica.

The turntable rotates on a 6 inch (8 inch might be better)  diameter lazy Susan ball bearing and rotation is by a hand crank driving a pulley beneath the turntable using a spare or used clothes dryer drum belt.  I had a spare dryer belt as I lived overseas and appliance parts are hard to get.  Track alignment is the realistic, "line it by eyeball" method and roundhouse  track selection is by a rotary switch.  A momentary push button switch is used to activate the selected RH track and the TT track.  A light in the TT shack comes on with the activation of the TT track and indicates power is on.

 Location of the control panel and the turntable should be fairly close to each other for two reasons.  One is the use of a clothes dryer belt will require it to be close.  The other is it is helpful for the engineer to be close at hand to correct derailments and to see the turntable as eyesight is used to align the TT and the tracks.

 

Picture of TT with TT crank (red knob) and Control Panel

Picture shows the track with crane car and caboose align with the TT and the off track

Train Lots 5-10-2016 272

 

Picture of main control panel track diagram with selector rotary switch (black knob with pointer) to select track for transfer of train from TT to spur/roundhouse track.

Train Complete 1-17-2015 152

 

Two pieces of 027 track or 17 5/8 inches was chosen for the turntable bridge length.    22 inches would have been better but space was in a premium and 18 inches diameter will handle all of my engines and coal tenders.  I cut a 18 inch diameter circle in my train board using a sabre saw and used the ¾ inch thick 18 in diameter cutout as a pulley by adding a rim of 1/8 inch Masonite around both edges as pulley flanges sticking out about ½ an inch.  

A recessed ring around the turntable hole, about 1&1/2 inch deep, was installed on the bottom of the hole and a 1/2" plywood bottom was added.  A 3/8" hole was centered in both TT bottom and the pulley.   A 2"x 2" x 3/4 inch block was drilled to take a 3/8 threaded hollow lamp rod in the center.  The block and rod were mounted about 1 inch from the rods end and drilled for a 2 inch long finish nail.  The block was glued and screwed to the pulley in the center.  A 6" lazy Susan bearing (Ace or Home Depot for $4) was screwed to the top of the pulley.  Holes were drilled through the pulley where the screws on the other flange of 6” lazy Susan bearing.  These holes allow the bearing to be screwed to the underside of the pit bottom. 

I did most of the work on the TT with my train board section standing on edge, leaning against a wall.  To build a TT to an existing permanent layout on legs would require lots of work under the table and looking up.  In such a case one might want to build two foot or so module to construct the TT and install as a unit.

The lazy Susan bearing will hold all the weight of the pulley and take the side trust from the clothes dryer belt.  The 3/8” threaded rod allows wire to feed power to the TT bridge and to secure the bridge to the pulley beneath the TT pit.

The 3/8" dia. threaded hollow lamp rod was installed through the pulley and the rod was pinned to the pulley with a nail.  The rod was measured to the length needed to go through the pulley, block, TT bottom and to the top of the TT bridge minus a ¼ inch, sawed off, and a hole drilled through the bridge to be able to pin the rod to the TT bridge to be built.

A turntable bridge was made out of wood and the bridge was pinned to the lamp rod with a finishing nail.  The 3/8” lamp rod is anchored to the bottom of the 18“  pulley and on top of the TT bridge with two lamp round thumb nuts. 

Small wheels were made for the ends of the Turntable Bridge to transfer the weight of the bridge and locomotive with coal tender to floor of the TT pit  (I used some small ball bearings I had for wheels).

See picture

 Turntable Detalils 5-29-2016 2016-05-24 005

 

 

A pair of wires was run up through the lamp rod and soldered to the outside and middle rail of the track that was put on the TT bridge.  Some slack was left in the wire and a type of disconnect like a plug or spring clips ( I used two electrical connectors cut from old 9v batteries) was installed to allow removal of wire to unwind the wire if it gets twisted too much (also try not to keep going is one direction too much!)

 

Picture of 18"dia. Pulley under Turntable with Clothes Dryer Belt and wires from TT Bridge

IMG_0006

 

 

Tracks were added to store trains around the TT being careful of spacing between tracks.  The tracks were wired to a Radio Shack rotary 10 position switch to select the track to be powered.  A momentary contact push button switch was installed on the control panel and wired in series to allow the selected track and turntable bridge track to only be powered when this switch is held down. 

I used a spare electric clothes dryer belt that is about 3/8" wide and 1/8"thick and about 8 to 10 feet in total length (not diameter).  This is the size of most any make of clothes dryer.  The belt  is super strong.  I made a hand crank out of a 6" long 1/4" carriage bolt as the driving pulley with disk and knob held on to the disk with a Tee nut and locking nut as the crank.   I used over sized Tee nuts for shaft sleeves for the shaft, top and bottom.  A small pulley was made for the shaft from a ¼ inch ID radio shaft coupling and two brass grommets soldered together to make a Vee to give more bit on the belt by the small shaft.  This Vee is necessary to keep the belt from slipping on the small diameter shaft of the crank and also make the diameter larger than the shaft.

 

Picture of Hand Crank Vee pulley made from radio tuner shaft coupling and brass grommets

IMG_0024

 

I made a 2" dia. take up pulley assembly and used a threaded rod to move it to make and adjust the tension in the dryer belt. I installed a 3" dia. pulley to make an S in the belt routing to allow belt tensioning.  A 2” dia. pulley was used to make the belt stay about  ½ inch apart after coming of the ½ inch Vee pulley on the hand crank to insure good 180 degree contact with the Vee pulley.  Pulleys are made from 1/2 inch plywood with flanges of 1/8 inch Masonite having polyethylene next to wood from coffee can lids.

 

Picture of Belt Routing - Belt length total is 8 to 10 ft not diameter on drawing.

 IMG_0077

 

Picture of Pulleys and Belt - Tension adjuster on bottom belt with wood box with metal strap, the crank Vee pulley is to the left of the picture.  The two pulleys force the belt to have maximum contact with the Vee pulley (180 degrees).

IMG_0019

 

 

Note that one track aligns with the TT and the approach track.  This is the only track that a wrecker caboose and crane car can be sent over the TT and be stored around the TT.  I made sure to leave this track outside of my future Round house to be built and detailed later.

 

Picture of Track that will allow work caboose and crane car to be stored

 Turntable Detalils 5-29-2016 2016-05-24 009

 

I added details like the lighted TT operator shack, ladders on the bridge to the pit made from cut up N gauge track ties, a TT bridge central tower for overhead wire with ladder, pigeons and poop, and Sharpie penned in rail and ties in the TT pit.

TT bridge has 1/8 inch smooth Masonite deck, grooved with knife to look like wood planks and painted buff to look like wood.  Some sieved coarse sand was glued into the pit bottom.

 

Picture of Turntable with center mast and ladder, exposed ties, birds, and pit track

Turntable Detalils 5-29-2016 2016-05-24 010

This project takes time, planning and careful measurements to make it all work.  Care must be given to aligning and screwing down the tracks so derailments are few or at least blamed on the TT operator !

The TT really did cost me less than $10 since I had a spare clothes dryer belt.  You could get a belt from a junked dryer, as a used belt is plenty good for this.  Buy a new one for your current dryer and use the old one for the TT !

If you do not want to place the TT close to the edge of you layout and be restricted by location due to the length of the clothes dryer belt one can power the turntable with a used DC electric drill or screw driver motor.  The drill motor could be powered with a small cheap HO DC transformer in both directions.  This would be easy to power the TT with a shorter belt and pulley on the drill and the the TT could be located anywhere.

The  TT has worked well since 1977 or almost 39 years.  It would not turn in 2015 and after investigation the cause was a broken solder joint on one of the grommets on the Vee pulley.  The original was soldered with a 100 watt soldering gun (the only soldering tool I had) and it lasted 38 years.  I re-soldered the Vee with a propane torch, with a soldering iron tip, that gets much hotter.

 

 Charlie

 

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