Earlier in the thread I mention how a friend told me of his need for a rotary turntable which needed to be long enough for his locos, but small enough to fit within the confines of his limited space. Cost was also deciding factor, where as I would rather build it, than buy it, I decided to accept the challenge. Using wood from my scrap bin, and a stereo jack that my buddy had from his days of playing around with stereo systems, construction was started:
I will use photos from two turntables to provide information to build a turntable that is similar. One example was a custom length for my HO buddy (built over a year ago) and the other was built this week.
- Select the scale trains that will be used. Next, choose the length of the table. For this example I am making a 90 foot table so I drilled a hole for marking with a pencil at a 45 foot radius. Let the line touch at least one flat side of the board, this helps when setting up to sand later.
- Cut the turntable pit floor. I cut near, but outside the pencil line for sanding in a later step. This allows me to sand down to the mark.
- Drill a 1/16th inch hole through the center of the pit floor. (the center mark for making the circle with the scale in step 1)
Next, make a jig for sanding the turntable pit round, in a scrap board hammer a finishing nail a little less than the radius of the pit floor from the edge. Place the hole in the center of the pit floor over the finishing nail. The edge of the round pit floor should just extend over the edge to allow sanded without touching the jig. As shown in figures 3 and 4.
- With the pit floor on the jig board, push the floor into the sanding surface until it touches the pencil mark. With this surface in contact with the sanding surface, "Clamp"
the jig board in place. Rotating the pit floor while the sanding disk rotates assures an even and round pit floor. "WHEN FINISHED DO NOT REMOVE CLAMPS" this jig will be used to round the ends of the rotary table in a later step.
- Cut the rotary table your scale height as required. The width of the rotary table should allow for track, walkways and hand rails. Tap a finishing nail through the pit floor 1/16 th inch center hole and into the rotary table, then mark the length of the rotary table for cutting (as in figure 5). Cut the table to length. The ends will be rounded in step 6.
- Where the rotary table was marked by the nail, find the center of width and length of the rotary table. Drill a 1/16th inch hole through the rotary table. Use that hole for alignment on the jig and sand the ends of the rotary table to match the curvature of the pit floor.
- After sanding the curved surfaces, check the match of the rotary table and pit floor.
- a simple set of stereo jacks will allow the turntable to rotate 360 degrees without losing power. The connectors are available at almost any electronics store or supplier. A reversing circuit of some nature is required whether it be electronic or toggle reversing circuit. These are inexpensive and easy to install.
- Mount the female end of the stereo plug in the pit floor. The female socket up towards the rotary table and the terminals downward toward the reversing circuit. Allow access to attach wires to reversing unit. The top of the female stereo plug should be flush with the pit floor.
- The rotary table receives the male plug. A hole must be drilled to insert this plug into the rotary table. The base of the plug should be "almost" flush with the bottom of the rotating table (as shown) to provide clearance for the rotary table. The weight of the table, will be supported by the metal to metal contact of the male and female connectors, and nothing should rest on pit floor. Allow access to the terminals on the top of rotary table for connecting feeder wires.
Another example of a rotary table.
Please note the previous table had the tapered sides for tapered girder plates (like on my SS Limited kit) while this one, for my HO buddy had straight sides for using straight plates from a bridge kit. Note the scrape on the bottom of the table, this occured because the clearance was not set correctly when first installed.
- Making the pit walls. To measure the circumference, I used a piece of tape to get a rough estimate of length. After taping, cut the tape, pealed it off and measure the length. In my brief experience to learned to add about 1/2 inch to my measured length.
- Cut a piece of masonite to the height that you will require for your pit rotary. That is measured from the bottom of the pit to the top of the rotary table. In this instance, the HOn3 SS Limited turntable kit that I used for reference had 3/4 inch girders, so my rotary table was 3/4 and my pit floor 3/4 so the wall height was 1 1/2 inches. The circumference measured was 39 inches so the wall length was 39 1/2 inches. As I started to wrap the pit, I used a clamp to hold the first point and used a screw to hold it in place. After that I rotated the clamp to the next spot to fasten and used screws or nails for fastening. Spacing around the circumference was about every 3 inches. I used a screw at about every 4th point. NOTE: I moistened the masonite on each side with a damp sponge before attempting to bend it around the pit.
- Solder feeder wires (I know these are an overkill, but they were handy), onto the stereo connectors. Insert the rotary table for a test fit. There should be no touching of pit walls or pit floor. Make adjustments now.
- Place the turntable on the layout, where you intend to install it. With a pencil, mark around the outside of the wall. Cut the hole for the layout "leaving the pencil mark. Install flush with surface, and brace to you satisfaction.
- Fill and sand as needed.
- For those of you using DC, a simple reversing switch circuit will work.
For those using DCC, wire in a reversing unit as instructed by the manufacturer. There should be 2 wires from the inbound track and 2 wires to the rotary table. The circuit checks for polarity comparison and reverses it when necessary. The example shown is an AR-1 from Digitrax.
- Adding details will improve the appearance of the turntable. Here, girder plates, hand rails and walk boards were added.
- Although the painting is still incomplete, you can see how the turntable fits well into a scene.
Table rotation is manual, but it has operated well for about a year.
- This project was very satisfying, my buddy Kurt had limitations for a size and cost and we met both goals. In conclusion, I wouldn't hesitate to do this again, by example, I made another one to use in this write up. Yesterday I disassembled the parts and returned to my scrap bin, for another day. I hope, if someone who has a need for a non commercial turntable, they may consider this method before giving up. Thanks for your time.