My turntable project


C

Chemdawg

Member
When I started my layout, I knew I needed a turntable of some sorts. However, the options I had were rather limited. I checked out the Atlas tried and true 305 setup, and it was WAY too small to turn any steam locos and tenders. OR even my A/B diesel units. Well when walthers came out with the 130 foot turntable, I was all excited, cause that was EXACTLY what I wanted. Well when I saw the price tag, it was out of my budget, and I couldn't find one anywhere.

So, I started drawing up a design to make my own, using the atlas as a base. This project has been ongoing for the last couple of months, and is getting really close to be put into the addition to my layout. I thought I would post the pics here and let everyone see.

I started out by measuring my longest locomotive. I can't remember what the length was, but I knew the turntable pit had to be close to 18 inches. So using a piece of 1/4" plexi I had here, I cut a PERFECTly round circle. Once I had that, I used picture matting to make 2" strips that were glued around the plexi to complete the pit.

Then I needed a bridge design. Since I couldn't find exactly what I wanted, I googled bridges till I found a real turntable that had a bridge similar. So I made a printout of the picture, and did some scaling till I had the bridge drawn to scale on graph paper. Once that was done, I used 3/16" basswood to make the two sides, then made the base very similar to the way I did my truss bridges on the layout. These first pics show these steps:

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The next step was to finish the pit with the hardwood type look. Since I was modeling this after the pic I saw, this is the way I did it. Whether it's prototype or not, to me it looks right for what I want.

Using strips of balsa cut 1/2 inch wide, I made the hardwood floor look randomly.

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Now with the pit finished, I needed to connect the bridge to the turntable below somehow or another. So I had my machinist make me a 2 piece spindle out of aluminum at work. This bolts to the atlas turntable right at the center point. The bridge sits on the top of the spindle.

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Now that the bridge is mounted in the pit, I was looking into different alternatives to supporting the ends. I was originally going to use N-scale trucks on the bottom of the bridge to ride in a section of N-scale track going around the perimeter. Instead I went with a single rail, and used a brass strip 1/2" wide bent to a Ushape that is on the bottom of each end of the bridge. That rides around the single track in the pit.


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Now one of the biggest problems I had was getting this to stop just right. Since the Atlas turntable stops at individual points and works well, I wanted to go one step farther. I wanted to use a rotary switch to turn to a position, and I wanted it to stop right there. So drawing up a schematic, I figured out how to use roller micro switches and a rotary switch to accomplish this. Now since the roller switches have a Normally open and a normally closed terminal on every one, I used the normally closed one for the motor control, and the normally open one for a LED. I also wired in a Forward/Off/Reverse switch so I could go forward, backwards, or turn off all power to the turntable. The microswitches are mounted on the bottom of the pit, and there is a piece of aluminum connected to the atlas turntable that hits each micro switch as it goes around. The only problem was getting them lined up just right. No matter how I did it, the bridge didn't stop in the correct position. So using some enginuity, I made an off delay timer that once triggered shuts off in about a half second. So once the bridge gets to it's correct index, it triggers the micro switch, which shuts the motor off after a half second. So it ALWAYS stops at the atlas stops.


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And finally the finished product minus weathering. This thing works great. It needs some tweaks, and whatnot, but the design worked great, and it cost less than 100 bucks to build. Plus I feel alot better knowing it was something I built.

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The next posts will be of the control panel, and I will talk about how I ran so many wires from the turn table location, to the control panel. More to come soon!!!!!
 
Here is the control panel that is mounted on the facia by the rest of my controls. To get the wiring to the turntable without running a million wires, I used network cables for the LED's and micro switches.


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When you turn the rotary switch, it will line up with one of the LED's and that led will turn on once the table is in position. The switch is basically an on off on which is being used as forward off reverse. The LED to the right turns green when the turntable is in forward position, and red when it's in reverse.
 
After looking through the pics, and looking at the mostly finished product, I was thinking.... Does this even look slightly prototypical?
 
Where did you get that metal block? Is it aluminum and how did you get the holes? Do you have your own CNC machine? or did you just drill them yourself?
 
The metal block that goes from the atlas turntable to my bridge? It's a two piece spindle that was made on a lathe. The bottom half is screwed to the atlas turntable base, perfectly centered, and the top half unscrews. The top half is threaded so a button head screw can hold the bridge to the top of the spindle.
 
Extension is built onto my layout, and I'm working on getting the pit aligned just right. The hardest part seems to be getting the track to line up with the ingoing and outgoing tracks. For now there will be three outgoing for the roundhouse stalls, and there will be 1 incoming. The turntable will turn 180 degrees around to turn my locos around. However, I can go up to 12 positions with my rotary switch, so maybe there will be other things for the future.
 
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