Let’s build a turntable

Discussion in 'The Academy' started by cnw1961, Nov 11, 2006.

  1. viperman

    viperman Active Member

    Coming along very nicely, and thank the wife for getting you started. You sure do know how to get the creative juices flowing!
  2. ejen34

    ejen34 Member

    Ingenius to use the truck, wonderful idea, this is yet another quality thread on The Gauge :thumb: Thank You!
  3. cnw1961

    cnw1961 Member

    Now it is time for me to say WOW. I never thought that this thread would arouse so much interest. Thank you! :wave:

    Today I started to build the pit. The bottom of the pit is a piece of 1/2" MDF . It has a nice smooth surface, which is easy to paint. I glued it to the pit wall (my wood ring) and secured it with eight small screws.


    After I determined the center of the pit, I drilled the hole for the center shaft. I made it .020" wider than the shaft to give the shaft enough clearance to move freely. Then I mounted the bridge on to the shaft. The bridge turned easily and I think, I could have operated the turntable without any problems. But on the ends of the bridge I could feel additional movements caused by the clearance of the shaft. And the bridge could be moved sideways a little bit. I remembered that I had some small ball bearings somewhere. After some rummaging in our basement (I am not the guy who keeps everything neatly lined up on shelves), I eventually found them.


    The use of bearings causes another problem. The clearance of the shaft helps to make up for inaccuracies of the position or angle of the center hole. If you eliminate the clearance of the shaft, the bearings have to be aligned and centered perfectly.

    I widened the hole for the shaft and glued a ball bearing to each end of the hole. I had to remove and adjust the lower bearing before I managed to get it right (in the pic you can see the small strips of styrene that I used to keep the bearing in the right position).


    Now the bridge can turn only into the desired direction, no more additonal movements.

  4. cnw1961

    cnw1961 Member

    I forgot to post this pic of the bottom of the pit with one of the gears in place.

  5. 2-8-2

    2-8-2 Member


    Great thread!

    Not only is your modeling superb, but the step-by-step is easy to follow and you have great pictures.
  6. COX 47

    COX 47 Member

    Great Job!! Lets see some more of your modeling....Cox 47
  7. Nazgul

    Nazgul Active Member

    Kurt, I have only 2 questions:
    How many of the TT's are you making?
    And...........Can I have one?!!!!!!sign1
    I mean, the next one should go a lot faster now that you got it all figured out................right?...........................right?:D
  8. cnw1961

    cnw1961 Member

    Only one picture today. I installed the gears to drive the bridge and to my great relief, it works absolutely fabulous. I attached my electrical screwdriver (how do you call this thing?) to the shaft that comes from the gears and when I switched it on, the bridge turned just as I hoped it would. Tomorrow I’ll try to find a small motor for my turntable.


    Now I only have to find a way to attach a phone jack to the lower end of the center shaft.
  9. cnw1961

    cnw1961 Member

    Thank you once again for your nice words, guys. Steve, be careful with what you say. To build this turntable is fun and I already regret that I need only one of them. I could easily be talked into doing it again. :D
  10. Ray Marinaccio

    Ray Marinaccio Active Member

    Lookin good Kurt.:thumb:
  11. belg

    belg Member

    Well Kurt, if you really would like to build another one but with more of an old time wooden frame I would really be glad to take it off your hands after your done. Lets say something with a timber frame on top about 100-120 ft long. Really great work it was a pleasure reading your thread, Pat
  12. pgandw

    pgandw Active Member


    Don't know how much you worry about being true to prototype. In American practice, the gallows and A frame turntables were rarely more than about 65ft long. The wooden structures just got too complicated to deal with the weight of the locomotive when you got above that size.

    Regardless of that, Kurts' work is indeed outstanding. I'd love to have one, too.
  13. cnw1961

    cnw1961 Member

    I got the ultimate motor for my turbtable today :) :) :) :) . It is a 12 V/DC motor that has a small gearbox attached to reduce the speed of the shaft. When the motor is running at full speed, the shaft does only 85 rpm. The bridge of the turntable makes one full turn in 30 seconds when the motor is running at full speed. And it is no problem to let the bridge crawl until it is hardly visible. Even then, the revs of the motor are still high. I will plug the motor to an old DC power pack and I will get the perfect control of my turntable. I think it is as good as it gets without an indexing system. But the guys who operated turntables in the real world did not have indexing systems as well. :D :D


    And I painted the bridge today. Now it needs some weathering.

  14. kirkendale

    kirkendale Member

    Kurt, I just can't stop saying it, WOW and WOW :thumb: This is looking great, your tutorial is great, the pictures are clear, the text is very informative. Looking forward to seeing more, keep them coming.
  15. MilesWestern

    MilesWestern Active Member

    Oh...my....goodness!!! That's got to be the best turntable I've ever seen!! FANTASTIC! I just can't stop complimenting you on your work, because, for one, it sincerly deserves praise! ;)
  16. cnw1961

    cnw1961 Member

    Did not have much time to work on my turntable today. Only weathered the girders. After having painted the bridge, it deserves a painted engine now :D .



    BTW, now that I know of these 12 V/DC motors with gearboxes, I would change the design of the transmission, if I had to do it again. I am happy with the performance of my turntable, but it is always better to keep things simple. With the new design, I would only need 2 gears instead of 4. That’s how I would do it:

  17. Illus

    Illus Member

    Fantastic job. That is a thing of beauty. Nice weathering on the girders.
  18. fsm1000

    fsm1000 Member

    Kurt, that truly is an outstandiing job you have done. Also I like the tutorial you are doing [wanna do mine? LOL].
    Anyhow, I do have a question for you.
    I generally work in wood 99% of the time. I haven't used plastic since my teens [remember the old spiderman models etc? :)

    My question isthis.
    How did you glue those sides on the table. They look very thin and I see no glue spots.
    What tools did you use? Can you show pics and maybe a pictorial of how to do it?
    You see I am thinking of trying my hand at plastics in my old age and seeing how great a job you did on this turntable, I figured I would ask someone who obviously knows how to do it.

    So basically, pics of your tools and if possible some on HOW you did it as well.
    I know you are busy [as are we all] so if you can't I nderstnad.

    Thanks again for a great tutorial. :)
  19. cnw1961

    cnw1961 Member

    Thank you guys for this overwhwelming response to this thread :wave: :wave:

    fsm1000, it is very easy to work with styrene. You can easily cut, glue sand or file it and you get good results in no time. In this picture you see nearly all the tools I use for working with styrene (sometimes I need a longer ruler as a stright edge or a bigger file).


    A straight edge and a knife is all you need to cut styrene. Scribe the styrene and then bend it to snap it off. Thin styrene (.013" or .020") can easily be cut, just like paper. (BTW, I use a piece of .300" window pane to protect my workbench when I cut styrene.)
    I use this knife with snap blades most of the time. The tip of the knife has to be sharp to get good results. For very thin styrene or delicate parts, I use the surgeon’s knife.
    I use this triangle as a straight edge. I think most people prefer to use a metal ruler, because it takes some practice not to cut the triangle and damage it. The big advantage is, that I don’t have to draw any lines on the styrene to see where to cut – saves a lot of time. With all these parallel and rectangular lines, I can use the triangle to measure and cut in just one step. With this triangel I can cut strips of .020" (.013 styrene).

    To glue styrene is even easier. I recommend liquid glues like this Revell glue that I use, because they are applied and spread easily. These glues melt styrene and after a few minutes the glued parts are firmly fixed. To glue parts, apply glue to one of them, hold them in place for a few seconds and then don’t touch them for a few minutes, that’s it. It might be necessary to fix big parts with adhesive tape sometimes, but this rarely happens. After the glue has dried, you can shape your parts with sanding paper or a file.

    I think that’s all you need to know. Get some styrene and glue and just start doing it, you’ll see it is very easy – as you can see from the pics, even I can do it :) .
  20. cnw1961

    cnw1961 Member

    Only a short update. I cannot finish the deck of the bridge and the electrics until next week. I need a piece of Atlas code 83 track and I have only Peco code 75 at hand. I have to go to the LHS next week. Today I painted the pit. At first I applied a clear primer with a paintbrush to seal the MDF board and sanded it afterwards. Then I spray painted it with white paint. After the paint had dried, I used a piece of cloth to apply several thin layers of acrylic paint. Don’t look at the rim of the pit too closely, I only painted it to hide the white paint that I applied first. Once the turntable will be installed on the layout, the rim will not be visible.


    Next step: paint the ring rail and glue it to the pit.

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