N Scale 3D Printed Turntable with a Controller...

Sumner Mar 8, 2021

  1. Sumner

    Sumner TrainBoard Member

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    Having posted more of an overview of the turntable in the past few posts I'll get back to posts that finish the build of the pit as I pretty much detailed the bridge in posts above. If I've missed anything or something is confusing please let me know. Also here is a link to the complete build on my site ..

    http://1fatgmc.com/RailRoad/Turntable/Turntable-Index.html

    Hopefully I'll have the complete build documentation finished over the next few weeks along with the Arduino sketches and all the print files. I'm done with the build except for a few detail parts but it does take time to document it and get it all posted on the internet. With that said lets get on to part one of the turntable's pit.

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    On this page we will start the build of the turntable pit. The first piece (build platform) is used as a foundation for the pit and won't be seen when the pit is finished. The pictures should be self-explanatory.

    All the pieces were printed with an Ender 3 Pro filament printer on 'standard quality'. This is a large print at about 8 inches requiring a large build surface.

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    I bought the slip ring on Amazon for around $20.00 ( HERE ). You can find it also on eBay. In some ways I wish I would of bought the 6 wire slip ring as it would of offered more power options for the table/bridge. Also I'd check the connections through the slip ring as soon as you get it. I bought it in Jan. but didn't install and test it until late April and one wire was defective. Amazon did replace it in a few days though. With a 6 wire I could of gone to one of the other unused wires.

    I'm using the 4 wires to power a light in the control 'shack' on the table, a flashing warning light, an overhead light on the table and track power. To do that with only 4 wires involved a little trickery (you will see it later). If I had 2 more wires to begin with the Arduino code would have been simpler and I would have had a little more control over the lights. It did all work out so all is good.

    NOTE: The 6 wire slip ring is about the same price and appears to be the same size but if it isn't then it isn't going to fit the parts I designed. Also if you want to use the wires in a different manner you are going to have to modify the code I'll post for the two Arduino's.

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    Above you can see what will be the visible pit floor with drains for the bottom of the pit along with a filler piece for the center of the pit under the bridge.

    The remainder of this page is devoted to mounting the slip ring onto the build disc. I ordered an assortment of #2-56 pan head and flathead screws to use from Amazon and an assortment of 4mm to 20 mm M2 flathead Phillips self tapping screws from eBay. The screws weren't that much and I'll have plenty to use on other projects (you can see some of them in the background of the next photo).

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    I used a small die grinder bit I had to countersink the screw holes in the slip ring.

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    Next we will move onto the part of the pit bottom that will be seen.When I have all the print files done for the turntable and other parts I'll post them on my thingiverse.com account ( HERE ).

    Sumner
     
  2. Sumner

    Sumner TrainBoard Member

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    Next we will place the pit floor on top of the build platform/disc.

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    Next we will move onto the wall and the track that the bridge runs on.

    When I have all the print files done for the turntable and other parts I'll post them on my thingiverse.com account ( HERE ).

    A link to the whole build....

    http://1fatgmc.com/RailRoad/Turntable/Turntable-Index.html

    Sumner
     
    Last edited: May 20, 2021
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  3. Sumner

    Sumner TrainBoard Member

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    On this page we will prepare the stepper motor for mounting. The steps on this page and the next page go hand in hand so look at both pages and decide the order of events that works best for you. Before you can cut the support uprights on the next page you have to determine how long they need to be and that will be covered here. Some of the final mounting of the stepper motor shown here needs to be done once those supports are in place and you can rotate the bridge.

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    You will find a link to the shaft ( HERE ) but if it doesn't work Google ( 5mm x 100mm Straight Metal Round Shaft Rod Bars ).

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    I started with a solid 5mm shaft connector but found the flexible one shown above to be a better solution. You can find it ( HERE ) or Google ( Flexible Couplings 5mm to 5mm NEMA 17 Shaft ).

    You can find the stepper motor ( HERE ) or Google ( Stepper Motor Nema 17 Motor 42BYGH ).

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    I'm showing how the stepper motor is held in place above but don't secure it with the plywood pieces until you have the uprights on as shown and you can rotate the bridge so that the motor settles into the correct position where there is no binding between it and the bridge. The slip ring is what will center it.

    Above you can also see a mounting bracket attached to the stepper motor. I left it on but I'm not using it at this point. The motor seems to stay in place with no other mounting needed.

    Next we will move onto the supports between the stepper motor mount and the bottom of the pit, which are shown above in the last picture.

    A link to my site page on this ...

    http://1fatgmc.com/RailRoad/Turntable/page-6.html

    Sumner
     
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  4. Sumner

    Sumner TrainBoard Member

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    On this page we place 3 uprights and a base for the stepper motor under the turntable pit bottom.

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    The length of the uprights is going to depend on how long a shaft you use between the stepper motor and the bridge and how far the shaft is into the bridge and into the stepper motor coupling. The measurements above are what worked for me you are going to need to calculate what you need. See the preceding build page for info on how to do that.

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    I didn't round the bottom off until later in the build but it would be a good idea to do that now before you go any further. The purpose of this is to make it easier to mount the whole turntable assembly to the layout later. Then you will just need to cut a round hole in the layout a little larger in diameter than the print and lower the whole assembly down through the hole. If the base isn't rounded it probably wouldn't fit through the round hole in the layout.

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    You do need to secure the ledge that has the bridge track on it now before adding the pit walls in the next step. I'd also setup the mount for the stepper motor now so that you can install and remove the bridge for later steps when you add the pit walls. Next we will deal with mounting the stepper motor and you should do that in conjunction with the upright install shown above.

    Next we will move onto the pit wall.

    When I have all the print files done for the turntable and other parts I'll post them on my thingiverse.com account ( HERE ).

    This page on my site ( http://1fatgmc.com/RailRoad/Turntable/page-7.html )

    Sumner
     
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  5. Sumner

    Sumner TrainBoard Member

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    On this page the turntable bridge track is put in place.

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    The Rust-Oleum was in a spray can.

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    In the picture above I hadn't painted the tie plates black yet. Don't forget that this is N Scale and if you are looking at the picture above on a computer monitor the parts are a lot larger than real life.

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    In the picture above you are also seeing the pit wall has been slid down over and past the bottom on the pit. Ignore that for the moment as that will be covered on the next page. I didn't have a picture from the bottom of the screws that hold the bridge track so used this later one.

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    The picture above was taken when I had printed and painted the bridge track but hadn't installed the stepper motor and turntable supports yet. It was a trial run to see how the bridge track fit the pit bottom. So you could mount the bridge track in the build but you would have to remove it temporarily while attaching the upright supports.

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    I feel that there is more bridge and pit detail than what you will find on most commercial turntables. At this point an arch still has to be added to the bridge along with guard rails and ladders down into the pit itself.

    When I have all the print files done for the turntable and other parts I'll post them on my thingiverse.com account ( HERE ).

    My web site page for this ( http://1fatgmc.com/RailRoad/Turntable/page-8.html ).

    Sumner
     
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  6. SLSF Freak

    SLSF Freak Staff Member TrainBoard Supporter

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    The paint job on that pit rail is quite convincing. Were you able to print that in one piece then? Looks outstanding..

    Mike
     
  7. Sumner

    Sumner TrainBoard Member

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    The rail, ties and the wall under it is a single print. I came up with a 100' table/bridge as it maxes the printer out as for as what can be printed on the Ender 3 Pro's build plate. The largest piece, which will be documented next, is the pit wall. The top of the pit wall, the part that will lay on the layout's surface, is larger/wider than the diameter of the pit.

    Sumner
     
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  8. Sumner

    Sumner TrainBoard Member

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    On this page the turntable pit walls are installed.

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    Finally things are looking like a turntable. A lot of hours of design work using Fusion 360 have gone into the project to get this far and more hours are still ahead as an overhead arch, guard rails and ladders still have to be designed. Also the pit build plate, pit floor, bridge track and now the pit wall are long prints using the Ender 3 Pro printer and documenting this is also pretty time consuming but I enjoy it.

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    I saw a turntable with blocks for walls vs. the more common smooth sides and liked it so decided to more or less copy it and I'm happy with the results. The pit walls will be painted to match the short wall under the bridge track.

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    The pit wall was designed to slide down past the pit build plate/disc and the pit floor and the bridge track. I decided to make the lip of the wall that the approach tracks and roundhouse tracks will sit on slightly lower than the surface on the bridge where the bridge track sit. I figured it would be easiest to shim the approach tracks up slightly if needed. Since the pit can end up at any height I used the stir sticks on the bridge as indicators that helped me determine the final pit wall height.

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    The pit wall is held to the desired height with #4 self-taping screws. I drilled pilot holes into the side of the wall and then screwed into the pit floor/bridge track area. I found that I needed two pilot hole sizes. One very small for the screw to screw into and a larger hole in the wall itself large enough for the #4 screw to pass though. If the wall hole is too small and the screw ends up screwing itself through the print filament it can cause the filament to split. If it does this it is out of sight but weakens the wall so make the wall hole large enough for the screw to pass though with adequate clearance.

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    If you left room between the rod to the bridge and the step motor shaft in the middle of the coupler you can still lower the bridge slightly if needed although it should be just barely above the bridge track at this point.

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    Next we will move onto wiring the bridge and then installing an overhead arch with lights and the wiring to it.

    When I have all the print files done for the turntable and other parts I'll post them on my thingiverse.com account ( HERE ).

    You can also find this on my site here ( http://1fatgmc.com/RailRoad/Turntable/page-9.html )

    Sumner
     
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  9. Sumner

    Sumner TrainBoard Member

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    Next the turntable's arch is printed and installed.

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    Next up is wiring the bridge track, shack light and arch lights.

    When I have all the print files done for the turntable and other parts I'll post them on my thingiverse.com account ( HERE ).

    Link to this info on my site ( http://1fatgmc.com/RailRoad/Turntable/page-10.html )

    Sumner
     
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  10. Sumner

    Sumner TrainBoard Member

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    Part 1 of wiring the turntable bridge/deck. Also part 1 of the track wiring.

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    Next up is Part 2 of wiring the table.

    When I have all the print files done for the turntable and other parts I'll post them on my thingiverse.com account ( HERE ).

    Link to my site for this info ( HERE ).

    Sumner
     
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  11. Sumner

    Sumner TrainBoard Member

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    I added the following two pictures to the preceding page on my site to hopefully show how to attach the decking to the bridge.

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    The deck is secured to the bridge with two 2-25 flathead screws. You could add screws if need but two seems to work fine in my case.

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    Once the track and center deck is in place you won't see these screws.

    Sumner
     
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  12. Sumner

    Sumner TrainBoard Member

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    Part 2 of wiring the turntable bridge/deck. This page will be prep work before starting the final wiring.

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    I could go back and edit the bridge file so that it has the cutouts above and below and one wouldn't have to do this. But it just takes a minute to do and I have my bridge done so you guys are going to have to do a little work like I did.


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    The clearancing above doesn't need to be much as the wires to the arch are very small.


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    You can make the cover pieces shown above out of about anything. I didn't add print files for them. I print some items, like wire clamps, on a 'raft' in Cura. I keep the 'rafts' and that is what I cut and glued onto the bridge above.

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    Use a VOM to make sure the two sides of the solder pad are isolated electrically from each other.

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    I make other solder pads that can be used on a number of different projects as shown ( HERE ).

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    You can find small bridge rectifiers on Digi-Key, eBay and other sources for a couple dollars.

    It is pretty easy to solder the components to the flexible PCB strip. Make the needed cuts in the copper that will be under the bridge rectifier (both traces) and the resistor. Next tin the foil next to the the cuts. Place the component on the tinned area one side at a time and touch the tinned area and component just long enough with a hot iron that the solder flows and the component drops into the liquid solder. Use a hot iron so that this happens quickly.

    I had a friend in Denmark get the strips for me from a firm in Germany and ship them to me as the German firm wouldn't ship to the U.S. (Thanks Jens). Since then I found a supplier that will ship. I just ordered some (late may 2012) and haven't received them yet but don't expect a problem. I'll post back here if it ends up being a problem say in late June or early July (2021) as they aren't suppose to arrive until mid June.

    These 2 conductor strips work very well in decoder installs as they are so thin you can run them places where even thin wiring can be a problem. They make adding LED's in some places a breeze as you can solder a SMD 1208 or smaller LED across the two conductors and if needed add a resistor as shown above to one of the conductors at the LED or some place before it. I could of used short pieces of them glued to something as the solder pads in the bridge to replace the ones I made for printed circuit board. They make nice short or long solder pads in decoder installs. Check out the install that Jen's did where I was introduced to them by his nice write-up ( HERE ) where he installed a decoder in a Kato FEF-3.

    Here are two links to the place I recently found the flexible 2 conductor strips where they will ship to the U.S.. ( HERE ) and ( HERE ).

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    If needed you can use something like the 'clamping' tweezers shown above as a heat sink on a component while soldering.

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    Checking parts out before installing/soldering into the bridge is a good idea. Above I checked out the AC to DC strip out using alligator clip leads from a section of DCC powered track to the strip and from the strip to a test LED I use.

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    Above is a wiring schematic of the wiring to the bridge, the slip ring under it and how the wiring will be done inside the bridge under the decking. Note that the LED wires to the shack and the arch on the right solder pad are opposite from each other. This might seem wrong but you need to do it in this matter and also make sure the wiring from the control panel (orange and brown wires) that go through the slip ring are also connected as shown between the solder pad and the control board (middle bottom above). The red flashing light and the white shack light are controlled using only two wires by reversing the current to the solder pad. Since the LED's are like diodes when the current flows one way one will come on and reversing the current turns the other one on. If I would of bought a slip ring with 6 wires they could have been controlled independently of each other (should of probably done that).

    As it is now if the shack light is turned on with the hand controller and you also then rotate the turntable the red flashing light on the arch will have priority and the shack light will go off while the table is turning. When the table stops rotating the shack like will automatically go back on. I look at this being a 'possible prototypical' feature as the shack light then couldn't cause night-blindness for the operator while the turntable is being operated by him.

    A link to the above info on my site ( HERE ).

    Next up is Part 3 of wiring the table.

    When I have all the print files done for the turntable and other parts I'll post them on my thingiverse.com account ( HERE ).

    Sumner
     
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  13. Shortround

    Shortround TrainBoard Member

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    Thanks for the pics and explanation of what you are doing. Back when I was a youngster, '87, I took a tech college course in dc wiring. And this is a big reminder of what I had to stop in '00. Of course things like tinny leds and 3d printing weren't here yet.
    Maybe after this time I'll be able to return.
     
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  14. Sumner

    Sumner TrainBoard Member

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    Part 3 of wiring the turntable bridge/deck. This page will finish the turntable wiring.

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    One might be confused easily by the LED wiring on the solder pad to the shack light and the red flashing LED at the top of the arch. The red and black (anode/cathode wires) are reversed on the solder pad as I'm turning on the two LED's separately with just the orange and brown wire to the solder pad that comes from the control panel. I turn the current on and off and reverse the current in those two wires to turn one or the other of the two lights on. When the current is flowing in one direction one LED will be on and the other off. Reverse the current and the off LED will come on and the other will go off. I'm using the fact that current can only flow one way through them. If it is the wrong way they are off and if the correct way they are on.

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    Above is a close up of the wiring on the solder pad. You want the red wire going to the flashing red LED to be on the same side as the orange supply wire. You want the red wire going to the shack LED to be on the same side as the brown wire.

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    Earlier in the build the wires were run from the LED's in the arch down through the sides of the arch and into the bottom of the bridge by the support for the arch there. At that time I also sprayed and brushed paint onto the wires inside the sides of the arch. You can barely see one of the red ones in the photo above.

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    Almost done.

    Next up is adding the detail parts to the turntable, the railings, ladders and electrical box to the top of the arch. I'll put them up on the next page as I design and print them but won't glue them to the turntable until it is time to install it.

    Link to my site for this info ( HERE )

    When I have all the print files done for the turntable and other parts I'll post them on my thingiverse.com account ( HERE ).

    Sumner
     
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  15. Sumner

    Sumner TrainBoard Member

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    I reordered the pictures/sequence shown above on my site ( HERE ). They are a little out of order as shown above. Before putting the deck on you need to finish all of the wiring inside of the bridge otherwise the deck will be in the way. Finish the wiring for the shack and red flashing light in the arch and also the white LED in the arch and most of the track wiring and the DCC AC to DC circuit. With all of that finished put the deck on and complete the wiring by soldering the two track feeder wires to the corresponding wires under the deck in the bridge.

    Sumner
     

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