This page last updated: December 21, 2012 as of March 2017
Rotary Dumper Building instructions
The code is posted to SourceForge : there is a subset that has only the Arduino code - that is all you need - the Rotary Dumper code. The Main download has Delphi code for the Missile launcher.
- Parts: Walthers Rotary Dumper, Arduino Uno, several servos, 2ea 12 and 1ea 18 tooth 48 pitch Tamiya gears, sundry wires and parts
- Walthers Rotary Dumper...#933-3145 'original' or #933-3903 'Wood chip' version (both discontinued and hard to find...) (as of Feb 2013 Walthers has re-released the Wood chip dumper)
- Arduino Uno (or a Mega), several servos, servo wires, gears for the servo to drive the shaft : order from Sparkfun, Lady Ada, ... Info and links
- Tamiya 12 tooth 48 Pitch (metric) pinion gears for the 'original' also need a larger diameter metal shaft, the 'new' shaft fits Tamiya gears.
- As of January 2013 I do not think they are really ANY Pitch. Tamiya 12 tooth are slightly Too Small. 12 tooth 32 Pitch ? would make them slightly larger than 12 tooth 48 pitch. 12 tooth Tamiya (metric 48) pinion gears : TamTech-Gear GB-01 #40502... 14 tooth is slightly small while 16 tooth and 18 tooth are too large to fit. GEEZ if you have to, follow their instructions and/or glue the plastic gears in place.
- All my shafts in the new kit were Bent , a 2-56 servo rod seems to work... just slightly smaller
- I glued the plastic gears to my 12 tooth Tamiya gears and will use them and hope the Super Glue is... The 14 tooth gears Growl like they are eating plastic, the glued on plastic gears sound sweet. Grease the hex screw and the rod used to align the gears so no glue capilliaries into them. Line up the gear teeth when gluing so they do not interfere with each other. Using super glue you only have 1 chance so use the rod to align and carefully move them together, then 'walk away' until it sets.
- 2 rails to be glued onto the Floor deck - between the parallel raised lines... wires to connect to power
- Dumper Remote Control parts...
I guess you could use an XBee - it needs a computer to send the signals.
Adafruit sells and has instructions for an IR decoder and a Mini Remote Control. It is kinda needed as it is what is used in my code...
- As of 2017 : I made a box with push buttons to control the dumper and do not use a remote control
- probably a lot of other thungs ? depending on how you mount, animate the dumper...
Walthers Rotary Dumper...#933-3145 'original' and #933-3903 'Wood chip' version . The plastic is the same, just different colors (Tan base, Red or dark Green dumper). If you had two you could mix and match the parts and have it all Christmassy.
Closeup to see lines to cut on to make a 'Coal' length rotary dumper. The latest version (Wood chip) does NOT have instructions on where and how to cut-modify the kit for Coal length-height cars. Modifying the length is simply cutting off the ends of things - they are mostly pre-scored (Coal version Base and dumper floor is shorter in length, the dumper itself is the same). The clamp height is adjusted by cutting off 5/16 inch (8 mm) from the base of the car clamps (at the end where it changes shape). BE ADVISED making the height adjustment means a locomotive will NOT be able to drive through the dumper! ... I am going to modify my coal cars by adding to the top edge to make them the same height as the Wood chip cars (evergreen stripstyrene item 169 .080 x .250").
[As of 2013 - I will use a B unit locomotive and standard height cars, er no as of 2014 I modified a GP40 to be a RC unit - de-cabbed it, the GP60B units have a dynamic brake that sticks out in the way, the GP40 did not have one so the cab was cut off and there you go.] Two rails will be needed to be glued into the dumper and these will have to be hooked up to the train rail electrical power to enable a locomotive to drive through the dumper.
I had one and bought three more. 2 new ones for drive through steel mill. 1 new one for drive through paper plant. I plan to use the old one for the rock barge...
- Rotary dumper and Conveyor action areas
- Paper mill action areas
- International Paper: cardboard plant : wood chip Rotary dumpers : 2 paper mill wood chip types
- Walthers Rotary Dumper kit for 62' Wood chip cars
- Scratch built using enclosed 'lazy susan', to be built as a 72' wood chip car rotary dumper .. OR NOT - My 72' car fits in the Dumper... Need to get a Wood chip hopper to test its length...
72'=9.93 (Mine is real close - depending on where you measure - 9.9 at couplers endish inner edge)
Wood chip dumper floor is 9 3/8" , Base opening is 9.5"
Coal car couplers are inside the floor edge , My 72' couplers are outside the floor edge, if 62' wood chip car couplers are inside the floor edge then Both lengths would work in the same dumper :) ... maybe. 2013: And they DO fit :) So only 1 rotary dumper... Well except that the positioners do not do 2 types of cars.. So two Walthers dumper-positioners (gave up on the hand made scratch built for now) as of January 2017.
Image of wood chip version. The 'front' is to the left. Black lines on the base are where I will cut out the floor (so the coal can fall through) with a Weller 8200-N 100/140 watt soldering iron that has a 'cutting' tip on it : Great for melt-cutting plastic. Measured from the outside edge : leave 1/2 inch and cut 2 5/8 inch deep. Glue metal rods (from coat hangers) underneath to support the supports. Glue plastic at an angle to deflect the coal down the hole. 45 degree at the front , at the back the clamps Must clear and be able to go onto their ramps. Angle up gradually to the back of the rear ramps. Model putty is used to angle along the edges and wherever it seems to fit.
Building the Rotary Dumpers
- Gluing the kit together instructions for the 'new' kit. Old kit is similar- it has detailed instructions for 'Coal' cars. (If building for Coal cars cut-saw the base sections - there are dotted lines on the image where the scribe lines are on the plastic. The Cradles on the Coal version will be against the Base walls : Suggest gluing them in while base is still wet to ensure insertion.)
- The instruction diagram has the base upside down - the scribe lines are on the bottom and parts 7 and 8 are reversed. (Double check by placing the car clamp holders next to the base.) The long ones go in the 'back'. As instructed the 'front' will view the underside of the dumper. I like the dumper to rotate towards me so i can watch the coal dump. ('real' dumpers do not want the coal dust flying out on them) Thus I put the decorative things on the 'back'. Ignore Step 2 and part of Step 3 as we are using different gears - they will make things Very much easier as the gears are tightened in place with screws , so they can be repositioned. These instructions do not say to glue the cradles onto the base AFAIK - the old one did. The parts that go through the base (5,6,7,8) extend past it - be carefull gluing as they will push back up out of the base and get twisted and tilted.
As of Jan 2013 Tamiya 12 tooth gears DO NOT WORK - they are too small... Super glue the plastic gears onto the pinion gears or just use the plastic gears ... Good luck with that.
Test fit the pinion gears in the cradle holes-enlarge if necessary- although if you are using 12 Tooth 48 Pitch gears they should fit and if you are not using 48 Pitch (metric) gears there will be problems with stripped gears.
(if necessary Drill-enlarge the holes for the metal shaft - the new one fits the Tamiya GB-01 12T pinion gear - the 'original' did not fit any pinion gear - just the red plastic ones) Slide the shaft through the base holes while sliding the pinion gears onto the shaft inside the base, then moving them into the spaces in the Cradle and tightening the set screws. Actually the set screws can be tightened after the final test assembly. This will allow adjustements and ensure they mesh with the dumper. Better yet, remove the rod and pinion gears until final assembly to allow easier handling.
Ignore Steps 5,6,7,8,9,10 ... Glue all that decorative stuff on AFTER EVERYTHING is done, glue them during final landscaping. I painted the railing white to 'stand out', painted the dumper various colors and applied the decals.
- (If building for Coal cars cut-saw the floor sections where they have the separation on the bottom -about 1" from ends. (Measure the floor section against the side supports for length, their scribe line is more defined.) (Test length against the base wall: the floor should just clear the wall for rotation) Cut the bottom just past the lip that mounts to the dumper .. you will need to cut-scrape off the last ridge on both ends to enable gluing the end pieces in there.) The side gussets have a 'bar' that goes down - test fit them as they go under the lip of the bottom floor piece. Now is the easiest time to glue the rails onto the floor. Figure out how to solder wires to the rails and loop the wires so they can rotate with the dumper without getting tangled. Drill holes beside the rails about in the middle length and run the wires soldered to the rails out the bottom and have them long enough to wrap around the dumper as it rotates and connect to the 'my back' (Walthers protoypical front) wall connection (wrap a bread wrapper coated wire around the wires past the outside of the round tube, just tight enough to keep them together, they still have to pull-move past each other during rotation - they pull differently depending on the direction. The wire keeps them from twisting and getting caught on other moving parts.) Having disconnectable wires is a good idea, servo wire connections work well and are small enough not to look ugly. Cut a hole in the wall for the wires to exit. Soldering and gluing the rails is easier NOW than when assembled with walls beside the floor, dont ask how I Know.
- uhm if building for Coal cars all cutting is done ... Dry fit - get a good look at things since this is where you glue all the pieces together then place (not glue) inside the Base. The floor section really can (and should) be glued inside the dumper AFTER the tubes and walls are glued to the ends, just tilt the floor and wriggle it in place then glue it to the end sections. (You did glue the clamps, cam followers and springs while placed inside the walls already, right? Be Very careful Not to get extra glue in the clamp area when glueing the walls together as they have to slide freely) When placing the dumper inside the base, have a car in the dumper to raise the car clamps so they do not hit the edge of the base. Read the instructions about placing the dumper into the base - it only goes in and rotates 1 way - the other rotation is blocked. Suggest you glue the dumper together and place inside the base to make sure it all fits - then remove from base and let it dry real good. After everything has dried, the springs can be 'stretched' to increase their strength. Stretching the springs prior to assembly only increases the difficulty of gluing on the cam followers. The 'new' version springs are magnitudes less dense than the 'original' and they need to have the top 'widened' so it does not go up inside the car clamp channel. Stretchable ? Get different springs to increase strength?
If building as a Speed-run or for painting, Glue the round tubes and the dumper walls first as they have to dry before being glued to other parts. When painting realize that the back of the clamp walls are open and you DO NOT want paint in there, on the clamps or on the dumper gears.
- Building the base - containing the Rotary dumper, Electronics and Positioner
- Everything depends on how you want the your layout to be. Permanent .. removable The more parts there are the more complicated assemby is. So many wires. Everything has to be mounted securely and be made to disassemble for maintenance and trouble shooting. I made a base 8" wide by 16" long from 1x4" and smaller pieces for internal bracing and dumper support. The dumper extends about 1/4" above the wooden wall.
As the positioner is at the exit, it is possible to have the Rotary motor, electronics and positioner all on the exit side. Makes for the front and entry flush agains a wall and the other two sides being 'held' somehow as the wires and servo are there. Be aware the connecting rail HAS to extend over the edge wall of the dumper on both sides... seems to require a removable rail piece - a rerailer on the exit seems like a good idea.
- A switch has to be mounted that will be used to reverse and stop the dumper rotation. I made a 'flipper' switch from 2 pieces of copper (used for making stain glass windows - a roll 1/4" wide that is sticky backed) sticking out from the wall. I glued a block of wood so it will press the flipper flaps together at the return point and another at the end point. Better is to use Meccano-Erector parts: glue a right angle to the wall and bolt an extension to it, thus it can be turned out of the way. This allows the the dumper to be inserted and rotated without disturbing the flipper. These contact the switches differently: one from the top and the other from the bottom. They are on opposite sides of the same 'block' on the end piece. Position so it 'stops' with the floor level : About on that wall line. Position so it 'reverses' Before it goes past the gearing :) A little Above the wall line. Using Meccano parts the height can be adjusted using washers and or bending the tabs. The great thing is they can be loosened and moved out of the way so they do not smash the flapper switch into oblivion when removing-inserting the dumper.
- Rotary Dumper needs a servo mounted with a gear on it that will drive a gear on the metal shaft that turns the dumper gears. Rotary motor needs to be mounted. On the 'red original' I used two large gears - 1 on the motor and 1 on the metal rod. Large gears have more area and will not strip as easy, also it has to clear the motor. On the 'new green' ones I used another pinion gear on the metal rod and a 48 pitch spur gear on the servo. About 1.5" diameter (thus about 70+- teeth) for the servo (glued to a 6-arm servo horn NOTE that the nail heads are on the side that mounts to the servo -Observe Clearance) spur gear and large (18 tooth is largest i found from Tamiya - that fits the metal rod) pinion gear for the metal shaft axle... (make sure the axle fits the 12 tooth and the larger pinion gears): Both outside driving gears the same pitch : 48 pitch)
Once the dumper is positioned in the base the location of the drive servo will have to be determined and constructed. A plastic right angle Servo mount is mounted to the dumper and the base to keep it from lifting and shifting. A servo horn is mounted so the rod goes through one of its holes to maintain the rods position - keep the servo force from pushing the pinion and rod away and thus not turning the dumper.
Video HO scale Walthers Rotary dumper_2013_04_22 at HO train Hobby YouTube video channel.
- Electronics need to be mounted. Locate inside the base and connect the wires.
- Positioner needs to be mounted
- Everything has to fit together and be secured see this for my previous attempt.
- Building the positioner
- Assemble : Must have a moving arm range of 8" to move a car.
Back and Front of the board. Can you spot the corrected Errors :)
Note the green wires on the end of the Ardiono - Buy Pro minis with 5 pins on the back Ground and Analog 4,5,6,7. They will be spaced so they can be connected to the board like the other pins.
- Electronics : General and Rotary Dumper
- All the wires (Servo and flapper switch) need to be connected and the dumper rotation adjusted to reverse and stop at the correct location. A button to reset-halt the program and a Button to Start-run the dumper program need to be Right There for Emergency Stop and normal start (Physically connected to the controller). Normal operation would be with an IR controller or an XBee or... DIY
Controller Commands : (minimum)
1: Start_Dump_Run (Will run continuously until out of cars)
2: Run 1 time (Dump the first car while still connected to the locomotive, then decouple and run the locomotive to the rest area)
3: Rotate_Dumper Forward (for testing : will stop at the reverse trigger)
4: Rotate_Dumper Back (for testing : will stop at the stop trigger)
5: Lower_Arm (for testing the location and angle, etc)
6: Raise_Arm (for testing the location and angle, etc)
- Positioner needs to be adjusted so it moves to the correct position and lowers-raises the arm correctly.
- Seems like if you can do this you do not need these instructions. HTH
- As of 2017 I have 3 buttons on the control box - the added button is the "Run 1 time" command, so the locomotive can dump its car and then pull forward and get decoupled when the positioner is hooked to the car.
Commands 3,4,5,6, and move the positioner forward, and back are set to run on an additional control box - for debugging purposes only - then disconnected when the dumper-positioner are actually installed.
- As of 2017 Mar 3 the control boxes have many buttons and 1 LED. The arduino boards have been redone... repeatedly. I have run servos from the Arduino power before... apparently this setup has too much going on. Several days checking and rechecking things to determine that the 6V power for the servos ground wire needs to be connected somewhere downstream from the board connections. Things worked great running hooked up to the computer and then when it was only the power supplies - No Go at this station. Look at the rats nest of wires :)
All wires connected to the board // two other boards - rewired.
Copyright © 1991..2017 by Ivan Lee Herring