Welcome to my model train Blog. (2017)
I am presently building an HO scale Digital Command Control (DCC) model train layout.
I installed an HO scale (120') foot Diamond Scale model train turntable.
Also using the Diamond Scale turntable motor kit #MK-111 and turntable indexing kit #LK-114.
Totally assembled the motor kit and tested it having my turntable rotate. The rotating gears inside the gear box were not rotating smoothly. There were also small constant clicking internal sounds. The output shaft driving the universal to the turntable indexing gear was also not rotating smoothly.
The (2) mounting hinge plates on the gear box were not flexing correctly to allow for any back and forth adjustments from the universal. The 3/16" Dia. worm shaft (soft metal shaft) from under the turntable moves slightly (in and out) and (up and down). Through the past many years individuals have been using the #MK-111 kit without any major problems.
The indexing motor is a 10.V-DC motor. Some individuals must be burning out their indexing motor,
or it would not be listed on the Diamond Scale Products parts list MK-130 motor replacement. (http://www.diamond-scale.com/pricelist.htm).
I did some actual V-DC testing using the Diamond Scale electronic indexing circuit board. The electric motor receives (2) different V-DC power supply values. Full speed rotation V-DC and slow speed indexing V-DC. This 10.V-DC motor is only receiving 1/3 of the required maximum power supply. Between (2.3V-DC) and (3.4V-DC) at slow indexing speed.
A HO scale (120') foot Diamond Scale model train turntable is 16-1/2" (16.5") long. Now add extra weight by having a large and heavy steam locomotive on the turntable. A Diamond Scale turntable motor kit #MK-111 not operating correctly and smoothly will have much added resistance from the internal gears. This will make it much harder for the electric motor only operating between (2.3V-DC) and (3.4V-DC) at slow indexing speed. Could this be why some electric motors are burning out? This is the main reason why I wanted a much smoother operating turntable motor. I took early retirement and was a highly skilled tool-maker. (+/- .0005"). I totally disassembled the #MK-111 kit. Only doing some simple modifications to the #MK-111 kit, the complete unit now operates much smoother and quieter.
(#1-A) Modification: (Gear Box Assembly)
Totally disassembled the gear box unit including the electric motor.
(#1-B) Modification: (Internal Gears)
All of the internal small gears are made from plastic molding injection machines.
(#1) There are high quality small plastic gears having less facial contact to reduce friction.
(#2) There are also lower quality small plastic gears having full facial contact to increase friction.
These plastic gears are removed from the molding machine using "ejector pins" leaving indentations into the part.
(#3) All of my plastic gears have flush mounted "ejector pins" also leaving "flash" on the full facial contact surfaces of the gears.
This is what has caused that small constant clicking internal sounds and preventing the internal gears to operate smoothly on mating faces. Using a small flat wide "needle file", I removed any and all "flash" from all of the gear faces. Totally washed all the gears with warm water and allowed to dry on a paper towel.
(#2-A) Modification: (Gear Box Assembly)
All (3) large gears are very close to the internal walls. There is also a small radius inside the corners of the walls. Some of my gears were rubbing against the internal walls, so I modified all (3) gear locations. At each gear location, I cut out the side walls to make (3) windows. Used a small file to deburr all edges including the internal face flat.
(#2-B) Modification: (Gear Box Assembly)
The (2) halves of the plastic gear box is assembled together using (4) round head sheet metal screws, screwed into (4) plastic mounting holes. Sheet metal screws are very much like wood screws having the same type of threads. This is not an accurate procedure to mount the (2) half's of a plastic gear box having (3) gear axles (1/8" dowels) requiring perfect axial alignment. (+/- .005"). For example a 1/64" inch = (.015") and it will only take (1) mounting screw to misalign the complete assembled unit. I drilled through the (4) --> GREEN mounting holes <-- on the (1) half of the gear box assembly locations using a 1/8" inch (.125") Dia. drill. I checked to insure that the 1/8" inch (.125") Dia. drill would fit through the (4) clamping holes on the other (1) half of the gear box assembly. Totally washed the (2) halves of gear box assembly with warm water and dried the parts on a paper towel.
(#2-C) Modification: (Gear Box Assembly)
Only test the function of the (2) gear axles not including the main drive gear through the (2) bronze bushings. Slide the (2) halves of the plastic gear box and test (rotate) how these (2) axles
(1/8" dowels) actually function. Repeat the same procedure with the main drive gear through the (2) bronze bushings. All (3) gear axles should turn freely. The main drive axle has (2) bronze bearings because of the extra stress from the universal. These (2) bronze bushings must in perfect alignment to operate correctly. If required, carefully remove and reinstall the (2) bushings. While slowly reinstalling a bushing, insure that the top face of the bushing is always parallel to the mounting face.
(#3) Modification: (Hardware Required)
The new screws and nuts now used to assemble the gear box.
* (x4) 4-48 (.112" Dia.) flathead machine screws (x) 1" inch long.
* (x4) 4-48 (.112" Dia.) machine screw nuts.
(#4-A) Modification: (Gear Box Assembly)
Through the many years there have also been many changes to these hinges regarding the mounting holes and locations.
(#4-B) Modification: (Gear Box Assembly)
The (2) soft plastic hinges with tiny wire pins will not function correctly if mounted in-correctly. All of the small mounting holes are only 1/16" (.062") Dia. Using the original supplied sheet metal screws or much larger in Dia. size screws, will cause the (2) very soft plastic hinges to twist and bend the tiny wire pins in the (2) hinges. This would prevent the (2) hinges from operating correctly. This would also place more stress on the gear box internal main drive gear.
Will be using 4-48 (.112" Dia.) flathead machine screws that will require 1/8" (.125") Dia. clearance
holes in the hinge. Using (2) larger flathead machine screws that will require larger Dia. clearance holes in the hinge to mount the gear box assembly under the layout. Also offsetting the (1) electric motor side hinge to make mounting of the gear box assembly much easier under the layout.
Required clearance of through holes, determined by screw size used. Use a small soldering iron tip and enlarge the (4) holes to required sizes. Use a small fine flat file and remove any excess melted plastic. Check the hole size using a standard drill to insure minimum size of hole.
#4 Screw (.112") = 1/8" drill
#6 Screw (.130") = 9/64" drill
#8 Screw (.160") = 11/64" drill
#10 Screw (.190") = 13/64" drill
(#5) Modification: (Gear Box Assembly)
This gear box has (3) internal gears with many large surfaces rubbing up against each other and the internal faces of the gear box. In time gear grease tends to collect and build up any tiny foreign matter. Gear grease will not function correctly with this type of operation having gear faces rubbing against each other. Instead I used small gear oil. There are many different model train gear oils available. I am using new improved LaBelle #102 medium gear oil with P.T.F.E.
During assembly of the gear box, I lightly brushed gear oil all over the gears. Just like locomotive maintenance, periodically add a few drops of oil through one of the gear box top open windows, when the motor is turning.
(#6) Modification: (Gear Box Assembly)
Make sure that everything is (100%) clean before final assembly. Remount the electric motor. Lightly brush gear oil on the motor gear. Lightly brush gear oil all over the gears. Replace the (3) internal gears into the same half. Assemble the (2) half's of the gear box assembly using the (x4) - (4-48) screws and correctly locating the (2) hinges. The (2) halves mounting faces of the gear box assembly, also do not mount flat and parallel to each other. Install the (x4) - (4-48) nuts and only very lightly tighten them with your fingers. Diamond Scale instructions state 10.V-DC Maximum is to be applied to the electric motor. Use a 9.V-DC battery and check CW motor direction and CCW motor direction. While the motor is turning, only slowly tighten down or back off the (4) nuts to achieve maximum performance. The (4) nuts do not need to be over tightened down. Once the gear box is operating at maximum performance, hot glue gun the (4) nuts to prevent any rotation.
(#7) Modification: (Gear Box Assembly)
Instructions state to apply (2) flats to the main drive axle from the gear box. This main drive axle is a 1/8" (.125") Dia. case hardened dowel that can not be hand filed. The 1/8" universal end has (2) small standard metal set screws. True clamping force can not be achieved when clamping (2) tiny standard metal set screw to a case hardened round surface. Over tightening the (2) set screws could also damage the universal mounting threads. Only adding (1) flat clamping surface on the main drive axle will achieve excellent clamping force. Using a small hand grinder with a small flat fine sanding disk, slowly grind a 1/16" x 1/2" long evenly wide flat on the main drive axle. Before starting to grind the main drive axle, color it with a red marker to make it more visible of your grinding results.
(#8) Mounting: (Gear Box Assembly)
Correct mounting of the gear box assembly is required to insure that the mounting hinges operate correctly. The 3/16" Dia. (soft metal shaft) from under the turntable (differential worm gears) moves slightly (in and out) and (up and down). Use a red marker and fully color the ends 3/8" (.375") lengths on both (2) shafts. Carefully remove and save (1) small set screw from the 1/8" universal end. Slide the 1/8" universal end into the gear box main drive axle 3/8" (red marker) and only lightly tighten down the (1) set screw. Temporarily cover up the (3) windows on the gear box using masking tape, to prevent any contamination entering the gear box. If you previously removed the 3/16" universal end from the turntable (differential worm gears), the left behind burrs from the (2) clamping sets screws will be required to be filled down using a small flat needle file. The 1/8" universal end is mounted to the gear box. Now take the gear box and slide the 3/16" universal end into the main drive axle 3/8" (red marker) and insure that the (2) gear box hinges are sitting flat against the mounting surface. Tighten down the (2) mounting set screws on the 3/16" universal end.
(#9) Mounting: (Gear Box Assembly)
For better mounting accuracy, only drill (1) pilot hole at a time for the (2) mounting screws.
* Place the gear box insuring that the (2) gear box hinges are sitting correctly flat against the mounting surface.
* The gear box is located at (90') degrees to the universal.
* With a fine point marker, only mark (1) hole location.
* Drill the (1st) required pilot hole Dia. size for the screw used.
* Using (1) screw and clamp the gear box the mounting surface.
* The gear box is located at (90') degrees to the universal.
* With a fine point marker, mark the (2nd) hole location.
* Remove the (1) screw that is clamping the gear box the mounting surface.
* Drill the required (2nd) pilot hole Dia. size for the screw used.
* Mount the gear box having both (2) mounting screws only partially screwed in.
* Only very lightly tighten down the (2) clamping screws to prevent any hinge rotation.
* Remove the masking tape covering up the (3) holes.
Diamond Scale instructions state 10.V-DC Maximum is to be applied to the electric motor. Use a 9.V-DC battery and check CW turntable direction and CCW turntable direction. Relocate the (1) set screw on the 1/8" universal (ground flat) to improve the performance on the gear box. The main drive gear has some lateral in and out travel. In the out (green) travel the gear will rub against the back internal face. This will allow the other (2) gears to have axle free movements. In the in (red) travel the gear will cause all (3) gears to rub hard against each other. This will cause a lot of noise and extra gear friction. The (2) gear box hinges will only release some of the excess stress on the internal gears.
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Posted by Grand Trunk Railway System at Oct.14/2017