BUILDING THE CMR 135' TURNTABLE KIT TUTORIAL
This tutorial was published in the March-April 2008 issue of N Scale Magazine.
I always wanted to build a turntable module on the JJJ&E when designing the original layout. This module was added to the layout after the mainline track work was completed.
I decided to order the CMR 135' turntable kit after reviewing many articles on this N scale kit.. The CMR 135' turntable was the only detailed turntable available in N scale when I built this kit. Walthers now has a highly detailed ready to run turntable available to the N scale community, however this kit offers a challenge to those modelers who want to build a turntable themselves.
I ordered this kit from CMR in Baltimore MD. The CMR 135' turntable kit was $115 plus $10 shipping and handling. Today the MSRP is $165. I was told that this kit would take 16-18 hours to build and weather. I was also advised to take my time and not rush building this kit as there were many exacting procedures required to make this turntable kit run efficiently.
The morning I started the kit, it was a beauriful day in South Florida. I decided to start this project outside on my deck in the enclosed pool lanai. The air temperature was 74 F and there was no humidity in the air ( quite rare in Florida) and no threat of a hurricane. The peaceful setting behind my house is an ideal location to build the CMR 135' turntable kit as I'm going to use Tenax &R/Plastistrut as a bonding agent to bond the acrylic pieces of the kit together.(See Photo 1).
Photo 1
Tenax 7R is highly vaporous and requires good ventilation when using it. You should never work with this substance in an enclosed room without proper ventilation. I will try and limit my work sessions to one hour daily and scheduled a little over two weeks to complete the turntable.
The CMR 135' turntable came packaged in a well constructed box. The instructions were very comprehensive and easy to follow. Many kits have poorly written instructions that are difficult to follow without numbered parts. The CMR kit is just the opposite as the instructions are well written and easy to follow. All the parts in the kits are numbered for easy identification. (See Photo 2)
Photo 2
The parts in the kit were placed on two acrylic boards. These parts would have to be removed with a heavy duty Xacto blade due to the thickness of the parts. (Photo 3)
Photo 3
For additional supplies to start with, you will need an acrylic bonding agent such as Tenax 7-R or Plastistrut; brush applicators and a syringe with different gauge needles to transport the bonding agent to the necessary acrylic parts. You will also need Squadron white putty to fill in any voids in the turntable deck wall. You also need some CA cement to bond other acrylic parts.
A heavy duty Exacto knife will also be needed to cut out the acrylic parts from the frames of the two acrylic parts boards along with rail nippers and craft tools. A small mixing spatula would also be helpful for mixing the Squadron white putty. (See Photo 4)
Photo 4
There are different acrylic bonding agents available on the market to "bond" the acrylic parts in this turntable kit such as Tenax 7-R. Plastistrut has a comparable bonding agent as well. There are also various commercial acrylic bonding agents used to build plastic display cases that could also be used.
I decided to use both Tenax 7-R and Plastistrut's bonding agent to test the properties and bonding capabilities of both produts for N scale acrylic kits. Plastistrut's bonding agent cost $5.99 for four ounces. Tenax 7-R cost $3.99/ounce/ The properties and bonding capability of both Tenax 7-R and Plastistrut's bonding agent are comparable. Plastistrut's bonding agent was more cost effective.
The volatility of both bonding agents is extremely high. The container of each bonding agent shouldn't be left open for any extended period of time as the bonding agent will quickly vaporize and evaporate very quickly. Again, either bonding agent should be used in a well ventilated room or as in my case, outside. One should not inhale the vapors and it might be wise to use a face mask to cover your nose. A pair of latex gloves might also be useful in handling these noxious substances, as they are very reactive and volatile.
I then placed the circular turntable base on a work area and then proceeded to cut the 120 ties needed for the turntable base and rail guide from the parts board. There are many extra ties if they are needed. Occasionally one or two ties will fracture when removing them from the parts board. This is slow work and care must be taken when removing the ties from the acrylic parts board.
This task took about one hour and fifteen minutes. As I removed each tie from the board, I smoothed the end of each tie with a very fine grit sandpaper to remove any flash.
I then placed all the ties securely in the turntable base. Some fit easily in the base and others were a snug fit. Make sure that all the ties are seated firmly in the turntable base. Photo 5 shows the 120 ties placed in the turntable base. They are not bonded in position with the bonding agent as of yet.
Photo 5
Photo 6 shows a close-up view of the ties firmly in place in the base. I contrasted the photo to clearly show the ties in relation to the turntable base. The indented area on each ties shows where the guide rail for the turntable bridge is to be placed.
Photo 6
The next section in the construction of the turntable deals with bonding the ties onto the turntable base and placing the guide rail on the ties while they are not completely bonded to the turntable base. This isn't as difficult as it might seem.
I used the bonding agent (Tenax 7-R/Plastistrut) to bond the 120 ties to the turntable base. The ties must be COMPLETELY SEATED when you apply the bonding agent to the ties and turntable base. If the ties aren't completely seated in the turntable base, The guide rail for the turntable bridge will not seat properly. If this is the case, the above procedure must be repeated.
As the bonding agent is setting between the ties and the turntable base, you must slide the guide rail through the notch of all 120 ties. At the 180 degree angle, use rail nippers or a blade saw to cut the guide rail half way around.
Guide the remaining rail through the ties to complete the circle. You now have one guide rail with two cuts at 180 degrees apart. The cuts in the guide rail are 1/16 " wide.
Photo 7 is a closeup of one of the cuts in the guide rail.
Photo 7
At this point in the construction of the turntable, the guide rail must be cemented to the turntable base with some CA cement. I placed CA cement on both sides of the guide rail at the turntable base on between the 120 ties using a common pin as an applicator.
I will now let the turntable base set up and harden, undisturbed for the next 24 hours so the bonding agent and CA cement can completely set up. So far, I've been working on this kit for 2 1/2 hours plus.
Today is another beautiful day in South Florida. It is a bit more humid outside and the temperature is 82F, but this is still the best place to work especially with the "volatile" bonding agent that we must use in constructing this kit.
The turntable pit was completely "cured" overnight. It is about 24 hours after I finished working yesterday. The first thing I did today was to use a razor saw and redefine the two cuts I made in the guide rails at 180 degree intervals. The instructions say to measure two inches to the right of each cut and cut the guide rail again. These cuts in the guide rail are easy to do with a straight back razor saw.
This cuts were needed for any DCC installation that might be considered. I will hook up a Lenz Reversing Loop Module to these two wires in the two inch cuts that I made in the guide rail. This will change the polarity for me when the turntable is fully operational and motorized.
I then proceeded to drill four holes in the area of the two inch cuts for wiring to the guide rails.
After the four holes were drilled in the turntable base, I used 22 gauge wire for the electrical connections. (See Photos 8 & 9) I bent the 22 gauge wire at right angles, tinned the wire and rails, and then soldered the 22 gauge wire to the guide rail in the turntable base (using black and red wiring).
Photo 8
Photo 9
Here is a closeup of the wiring to the guide rail. (See Photo 10) There is little room to work and "tinning" the guide rail and 22 gauge wire helps immensely before you solder. You should use a soldering station with a very fine electronic soldering tip. I use a Hako soldering station that is digitally controlled. This soldering unit makes soldering a pleasure especially when you have to solder in confined areas. The electronic soldering tip is primarily used for soldering circuit boards and decoders. I use it all the time for soldering in N scale, especially when I'm working with decoders for DCC control.
Photo 10
The next step is to build the pit wall. You must remove all the pit wall parts from the parts board. The 1/16" parts have to be removed very carefully as they are quite thin. I broke one of the pieces, but it was not a problem to repair.
You can build the pit wall directly on the turntable base or you could build it apart from the base. When the pit wall is finished using the second option, you cement the final pit wall to the base of the turntable.
I chose to build the pit wall directly to the turntable base. I used some very fine sandpaper to smooth down any irregularities in the pit wall structure. Then I proceeded to build the pit wall, layer by layer, using the bonding agent after each layer was added.
The wall of the turntable pit must be lined up perfectly or else the bridge will interfere with the pit wall when it rotates. (See Photo 8) There is a scribed line on the turntable base to follow to get the correct position of the pit wall.
The final height of the pit wall is about 10/16". The pit wall must be coursed like brick for strength. Overlap the starting point from one layer to the next. The final two layers of the pit wall are lipped, which should be raised enough for most road beds of the track to the turntable.
Photo 11 will give you some perspective about the depth of the turntable pit in relation to the turntable wall. I used a small jewelers screwdriver to show this perspective.
Photo 11
At this point in the CMR 135' turntable kit construction, I will let the walls of the turntable pit "cure" for at least 24 hours before continuing. You must not rush with the construction of this kit. The walls of the turntable were bonded to the turntable pit using Tenax 7-R/Plastistrut bonding agent.
The nest step is to construct the turntable bridge. I'm about 4+ hours into the construction of the CMR 135' turntable.
The next morning, it was time to start building the turntable bridge. The bridge parts were removed from the acrylic parts board. I bonded the interior braces individually. These braces keep the bridge girders properly spaced.
There is a scribed line on the girder to show the position of each interior brace.Once one complete set of braces was bonded to the girder, I bonded the interior braces to the second bridge girder. (See Photo 12 & 13). The interior braces must be properly aligned and kept square to both girders.
Photo 12
Photo 13After the initial set, I proceeded to glue the exterior ribs to the girder using CA cement. The exterior ribs were made out of a hard paper product. I think these exterior ribs should have been made out of acrylic as well. There are also other detail parts that are made out of this paper product. They should have been made in acrylic for more strength. If a kit of this magnitude is being built, all parts of the substructure should be made in acrylic and not hard paper for the obvious reason stated above. (See Photo 12)
The next step is to add the track rails to the bridge platform and to fabricate the wheel assembly and wire it underneath the bridge.
So far, This project has taken six hours up to this point.
I will also add Squadron white putty to the interior walls of the turntable pit to remove any imperfections in the acrylic layers.
I will closely examine the acrylic layers with some magnifying loops to see If I have to putty the interior walls of the turntable pit. I will use the white Squadron putty for this step if it is necessary.
The next step in the construction of the CMR 135' turntable is to add the deck for the track to the bridge girders.
The deck has to be snapped in place on the bridge girders in four places. Initially two didn't line up properly and that is a common experience according to the instructions.
I then used a fine file to slightly shorten the male connectors of the bridge girders. Once this was accomplished, the deck snapped in position and I bonded the deck to the bridge girders with the bonding agent.
I then placed the two track rails in position on the deck. There are small grooves that show you the exact placement of the track rails. The track rails were then cemented in place. with CA cement.
As the cement was setting, I checked the track rails with a NMRA track gauge to make sure they were in proper gauge. I made a few adjustments at this time and I placed two gauge "spacers" on the rails, which were provided with this kit.
I modified the kit slightly by adding Evergreen strips along both walkways on the bridge. After the bridge is airbrushed and weathered, I will add the detailed heavy paper walkways on top of the Evergreen strips. These paper walkways came with the kit. There is also a detailed heavy paper strip to place between the track rails. (See Photo 14)
Photo 14
I also added about 3/4 ounce of lead weight to each end of the bridge so that the wheel assemblies on each end of the bridge will firmly contact the guide rail below in the pit. I used A-Line lead weights for the necessary weight on each end of the bridge deck. (Photo's 15A & 15B)
Photo 15A
Photo 15BThe bridge itself was nicely weighted with the addition of the lead weights and will allow the bridge roller contacts to make good contact with the pit guide rail.
You can see the bridge trucks at each end of the bridge. The wheel assemblies will be attached to the bridge trucks. There are four wheel assemblies in the kit and I was missing one assembly. CMR is mailing me the missing wheel assembly.I tapped three into each brass axle in the meantime.
I will properly start to airbrush the bridge a grimy black, while waiting for the fourth wheel assembly to arrive.
At this point, I decided to putty the inside wall of the turntable pit with the Squadron white putty using a small dental mixing spatula. This was done to smooth out any irregularities in the turntable pit wall. I'll let the putty dry overnight to allow it to completely harden. The next morning I smoothed the putty on the walls of the turntable pit with various grades of very fine sandpaper. I didn't take a photo of the unfinished putty on the walls of the turntable pit.
It is now eight hours since I started this project. The turntable pit is finished except for the final smoothing of the pit walls with extra fine sandpaper. The bridge is almost finished. All that remains are the wheel assemblies which have to be wired to the bridge.
I then must build the center shaft assembly and add a center arch to the bridge and add an operators control cab to one end of the bridge deck.
You must be careful to remove enough of the putty from the pit wall to allow the bridge to turn freely in the turntable pit. The bridge has to be placed in the pit to make sure the Squadron putty added to the walls of the turntable pit doesn't impinge on the movement of the bridge deck. (See Photo 16)
Photo 16
In Photo 17, you see the center of the bridge deck resting on the turntable pit floor.
Photo 17
The Evergreen strips provide support for the detailed heavy paper walkways that will be added to the deck after the bridge and deck are airbrushed and weathered. This was a modification from the original instructions as the heavy paper walkways aren't strong enough by themselves.
Photo 18 shows the end of the turntable bridge and its relationship to the turntable deck. The bridge will be shimmed slightly, once the wheel assembly is put in place so it is level with the top of the turntable pit.
Photo 18Photo's 19 & 20 are both closeup magnifications showing the placement of the lead weights at each end of the bridge assembly. This will provide the wheel assemblies with more weight to contact the guide rail in the turntable pit floor.
Photo 19
Photo 20
Next, I airbrushed the bridge of the CMR 135' turntable a grimy black. (See Photo 21)
Photo 21
When the bridge is dry, I will airbrush a wash of earth, dust and blue windshield wiper solution on the bridge to create a thin layer of dust and grime. I use 80% blue windshield wiper solution and 20% acrylic paint for all my individual washes.
When these washes have dried, I will dry brush different layers of rust and dirt deposits near the exterior ribs and other parts of the bridge. I use an 18/0 sable brush for this dry brushing technique.
Next, I will airbrush the turntable pit with a primer and then airbrush aged concrete as the final color for the turntable pit.
I also plan to build the center shaft assembly and fit it to the bridge once I receive the fourth wheel assembly from CMR. I can also add the heavy paper detail parts to the walkways once the wheel assembly and wiring is complete.
AS previously stated, when I built this kit, I was missing one of the wheel assemblies from the original parts list. I contacted CMR and they sent me several replacement wheel assemblies. I soldered the wiring to the wheel assembly on three of the four wheel units. (See Photo 22)
Photo 22
You must tap the wheel through the axle on each wheel assembly to firmly engage the wheel in the axle. I used the wire that CMR supplied in the kit to solder two wheel assemblies together electrically. The joint in the middle of each assembly will lead to one of the rails and the other will go to the opposite rail.
I only have one axle support on each assembly. When I'm ready to anchor the complete assembly, I'll attach the axle supports that are missing.
I then added the detailed heavy paper walkways to the Evergreen acrylic strip supports on the bridge (See Photo 23). I painted the turntable pit an aged concrete (Polly Scale paint). When the paint dried I made a wash of blue windshield wiper solution, mud, earth and dust and sprayed a thin wash on the turntable. The formula for these washes was discussed elsewhere in this tutorial. ( See Photo 24)
Photo 23
Photo 24
I also hand painted all 120 guide rail ties a Polly Scale Rail Tie Brown.. All the edges of the ties have to painted as well. I used an 18/0 very fine sable brush to paint the edges of the ties in the turntable pit. This took considerable time to do. Then I made a wash of blue windshield wiper solution and Polly Scale Engine Black to spray on the turntable pit to give the concrete and aged effect.
When all these washes had dried (See Photo 24), I used some very fine natural rock ballast and spread the ballast on the floor of the turntable pit.. The ballast was cemented in place on the floor of the pit with a mixture of Aileen's white glue, water and alcohol. I used an eyedropper to apply the glue mixture to the ballast in the base of the pit.. Using an eyedropper to spread the glue/water/alcohol mix keeps the ballast in position. It takes longer to glue the ballast this way, but in the long run, the ballast will remain in its original position.
I also weathered the bridge of the turntable. I used a thin wash of blue windshield wiper solution, mud, earth and dust and lightly airbrushed this wash on the turntable bridge to create a dull weathered look.
When these washes had dried, I detailed the exterior ribs of the deck and bridge girders with burnt umber and burnt sienna. This creates a rusted appearance on the bridge deck. See Photo 25, 26 & 27)
Photo 25
Photo 26
Photo 27
I still have more work to do on the turntable. The wheel assemblies have to be shimmed and cemented in place after the final wiring to both guide rails is completed. The arch of the bridge deck has to added as well as the hand rails of the deck. The center shaft assembly also has to be cemented in place. The control cab for the bridge has to be built as well.
When the wheel assemblies are shimmed to the proper height, there will be enough clearance of the turntable deck to compensate for the fine ballast That I added to the turntable pit.
This has been a great kit to build as long as you proceed slowly and follow the instructions. I highly recommend this kit if you are interested in building a quality turntable for your layout. The CMR turntable kit also comes in a 105' lenght as well.
Next, I added the wheel assemblies to the underside of the turntable. The wheels turn easily because of ball bearings added in their design. I also wired the wheel assemblies to the bridge track rails. (See Photo 28)
Photo 28I then painted the walkways on either side of the bridge a Polly Scale Rail Tie Brown. I'll weather the walkways once I have added the handrails, arch and arch supports. At this time I airbrushed the natural rock ballast I added to the turntable pit floor a grimy black. This simulates an accumulation of cinders in the turntable pit. (Photo 29)
Photo 29
I let the new "cinder" base in the turntable pit completely dry for at least 24 hours. Then I checked the bridge and wheel assemblies to make sure they were resting on the guide rail throughout the 360 degree circle of the truntable. (See Photo 30)
Photo 30
Photo 31A & 31B shows a closeup of the right and left wheel assemblies.
Photo 31A
Photo 31B
Now the center shaft assembly will be glued in position after the arch, arch braces and handrails are added to the deck. (Photo 32)
Photo 32
In Photo 33 we have a diagram of the center shaft assembly. This assembly will attach to an indexing motor that will drive the turntable. The diagram of the center shaft assembly comes with the instructions.
Photo 33
I'll add a stationary decoder to the motor to help power the turntable. I use a Lenz 100 system command station and will use the Lenz LH 100 hand held device to control the turntable's movement.
I then mounted the stock arch that came with the CMR turntable kit and really wasn't happy with the way it looked.
I was able to find a cast metal Diamond Scale Arch at my LHS which looked much better than the stock CMR arch. The Diamond Scale Arch was priced at a bargain $4.99. This "find" was located in a spare parts box at my LHS.
I assembled the Diamond Scale Arch for the turntable and mounted it on the walkways of the turntable deck. I airbrushed the bridge and arch an initial coat of Polly Scale grimy black paint and will airbrush a second coat when the first coat is dry. Burnt umber and Burnt sienna will dry brushed on the deck and arch to make it look aged and rusty.
Photo's 34 & 35 show the arch in position on the deck. I have to bend the arch slightly to a more upright position. Still to be done is the hand railing on the bridge deck., the control cab and some additional weathering of the walkways and arch.
Photo 34
Photo 35
I added the control cab on the bridge deck, handrails and I did do some final weathering of the deck arch, the deck girders, the control cab, the handrails, the walkways, the wheel assemblies and connecting power wires.
I used Burnt umber and Burnt sienna for the rust effect.
The bridge deck was given a wash of 80% blue windshield wiper solution and 20% of the three earth tones, Dust, Mud and Earth.
The turntable pit was weathered with a mix of 80% blue windshield wiper solution and 20% grimy black and/or Steam power black. Very fine natural rock ballast was used to simulate cinders.
The ties in the guide rail on the pit floor were weathered with Railroad Tie Brown, and a wash of blue windshield wiper solution, Dust, Mud and Earth colors.
The walkways were weathered with some Rail Tie Brown, reefer white and dull Aluminum. I mixed small amounts of the reefer white and dull Aluminum together.
The bridge arch was weathered with grimy black and Burnt Umber. The light bulbs in the arch were painted silver.
The handrails were weathered with grimy black, Burnt umber and Burnt sienna at the base of the handrails and the bridge deck.(See Photo's 36,37,38 & 39)
Photo 36
Photo 37
Photo 38
Photo 39
The 135" CMR turntable now has to be installed on the JJJ&E. I have a 3x5' space set aside for the turntable module which will be adjacent to the main switching yard and double track mainline of the JJJ&E.
(Photo's 40,41, 42 & 43) The turntable has been placed on the turntable module of the JJJ&E adjacent to the switching yard.
Photo 40
Photo 41
Photo 42
Photo 43
This is a well thought out kit and the instructions are easy to follow. It will take between 14 and 16 hours to finish and weather. The CMR 135' turntable will become the focal point of any layout.
Have fun with it.
Stay cool and run steam........