DOODLEBUGS Class M-115, M-150 and M-175

DOODLEBUGS Class M-115, M-150 and M-130/175/184

                                      scroll down and click on pictures to enlarge



Class M-115 doodlebug, numbers 115-126.

Shell 3D print, all stainless steel detail parts attached.

Air Eraser treatment and primed.

Assembled Tomytec chassis with all underbody details attached.

Class M-150 doodlebug.

Numbers 150-157.

Shell 3D print, all stainless steel detail parts attached. Air Eraser treatment and primed.

Class M-130/175/184 doodlebug.

Numbers 130-131, 175-183, 184-187.

Shell 3D print, all stainless steel detail parts attached. Air Eraser treatment and primed.

Class M-115 doodlebug, car numbers 115-126.

3D printed shell cleaned, all applicable stainless steel details attached.

Detail Associates steam engine bell and markerlights added (last ones to be replaced by 3D printed parts),

Air Eraser cleaned but not yet primed.

Riding on modified Tomytec chassis with ESU decoder with Caterpillar sound; sugarcube speaker with soundchamber.

Class M-150 doodlebug, car numbers 150-157.

3D printed shell cleaned, all applicable stainless steel details attached.

Detail Associates steam engine bell and markerlights added (last ones to be replaced by 3D printed parts), outside MTL brakewheel added.

Air Eraser cleaned but not yet primed.

Class M-130/175/184 doodlebug, car numbers 130-131, 175-183, 184-187.

3D printed shell cleaned, all applicable stainless steel details attached.

Detail Associates steam engine bell and markerlights added (last ones to be replaced by 3D printed parts),

Air Eraser cleaned but not yet primed.

3D printed underbody details (boxes, 2 fuel tanks, water tank, air reservoirs, 2 brake cylinders), 4 truck side frames for Tomytec trucks, and 6 marker lights. Cleaned, Air Eraser treatment, Mr. Surfacer Primer 1000.

Showing placement of underbody details. Bottom of Tomytec chassis has been covered with 0,13 mm Evergreen styrene sheet.

Stainless steel etching with all details needed for 1 motorcar. Suits all different models.

Tools used to apply all details.

MAGNIFIERS with light, narrow/sharp tweezers, flat nosed pliers, pointed scalpel, chisel blade cutter, medium Zap A Gap, UV hardening repair glue, Dremel tool with grinding disk.

Lead sheet weigth of about 50 gram. Fits against inside roof a doodlebug.

Original/basic Tomytec chassis used, TM-23 and TM12R.

Both were readily available at time of building but others could be substituted as long as axle distance is 12 or 14 mm and wheel diameter 5.6 mm. Will build 2 doodlebugs.

Front end top and bottom. You can clearly see the side splices and 1 mm bottom styrene sheet. The irregular orginal nose has been squared using styrene scrap pieces. If those pieces stick out a bit, take your Dremel/grinding tool and remove the excess pieces at slowest speed.  

Adapting both chassis: cut in half, all bottom and top protrusions removed. The first splice is a 1 x 3 mm Evergreen strip on the inside of the chassis sides. Make sure chassis is straight (use liquid plastic glue - makes shifting/repositioning easy), cut/file a 1 mm thick bottom sheet to fit and fill in the gap in the upright sides.  

Rear end top and bottom. You can clearly see the side splices and 1 mm bottom styrene sheet. In this case the rear end has been adjusted to accept the 2 staircases and the coupler mounting pad for the passenger versions. In case of the all freight/mail version the corner recess can be omitted. No problem if those scrap pieces are a bit oversized to begin with. Just take your Dremel/grinding tool and remove the excess pieces at slowest speed.  

In case of the 75 feet cars the modified chassis should be 138 mm long and in case of the 80 feet cars 147,5 mm.

I recommend a distance from chassis front end to front truck center of 14 mm. For rear of chassis to rear truck center I recommend 19 mm distance.  That leaves 105 mm truck centers (versus 105.7 mm prototype).

In case op the 80 feet cars that means 114,5 mm truck centers (versus 115,2 mm prototype). See text below.

Front end, shows coreless motor with original flywheel attached, glued (ACC) to chassis bottom, with original driveshaft. Enough room between 2 motors to accomodate sugar cube speaker. Make sure the shaft has some lateral room/play to move to avoid binding.

DC version with original Tomytec motors and original drivershafts. All freight version (see wide ends on left side of picture). No lights installed yet.

Rear end of passenger version, shows coreless motor with original flywheel attached, glued (ACC) to chassis bottom, with shortened driveshaft (brass sleeve over ends of original shaft) to create room between 2 motors.

DCC version (first prototype without room between motors). Coreless motors + original flywheels and original driveshafts. Passenger version (see narrow ends on left side of picture). ESU Decoder mounted over left/rear truck (on scrap styrene supports) and sugar cube speaker mounted over right/front driveshaft (also on scrap styrene supports). No LED lights installed yet.


N-350 DOODLEBUG Class M-115 3D printed shell, cleaned and primed, etching, 50 gram weight (no couplers, decals)

                     DOODLEBUG Class M-115, shell 3D TAN printed and ordered directly from Shapeways

N-351 DOODLEBUG Class M-150 3D printed shell, cleaned and primed, etching, 50 gram weight (no couplers, decal)                                          DOODLEBUG Class M-150, shell 3D TAN printed and ordered directly from Shapeways

N-352 DOODLEBUG Class M-130/175/184 3D printed shell, cleaned/primed, etching, 50 gr weight (no couplers, decal)

                     DOODLEBUG Class M-175, shell 3D TAN printed and ordered directly from Shapeways

N-355 DOODLEBUG underbody details + truck sideframes 3D printed, cleaned/primed (kits 350/351/352)

               DOODLEBUG underbody details and truck sideframes, 3D TAN printed and ordered directly from Shapeways

N-356 DOODLEBUG detail parts etching and 50 gram lead weight (only needed if you order body shell and underbody parts

               and truck sideframes directly from Shapeways)

N-357 CORELESS MOTOR, 8 x 16 mm, 12 V, 1 mm diameter single shaft

The steam engine front top mounted bell (Miniatures by Eric), the smokestack (MTL) and brakewheel (MTL and only applicable for class M-130) are included in principle, but availabilty cannot be guaranteed at all times....... sorry.  


Between 1929 and 1931 the Santa Fe took delivery of a total of 35 EMC doodlebugs in a few configurations: 75 and 80 feet long,

mail-passenger, mail-baggage and mail-baggage-passenger. All were powered by EMC Model 148 gasoline engines.

Operation was almost only on branchlines. All were modified/dieselized around 1950 using a Caterpillar D-397 engine and the last ones were retired around 1960.

All 3 models represent the modified/latest version with the "gullwing" paintscheme.

Invaluable information can be found in the book THE DOODLEBUGS by John McCall, published by Kachina Press. But The Santa Fe Historical and Modeling Society and variuous internet sites are also good sources for useful information.


The biggest challenge is the drivetrain, but happily Tomytec makes a number of usable chassis.

The 15.5 mm chassis width fits perfectly inside the 3D printed shell.

One of the characteristic features of the doodlebugs is a 7 feet 10 inch wheelbase front truck with 36 inch wheels and a 6 feet 4 inch wheelbase rear truck with 33 inch wheels. In N scale that means15 mm axle spacing for the front truck with 5,7 mm wheels and 12 mm axle spacing for the rear truck with 5,2 mm wheels.

Therefore you will need 2 Tomytec chassis to build a correct model (cut them in half and attach 2 different halves to each other) or build 2 dooblebugs if you want to use the other halves as well,

The closest models I could find (quite easy to obtain and not very expensive) are TM-23 for the rear truck (12 mm) and TM-12R for the front truck (14 mm). There is also TM-18 with a 15,4 wheelbase but I could not find a supplier anymore (all out of stock).

All wheels are 5,6 mm..... the difference being not very visible behind the truck sideframes.

There is a very helpful site on TRAINWEB.ORG. Search for TOMYTEC CHASSIS DIMENSIONS (Google).

All Tomytec (and other) chassis specifications are clearly presented.... easy to find similar chassis. Main point is 14 mm axle distance on front truck and 12 mm on rear with 5,6 mm wheel diamater on both. Chassis width of 15,6 mm is best but smaller can be modified of course.

There are other Tomytec chassis available that you can used as well. The total length is unimportant because you have to adjust the length (between truck centers) anyway. Only wheel size and truck axle distance are important (keep in mind that the 3D printed trucks are designed for 12 and 14 mm axle spacing).

The big advantage of the Tomytec trucks consists of the 3 mounting holes in their sides. The 3D printed sideframes are an easy fit. Attach with a tiny drop of rubber cement glue and they can even be removed and reattached if need be.

The fact that these chassis are plastic makes changing the truckcenter distance a breeze.The prototype distance is 55 feet 5 3/4 inch (105,7 mm in N scale) for the 75 feet cars (Class M-115 and M-150) and 60 feet 5 3/4 inch (115,2 mm) for the 80 feet cars (Class M-130/175/184). In all cases the rear spacing is 11 feet 4 1/4 inch (21,6 mm in N scale) and the front spacing is 8 feet 2 inches (15,6 mm in N scale). For the model I suggest  between 0,5 and 1 mm extra distance on the nose to avoid interference between trucksideframes and nose side steps. That results in a little shorter truck center distance.

There is one little issue.... the wheels in these 2 different Tomytec chassis turn in opposite direction...... so you need 2 motors in each doodlebug, one for each truck. Happily the Tomytec motors are rather small and the (cheap) coreless motors I can supply for the other 2 halves are even smaller (8 mm diameter, 16 mm length). Connecting these motors to a single (sound) decoder poses no problem at all.

Start by disassembling the whole chassis: remove the trucks, the motor and the metal contact strips. Be careful to save everything, especially the small plastic retainers that keep the contact strips in place. Now take you Dremel with a metal cutting disc and remove everything protruding BENEATH the floor. Underside of the frame should be flat EXCEPT for the ring around the truck mounting hole. Also cut off all protrusions on top of the frame sides. Top of frame sides should be level (see pictures above) and height of side frame is 4 mm. 

The chassis halves will fit at exactly the right height inside the 3D printed shell (underside of chassis just a bit inside the shell).

With 1 mm styrene sheet and some Evergreen strips create a "bridge" between the 2 halves keeping the truckcenter distance in mind. Also "shape" the front and rear extensions (see pictures above) using 1 mm Evergreen strips to create a snug fit inside the shell with the truck centers positioned as mentioned above (floor and sides of Tomytec chassis have a 1 mm thickness).

Cut out the middle part of the metal contact strips, just beyond the locating hole. Solder flexible thin wire leads to these 4 parts to connect to the motor leads (in case of DC) or to the red/black DCC decoder leads. Check the spring tension on the metal truck strips and adjust if necessary. Besides using the plastic retaining clip (check orientation to avoid contact wuth drive shaft) I also used a drop of ACC glue on the metal contact strip beyond that retaining clip.

You can use 2 original motors or 2 coreless motors. These last ones - 8x16 mm size - run even slower, better and almost noiseless. I even succeded in cutting of the flywheels of the original motors on one side and reinstalling them on the new coreless motors. The advantage is the use of the drive shaft coupling inside the flywheel. It as possible to shorten the original drive shafts a bit, resulting in just enough room between the 2 motors to accomodate a sugar cube speaker with a bigger sound chamber (in the pictures you see its also possible to mount the speaker just above 1 of the drive shafts, but then with a smaller sound chamber).

Just glue the motors on the bottom floor of the frame using ACC glue and be sure there is some lateral play/room for the drive shaft to avoid binding.

Installing LED's in the nose and rear is also possible. I assume the best way is to glue the LED's inside the openings of head and read light and use the solid leads to make contact with strips above the trucks, avoiding stray light as much as possible. Do not forget to install/include a resistor in one of the wires. 

The shell is next. If you buy the 3D printed shell directly from my Shapeways shop you will have to do the cleaning and possible AIr Eraser treatment yourself. To remove the last remains of the support material during the printing process I found blasting the whole model with aluminum oxide to be very effective (see the internet for various discussions). 

If you buy from me I will clean the shell, drill/clean all holes using a 0,3 or 1,0 mm drill, use the Air Eraser to remove all left over "white fuzzy stuff" on the shell and prime/airbrush the shell using diluted Mr. Surfacer Primer 1000. I will also use the Air Eraser on the etching for improved painting and also prime the etching.

The stainless steel etching contains all the necessary details for all 3 versions. In the pictures I attached all details already but it is probably much easier to prime and paint the etching black and paint the shell first before installing the details. You only have to be very careful with the ACC glue (apply from the inside with as needle/tooth pick).

In the picture above you wil find almost all equipment to apploy all etched parts to  the models. For me most important are the magnifiers.

Using a steel ruler or other hard flat surface as a base "punch out" the needed part with the square chisel blade as close to the half etch line as possible. If the blade gets dull, sharpen it with your Dremel/grinding disk.

The flat nosed pliers (be sure the jaws are flat, line up and are square and undamaged, use your Dremel/ginding disk if need be) are needed to hold the parts that need bending: the wire cage above/around the front headlight, the "boiler tube" cowcatcher, the side steps under the cab side doors and the front and rear bottom handgrips .

Be careful: the stainless steel can only take a few bends bends...than it breaks...certainly on the half also takes some force to make a nice square bend.

For the front headlight wire cage: grip the circular part exactly (and I mean precise) inside the jaws of the flat nosed pliers. Squeeze the flat nosed pliers STRONGLY. Position the metal chisel blade flat against the protruding horizontal part (the T wire) and make a sharp 90 degree bend.

For all side steps: viewed from the side of the model the distance between the 2 horizontal bars and the shell should be equal on all steps. ONLY FOR THE 2 SIDE STEPS UNDER THE CAB DOORS: grip the side step STRONGLY inside the jaws of the flat nosed pliers with the mounting ends protruding outside just that distance and make a square 90 degree bend using the metal chisel blad; turn the step around holding the mounting ends inside the jaws, about 1 mm away from the first bend and make the 2nd 90 degree bend using the chisel blade.

For the "boiler tube" cowcatcher: FIRST,  hold the etching with only the little tab on the bottom of the etch protruding from the jaws. Grip the part STRONGLY and using the chisel blade or a small hammer bend the small tab about 90 degrees, keeping the halfetch inside the bend. SECOND, bend the top/straight halfetch 90 degrees, keeping the halfetch inside the bend. THIRD, bend the "boiler tubes" a little over 90 degrees keeping the halfetch on the inside of the bend.

The 2 tabs should "latch" just inside the 2 square holes in the top of the etching (just bend only once, fragile).

Recently I found a very useful UV hardening glue (see picture). It comes in a 3 gram tube and remains soft until you apply the included blue UV light. It then hardens rock solid within seconds.

Keeping the top of the "boiler tubes" against the vertical backboard (squeeze gently between 2 fingers and the 2 tabs should "latch") apply a tiny drop of this UV hardening glue on the backside ot the etching on the protruding tabs. When you are satisfied that the tops of the "boiler tubes" are flat against the backboard, apply the UV light. In case you applied a little too much glue: the excess can easily be removed with your Dremel/grinding disk. Now bend the 2 diagonal braces about 45 degrees, just as the 2 gluing tabs, aother 45 degrees. The whole assembly can now be glued inside the nose of the shell using regular ACC glue. Positioning is easy, just slide upwards inside the nose against the "ridge".

Bend the 2 diagonal supports a little outward to position them against the underside of the shell and glue them  using the UV hardening glue. Use the narrow tweezers to apply the 2 front steps the same way, using the UV hardening glue on the underside. The soft glue will allow you to position them perfectly and then apply the UV light. I found these steps to be a little long.... Hold with the flat nosed pliers and grind off a little using your Dremel/grinding disk before attaching.

You will be surprised how strong/solid the cowcatcher is right now......

One last thing: the coupler "hole" is a little too small and you will need to file the front part of the bottom lid of the MTL 1015 coupler about halfway (and possibly the sides of the 1015 and the underside of the coupler halves also a bit). Remove the trip pin and insert the coupler from behind, then reattach the trip pin.

For the front and rear handgrips: grip these handgrips STRONGLY about halfway with the mounting ends protruding.

Using the chisel blade make a 90 degree bend.

My favourite way of applying all handrails is dipping the mounting ends in a small puddle of ACC glue (hold the part with sharp/narrow tweezers). Just push them in all the way and using the sharp blade of my scalpel lift them up a bit, just a little away from the shell. If need be extra ACC glue can be applied on the inside of the shell. In case you accidentally spill some glue on the outside of the shell: using an old toothbrush you can easily remove all excess before it hardens.

One last thing: depending on the curves on your layout you may have the alter the shape (bend to the outside) of the side steps above the front truck (and rear truck in case of M-130 class) to give the truck(s) enough room to swivel.

Attach the side step first, bend to the outside using a finger (supporting/squezing the shell side with 2 fingers from your other hand) and using the flat nosed pliers make a reverse bend at the top horizontal step.

If I do not forget the holes for the bell (0,8 mm and made by Miniatures by Eric), the marker lights (0,9 mm) and smoke stack (1,0 mm made by MTL) and brake wheel (1,0 mm made by MTL and for M-130 class only) are all drilled out.

All these parts are included in principle and I am trying to keep a fair supply but cannot quarantee availability at all times.

I glued a sheet of 0.13 mm Evergreen styrene to the underside of the chassis using ACC glue to cover up all holes.

Position the underbody details using pictures from the doodlebug book or internet pictures.

The 3D printed underbody detail set includes 6 marker lights.

In the pictures you will see the old Detail Associates marker light castings but the 3D prints are sharper and more prototypical.

Paint the underbody details black (ATSF red for the 2 diesel fuel tanks) before installing them. Install the black maker lights AFTER the shell has been painted..... masking them is not easy and not necessary that way.

Last job is painting. These cars were painted ATSF olive green, with an ATSF red/yellow cab/front. The roof, underbody and all handrails were painted black. The lettering was "dulux'' gold (medium yellow). I recommend Microscale Kristal Klear for all windows, head and rear light. Microscale decal set 60-168 has the gullwing nose decal and all lettering. I painted the sides and end olive green first, then masked (Tamiya tape) the sides to airbrush the roof black. Then masked the front before the front door to apply the yellow and last added a masking tape over the front and side windows to apply the red.

Included is a 50 gram weight to be attached to the inside of the roof (completely out of sight). Some Tomytec chassis I bought had

1 rubber tired wheel. I decided to simply remove the rubber tire to improve current pickup; the motor car is pretty heavy and pulls well, certainly more than enough to pull the few prototypical freight cars or trailer car up a grade. If you want to add sound: ESU has a good decoder with Caterpillar sound. There is more than enough room between the roof (weight) and drivetrain (see picture).

Enjoy your little doodlebug!