Modeling Information

Handy reference material, all in one place!

Index of Topics

The following topics are available on this page - click the link in the index to rapidly find the information.

AAR Car Types

Car Types identify specific car types and functions, which is useful for matching cars with customer needs.

Code Car Type Description
FC Flat Truck/Trailer service (TOFC)
FD Flat Depressed Center
FL Flat Log Service
FM Flat General Service
FP Flat Rack-pulpwood
FW Flat Well-hole
GA Gondola Bottom Door, crosswise hinge, drop between rails
GB Gondola Solid Bottom & Sides - Fixed or Drop Ends
GD Gondola Solid Bottom, Side Doors, Fixed or Drop Ends
GE Gondola Bottom Door, crosswise hinge, drop between rails, Drop Ends
GM Gondola Solid Bottom & Sides - Drop Ends
GP Gondola Rack-pulpwood, side doors
GS Gondola Bottom Door, outside rail dump
GW Gondola Well-hole
HD Hopper Open Top,2+ bay hoppers, Outside Dump
HF Hopper Open Top,2+ hoppers, Inside Dump
HMA Hopper Open Top 1 bay ore jenny Inside Dump
HM Hopper Open Top 2 bay hoppers, Inside Dump (classic twin)
HT Hopper Open Top 3+ bay hoppers, Inside Dump
LO Hopper Closed Top 1+ bay hoppers, Inside Dump
RA Reefer Brine Tank - crushed ice and salt for meat services
RB Reefer Beverage, Ice, Water, or Vinegar - no ice/ventilation hatches
RCD Reefer Dry Ice
RP Reefer Mechanical Refrigeration
RS Reefer Bunker Ice
SC Stock Single/Double deck
SF Stock Double Deck
SH Stock Horse service
SM Stock Single Deck
SP Stock Poultry
TA Tank Acid service
TG Tank Glass / Glass Lined
TL Tank Lead Lined Acid Service
TM Tank General Service
TP Tank Pressurized
TW Tank Pickels/Brine/Vinegar/Water (Wooden Vats)
VA Ventilator Fruit/Vegetable - Solid/Ventilated door
VM Ventilator Fruit/Vegetable - partially insulated
VS Ventilator Fruit/Vegetable - insulated, swinging side doors
XA Box Automobile, large side or end doors
XF Box Furniture Service (Hi-Cube, large doors)
XI Box Insulated box, no ventilation or refrigeration
XM Box General Service, side or side and end doors
XT Box Enclosed Tank, no doors

 
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Scale Conversion Table

Instructions:
To convert one common model railroad scale to another, find the original scale in the table along the top, then scroll down to the scale listed on the left that you want to convert to. To enlarge, increase by the percent shown. To reduce, reduce the item by the percent shown. This works for drawings on photocopiers or scanners as well as for 3D printing. Note that for "G Scale" we assume 1:22.5 for G-1 and 1:32 for G-2 (the most common), but there are several "scales" used for G-Gauge track.

  Proto G-1 Scale* G-2 Scale* O Scale S Scale OO Scale HO Scale TT Scale N Scale Z Scale
Proto (1:1)   2250% 3200% 4800% 6400% 7200% 8710% 12000% 16000% 22000%
G-1 (1:22.5) 4.44%   142.2% 213.3% 284.4% 320.0% 387.1% 533.3% 711.1% 977.8%
G-2 (1:32) 3.13% 70.3%   150.0% 200.0% 225.0% 272.2% 375.0% 500.0% 687.5%
O (1:48) 2.08% 46.9% 66.7%   133.3% 150.0% 181.5% 250.0% 333.3% 458.3%
S (1:64) 1.56% 35.2% 50.0% 75.0%   112.5% 136.1% 187.5% 250.0% 343.8%
OO (1:72) 1.39% 31.3% 44.4% 66.7% 88.9%   121.0% 166.7% 222.2% 305.6%
HO (1:87.1) 1.15% 25.8% 36.7% 55.1% 73.5% 82.7%   137.8% 183.7% 252.6%
TT (1:120) 0.83% 18.8% 26.7% 40.0% 53.3% 60.0% 72.6%   133.3% 183.3%
N (1:160) 0.63% 14.1% 20.0% 30.0% 40.0% 45.0% 54.4% 75.0%   137.5%
Z (1:220) 0.45% 10.2% 14.5% 21.8% 29.1% 32.7% 39.6% 54.5% 72.7%  

 
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Vallejo Paint Colors for Model Railroads

Vallejo paints are widely available, and their fine pigments produce a smooth finish. They can be thinned 50:50 (or more) for spraying. Be sure to use their thinner and not alcohol! They cover well with brush straight from the bottle, although I prefer to wet the brush first.

Generic Paint Name Model P/N Air P/N Color Name Notes
Aged Concrete 70.884 71.045 Stone Grey  
Black 70.950 71.957 Black  
Boxcar Red (lighter brown) 70.846 71.080 Mahogany Brown Use Vallejo 71.074 Beige to lighten
Carmine Red 70.908 71.003 Carmine Red  
Coach Green (Dark) 70.888   Olive Grey  
CP Gray 70.990   Light Grey  
CP Maroon 70.946   Dark Red  
Flat Red 70.957 71.102 Flat Red  
Flesh 70.815   Basic Skin Tone  
Gray 70.992   Neutral Grey  
Great Northern Empire Green 70.980 71.018 Black Green  
Great Northern Empire Orange 70.851 71.130    
Grimy Black 70.924 71.055 Russian Uniform WW2  
Mortar 70.993   White Grey  
Primer 74.601      
Red 70.926   Red  
Reefer Orange 70.910 71.083 Orange Red  
Reefer White 70.951 71.001 Pure White  
Reefer Yellow 70.834 71.078 Natural Wood Grain  
Wood Tones 1 70.819   Iraqi Sand  
Wood Tones 2 70.846   Mahogany Brown  
Wood Tones 3 70.981   Orange Brown  
PFE Light Orange 70.851   Bright Orange See GN Empire Orange
Concrete   71.045    
Dust 70.820   Off White  
Engine Black   71.251    
Oily Black   71.021    
Oxide Red   72.712    
Rail Brown 70.795 71.139 Green gold  
Railroad Tie Brown   71.029    
Weathered Black 70.994 71.054    
Caboose Red 1:1 Mix 70.908+70.957 1:1 Mix 71.003+71.102 Carmine Red + Flat Red  
Mud   1:1 Mix 71.075+71.143    
Antique White 70.918      
Boxcar Brown 70.850 71.041   Use Vallejo 71.074 Beige to lighten
Canadian National Orange #11 70.911   Light Orange  
Coach Green 70.894 71.017 Cam Olive Green 70.888 Olive Grey alternative
Earth   71.122    
Missouri Pacific Lighter Blue 70.961   Sky Blue  
Platinum Mist 70.883   Silver Grey  
Pullman Green 70.894 71.019 Matt Light Olive  
Reefer Grey 70.987 71.047    
Roof Brown (Orig) 70.941   Burnt Umber  
Rust   71.037    
Southern Pacific Daylight Red 70.910   Orange Red See Reefer Orange
Southern Pacific Lark Light Grey 70.884   Stone Grey See Aged Concrete
Tuscan 70.859 71.036    
Aero Light Gray Primer 74.601   Grey  

 
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LED Resistance Calculation Formula

Having the correct minimum resistance will extend the life of your LED lighting and prevent blown LEDs. For most hobby lighting needs, a 1/8 or 1/4 watt rating is sufficient.

Each LED has both a voltage rating and a current rating, such as "3V 20mA". This information is used to calculate the resistance needed based on your supply voltage. While not a hard rule, most white LEDs are rated at 3 VDC and red, green, and yellow are 1.8 to 2 VDC. Use 1.8V if you aren't sure as this will calculate a higher resistance and offer additional protection.

  • Start by subtracting the LED voltage from your supply voltage. For example, a Warm White LED rated for 3V on a 12V supply results in a 9V differential.
  • Convert the MA rating to a decimal value. One milliamp is 0.001 amps, so a typical 20ma rated LED would use 0.02 as the value.
  • Divide the voltage obtained in step 1 (9) by the MA decimal value (0.20) - 9 / 0.02. This formula yields 450. Since a resistor does not exist with a value of 450 ohms, we round UP to a value of 470. 

Resistors typically have 3 color bands - two value bands and a multiplier. It may also have an optional tolerance band often using silver or gold. There are high-precision resistors with 5 or even 6 coding bands, but these will not likely be cost-effective for model use and won't be discussed. 

For reference, here is a resistor color-code chart:
Resistor color code table

For our example above, a 470 Ohm resistor would have a color code of yellow-purple-black.

If there is no fourth band, the tolerance is 20%. A silver band represents 10% tolerance while a gold band is 5%. 20% tolerance resistors are fine for model railroad work as long as your resistance exceeds what you have calculated.

 
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