Speed Step Charts/Spreadsheets/Links
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“Scale Speed Calculator” is a small utility that calculates
“Scale Miles per Hour” for the most commonly modeled scales
by entering a time (seconds) and actual distance traveled (Inches).
This program will work with any Scale.


I like the 30 & 3 MPH “Speed Trap Tables” with a
MPH plotting procedure and a digital stopwatch.   
This Excel spread sheet estimates the Decimal Number for you when you put any Mph into the black cell that is on the Max. to Start line.


To start my MPH procedure, program
CV2 (Start) to 60 and CV6 (Max) to 255.  
Measure your high Start setting in MPH,
and your Max., running speed in MPH.
Plot these two points on some graph paper and draw a straight line though them to 5 MPH. Read your CV2-5-6 numbers at 5-30-60 MPH. 
Some Graph Paper for "Decimal Numbers vs. MPH"
(0 to 255 or 0 to 32 Range) is available.            
Graph Paper.pdf


A much more complex Excel Spreadsheet can use
any three points to calculate a “curved line”. 
This three point curved line is then used to calculate the
CV67 to CV94 values of the 28 step user loadable speed table.
This type of table is available to all DCC decoders. 
There are 9 pages of DCC information on this subject. 
(For a 28 step user loadable speed table,
Decoder Pro software is much easier to use.)


Different shapes of curves generated by the
CV28Step program can easily be done by choosing different
Start, Mid. and Max. Mph speed targets.
The following have 8 different types of curve shapes
all from the same data.
Curve Shapes.pdf


A simple way to estimate the Start CV2 is with a
DC Volt meter and a NEW decoder with address 03.
DC Volt meter.pdf


For a Quick Tour of DecoderPro:

To Download the
JMRI Manual for DecoderPro


Just by knowing your “Start” CV number at 5 MPH. and 
your Maximum” CV number at 60 MPH, these two numbers can be put into a JMRI Decoder Pro Motor Speed sheet. Instead of selecting the "Match Ends", select the "Constant Ratio Curve" tab.
This will provide a Speed Curve starting with small "voltage increments".  This method provides an
even better speed table than one built with CVs 2, 5 and 6. 
This method makes a very "quick" 2 stage speed table.
The best thing about JMRI DecoderPro is that it can program your DCC locomotive for you, and save all of your CV information to a file.    


How to Consist Engines of Different Manufacturers Using DCC/DecoderPro:

For a free download of JMRI Decoder Pro software:


Other information sources:

“Using CV to match Locomotive Speeds” by Mike Polsqrove,
MR, Nov. 2006 page 76

“DCC Speed Steps” was published in the
August 2008  issue of Scale RAILS pages 26 to 29.
These slides were made for the
75th NMRA Anniversary Convention in Milwaukee, WI. 

The NMRA 75th Anniversary Convention, Milwaukee, WI. 
July 11-18, 2010
Frey Clinic 2010  and Clinic Handouts 2010

This page was last updated 03/19/16