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…......................--- N Scale SpeedTrap Speedometer – Pt. 1 ---

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I've started to speed match my locos to the 128 speed steps on the throttles I use. Speed step 10 = 10 mph, 45 = 45 mph and so on up to speed step 65 which is 65 mph. For most all of my locos that will be the top speed. For some locos used for passenger service I might up that to speed step 90 which would be 90 mph. Even with the passenger locos having a higher top speed 65 would still be 65 mph.

I feel there are a couple advantages to speed matching to the speed steps vs. to another loco which is a common practice. If all the locos are speed match to the DCC speed steps they will be closely matched to each other. If you consist 3 locos and run the throttle to speed step 50 they will all be going 50 mph. Also I like knowing that if I see 22 on my throttle screen I know the loco is going a scale 22 mph.

I haven't so far found it very hard to speed match them like above with JMRI's DecoderPro. My ESU decoders have easy settings to use for the max, middle and low end of the speed range for a loco. Setting those in a few minutes by setting the throttle on 65 and then messing with the max number so that is a scale 65 mph and then doing that for the mid and low end usually ends up with the loco being very close to scale mph from 0-65 mph (speed step 0 to 65). There are other settings in DecoderPro to fine tune it but so far doing the above has proved to be just fine. The Digitrax decoders I have done this with so far have only 2 settings but still they seem to match up pretty close after a few minutes.

Locos that won't be consisted I'm also not as worried about getting exact. If my throttle say 22 and it is going 19 mph are 24 mph isn't as big a deal as if the loco is going to be used in a consist.

The slow part to doing the above has been doing it by timing a full or partial lap on my oval test track and then seeing what scale speed that is. I know the length (circumference) of a lap and from it and the time can figure the scale mph. I've set up a spreadsheet that has the times for a lap for 0 mph to 90 mph in seconds and use it.

Recently I saw a YouTube where the person was using a track speedometer that sits above and alongside the track. The loco runs through it and the scale speed shows on the display. I looked for one to see how much it is but I think it has been discontinued. Finishing the HandCab project and doing a little coding for it and what I did for the turntable project got me thinking building and coding this should not be very hard compared to those projects so that is the plan.

Took about a day to design the vertical uprights. Printed them and wanted to make some changes so tweaked the design a bit and printed what is shown in an image further below and above.

Hopefully another day will be all that is needed to finish the case type part that will house the electronics on the top. Some of the items, like the part shown above to hold the ESP32 were stolen from my HandCab design. Having a program with the power of Fusion 360 that you can use free if you are non-commercial is wonderful.

I plan on doing another of these for use on straight track. Shouldn't take long using most of the elements of this one.

I printed the uprights with the resin printer as Chitubox makes it easy and quick to put in the supports for something like above. I'll probably use the filament printer for the rest thought as it works well for printing the rest of the speedometer and has a larger build volume. I designed the uprights so that they would fit in the AnyCubic Photon M3's build volume and they barely did.

The parts come in under $50 for the speedometer.

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