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Peter's Model Railroading | Articles | Tools | Measuring Things
Coupler Height Gauge


I started off with a 15" by 6" piece of MDF upon which the jig will be built. Any base material will do, as long as it stays flat over time. The length depends on the equipment to be checked. I will be running mostly 40-foot or so equipment, so mine is large enough to handle a 50-foot car or engine, just to be safe.

After measuring an actual freight car's "scale" wheel flanges, I realized that 0.040" is thick enough for the wheels to ride on (if you use deeper flanges on your equipment, you'll have to adjust the thickness of the styrene accordingly). The point is that the bottom of the wheel flanges shouldn't ride on the base. I cut two one-inch strips of 0.040" styrene and glued them to the base using superglue. One check here is that the height of the styrene verifies that the wheels all adhere to a minimum flange height. I glued the styrene pieces the same distance apart as my rails on the layout, so that wheel gauge can be checked quickly that way as well (although not as precisely as with an NASG/NMRA wheel gauge).

The next step was to deal with being able to install couplers on my cars and engines so that they all line up with each other. I settled on a scale 3-foot height from the tops of the rail to the vertical center of the coupler. People typically use the Kadee coupler height gauge for this check. That works fine, but what I really need to know is, do I need to adjust the truck/body height so that the coupler will wind up sitting at the correct height? The Kadee coupler height gauge also checks for that. But rather than spend $15, I decided to just make my own. Also, from my experience with the N-scale jig referenced above, it is a pain to only have one of those gauges on one side, because I had to always pick up the cars and engines and flip them around to check the other coupler. Needing two Kadee coupler gauges would now total $30. After some measuring I concluded that two pieces of 5/8" thick MDF cut to 1/4" width, one glued to each end of the jig, will tell me exactly whether or not the location of the coupler on the car or engine will be correct, before installing the coupler itself. The photo shows one of those pieces glued down, centered in between the two strips of styrene.

This photo shows the coupler on this box car is at the correct height. The top of this S-Helper Service coupler matches the top of the draft box, which matches the top of the MDF block. If you use the metal uncoupler pieces, you may want to cut a little relief into the bottom of the MDF blocks, so that you can push the coupler right up against the block. My layout's standard is to not have those. I will be cutting the metal piece off next.