Clever!

I really like both of those, and I'm going to appropriate them for my work bench.  The coupler gauge screwed to a piece of track is an old trick, but I've never seen it mounted with a spring so it could be spun around - nice touch!  And the car floor - very handy.  I may make a couple out of brass, one for Kadee boxes, and another for Accu-Mate, but you get credit for the concept.

Thanks for sharing.  Homebrew shadetree tools are sometimes the most interesting, aren't they?

I've since made two coupler

I've since made two coupler mounting gages.  While the floor fit all the cars I tested it was a little loose in some.  Not much but I wanted a tight fit,  I used some styrene and just made it a little wider and used the floor for a template. 

Are there big differences between Kadee and  other coupler boxes>

I may take a shot at brass also.  much more durable.

Had to make some

Had to make some adjustments.

After experimenting with the coupler jig I found that the thickness of the car body frame wall varies.  while the cut out floor section worked on most cars it didn't work on cars with thinner wall thickness.  so, using a Kadee coupler as a guide, I made a new template with a new centered hole, that I align with the outside of the car body (as you would normaly with a Kadee coupler).  This now works on any var body regardless of thickness.

Different boxes

The Accu-Mate proto coupler boxes use a different screw location than the Kadee #5.  I don't know about other designs, but that's at least two.

I did a coupler height gage years ago...

But I like the use of the rerailer there. Mine is just a piece of flex track glues to a 1 x 3. Maybe I'll get a longer piece of wood and put a rerailer in the middle and wire an old power pack and make it a full test track.

Doug, I actually thinking of

Doug, I actually thinking of doing the same.  I've hooked up a power pack to this while checking just to see if it would move.  As soon as I can acquire more room I want to stretch it out.

Careful!

If you're going to power that track, watch out.  Some Kadee coupler height gauges are not insulated, which means they'll cause a dead short.  I'd suggest putting a small gap in one or both rails in that case.

Thanks for the heads up,

Thanks for the heads up, Ken.  I'm using the Kadee 206 which is insulated.  The 205 is not.

Good deal

I thought you were.  However, I figured it would be worth pointing out for others, since I expect this thread will inspire a lot of people to build something similar.

An oberservation

I noticed that the gages appear to be the Kadee engineered plastic type, less expensive than the metal. However when using them to replace #5s with new scale couplers, I noticed all the cars were coming out to low. After resetting a lot of cars, I figured something was wrong. I bought a new metal one and every thing was fine. After inspecting the two gages together I found the gland hand gage is warped up slightly on the plastic gage. I sanded it level but only use the metal one if I don't need two at the same time . Better check your new plastic gages with an old metal stand by. The new metal one was the same as the old metal gage. Bill Faith

thanks for the heads up,

thanks for the heads up, Bill.

I went and checked the coupler height against a NMRA gage and the center lines line up correctly. 

One thing I did notice was the gear box mounting height portion has a tendency to lift up when i turn the gage.   Something i need to be aware of... thanks for directing me in that direction.