First and foremost I have no knowledge or experience in building/maintaining wheels. So I have to try it!
I was reading Roger Musson book and decided to build a truing stand out of scrap I have. I'd also read that some incorporate a dishing mechanism. Now I couldn't find any pics so I decided to do my thing for if you reference all from a fixed point you can dish true and tension at the same time without having to remove the wheel checking dish.
I simply added a steel rule, a slide with a magnet to hold it in place, Calculated what the dish position of the edge of the rim should be, placed the wheel, placed the slide with the guide at the measured position and the test scrap wheel is actually dished correctly. Flipped the wheel over and same position.
To me this saves the hassle of having to pull the wheel on and off to check the dishing, it also saves having to measure using feeler guages or guestimating the out of dish distance. Ie: 5mm = 2.5mm out of dish using a dishing tool. If my setup works as it should then 1mm out of dish is 1mm, it's a direct measurement as you are doing it whilst you are setting up and truing the wheel.
Working all adjustments to the set guide gives you Dish/Truing and Tension if you have a tensionometer or such.
In building a prototype, I stopped (See Pic) for it seems too simplistic. Am I missing something?
Thanks for the responses, I use an outside caliper to measure both the hub and rim widths. The inside of the left support where the locknut meets is square to the ruler and both permanently in position the guide slide is then placed at the resulting measurement.
The objective when set is to bring all wheel adjustments to the guide, this way even if truing your always bringing/maintaining the rim to the dish position instead of accidently going the other way.
Won't take much to scrap up a dishing tool even if it's for checking to see how accurate/inaccurate my set is.