One set is metric and the other Imperial but the thin steel cabling used to string the stud/nut combination is convenient for keeping the set together but makes it very difficult to use.
Thanks for the heads up on the cable type Paul. I can see now how it could be inconvenient, especially on smaller ones. Perhaps for your board you could use some kind of pin with a slight curve that would fit through the cable hole and hold them relatively well for storage. Did you find the thread quality to be pretty good? Look forward to seeing what you come up with.

Here's another one. Thread-forming taps, which displace rather than cut metal to form threads, need larger tap drills. There is a formula for this too and it includes an allowance for depth-of-thread...
Thanks again Marv for including thread-forming formulas. I've never used them but understand they create very high quality threads. I agree about calculators. TI36's (solar) have been around for ages and keep several around the house and shop for what ever comes up and are way cheap ($10-15). Even taught my students back in the day to solve Kirchoff laws problems with them. I do find I am using the "RealCalc" app on my C-phone more and more and does pretty much all I need. I've built a pretty good collection over the years in Excel that I use on my tablet or phone in the shop and find it handy without having to remember too many formulas or look them up. Not as extensive as yours or as complex but did build one for Catanary calcs on tubing and round bar of various materials.

Thanks Much, ~PJ