Since calipers and micrometers were useless for most of the measurements, I did some measuring with shims and here's what I found...
I could fit about 0.4mm worth of shims behind the pin on the Tamiya hex to take out slop. Then I tried taking out the tube spacer (between the two bearings) and found I could barely fit 0.5mm worth of shims. This means that even if I wanted to make a thinner spacer, it can only be to be thinner by less than 0.1mm. In short, the spacer is as narrow as it can be so we'll leave that alone.
Since the B44 hex has some distance between the inside wall and the pin hole and the Tamiya hex does not (in fact it's a negative distance since the pin hole isn't even a complete circle), we know that we need to reduce the distance between the inside wall and the pin hole until it's the same as the Tamiya. At this point, the B44 hex would break in two. Taking into consideration there's about 0.4mm of play that we can use up, we can leave some material there. But since the Tamiya distance is negative, ... we're really talking less than 0.4mm. Maybe even 0.2mm. That's the same thickness of a medium shim that you can easily bend with your finger tips.
In other words, unless you're going to use the B44 hex backwards, it's no good. And even then, you either need to drill or mill the pin slot wider (from 1/16" to 2.0mm) or use the smaller pin and live with the slop.
What I did manage to use the caliper for was measure the hex sizes. The B44 one is ever so slightly smaller than the Tamiya one. B44 being about 9.5mm while the Tamiya was 9.6mm. The B44 fit was acceptable on the Rulux rims but just downright sloppy on a Tamiya rim. The Tamiya hex was good on the Tamiya rim but even better on the Rulux (except for the offset causing the rubbing).
Since I had the 0.4mm worth of washers behind the Tamiya hex and pin, I mounted up the wheel and it could spin but I decided to do a comparison. I couldn't fit any more shims there, so I put a 0.1mm shim inside the wheel and gave it a whirl and it spun noticeably freer.
I'm giving up on the B44 hexes and will just start with making a 0.5mm washer to put in each wheel and see how I go from there. If I want more steering, I can aways take that out and dremel the wheel later.
Thanks for all the help, guys. I knew I'd get answers I needed on the Oople forum.
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