I made an hellacious mess out of an Atlas 2-6-0 by trying to relocate the 'traction tire' driver to the center, making an 0-6-0, which meant I actually had to swap around four drivers as the axles are not interchangeable.
I had to make my own quartering tool to dig my way out of that mess, pretty much the same idea, just not brass- styrene. And with the crankpins in. Again, the idea is that you really don't have to be precisely 90-degree, but all the wheels have to be precisely the same. I lived to tell about it, got it fixed, but it wasn't either pretty or fun.
And that, gentlemen, is why my Atlas 2-6-0 to tank 0-6-0 kit never made it past concept stage. Egad what a mess.
But the bottom line is that you don't have to be a machinist to do this. If you're doing just one locomotive, you can make one out of styrene and glue it up to 'lock in' one driver as the control, and then just put the other wheels in there and adjust them to agree.
