[aldaeron]

I did not think of a boring head. Good call!

I do have a decent enough background machining and detailed tolerancing myself, but am having trouble coming up with what is acceptable and how to measure it.

If the nominal center to center spacing is 2.103 for 84T 20 DP spur gears, what is an acceptable tolerance when considering bore size and center to center spacing? .001? .003? .005? .010? I can't afford to buy a set of plug gauges so will a measurement with a caliper be close enough? I would prefer to not get a gearbox built and have to run it then examine tooth wear to see if I manufactured precisely enough.

If the DRO is perfectly installed (unlikely), the 4" wide vice is perfectly square to the table (hard to measure with a 4 inch vice), the screws have some backlash (even when locked) and the head has much more flexure than a large knee mill (to the point that its .001 or more), what error am I adding with such a cheap mill that the DRO cannot measure?

Appreciate the feedback though!

-matto-