Awl --
Apropos of the recent threads on coolant, what's a typical/decent refractometer to buy? Not to buy? $$?
In some threads a while back, some mentioned difficulty using them with dirty coolant (tramp oil) or maybe even old coolant.
Are the mfr's of a given coolant fluent in what concentrations are useful for particular kinds of tasks?
Suppose you are 20% too dilute, and then 20% too concentrated. What diff's would you see in machining "efficiency" (speeds/feeds), tool life, cut finish, etc?
Has anyone ever milled with plain water? Rust issues aside, of course. Many cut ops DO use water -- highspeed alum saws, for one (at least a while back). And some grinding. Water is perty neat in grinding stainless on sanding belts, greatly increased the removal rate in some 1/8 rod that I had to grind to a semi-accurate size -- about .005 in a 1" length.