Coolant ratio strips saved my finish quality after months of guessing

I kept fighting with rough surface finishes on my lathe parts and couldn't figure out why. New inserts, slower feeds, different speeds, nothing helped. Then last Tuesday I grabbed a cheap refractometer from the tool truck and checked my coolant mix. Turns out my concentration was way low, like 4% when the jug says 8 to 10%. Bumped it up and the difference was night and day, no more chatter marks and the parts come off almost polished. I always just topped off with water when the tank looked low, never thought to test it. Anyone else run into this or do you stick to a strict schedule for checking your mix?

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felixb2513d ago

Read somewhere that coolant bacteria can throw off your readings too, so now I check mine weekly before long runs. That 4% to 10% jump makes sense, water topping is a trap.