Spent a whole shift chasing a weird finish on a 4140 part
I was running a simple facing op on a lathe, and the finish looked like garbage, all torn and fuzzy. Checked the insert, speeds, feeds, everything. Finally, after like five hours, I noticed the coolant mix was way too weak. Topped it up with concentrate and the next part came out smooth as glass. How do you guys keep your coolant concentration right without a refractometer?