Water for Tool Grinder
Advice on water and coolant for a knife grinder. June 18, 2010
Question
What is everyone using for water in their grinders? In the past I have used spring/purified water. I am currently using city water, and seem to be getting a lot of oxidation (rust) on my heads.
Forum Responses
(Solid Wood Machining Forum)
From contributor J:
Our shop has well water. Never gave it a thought. Very interesting. I know you were looking into coolants a while back. Did you end up changing to something different? Maybe has a different Brix ratio?
From contributor R:
I too use regular tap water, but keep in mind water is different in many parts of the country. Our water is very hard. Distilled water is best, but costs more. Every time you add water due to evaporation, make sure you add some more coolant and change the water at least 4 or more times per year depending on what you grind (change more often for carbide grinding).
From contributor D:
Contributors J and R are on the right track. The water's most likely not the issue; the issue is the mix of water vs. coolant. There is a device called a refractometer that every grinding operation should have. It allows you to check where your coolant stands on the Brix scale. You should check it every Monday or so and depending on the reading, you either need to add more water or more coolant to the mix. And yes, for sure, change the coolant regularly.
Lastly, if you aren't grinding much carbide, you may want to try a soluble oil coolant instead of a synthetic. Soluble oils still mix 25:1 or so with water, but they are much better at preventing rusting on tools and the machine.
From contributor A:
I have no idea what a Brix scale is, but I can tell you what tooling companies and grinder technicians have told me, and from experience I know it works. You only want enough coolant in your water, and it doesn't have to be any type of special water, so that your cutterheads and knives do not oxidize (rust). Regardless of what type of wheel you're using. In some applications, stone or vitrified grinding does not necessarily require water, depending on the grit and the feed speed. It is necessary to use it with borazon and diamond wheels. Problems arise when you have too much coolant. Your wheels will clog and burn your cutters, with you cleaning your wheel more often than necessary.
