Oil or Coolant for Cylindrical Grinding?

Hey guys,

Today I got my Norton 10x20 U4 cylindrical grinder wired up and running. It still needs a bit more cleaning, but it's functional. The reservoir for the coolant will be cleaned. This grinder will be seldomly used so I'm wondering what fluid would be better to let sit in the reservoir long term. Also, which fluid gives a nicer finish?

thanks,
Mark

Cant tell you what is proper, just what worked.
Semi synthetic Trim (906?) coolant at 5% on a refractometer

The semisynthetic seems to hold up a while in the sump, does get funky after though setting a few months in our hot humid southern climate.

Ground mostly 4140, 300 and 400 series SS.

Held a tenth and finish was good using coolant on a 50 something model Cincinnati.

These done with the most ordinary of water based. Since this grinder is only sometimes used, the coolant is always fresh and then PITCHED afterward - else it is shortly a terrible brew here in Houston

Only oil use I have seen was the gear tooth grinding at Pratt & Whitney Aircraft fifty years ago

Going slightly OT with this question. Do those mist coolant devices work for cylindrical grinding or does one need flood the wheel?

John

I use Rust-Lick syn. Lasted almost 3 years. I have a small pump which pulls coolant from the "Clean" tank, runs it through a household .5 micron filter and returns part to the first separator using a spray bar to add some oxygen, and the rest return to the clean tank. There is a timer to control the pump . It runs 1 hour a day. Coolant lasted three years, pump died and I didn't notice for a couple weeks. So now had to dump coolant and clean gross looking crap.

This idea Toms presents , I have not read of it before anywhere, a spray recirculation adding oxygen to prolong the coolant life , in a major way. Apperently these bacteria are anarobic....can only live in liquid lacking oxygen ...
so oxygen added through a spray nozzel an hour a day kills them....well worth looking in to. ........ That has to be the most non toxic biocide one earth.
Its kind of counter intuitive bc of seeing several industrial wastewater situations where the water is intentionally oxygen enriched to facilitate bacterial action........... to enable bacterial growth therefore breakdown contaminants, and it seems possible coolant could contain aerobic AND anarobic bacteria so a chemical biocide might still needed, but based on Toms practice, I want to do it
....Thank you Toms

Dave

Here is a few shots of the system. The spray bar under the sump cover.

The plumbing is not so neat but functional. That valve is used to limit the flow to the spraybar. The return from the top sump to the pump tank, can not handle the output of the pump, so the valve throttles the flow match.
That is a standard household water filter using .5 micron filters. The pressure gage measures the back pressure from the filter, 4psi when new, 10 psi change filter.

My old Norton 10 x 20 Universal, presently undergoing a rather leisurely renovation, has a fairly large coolant tank, I think you may be best served by replacing the drain plate with one that has a pipe nipple that you can drain into a large bucket- put the pump in the bucket too. Better to lose five gallons rather than 25- mine has a capacity of 30 gallons.

A similar "optimization" on somewhat smaller tanks is to fill much of the volume with bricks or similar.

Back when I did this sort of thing, I used water-based. This is similar to my hone- just because it holds 15 gallons doesn't mean you need 15 gallons. That was for high volume production work I'm never going to do. Redesign it to use far less, maybe a gallon, use a filter, then pitch the stuff before it goes bad. BTW, if you're after really fine finishes, you need a filter.