[ESjaavik]

This is concerning a small (apx. 1000Kg.) toolroom mill, but now only used intermittently as a hobby machine.

I have torn down and built up my mill. This included cleaning the coolant tank, which is actually the lower part of the main casting. I scrubbed it as good as I could using a strong caustic solution that is used on walls before painting. There was a lot of slimey goop in there, and I tried to get everything out.

Is there anything more I can do to avoid that goop to get back to life when I put in coolant?

The last coolant used (don't remember name) allowed this goop to grow. The previous one called Zeronite did not. But on the other hand it was not very nice to the paint. Can anyone tell us what different "families" of soluble oil coolants there are, and the pros/cons.

Should I drain the coolant tank during periods of little or no use, and store coolant in an airtight container? I guess these aliens need oxygene to breed.

[Bloy2004]

In my limited reseach, I've learned that maintenance is a big part of "storing" coolant. There are "skimmers" that take the impurites off the surface of the coolant, which I believe are the promoters of the "spoiling" of the coolant. Basically, keeping the coolant clean as best as possible seems to allow a longer shelf life(intermitant use).
Please... anyone with experience...please correct me if I'm way off...

[HuFlungDung]

Bloy is right It is the thin film of machine oil that provides the medium for slim bacteria to munch on. And keeping the coolant in an air-tight just aggravates the problem, because anerobic action is also part of the stink. I suppose not enough air penetrates the oil slick, or a slime skin once formed.

I got sick of cleaning the machine sump as Einar wrote about, so I simply use a five gallon pail as a sump now. It is easier to rig up a skimmer and also easier to dispose of the coolant and to disinfect this kind of sump.

Unfortunately, I think it is impossible to eliminate slime bacteria no matter how much you scrub. So it becomes a matter of replacing coolant regularly. This is the most affordable for the infrequent user.

The synthetic coolants last quite well, but I still only get maybe 3 months of use before I change it. The weaker dilutions, although cheaper, have a shorter life. But it may make more sense to just mix up a little bit of weaker solution and be happier to dispose of it more frequently. Again, the pail sump allows you to mix up less coolant and yet still have sufficient depth to cover a small submersible pump.

[nervis1]

I have a 40 gal sump that was rotting every month or so but since I got a skimmer I've had the stuff in there for 3-4 months without any problem. That little guy just skims all the goop right off the top along with floating chips and the occasional scorpion or grasshopper if you live in AZ.

[Mouldmaker]

If you have bacteria in your coolant system, try using a cleaner which is added 24 hrs to the coolant prior to it being replaced. This will clean your coolant system (coolant system includes pump, pipes, etcc... not only your sump) and kill all the bacteria present in your coolant system. Your coolant supplier should be able to supply you with this system cleaner.
Another important aspect of coolant maintenance is the usage. Do not leave it for long periods without being used. If possible, use it on a daily basis, for example, starting the coolant pump for 30 min daily.

[dcook]

There are numerous germicides available to put in your coolant. Also many coolants have germicides in them. Low use/stagnant coolant, especially with an oil film will become rancid at some point. A skimmer is your best buddy. It is unfortunate but most germicide-based coolants will take the paint off of a machine. Epoxy based paints resist this the best. Alcohol based paint (Japan) will come off within a few days. Keeping the machine as clean as possible is good insurance.

[ESjaavik]

Thanks for several good advices.

It seems the Zeronite must have been a germicide-based coolant, because it stayed fine for a long time and attacked paint (and seemingly also rust!). Would it help if I apply car-wax when cleaning the machine? I will probably see if I can hunt down a can of the same stuff again. It was given to me because the machinist didn't like the smell of it. It did however smell a lot better than the goop!

Does anyone here recognize the name? I tried to google for it but did not come up with anything useful. So I don't know where to call to get it.

[Mouldmaker]

I dont think applying car wax will help as it will contaminate the coolant even worse. Keep the coolant as clean as possible to keep it free from bacteria.

[bob1371]

In my little hobby machine that I never have time to mess with I started by adding a skimpy brand skimmer. Every other week or so I just add a cup of household bleach to the tank. Pretty cheap and So far I dont believe it has affected the usable life of the coolant and it keeps the nasty stuff from growing.

Bob

[ESjaavik]

Bob,
I Googled the skimmer you mentioned. How does it work? Does all return oil have to pass over it, or is it just like a cat's tongue licking off any oil that happens to pass it. If so: do you leave it on for some time even if not actually milling?

And what are those germs? Or rather how harmful are they? I still don't know if there is life on Mars, but there sure is in my coolant tank. Is it out to get me?

[dcook]

The bacterium that grows in a coolant tank can become very harmful. Skin rashes and/or burns from the bacteria are common. Eye irritation and in severe cases blindness can occur. If you find yourself especially allergic to poison ivy watch out. You can build your own skimmer from common items. There are several styles commercially available. Two of the most common are belts and discs. A belt hangs into the coolant tank below the top of the coolant and slowly rotates; the oil will stick to the belt and is scrapped off into a container. The disc skimmers work the same way but normally use a UHMWPE disc partially submerged vertically in the tank and again the oil is scrapped off. I like the disc skimmers better. They seem to do a better job. The disc skimmer is the easiest to make yourself.

[oldguy]

Avoid coolants with "biodegradable" on it. May not be politically correct, but that is just another term for "it rots." Check compatability, but perhaps an antibacterial additive could stop it. Never tried it, but chlorine bleach, a small amount, might work to stop it from starting, but it wouildn't reconstitute the rotted stuff. Just a thought.

[Stevie]

Just buy some EXXCool 2000 made by Esso (Imperial Oil) fully Syn coolant; I changed the CNC at a place I was at for 18months; it never got smelly again; it's only drawback is it's a bit sticky if you let it dry on the part

[IndHobby]

I run a biodegradeable Syn-Lube GM and I've never had a problem with it. You can always run a fish tank bubbler, that keeps anerobic bacteria under control and keeps the coolant circulating.

[Rich Monfo]

if you need some info on coolant/oil skimmers check this website out. This is the type of skimmers
we use on some of our smaller mills and we don't get a scent what so ever. Like everything you need
to do a bit a spring cleaning every so often maybe once a year or so. The tank never seems to be all that goopy as the term was used earlier. but here is the website to look at .
www.abanaki.com

Good luck

Rich.

[Zagroseckt]

oh deer. hmm never thought of coolent.

What about bleech? no bleech would eat any lines and mess up the pump wouldnt it.

umm
Any one try refrigeration?

I know that sounds silly but i gota ask...
i've got about 5 dorm room sised friges i can pull the guts out of and rig a cooling elemint into the sump.
I'll need to do this befor i get done designing the thang tho.

And just how much does coolent cost it may be more cost effective for some of us to design in a desposabul sump. (the 5 gal buket idea)

I'm in mid design on mine. it's going to have about a 2ft by 2ft work earia with half a foot on on each extream to move the tool around the workpice.

And since i definitly want to work with aluminum (im going to be boring injection molds) i'll need coolent.

i didn't even know it could rot... heck i dont know where to buy it yet
I've ben consentrating on what kind of rale screw design i was gona use for the gantry.

[WORKALONE]

I have been informed that the fungus and bugs growing in a coolant reservior will eventually be come immune to the antibacterial chemicals in your coolant the same way a bug in a person becomes immune to antibiotics that are taken too much. Changing the brand or even brand type will start the cycle all over again and give you a longer period between changing and cleaning of your sumps. An aquarium bubbler to airate, a submergable pump to circulate, a skimmer to remove the tramp oil that smothers the good bugs that eat the bad bugs. A moving body of water (stream, River) is always clear and clean. I use a bit of Triadine(an anti bacterial chemical) in my 5 sumps to control the thick scum(fungus) that will appear from time to time. I also use a colesing unit (skimmer) named "Zebra Muscule" from Zebra Skimmers with great success. www.zebraskimmers.com. A lathe usually is the "Black Hole of Calcutta" when it comes to a bad enviroment for coolant in the casting sump. Zebra fixed that problem for me. My FX-20 Ikigai now has the Zebra Muscule inside the casting sump. I have an Okuma lathe with a separate sump under the machine. I removed the perferated chip pan and built a longer one without any drain holes. Now the coolant flows to the end of the pan into a Fadal reservior on casters that is easy to maintain using all of the devices mentioned above.

[greggv]

You might also try adding a little household bleach to the mix. I've heard this keeps the growth away.

[nervis1]

I just got one of those zebra coalescers too, miracle it is. I got mine from KBC for 300 bucks, 150 less than zebra sells them for.

I also got rid of the oil based lube, went a full synthetic.

[JEFFY]

Fish tank bubbler works great to help control the scum. A pump to circulate on big tanks is also needed if not its just a big pond.
Bleach not a very good idea, very temperary fix unless you add a little every day as the chlorine evaporates.(chlorine was not an option in my case)
I had worked with big(huge)tanks of coolant and areation was the key of keeping my tanks clean of scum.
I don't know if this will work for all the types of coolant out there but one of the things I found was that sometimes if my tanks got contaminate with oil of another form(oil from other processes or from general contact lube) I would have problems, it would look like a oil slick on top, if that happens you have to get rid of that by breaking it down or skimming. to break down non water base soulable oils, I found adding a VERY VERY LITTLE BIT of soap helped. DAWN dish soap worked with areation. I would have a quart spray bottle with ABOUT 1/8 cup of soap and the REST WATER, when ever I saw a lot of scum I would give it a spray or two and it would help break the water surface tension allowing the areation to work. Keep unwanted oils out of your tank, get some areation and skim it for the non soluable oils and you will be a happy camper that won't smell like a sewer.
One more thing to remember don't give the bacteria a chance to start, when you change your coolant make sure you scrape the bottom of you tank clean, as that sludge will contaminate the new coolant with bacteria. this is the one time that you can use the bleach to kill off the bacteria and fungus. Hope it helps