That’s basically the news 
The hot water tap works in the workshop bathroom now. Also the utility sink in the clean room, if anybody actually uses that anymore.
Let me know if you see any suspicious puddles around either sink.
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Speaking of the clean room, the DI water filters in there are in bad shape. They’re all growing algae and it’s in the reservoir now as well. I was told to use DI water to mix the Tormach coolant, but algae water might be worse than tap water.
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I’m skeptical that the DI water is really DI anyway. I don’t think anyone’s been paying attention to those filter cartridges.
If we really can’t get away with tap water to mix coolant (Austin water’s fairly soft) then we probably either need to get an RO system (with an opaque tank!) or just buy distilled water by the 5-gallon jug
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I would be stunned if DI water is required for the Tormach coolant. Standard water should be fine.
If we’re really that concerned, we’d need to get a refractometer and then you can dial in the dilution properly based upon the chlorine and mineral levels.
The bigger issue I found is that a lot of the coolants that are less toxic tend to start having nasty crap growing in them over time. This is especially likely given that wood dust provides both food and transport for microbes.
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The main reasoning is that the corrosion inhibitors in the coolant are rendered less effective by dissolved ions. The dissolved ions compete with the inhibitor in binding to the metal surface. The problem compounds over time as coolant is topped off without replacing the entire tank. The ion concentration will increase each time new coolant is added, since the dissolved ions don’t evaporate with the water. I couldn’t say if that’s a big enough issue for us to worry about, but it is what’s recommended by the coolant manufacturers.
Buying type 2 deionized water isn’t that expensive, something like $60 for a 5 gallon container. Seems like pretty cheap insurance to me.
I get the theory, but I too am unclear how much practical difference it makes. I’ve read anecdotal reports of coolant lasting longer mixed with DI than tap.
Buying water in the volume we’d need sounds like a reasonable expense compared to maintaining our own DI setup.
The tormach holds ~12 gallons. I found a 200L barrel of type II DI for $525 ($10/gal) but I’m doubtful we’d use it up before it grew friends.
Are we using “DI” for all coolant mixing, or just the Tormach?
Yeah, seems like we wouldn’t use a whole barrel quickly enough. But I’m not really sure how quickly we go through coolant. We can always start with the smaller container and if we’re needing to buy those too often we can reevaluate. A small RO system paired with new DI mixed bed filters would be something like $500.
And I agree, it is hard to tell how much difference it makes in reality. The coolant lasting longer is interesting, but it would be nicer to know how it affects machine wear/maintenance/lifespan. Probably not much out there on that though. There is an old empty 5 gallon container of DI sitting by the gorton mill, so I’m assuming that was used before the DI system was around.
Right now, the Tormach and the horizontal bandsaw are the only tools that have a working coolant system right? I know we just use tap with the bandsaw, but it’s already pretty rusty anyway, and the blade gets replaced before it rusts.
There’s been some repair efforts made on the coolant system for the lathe, but I don’t know if it’s ready to fill yet. The coolant system on the new drill press has a 7gal tank.
I believe their is an unused filter system in the maintenance closet. I dont recall what type it is specifically, mayne just a fliter style. Not sure what it was purchased for.
That one was for filling up water bottles in the shop.
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Erm, a handheld refractometer is like $150, no?
With that, we can use tap water AND measure the concentration so that when we top it up we can see how much more coolant to add to bring it back in line with what is required–which is a problem even with DI water.
I’m not against having DI water as PCB rinsing generally uses that. However, I think getting a refractometer is probably a better idea in the short term.
A refractometer would be a nice addition, and Tormach even sells a basic handheld one for $80, but it doesn’t solve the DI vs tap question. It would let us maintain the coolant concentration we want, but it wouldn’t do anything to change the properties of the water itself. We could potentially increase the coolant concentration to counteract that I guess, but the coolant isn’t cheap either at $45/gal
Just to be clear, ions would be like sodium, calcium, chlorine, magnesium, iron, sulfur, etc, readily present in tap water and are not removed by simple particulate filters. DI filter can.
The presence of some ions- like sodium/chlorine (table salt) facilitate corrosion. But calcium ions are actually helpful in that it inhibits coolant foaming. Because calcium is what makes “hard” tap water where soap won’t foam correctly. But foaming is undesirable in milling and lathe coolants, so calcium may help. But it can also break down the emulsifier, so… I don’t know.
But distilled water should be ion-free. Regular $1-a-gallon stuff from the grocery store. From there you just have to look at how much you actually consume. If we go through 10 gal regularly, no one wants to carry 10 gallon jugs in and out of their car and we have no place to keep like 10-20 individual gallon jugs on a shelf so we don’t run out.
5 gal a month? Buying distilled would be a very practical option.
That’s a good point, ASTM graded DI water is probably overkill. We wouldn’t even have to get a bunch of 1 gallon jugs, we could just buy a couple of the water cooler type 5 gallon jugs. When the coolant gets low, just dump a whole jug in there with ~1/4 of a jug of coolant.
I wouldn’t be too worried about the lack of calcium, all of the coolants have anti-foam agents in them, plus we’ve been using DI water already and foaming hasn’t been an issue.
Depending on how much coolant we use in the future once the lathe is fixed and people are using the new drill press, there could still be a point where it makes more sense to maintain our own DI system, both convenience and cost-wise.