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Machine tools in an unheated garage


Aug 31, 2007
What are the risks of storing a mill and a lathe in an unheated garage, in a climate where winter can go as low as -40 Celcius ?

Can it be mitigated with generous oiling of everything ?
I'd say it depends on the humidity level, you did not mention that, and your location is blank. My machines were stored for several years in an unheated space with winter temps as low as -20F with no rust, but also minimal humidity. A warm humid day, after a cold spell will make machines sweat like a glass of sweet tea on a warm summer day, that is where you will get rust.
The risk is that the mill and lathe will get rusty!! Oil isn't the best coating to use, I like LPS3. Plenty of threads here on rust proofing. It's not possible to get a coating everywhere, so what I would focus on is keeping those at as steady a temperature as possible and keeping that temperature above the dew point so you don't get condensation. I've used, in a humid SE USA climate, an insulated box with a small heater of some sort (incandescent light, Golden rod heater, etc).
i have my whole shop in a non heated biulding the only issues i have is rust if i dont keeping thing clean and oiled.
My shop is only heated if I build a fire.
Seasonal transition, from frigid to frying.... that causes the condensation to accumulate on all the big items in my shop.
My big problem is that this occurs many times between winter and summer... too many big swings in temperature here in Kansas.
What I think would solve the problem would be to stick one of those magnetic block/oil pan heaters to the thickest part of each machine, and let it run. That way, the iron would absorb the heat and not be at sub-artic temps when the weather abruptly changes to a balmy 60 degrees one day and causes them to sweat.
The drawback is that they would ideally need to be on a thermostat that would allow me to have them turn off when the machine got to, say, 60 degrees, or something like that. Not let them run constantly. The machine would get too hot to touch, theoretically, and would be cost prohibitive.
But, like I said, a heat source attached to a heavy casting would impart heat that would migrate to the rest of the thing... not sure if a heat lamp could get that much heat into them, or not.
I would think that below 32 degrees there will be no more rust. I would worry about any water based coolant freezing and breaking stuff. The rust only occurs as the dew point is crossed.
At -40 plastic and rubber may break if touched, including electricaL cords.
The first question is how long will they be stored in this unheated garage? If one winter a good coating of WD40 or similar will work. Every month spray some more on. Keep the WD40 in the heated house or it will turn to sludge in -40.

If for years, coat all the unpainted metal surfaces with boat trailer grease.
Condensation comes from moving air streams ,and changes of temperature..........the vintage car and bike storage places put a plastic bag around and de- air it as far as possible ,then refill it with dry air or for very valuable stuff ,dry nitrogen.......be wary of various de- humidifiers ........all of them need careful supervision to avoid bad outcomes .
Incidentally ,US Army research into gun corrosion found no rust at relative humidity less than 30%RH...........this is why valuables are stored in salt mines ......the humidity is around 3%RH ......a similar effect in the Chilean high desert.....even in salt water ,nothing rusts.
I agree with Joe E on the magnet oil pan heaters , but don't put them on one end , try to get them as much in the middle of all the mass as you can . That way the heat can move out both directions . The good ones are made by Kat's . I have a few of them , 2 300 watt's & one 200 watt , as you probably guessed the 200 is smaller than the 300 . If ya need I can get ye dimensions of the heater part tomorrow .
What are the risks of storing a mill and a lathe in an unheated garage, in a climate where winter can go as low as -40 Celcius ?

Can it be mitigated with generous oiling of everything ?
What kind of machinery are we talking about here?
A couple hundred thou apiece new machines or some clunky old estate sale bargains?
If you don't keep your machines in a climate controlled shop they're gonna rust. Period!
That is just the reality of ferrous materials.
My shop is unheated. We dont get -40 but we get -25f (btw, -40c = -40f)
I use chainsaw bar and chain oil on my machine tools. It clings to surfaces better that vactra, etc. There may be better products but bar oil is cheap and what I use
A couple of times a winter I take a 1 1/2" china bristle brush and paint all the bare parts with that oil.
Some additional random thoughts:
Expect some of your paint to flake off in those temperatures. My old Monarch looks like it has leprosy.
Also, I recommend you not run your machines in those temps though not for the reasons you might think.
I spent a couple of days doing a job on my lathe last winter. It was a balmy 21f and I froze the tips on 2 of my toes.


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biggest thing like others have said is the moisture when it heats back up, when its cold, no big deal, when its warm everything sweats, even the concrete unless you keep it slightly warm and dry, wood stoves work well for that and having a water and vapour tight storage area with good dehumidification.
only times things got rusted was when there was a leak into my shop and the RH was id guess in the 98% range for a week and everything was wet with gallons of water. what a pain.
I like WD-40. Not gonna put LPS-3 or cosmoline on unless storage. Goo.
So cold shop.
My grinders get very unhappy with temp changes and size control so the building is kept within +/- 4 degrees all year long.
Now my garage shop up north at the cabin where most is making or fixing parts for bikes, quads and sleds.
No temp control. WD-40 spray down on both the machines and tooling which was learned.
The SG needs lots of warm up cycles in the winter or size control a bitch.
The lathe and mill just need the spindle turned on for a few minutes and a bit of moving the slides before making.
Your mileage may vary.
the rusting is caused when the temp of the machine is colder than the air temp, water condense,s on the tables ect and you get rust, the more the water % in the air the more rust you get. keep the machine warm and there will be little rust.
Wern't the incandescent bulbs just outlawed nation wide recently?
Though I prefer LEDs for lighting...
A lot of people will need to use a 200W heater in their well pump enclosure to keep it from freezing in winter instead of a more focusable 100W incandescent bulb like they used before.