That is great info at least- I was surely gonna be excited to time my open-box-to-first-print time, but thinking about what you’ve said, I’ll be waiting overnight before firing it up!
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No. Mine was in an unheated truck at 9F and then in my garage at a similar temp for several days. It never got over 10F. When I brought it inside I left it for a day to warm up before I powered it up and it’s working fine.
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So the only remaining detail that will be useful to know…
Does the GF ship with the coolant evacuated from the laser tube, or is it fully filled in the glasstube…
I seem to remember lots of bubbles my first time turning it on, but I failed to notice if the coolant was simply evacuated until first power on or not… (Having the coolant evacuated could allow the coolant to expand safely during shipping)
Anyone letting their GF go below 32F for the winter after having used it? 
I do not believe it’s in the tube when shipped. The color of the tube changed when I powered it up.
Having the coolant evacuated could allow the coolant to expand safely during shipping
So we still have the question, what happens to the tube & coolant at sub 32F temps… I dont know that I saw an answer to that above. But the -9F temps during shipping is very interesting, we know it survives that (though the glass may not be in contact yet with any fluids)…
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This is what I meant in my other post about “self heating mode”. There is something on the order of 800W of demand when the unit is running. I think I read that somewhere. Even when running in a coldish shop (with coldish shop makeup air flowing into the unit), the unit still heats up when you use it. Presumably there is a way to make the unit draw some power without turning on the laser.
The question I had was whether the unit could be programmed (as a feature request) to draw some power automatically to heat itself in a standby mode to keep anything untoward from happening in the instances when the ambient temp drops below 40F.
For example, running the coolant pump intermittently would create heat and also keep the coolant from freezing, if in fact there is an issue with it freezing at some certain temperature.
That’s super interesting. But doesn’t the machine suck cold air in, even when idle? In a “warm” machine, I’d never run bitter cold air in there without worrying about cracking something (warm glass getting a blast of -9 F air on it… yikes). This could be the basis for their 40F minimum storage temp guideline to reduce extremes which could crack the glass - assuming GF customers have it plugged in and in idle mode 100% of the time.
Honestly, I dont understand at all who would leave the power switch on 100% of the time. Bright lights, and fans running give me 3 worries: electric bill, wear and tear on components, and noise! I always turn mine off.
Would be AWESOME to have a device I could leave inside the machine that would regulate temperature to a given setting (i.e. 45F). Without any fans sucking cold air in, this could be a solid solution! Reminds me of dog bowl heaters that you leave in an outside dog dish.
Since my GF is in a lower part of the house I can’t hear the fans at idle or see the lights. The electric use at idle is not very high. 41 watts on the Pro with the pump running. But understand why folks might want to power it down for convenience and energy efficiency.
However, as far as the wear and tear on components, the power on/off process is typically much harder on larger electronics than continuous running at idle. For a well designed piece of electronics it technically shouldn’t matter whether it’s left on or powered down. But the constant thermal change from hot to cool, hot to cool causes wear on the best of electronics, solder joints, etc. I tend to be in the camp of shutting the machine down only when it’s done for the day.
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What do you think about putting a small heating pad on top the crumbtray, always on… Attempt to maintain a ~60F temperature in there…
This one has 6 temperature settings…
My basement with the GF is cold since I only heat the upper floors with wood. Its in the mid 40s down there right now. I have a brick that sits on the edge of my wood stove all day. If I want to use the GF in the next hour I’ll turn on the furnace and lay the warm brick and a remote temperature sensor at different ends of the crumb tray with the lid closed. Once the temp sensor works it’s way up to the mid 60s, about 15 minutes, the GF is ready to turn on. BTW: the brick is probably only about 150F and gives off a slow radiant heat for quite a while.
Same way my Grandparents used to get their beds warm on a cold winter night
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Based on the number of aunts/uncles I have, I’d guess my grandparents used an alternative to the brick. 
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Love the brick method. ;-).
So what I really really want is a way to regulate the tempurature of my GF interior to minimize thermal contraction/expansion during winter, and maybe so that it is always ready to go (warmed up like your brick). It’s not a production machine for me, so I’m fine having a few weeks of downtime a year.
That’s why I was thinking about the temperature regulated heating pad above.
Now “ready to go” could only work when the outside air temp is high enough (40-60?) since you don’t want to have a blast of cold air hit the warm components inside (causing hot/cold spots, weird expand/contract… boom). But could equally run the outside air through a regulated heat box, to avoid temperature differences… probably more complicated than I want to hassle with.
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Received a new GF this afternoon. Has not yet been powered and there is definitely fluid and a few bubbles in the tube.
It was about zero at the local UPS office when it arrived, 13F in the afternoon when delivered. I quickly unwrapped it, dropped a wireless temperature sensor inside, closed the lid and put the box top back on. The sensor dropped to 32F and stayed close to that for hours. So the UPS hubs must have some heat.
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Interesting. But clearly they aren’t caring about sub 0F temps, and the tube is not evacuated. So that tells us a story doesn’t it. That there is no danger at that temperature. Perhaps the liquid is non expanding
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The company is not likely to give us any official insight. I say this with 27+ months experience of unanswered simple questions.
Each of us will make our own assumptions. Mine is that the company is not comfortable that the units will maintain reliability if someone were to store a machine at very low temperatures and turn it on before coming completely up to an operating temperature. If you store it at 40F and turn it on it may not operate until reaching a safe temp but isn’t likely to suffer from thermal issues. If you store it at zero F and turn it on then it’s completely plausible that something really bad might happen. But who knows.
If the company says don’t let the unit go below 40F then they aren’t relying on the common sense of their customer base. For every smart person on this forum there is an idiot thinking they are a smart person.
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Understood.
1.) But they should understand I’m asking about a factual physical property of the coolant (freezing point, and does it expand). Not asking the company to make a guarantee or contractually binding statement that could bite them. Maybe some geek talk about “yeah the lubricant can slough off the runs when too cold, and you dont want to delubricate your machine”. The degree of silence is stupid. I did write to support@glowforge.com and was copy/pasted the same 40F line from the manual, I asked for more info of what could possibly happen at lower temps, and got the wall (sorry we dont test beyond that). But maybe they all live in sunny california/seattle and just can’t relate to the polar vortex
I’m not even looking for how to get it safely powered on from 0F… Simply looking for safe (longterm) storage that wont crack parts.
2.) Beyond that, as a 2nd avenue of strategy… I’m happy trying to maintain 40F in my GF, which is why I brought up the heating pad.
I think the anecdotal reports here are telling me that for #1 the coolant probably doesn’t expand, and probably doesn’t freeze above -9F. Maybe it gets less viscous, who knows (who cares). For #2, I’d like a PID controlled temperature regulated heating pad, ideally a neck pad (or something of that size) that I can simply drape over the crumb tray with a cord hanging out, for the winter storage (not intended for running).
That’s my mind at the moment
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I wonder if a reptile heating pad/rock would be a good warmer?
Pet Mat, Motina Reptile 14W Heating Pad 110V Reptile under Tank Warmer Mat Heat Pad With Temperature Controller (11’‘Wx11’'L) https://www.amazon.com/dp/B07433D9NP/ref=cm_sw_r_cp_api_-BguAb8RG7Z7G
Heating pads usually have a timed auto-off, where these are thermally controlled. Interesting.
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In addition, I would think you could also run a bead of silicone or caulking around each connection to further seal them, but use a rubber gasket of some kind if you’re using PVC hardpipe to connect to glowforge itself. I’m going to look at options for hard pipe, since my unit will be immediately next to a window. Im not a fan of flex…it kills airflow cause of all those ridges.
That is super interesting. That’s a great idea.
Found this 10x20.5” mat with 68-108F temperature control.
Almost perfect for GF
iPower 10" x 20.5" Small Warm Hydroponic Seedling Heat Mat and 68-108°F Digital Thermostat Control Combo Set for Seed Germination https://www.amazon.com/dp/B01IDQD32Y/ref=cm_sw_r_cp_api_rlvvAb3A4Q7GY
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