So today i found my MPCNC al crooked and out of square.
Turns out what i had feared during the winter had come true in the summer.
I use an converted glasshouse (kas) as hobby space and the last few weeks have been exceptionally hot.
The PLA has started to become soft in the heat and the XYZ gantry was completely unuseable.
Here are some pictures: https://photos.app.goo.gl/xiy3JPhnCGhzC78y5
Well off to print a new XYZ gantry i guess. in petG this time!
I don’t think pla or petg is uv stable.
I think glass reflects UV though.
I know it’s a bummer. But it does look funny. Like the MPCNC is sad.
Newer PLA has a Glass Transition temp of about 65, your machine looks like it got well above that, PTEG is at 85, I think you need to find a different storage spot. I don’t think PETG will help much if it stays really hot for several hours you are inviting creep to really speed up. The parts are under a lot of tension.
Well it sure made me sad 
Unfortunately that isn’t an option. i will try to cover the MPCNC with a better isolating tarp or something when not in use. I think (hope) the 15 degrees difference in glass temp will also help… and i must say, last week was exceptionally hot for dutch standards.
Maybe. Usually greenhouse glass let’s more in than house glass. I’ve gotten sunburnt working in a greenhouse before.
Well the MPCNC was under a clear plastic sheet when not in use, to keep out dirt and water (the greenhouse is far from waterproof as some glass from the roof has broken during storms and such)
I am now looking for a sheet that will keep out heat, water and dirt 
Any suggestions?
I have printed a new XYZ gantry and will install it this weekend
It’s always going to be too hot in a greenhouse, that’s their purpose in life. Unless you print your parts in cf nylon or abs, I think it’s going to sag.
While i agree with you that this location is not optimal, i have to do with what i have.
I am stuck in my dad’s greenhouse for at least the next year and have already printed a new XYZ gantry in PETG.
This gives me about 20 degrees celcius it can take extra. We will find out if this is enough soon.
In the meantime i would like to give it the biggest change of succeeding i can get so i will try to find a sheet of something that can reflect most of the heat.
If you used some bivy sack type material you could reflect a lot of the light, but if it’s just reflecting and hitting the inside of the greenhouse, it will warm the air up in the green house. If you don’t reduce the air temp, it probably won’t help.
Of you put a sleeping bag on it, it would insulate the machine from the air, but it just slows down the process. It would basically average out the temperature over a few hours. It might help if the temp went from 25C to 30C and then back to 25C. The machine might stay closer to 27.5C.
Do you need it to still work as a greenhouse? You could cover the glass (tarp, white paint?). You could vent it really well, by opening the windows and adding a fan.
Or you could bring out some ice/dry ice or bring it inside when it gets super hot. That’s kind of redicilous though.
Is that black piece a fan on your spindle collet?
Emergency blankets, those foil looking ones that firefighters use, might do good for help in isolating from heat. That and fans blowing out of those broken panes…