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Very small and thin transparent enclosure
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jmaja:

--- Quote from: reboots on April 13, 2019, 07:36:26 pm ---Do not allow your machine shop to use any kind of process coolant or lubricant other than water.

--- End quote ---

What is the reasoning behind this? Machine shop would like to use the same cutting fluid mixture they use for other stuff. Mainly water, but does include other stuff to make it non-corrosive and better lubricant. Is PC sensitive to these chemicals?
Ian.M:

--- Quote from: jmaja on April 16, 2019, 06:56:23 am ---
--- Quote from: reboots on April 13, 2019, 07:36:26 pm ---Do not allow your machine shop to use any kind of process coolant or lubricant other than water.

--- End quote ---

What is the reasoning behind this? Machine shop would like to use the same cutting fluid mixture they use for other stuff. Mainly water, but does include other stuff to make it non-corrosive and better lubricant. Is PC sensitive to these chemicals?

--- End quote ---
Very!  If exposed to the wrong solvents or certain oils, Polycarbonate becomes very brittle and then cracks readily and can even craze like broken safety glass just from internal stresses and diurnal temperature cycling.
https://www.theplasticshop.co.uk/plastic_technical_data_sheets/chemical_resistance_guide_polycarbonate_sheet.pdf

A little dish soap can be added to the water to lubricate the cut as well as cool it, but you wont be popular with the machine shop unless they are set up for a lot of plastics work with a separate mill, free from metal cutting fluids, as the dish soap will FUBAR their soluble oil coolant and may wash away too much oil from the mill table mechanism causing it to rust.
Psi:
+1 for heatshink tubing.

Not the normal heatshrink though, you can get special stuff that is thinner than normal heatshrink and sets much harder.
It's the stuff used on RC speed controllers and the like.
I think it's usually called 'thin wall' or 'ultra thin wall'
jmaja:
Machining seems to be quite challenging. The 6 mm thick part we used as stock bends too easily making very difficult to get the thin walls (0.8 mm) right. One had 0.8 mm, but the next only 0.45 mm, which was way too flexible, but still surprisingly difficult to break. I even hit it with a hammer (not that hard) and it survived. The enclosure appears to be too flexible in total making it probably leak in use. It's now only 4.7 mm thick with 0.6-2.2 mm walls. Probably will try to use ~6 mm total thickness allowing for 1.2-2.8 mm walls and more margin for the O-ring.
reboots:

--- Quote from: Ian.M on April 16, 2019, 10:38:37 am ---
--- Quote from: jmaja on April 16, 2019, 06:56:23 am ---
--- Quote from: reboots on April 13, 2019, 07:36:26 pm ---Do not allow your machine shop to use any kind of process coolant or lubricant other than water.

--- End quote ---

What is the reasoning behind this? Machine shop would like to use the same cutting fluid mixture they use for other stuff. Mainly water, but does include other stuff to make it non-corrosive and better lubricant. Is PC sensitive to these chemicals?

--- End quote ---
Very!  If exposed to the wrong solvents or certain oils, Polycarbonate becomes very brittle and then cracks readily and can even craze like broken safety glass just from internal stresses and diurnal temperature cycling.
https://www.theplasticshop.co.uk/plastic_technical_data_sheets/chemical_resistance_guide_polycarbonate_sheet.pdf

A little dish soap can be added to the water to lubricate the cut as well as cool it, but you wont be popular with the machine shop unless they are set up for a lot of plastics work with a separate mill, free from metal cutting fluids, as the dish soap will FUBAR their soluble oil coolant and may wash away too much oil from the mill table mechanism causing it to rust.

--- End quote ---

Seconding Ian.M's explanation, which describes my experience. As as alternative, your machine shop might prefer to machine dry with compressed air for cooling and chip removal. You may still need to wash the parts in detergent to remove any oils from the tooling.
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