Lets start with the making of epoxied stator.
What we want: Make the stator iron and windings waterproof by filling up all cavities and wetten all surfaces with epoxy.
What we need:
A vacuum source (see above to get some examples),
a vacuum chamber
some hose OD 12mm ID 8mm, a thighting ring with ID 17mm,
Isopropanol 99% (from pharmacy) to prepare the stator
an M20 IP68 PVC cable clamp to adapt the hose to the lid
an electronic balance with accuracy better than 1g (kitchen balance might be too bad, check before use)
some gloves, stirring tool, a one way cup for mixing epoxy,
special epoxy with low viscosity and long geling time like Epoxid-Gießharz WASSERKLAR + Härter W 300 | R&G Faserverbundwerkstoffe ,
Prepare the stator with Isopropanol using the marmelade glass with the intact lid. Shake and roll it for some minutes, so all grease and oil is removed which might have been used during production.
Pour the isopropanol into an other container, maybe you can use it once more. Do this in fresh air so you dont get dizzy. Use gloves to handle the stator from now on, so the fat on your hands is not getting on the stator. Let the stator dry for half an hour in dry, warm condition. If you want to be absolutley sure there is no water left, put it in an oven at 50°C for half an hour.
Prepare the lid, drill a hole into the center.
Widen the hole until it has a diameter of approx. 20mm.
Clean the lid with soap and water, let it dry. Mount the hose with the cable clamp. Use a rubber ring for thightening on the outside of the lid, ID 17mm. Do not tighten too much, otherwise the rubber ring is sqeezed out. Do not use any additional washer, this will make it untight.
Now its time to test your vacuum chamber.
You can use some warm water for testing, lets do it!
If it is boiling your vacuum is good.
Dip the cable ends into fluent wax to tighten them against epoxy.
Apply heat shrink you can pull off again later if you want, i use it to prevent cables being glued together forever. Close them by using a gripper while they are hot.
Use some larger heat shrink tube to gather them together.
Wear old cloth and put gloves on, use tissue to wipe away dripping epoxy.
Now mix the epoxy, i needed 150g, use 170g for safety. With the superprecision balance i can only measure up to 100g, so i needed to mix twice. Use a calculator and make sure you get it right! Some balances shut off after some time, make sure you know the weight of your empty cup. 1% accuracy for the mixture is good enough, dont panic. Mix and stirr it at least two minutes. Pour the resin into your vacuum chamber where the stator is already placed. Note the time, 16:20h. From now on you have 5 hours pot time and 10 h until the geling starts. Plan for the next 10 hours.
Make sure your vacuum chamber has a good stand, put on the lid and let the hose stand vertically. Use a long hose and make it go in spirals so no epoxy can reach your fridge compressor. The epoxy will be foaming when you apply vacuum and climb up a bit into the hose. Let your fridge compressor run until you see no bubbles coming out of the stator any more, which is normally taking 60 minutes. Wave the vacuum chamber around to let the air trapped beneath som cavities to get up and out. Now, do not switch the compressor off, it might take a long time until you can restart it because of the so called clixson, which is a device modeling the temperature of the compressor. You might use a fan to cool the compressor and the clixson. If the compressor switches off, dont panic. Cut off the power, let it cool down, normally after latest 30 minutes you can switch it on again.
Instead open the vacuum by pulling off the hose from the compressor. Let rest 15 minutes without vacuum applied, so the epoxy is sucked into cavities and can distribute.
Now apply vacuum again until no air bubbles proceed, which is normally taking less time than in the first run.
Do this over and over again until there are no air bubbles visible when applying vacuum.
Now you can decide how to proceed and plan your time. You can warm it up inside the chamber to speed up the process but be careful not to miss the best time window for taking out the stator and hang it up for dripping.
Flip it over from time to time to allow a homogenous thickness distribution of the coating.
Clean the bearing seatings with tissue from time to time. The threads are not endangered you can recut them with a tap after curing. Maybe you want to clean the leads heat shrink tube as well.
If you are satisified with the thickness use a hairdryer or an oven to warm it up to 50-80°C and speed up geling so the resin cannot run away and thin out the coating. Keep it at this temperature for the next 10h.
This was almost too late! I keep it at room temperature after it was heated in the chamber.
Your comments are welcome!
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After 4 hours curing i pressed together all surface irregularities simply using my gloves.