Jul 31, 2012, 04:54 PM
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Stator coating

I thought I should know what the green goop on stators is. I just realized it's powder coating.
Now to find a source in small quantity's.

After reviewing this thread I see it needs updating. As soon as I'm back online at home I'll do a start to finish post on this process with pictures. In the learning process I tried allot of unnecessary steps, but here it is in a nutshell. KISS comes in handy here.
1) Clean the stator of loose coating and oil.
2) Lay out some foil to catch excess powder and pile on some coating. I use my finger tips and/or a little shovel I made. The pile can be shoved and flattened with a small screw driver or something, if needed. If you don't like it dump it off and start over.
3) Cook in convection oven at recommended temp for about 20 Min. I have not tried a regular oven but wouldn't be surprised that it would work fine.
4) Clean up, if needed, is easy with an Xacto knife, needle file, sand paper. rotary tool with diamond dust burr, you get the idea, just avoid removing metal.
5) Repeat on other side. The coating does not soften when once cooked.
6) If you don't like the results, remove the blemish and re coat and recook.
This has proven to work very well and holds up to over heat as well.


Last edited by zeroback; Today at 02:17 PM.
Last edited by zeroback; Apr 21, 2013 at 12:26 PM. Reason: To save reading the whole thread to get to this
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Jul 31, 2012, 07:44 PM
Registered User
sneu's Avatar
Originally Posted by zeroback View Post
I thought I should know what the green goop on stators is. I just realized it's powder coating.
Now to find a source in small quantity's.
Not just any powder coating it is a epoxy that is designed for coating stator laminations. 3M is one supplier but good luck in getting samples. FYI it is usually applied using a fluidized bed process--not electrostatic.

Steve Neu
Jul 31, 2012, 09:13 PM
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Thanks for that tid bit of information. I gather from the 3M comment that it's for sale in industrial size batches. My thought was leaning towards the aluminum/ metalized (looking) powder coat used on T-tops for boats. In SoFla there are several company's in the area that sell that type of finishing. It certainly is some tuff stuff when applied to boat parts. Leads me to believe that it has to be a better remedy for the stator goo blues than the what I have currently available. My other thought is if the shiny material in the finish is metal perhaps that would help heat transfer. On the same token I would think that even standard powder coating would beat JB, IC-2000, nail polish etc.
As a test I can probably send a stator out with some boat parts that are being treated and see how it works.
Aug 01, 2012, 07:11 AM
jackerbes's Avatar
Can they dip it? Or do they spray it? I think that dipping is one of the keys to getting a good coating, that and the viscosity as it is applied.

I wonder if anyone has tried the classic stator paint Glyptal? That has worked on electric motors and various places and parts on motors, cars, and motorcycles for most of the last century or so. It was the often seen red coating. The attached is the specs for it but I have not brought myself to cough up the $50 per quart or so to buy some...

Has anyone ever tried Glyptal 1201 (not 1201A aerosol paint) with a dip application?

Aug 01, 2012, 08:54 AM
Registered User
sneu's Avatar
The electrical grade Epoxy is quite hard and provides good protection for edges of the stator where the wires come in contact preventing what is called "cut through". There is little to be lost trying other materials and they may well work well enough---but the real stator coatings have traits that were developed for motor use.

Aug 01, 2012, 10:17 AM
Suspended Account
Oops.I just realized metal in a coating would be contrary to a dielectric.
Back to the drawing board.
Last edited by zeroback; Aug 01, 2012 at 12:09 PM.
Aug 01, 2012, 01:36 PM
modisc's Avatar
Originally Posted by zeroback View Post
Oops.I just realized metal in a coating would be contrary to a dielectric.
Back to the drawing board.
I thought about the powder paint before, but it seems it will be really difficult to put a "thin but evenly distributed" layer of the "green stuff" on the stator. And as Steve said, not all type of powder paint will work well for stators. So i turned to kapton, and it works really well. 0.125mm thick kapton is strong enough for most of my motors, with the edges of the teeth sandered. I have stocked some 0.15mm thick and 0.2mm thick kapton, but they are comparatively much harder than the 0.125 film.

Here is a pic of the stator i just prepared for a rewind with 2.24mm wire (copper diameter, QZYXY-200 degree C) . 2 layers of 0.125mm kapton is covering the edges which are already aggrasively sandered, as you can see. The films are hold in place by CA glue, to make the winding job easier. The kapton does a very good job, and i personally think it is much better than the DMD white insulation paper used by Scorpion motors.

I disassembled many scorpions by heat, and most of the time, the DMD paper will melt a little bit. But when I disassemble 2 of my personally rewinded scorpion by heat with the kapton as the insulation film, the kapton is totally unchanged and undamaged and even can be reused.

For a normal RC motor (outrunners), I would not bother this much. Just cut the kapton film into proper size, and fit in the slot, and do a winding job. works really great.
Aug 01, 2012, 09:57 PM
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How to build a fluid bed for powder coating (2 min 27 sec)

A couple of links I found on the process
Aug 07, 2012, 09:35 PM
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olmod's Avatar
I have used an epoxy not fast setting rather a slow setting that goes very hard and added some micro balloons as a filler when warmed on a lid off a jar and mixed well ,i use a depth of around 1 mm and simply dip the ends only of the stator in and let cure hanging in a warm room on a coat hangar,after cure any excess can be removed by hand using a needle file. you can add your own colour to the mix if you wish it helps to see better. it also helps to warm the stator prior to the dip.
Aug 08, 2012, 08:58 AM
Suspended Account
Thanks for the tips. The problem I have had with the epoxy (JB weld 24hr cure) is that it dose not get near as hard as the powder coat. Under pressure of the wire it tends to crack or mush out allowing the wire to catch the sharp edges. I have thought about this and it maybe in part that I'm mixing small amount and the ratio is not exactly 1:1. I was considering mixing the entire amount in the tube to insure proper ratio. I have the same problem with the rubberized CA that it moves under PSI. This mushing out effect is proportional to the size of the wire. Using small multistrand wire those chemicals work OK. Using larger wire, like 21, 22 , 23 AWG the amount of pressure exerted during a bend exceeds the goops ability to hold. A harder/stronger epoxy would solve this problem. I've seen on a kite (CF source) building supply site a $45.00 an oz (or so) epoxy from 3M. I just haven't had the money to experiment with it.
Aug 08, 2012, 09:11 AM
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The fellow who made the video on a HM powder coating rig has 4 more very short video's on Ytoob. It seems like some one edited part 2 into several 7 second video's that are missing pertinent info. It makes no sense that the guy that went to all that trouble to produce a video and then leaves the rest of his process hidden. At least there is enough for a starter kit. http://www.powderperfect.com/diy.asp I found some more info here and am researching the best deal on supplies as there are a few PC retailers out there.
Last edited by zeroback; Aug 08, 2012 at 09:17 AM.
Aug 10, 2012, 11:18 AM
low tech high tech
vtdiy's Avatar
Originally Posted by zeroback View Post
Thanks for the tips. The problem I have had with the epoxy (JB weld 24hr cure)
I believe JB Weld has powdered metal in the formulation, if that's important to you. Also, OTC epoxies generally cure and increase in hardness over a long period of time, not just overnight.

Hardness and cure also depend on mixing quality and proportions -- hard to achieve good quality mixes with a pre-thickened OTC glue epoxy squeezed in small amounts, measured by eye, out of a couple of tubes, and then stirred with a stick for a minute.

There will be a lot of uncured resin and hardener in the cured coating.
Aug 10, 2012, 11:22 AM
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vtdiy's Avatar
What about liquid styrene? As in styrofoam dissolved in acetone until a saturated solution? Too weak?
Aug 10, 2012, 11:55 AM
Scratch builder
I would think Styrene will melt at armature temperatures.

I've seen fiber laminations used just on each end of the stack for insulation. They are sometimes slightly oversized to be sure to cover the edges of the laminations.

Electro static fluidizing is not the easiest process to duplicate at home. Even here at work I've seen a many ruined stacks. We also use epoxy powder as a spray process. The parts are heated and the epoxy powder is sprayed onto them. Nozzles aimed to match the skew of our armatures blow the powder through the slots as the part rotates.
The powder liquifies a bit when it hits the heated part thus the name "fluidizing". Subsequent oven curing is necessary.

The powder used for electro static coating must be kept free of moisture (humidity) as in a refrigerator. If not, it will not puff up in the electro static bed. It sticks to anything grounded and is a pain to clean off reliably. Very messy in general. The whole room is a shade of blue from the powder.

I've never tried it but maybe many coats of engine spray paint could be applied to the end lams? I would probably oven cure to get maximum toughness? Has anyone tried it?
Aug 10, 2012, 12:17 PM
low tech high tech
vtdiy's Avatar
Sorry, should have said polystyrene, not styrene. And it looks like the temp limit is 80C.

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