Where I left off last time:
I had new bearings coming from Germany, I had the armatures checked-out and turned-down, I had cleaned all of the parts (gears, bolts, etc), and was ready to clean-up the motor housings, both internally as well as externally.
Internally they looked like this (from last post):
Externally, both of them had a layer of sticky "gunk" on them that I felt had to be removed. However, I was really concerned about washing them with water and some sort of soap or solvent, as I didn't want the windings to get wet.
So, lacking a good idea on how to accomplish that task, I set it aside for the time being and moved-on....
Internally, I think I must have used an entire can of QD Electronic Cleaners (from NAPA) on each of the motor winding and housing assemblies, and it did a fantastic job!
It was while I was cleaning-out the inside of the motors that I realized how I could clean the outside, with water, and some sort of cleaning chemical, and not have to worry about having wet motor windings when I finished!
Some biographical & historical information first, though. My background is in the Commercial HVAC Service industry, and for many years I was a Commercial HVAC Service Technician. Maybe 20 years ago, while working for a Manufacturer based here in the Twin Cities area, we had some compressors "go down" in southern Florida, the result being water got inside of them. (Water in a refrigeration system can produce hydrochloric and hydrofluoric acids, and thus the combination is "not good".) Once we solved the issue of how the water got into the compressors, we had to dry them out, and one of the Engineers at the Company (and still a good friend of mine) devised the following method to remove the moisture:
* Isolate the compressors and hook them up to large, commercial, vacuum pumps.
* Disconnect the line voltage (460V AC) wires coming into the compressor, and at the compressor terminals, hook-up a Variac (115V AC) in order to power-up the motor windings...but at a low voltage.
* Adjust the Variac to a certain voltage and amp setting, and let the windings "cook" the water out of them.
* Change vacuum pump and compressor oil every 3-4 hours or so, until we got a reliable, and repeatable, vacuum level of 350 microns or so.
To this day, as far as I know (and I do ask.), those compressors in southern Florida are still up and running.
So, back to my issue: I had two motors that needed to be cleaned-up, and I needed to figure out a way to remove any water that may have gotten inside the windings while doing so.
So I got on Craigslist and bought this for $20:
An old pressure cooker.
Except I wasn't going to make pressure with it, but rather I was going to use it as a vacuum chamber.
So I removed the pressure gauge and vent, installed a Schrader fitting and a plug, and sealed the pressure relief valve with foil tape. I figured it wasn't designed for vacuum, and would most likely leak at the seal/lip around the circumference, so I covered the edges with foil tape as well.
An overnight test, and....success! It held a vacuum!
So the next day I put both motor housings inside:
About 30 hours later I shut everything down and checked the micron gauge, which was at around 280 microns. I let it stand for 15-20 minutes, came back....same number! Voila! No more water! (If the micron gauge number had changed, that would indicate moisture that was still being boiled-out of the windings).
In other words, whatever moisture that may have gotten into the motor windings was absolutely & positively removed!
So it was time for re-assembly, and this is what I had to work with (check-out those "squeaky clean" plastic gears!):
Except look closely and you'll see only one bearing on one of the armatures. Why?
That will have to wait until next time!
