Shakeproof Washers Data
I have been looking closely at the Supply Unit lately, a bit nervously at first, but the more I study it, the better idea I have for developing a logical game plan in place for restoring it. The biggest part of that plan is going to be getting all the parts and things required on hand and ready to go before I start.
The Supply Unit will have to be fully disassembled in order to get everything done. So far, that process appears to only involve unsoldering one electrical connection, to the Blower Motor mounted to the front panel. I think (subject to further study) all other soldered connections can remain intact, provided I sort out the best sequence for unbolting all the other components for removal. The most challenging bit I can see so far is the removal of the front panel. It will be captive on the two drop cords until I can move it far enough away from the chassis of the Supply Unit to access the phenolic panel terminal board all the Drop Cord wires are screwed on to, directly behind the panel.
One of the things I have needed to sort out has been the types/sizes of Shakeproof Washers used in the Supply Unit, since as I already found, very few original internal toothed washers survived the 1966 Overhaul at 202 Workshop. This has been quite a challenge.
I started by listing the Shakeproof Washers from the Hardware List for the Wireless Set No. 52, taken from the 1945 Issue of the Master Parts List. This list of washers was only 10 items long and no data references were provided at all, just a 4-digit part code that could have been Canadian Army, or Shakeproof in origin. To get more data to play with, I went to the Illustrated Parts List for the Wireless Set No. 19 Mk III Cdn and added all the Shakeproof Washers from it to my list. That gave me 20 washers overall to play with, along with their related VAOS Numbers.
The other valuable thing about the 19-Set Parts List is that it is stuffed full of exploded illustrations showing the exact relationships for all the parts, including the hardware. It took a few days, but I was able to search each diagram, find the Shakeproof Washer and link it to a specific type and size of screw, or hex nut either American Standard, or British Association. That gave me 17 bits of data for 40 possible machine screw sizes, with a grey area for shouldered screws when the washer was fitted to the shoulder and not the main shank of the screw.
For the 14 American Standard Size Gauges I could identify, it started to look like the last two digits of the Parts List Shakeproof Washer Numbers related to the Gauge Size of the Machine Screw. That led me to suspect the first two digits probably held additional useful information, but there were just too many options. So yesterday morning I decided to call in the experts at Shakeproof in Wisconsin, USA and ask if they could help. I have now received a reply back from the Shakeproof Sales Team that I was indeed on the right track.
Shakeproof did have a ‘smart number part number system’. It is geared towards the American Standard Size Gauge and the last two digits of the part number for the washers identify the machine screw size up to #12. At ‘14’ it switches to standard inch fractions, more or less logically. More on that will follow shortly.
The first two numbers on the part numbers for the washers identify the tooth pattern and the material used in the washers.
I am currently updating the spreadsheet I have created to sort this all out and when completed will post a copy of it here for future reference, and include a discussion of how the BA Machine Screws fit in.
David
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