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Thermal overload breaker thred size help

Froneck

Titanium
Joined
Dec 4, 2010
Location
McClure, PA 17059
A bit off topic but I'm building a 50A 12V DC power supply. Purchased 50A thermal overload breaker panel mounted push button reset on ebay. Though in the photo the knurled nut was on the breaker it was not included. I contacted the seller and was told not included, I mentioned the photo included the nut. My option was to return it for full credit or $3 credit. I took the $3 so as not have to bother returning it.
However in checking thread size I'm coming up with 11mm or 7/16" But thread pitch is either 1mm or 25tpi. My thread gauges don't seem to fit quite right, threads are not the cleanest. I put it on optical comparator and 1mm seem to be the best guess. Does anyone know what size knurled nuts are available? Ebay as a few, those with size and pitch and not near what I need though 7/16" is available but thread pitch not listed. Others are listed but rather than size application is listed. 11mm X 1mm Tap is available probably from China.
 
Seems that 3/8-27 was a "thing" on some switches and related things.... I'd have to check some in the lab to see.
 
As I mentioned none of the inch thread gauges fit 25,26 or 27TPI However 26 seems to fit best. On my optical comparator 1mm seems to be the pitch. Using a shadow image on threads is kinda blurry due to the pitch of the threads. I tried surface illumination that I usually use to measure thread pitch but due to the poor surface finish it to is a bit blurry. It is dam near 1mm. My Guess is it is 11mm X 1mm, McMaster does stock a tap that size.
 
I checked, and the things I was thinking were similar (standard toggle switches) are a 0.465-32 thread. (15/32-32)
 
I have a few items with the nut, they are different sizes but none 11mm. Have 7/16" nut threads not correct. Found 12mm on ebay. I guess it would be best to buy cheap Chinese tap. The one on McMaster will be over $100 with shipping!
 








 
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