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Part 2, Shield and Insulator, Spark plug 32070-42

The next part was quite interesting to make, it had a bakelite insulator clamped between 2 thin steel shells. 3 little pins fit in the bayonets on the lower shield and the fine threads go on the HT lead. I started by learning everything I could about Bakelite, quite interesting stuff! The 4 pictures below are of a very, very rare original Harley XA Shield, this was my example.

 
 

 

I ended up having the insulators CNC machined from a solid sheet of Bakelite and started with all the tools needed to make the steel shells. I started by cutting about 30 rectangular pieces of stainless steel and pressing the first stage using a hydraulic press and a bathtub shaped female die that would double as a drill guide later.

 
 

After pressing, the bathtub shape still had a big flap that needed to be removed, so after cutting off the corners with a nibbler, I made 2 sanding dies and a new lowered support on my beltsander so that I could remove the excess material in a precise way

 
 

The threaded connectors and small pins for the bayonet were all CNC machined, and so was the next set of tools that are designed to fold the edge of the shield. I made a brass tool to position the threaded part to the shield for TIG welding, this same tool is also used as a drilling jig for 2 of the small holes for the pins.


 
 

Using a steel frame and a 12 Ton car jack I folded the edges of half of the shields 90 degrees. Later when the welding is done and the pins and insulator are installed, the edge will be folded all the way around the edge of the other shield.


 

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