Saturday, January 9, 2016

Finishing Aluminum Parts

The aluminum bits on the Interceptor were in good shape overall but corroded and scratched. They still had the original factory finish which gave me a good guide for polishing. 

Original state......good shape but in need of refinishing. 

I don’t like to remove more material than necessary when polishing as voids in the castings may pop out. This happened on my transmission cover & had to be repaired with low melt temperature rod. Starting out with the highest grit paper that will remove the largest scratches, usually 320, a progression of papers is taken to 1200 grit. Each grit is applied 90 degrees to the previous one and a rubber block is used to minimize dips and waves. The parts then move to a stationary buffing wheel where sanding scratches are removed. Rubbing compound is worked by hand for the final gloss. I use “Semi-chrome” or “Mother’s Billet” for this final step. I find that working with paper keeps the degradation of the surface to a minimum, although it is a lengthy process. 

Filling a 3 mm void which came out of the casting during sanding. 

There was small black spot to start which opened up quite rapidly. 

Pit filled and case polished. A small pit remains but overall it looks good. 
I am afraid to polish any further as it may expose more voids. 

Finishing complete, with the exception of the transmission inner side cover.  
It will be polished when it is rebuilt. 

The brakes had hardware riveted in place. They were left in place and painted to replicate CAD.

Another diversion....The Hornet forks are dripping from the damper rod bolts and fork seal retainers....time to disassemble and reseal. On with my quest for a somewhat leak free BSA ...... I thought engine may leak but after 400 miles or so but it is sealed up pretty good. 

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