Monday, February 3, 2014

Turning Brake Drums

The brake drums were rusted and I suspected they were out of round. I made a simple fixture by machining aluminum round stock to accept the hub bearing surface. A bolt in the center was used to draw the hub down to it. The fixture was machined in a 3 jaw chuck and the hub put onto it without removing it from the lathe. This ensured everything ran concentric. If this fixture is setup again it will be put into a 4 jaw chuck and indicated concentric.  

A simple fixture turned in a 3 jaw chuck.  

 The hub was checked with a dial test indicator to see how far out of round it was. 
It measured .005 inches out on the radius. 

Very light cuts were taken and the drum was opened up about .020 in on the diameter. This is the minimum amount that could be removed and still get it to clean up. The resulting finish is good and new brake shoes will be fit to the larger diameter. Both drums were refinished in this manner. 

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