03-31-2017, 11:11 AM
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#9
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Senior Member
Join Date: May 2010
Location: Windy City
Posts: 2,919
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Re: What are these?
The jacks are white iron, much harder than grey cast iron so they wear little in the tumbling machine. This is a common fettling process in a foundry. If you take a file to one you will find it is quite hard.
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