Re: Earlier runs often better than late runs


dh30973
 

I’ll add my two cents to this discussion. About 13 years ago following his death, I purchased Gordon Cannon’s business of diesel detail parts, Cannon and Company, and continue to run it to date. The vast majority of the molds he created were made old school with a 2D pantograph and small precision milling machine with hand ground cutters in brass. Maybe a dozen were made by someone else for him in 7075 Aluminum by means of CNC machining. The advantage of brass is easy cutting and polishing, with the aluminum being slightly harder in both regards. The brass as Dennis noted is easily damaged by both stuck and partly ejected parts as the mold closes on the part. Repair can be sometimes be done but is tricky. The aluminum is more durable. Some of my brass molds have shot tens of thousands of parts with out any issue while others are getting long on the tooth. A lot seems to depend  on how much draft Gordon included. The ones with very little to no draft are more prone to sticking and therefore getting smashed, while others eject freely. But more draft makes parts with less fidelity, so there is a trade off. 
Apparently the tooling now being done by the big manufacturers and done in China are cut in steel by means of EDM. While those have the capability of millions of shots it is unlikely they will actually ever make that many. Our hobby does no longer support those quantities like the old days of Athearn blue box kits. 

Dave Hussey
Cannon and Company 

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