View single post by Mike Kearns
 Posted: Wed Mar 11th, 2020 08:21 am
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Mike Kearns



Joined: Fri Nov 24th, 2006
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 1951 - A very interesting blade material variation has surfaced, mentioned in the Hueglin patent for blade design and assembly U.S. 2542251 - 





 




This Diehl circulator example has factory plastic blades, a scarcely encountered material mentioned in the 2542251 patent, kindly shared from the Welker Collection: 





The circular depressions in the backs of the blades are likely for balancing purposes:





The black plastic blades seem to have a coating of aluminum colored paint simulating cast-aluminum:








Last edited on Sat Apr 25th, 2020 07:52 am by Mike Kearns