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Post by dakota on Oct 17, 2013 12:57:32 GMT -5
What is the recommended steel for the K27 frame? I can find 3/8 x 2 1/2 bar shape in 1018 cold roll everywhere but that is low carbon. Reading about A36 hot roll does not sound good, poor quality control.
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Post by Ed Hume on Oct 17, 2013 15:10:16 GMT -5
If you look at the carbon composition range that Kozo specifies in the first series article, 0.2 to 0.25%, these are usually called mild steels and overlap with low carbon steels as well as medium steels so the use of only the medium word to describe them was unfortunate. I have corresponded with Kozo-san on this very issue. Kozo-san was referring to steels having the “easiest machining characteristic” among steels. He advises that “Steel containing a higher carbon, say 0.45%, is undesirably hardened if it is quickly cooled.”
So 1018 is a completely suitable choice as is 12L14 and the other commonly available steels. You can buy 1018 as precision ground as well as ordinary cold roll but the precision ground stock is typically not longer than 2 ft.
If the part is never subjected to silver soldering or heating, a higher level of carbon only implies less ease of machining which can mean taps more easily broken off in threaded holes, more tool wear, etc.
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