Anonymous wrote:
Hi Howard,
yes you are correct but it is not always available, whereas I have found that 6063 is much easier to find and in a larger number of sizes, at least here in New Zealand. If using 6061 then the thickness could be reduced by about 20%. I would keep the diameter the same to allow for the splice.
David.
David:
Availability is an issue in many places I suspect. 6063 is usually a simple extrusion where 6061 T6 is usually drawn tubing. That alone makes a big difference in strength. My biggest objection to 6063 is that it does not tolerate flexing nearly as well. It will fatigue much faster........As you say it needs to be thicker so that any flex is within a very limited range because of the nature of fatigue. 6063 just does not give me that "warm and fuzzy feeling". Again, I think some sort of elastomer surrounding the mast so there is not an abrupt sharp pressure point would be something I would look seriously into.... I'm talking about virtually no detectable flex without extreme pressure. An outer sleeve only slightly larger than the mast with a welded circular flange that bolts to the partner, the intervening space filled with an elastomer. It would not be hard to build, and would give me at least some additional peace of mind. Losing a mast is the stuff of nightmares!
..........Maybe I'm making it too complicated, but I've been fixing broken stuff all my life. Wedges made of appropriate material perhaps.....
H.W.