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Old 21st February 2007, 02:55 PM   #17
geo
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Join Date: Aug 2006
Posts: 327
Default RE: Some Streamlined related....

Quote:
Ola_H wrote:
Geo: Here is an image of the "new" North design:

http://www.surfzone.se/forum/attachment.php?attachmentid=10042&stc=1&thumb=1&d= 1135038221

(remove the linebreak after "?" when copying to your browser)

Just a simple one piece solution. I suppose its still machined but theoretically you could forge it too. Either way, I think it would still easily outlast the mast foot itself.
Ola,

the design looks tough, by sure a great move from the usual two part with threaded pin that I see around. The threads were the weak point there.
By sure, this will be way safer. In this case, as any mechanical engineer will tell you, the weak point is where diameter abruptly changes from the "pin" part to the wider "tendon cup" part. Stress will concentrate there and, in case there is surface uneveness of any kind (scratches, corrosion, machining defects) fatigue will have its way. The bevel on top of the "cup" section will help for this, but not avoid it. Only, with such a thick part, it will take quite a lot of time for a crack to develope. I still can't see any reason to prefer this over a two-pin cup that simply is not subject to such issues. And that, I guess, is times cheaper and lighter.

SteveC,

that's the point: everything can be done, but...
Stabilization, hardening, forging, dealing with tapering radius and bevels... why? Why mess with expensive, heavy, complicated mechanical engineering to produce parts that have the habit to cleverly hide their integrity status, when you can have a simple plastic part that simply can not break (unless maybe it's so worn out that shows very clearly its state and you would never dare to use use it, and probably nevertheless it would never break even that way)?

These new parts seem OK, I guess the Chinook one is OK too, but a) in the meantime probably thousands have had to do the swim in, and 2) anyhow a simple inexpensive plastic cup will do the same job or better and be lighter and inexpensive.
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