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Fix for set screw in mirage drive spine
http://www.hobie.com/forums/viewtopic.php?f=71&t=47199		 Page 1 of 1
Author:  Surfoos [ Sat Apr 13, 2013 7:54 pm ]
Post subject:  Fix for set screw in mirage drive spine
The area under the set screw on my mirage drive spine cracked. The set screw lands on a flat on the shaft for the fins. The dealer said the spine is only around $20 (US), but since my fin shaft had already slipped out of place twice due to the screw backing out, I opted for what I think may be a better solution:
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I drilled holes through the shaft and spine, and I sawed off half of the threads for the set screw. Here is the final product:

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That's a 4-40 UNC stainless screw with a self locking nut in a 7/64 inch thru hole. The fix has been working great. See my web site at the link below if you would like more details.
Author:  davew [ Sat Apr 13, 2013 8:20 pm ]
Post subject:  Re: Fix for set screw in mirage drive spine
Exellent repair - I too have had problems in this area.

Hobie engineers please take note
Author:  Surfoos [ Sun Apr 14, 2013 9:47 am ]
Post subject:  Re: Fix for set screw in mirage drive spine
davew wrote:

Hobie engineers please take note


True...a metal set screw in plastic threads pushing on an immovable steel part causing permanent strain in a thinned area of plastic under cyclic loading... I suspect it will not age well. A screw in double shear is usually a preferred connection. Maybe they were worried about corrosion of small parts, parts count, or the need for another tool (a #1 small cross point screwdriver).

This fix may have been easier than replacing the spine. I just punched the fin shaft out, drilled, then hammered it back in. Did not mess with the cables or the idler pulley. The process I feared was drilling through the stainless steel shaft. All I had was a hand drill (no press). Turned out, with a little oil and a sharp bit, it only took a few minutes of drilling.

Another tid-bit: The drive started clicking when the set screw came loose. I doubt it was the sound of the loose set screw tapping the flat on the shaft - I usually blame clicking on the cable to gear teeth alignment - but the drive does seem to operate more smoothly now. If I were a Hobie engineer I would consider purposefully loosening the set screw a turn or two and see if it causes clicking. That clicking sound is so annoying.
Author:  stringy [ Mon Apr 15, 2013 4:59 am ]
Post subject:  Re: Fix for set screw in mirage drive spine
Nice fix. 8)
Should be in the 'Repairs/Problems' section.
Author:  davew [ Mon Apr 15, 2013 1:38 pm ]
Post subject:  Re: Fix for set screw in mirage drive spine
The shaft also needs a screw driver slot at the ends to allow alignment adjustment.
Author:  bjb [ Mon Apr 15, 2013 5:17 pm ]
Post subject:  Re: Fix for set screw in mirage drive spine
davew wrote:
The shaft also needs a screw driver slot at the ends to allow alignment adjustment.


That's a great, simple idea. Certainly would make aligning the shaft when
re-assembling a lot easier.
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