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Vincent DePillis

Member Since 19 Jan 2005
Offline Last Active Nov 24 2016 02:45 PM
*****

Topics I've Started

clamping sheave in Masthead

09 November 2016 - 10:36 PM

Working on custom alu masthead crane. Sheave is Harken 712. Harken says sheave should be "clamped" in place, so that the side plates of the sheave do not spin relative to the fixture in which the sheave is mounted. Question is how to best to do this. One thought is to use a bolt for the pin, and just squish the side of the fixture together slightly. Danger there is that the fixture will not distort evenly, so that the side balls will not be loaded evenly as they rotate. Could also put in set screws that will reach through the side of the fixture and engage the sheave side plate.

Anybody do this before or have a clever idea? The fit of the sheave in the fixture is ok, but not snug enough to "clamp" the sideplates in place.

recommendced clearance - pin to sheave

08 November 2016 - 08:59 PM

Making up new masthead fitting, using 4" Harken Halyard sheave (bushing bearing with side balls). Nominal axle pin is 1/2 inch. Bushing ID is about .505" Could use a stock 1/2" clevis pin, but that measured .494" and the fit seemed sloppy. Could easily have some rod turned to .502 and have something that you can just insert with hand pressure and some lubricant.

Am I overthinking this as usual?

Titanium and aluminum - Corrosion?

02 November 2016 - 05:06 PM

Will titanium fasteners or fittings cause corrosion in aluminium to which they are attached, in the same way that stainless will?

delam in Omohundro Mast

10 October 2016 - 02:17 PM

I have an omohundrow carbon mast on a Corsair F31R.  
 
Noticed a crack adjacent to the spinnaker exit box.  Investigation revealed that there is a significant amount of woven material scabbed on to the mast, to the side of and below the exit box.  The crack developed because this material is delaminating from the  underlying uni material-- presumably because they applied it ON TOP OF the primer.  
 
Questions:  
 
Was this this factory practice?  
 
Anybody else have this problem, and if so, how did you fix?
 
Will my mast break off if I go do Round the County and fix it when I get back?