Bill, before you take the mast to Tony DeLima, if you have removed the track,
sand the bugger with your ROS and 80 grit and get that outer epoxy coating down
to the Carbon. You will not regret it. Coat later with 2pt LPU, I have some I
can share with you, if you need, in either clear or white. You willonly use a
small part of a can.
I have a very strong feeling that the center sleeve connecting the two pin
holding collars is the right way to go! But that's just me.
I think that when the boat is rigged and the vang attached, even if on the
beach, it will want to twist when you disengage the spring pull pin. Two pins
will be impossible, better just rivet it to the mast and drill out the rivets
if you break it.
The design I drew has two key features that make it work, 1) the HMW adhesive
back shim material, inside the central sleeve, that leaves no play and 2) the
HMW key. Moving that sucker up or down to the hole, you just hear a pleasing
thunk when the pin drops in the hole just like the door slam on a new car. No
play whatsoever, just right.
Its not even hard to make. Just wrap the sleeve slightly big in diameter and
length (wrap 3-5 layers of Mylar under the carbon windings using the actual
mast tube as a mandrill), measure the gap of the fit and order the adhesive
back HMW sheet of the appropriate thickness from McMaster Carr (comes in 2
days). Make the two collars (in one piece) by winding several to quite a few
layers of 3" carbon uni around with only a thin layer of Mylar windings over
the sleeve as a mandrill. On those windings put your nylon bushes (or use a
bit of SS tube from me) and a few more outer windings to bind it all in, check
alignment of the bushes is parallel to axis. The collars seem aesthetically a
bit thick in my diagram to allow a bit of meat to thread the spring pull pin
into. Fill in any vacuoles with epoxy 410 peanut butter. When the epoxy is
set, table saw the sleeve ends and the collars into two and make the ends
neat. Then run the sleeve through the table saw longitudinally to make the
keyway. Epoxy the collars on the ends of the newly slit sleeve, without twist
(by lying sideways on the bench), at the correct spacing of course - based on
the height of your vang pivot piece. Just use a small hand file to remove some
of the material from the collars over the keyway so that the keyway is clear
from top to bottom and you are done. The ring pull pin can be screwed into a
3/8 #16 course thread hole tapped in the front.
To make the key, use your oldest kitchen HMWPE cutting board put through the
table saw to make material of the right width and height. I drilled the rivet
holes in the key and then used a forstner bit to countersink the pop rivet
heads. Make a few extras to hand out to your mates.
I'd suggest you don't drill any locating holes in your mast untill the boat is
rigged with mainsail up and mainsheet on. Set the vang lever to the middle of
its throw and remove the spring pull pin and drill your 1/4 inch hole in the
mast face for a perfect fit. Add locating holes as required for more vang
throw.
Good luck with it, however you decide to build it!
Greg
----- Original Message -----
From: WFS03@xxxxxxx
To: gregoryrryan@xxxxxxxxxxx
Cc: swiftsolo@xxxxxxxxxxxx
Sent: Thursday, July 13, 2006 9:42 PM
Subject: Re: Vang Fabrication
Greg,
Thank you for the suggestions. I had seen the new vang sleeve/collar design
on one of Bram's boats last year at the regatta. I envision making the collars
without the carbon center sleeve, so that I can remove the pivot base that has
the permanently bonded 1/4" SS pin. The separate collars will be held in
position on the mast each with self-retracting pins, like the one you show on
the Power Point. With two separate pins used to position the collars, making
on-the-water changes to the vang position on the mast will be difficult.
Alternatively, I can build the assembly with the center sleeve and collars
with the nylon bushings for the 1/4" pin. Then install and bond the pivot base
to the SS pin that is installed in the nylon bushings. The pin and pivot base
will not be removable from the collars. The entire assembly will be positioned
with one self-retracting pin.
Your idea of using the HMWPE to position the collar is a good one, but maybe
overkill for my fabrication abilities. Do you feel that one pin, used for
positioning the assembly on the mast, will be sufficient to hold the vang in
position on the mast, given the compression loads involved?
btw, I am taking my mast down to Forte in CT tomorrow for Plexus retro-fit of
the mast track.
Bill Scheumann
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