Bram I have tried the epoxy to mast track bond and it doesnt work for our
application. I would not waste my time using this method again. These
polypropylene tracks are maybe the most inert and most difficult to bond
material ever made.
I smashed the track on my 49er when a spreader came loose. I removed the old
track and bought a new one. Since I could not get Plexus (Thankyou Vanguard) I
tried roughing the track with sand paper before using thickened epoxy with
410. Of course it stuck but differential expansion and torsions tore it off
again in short order. The ONLY sucessful way to bond polypropylene in high
load situations is with methacrylate glues, of which Plexus is the best choice,
but there are many other brands. Getting the old 49er mast track off the mast
was a chore because the plexus bond was so good. I eventually had to sand it
off. Methacrylate glues are two part and can be obtained in a continuum of
final flexibilities which varies inversly with overall tenacity. For small or
touch up jobs McMaster-Carr supply company has small 50ml ml twin tubes of
methacrylate glue from DEVCON if you dont want to buy a huge tube of this
stuff. It has a 10-20 min setup time. Nobody will regret having some of this
stuff in their shop.
--Work fairly fast with everything setup and aligned (holding tape pieces
already precut and distributed) before you start. Mark the mast with long
strips of masking tape just either side of where the track will go to indicate
alignment. Check straightness. It is possible to use a sharp blade to remove
the excess methacrylate glue with the masking tape just before it finally sets
making a very neat job of it.
Here is the McMaster Carr info for small pack sizes.
Greg
74695A12
Bayonet Mixer Nozzle, 5.9" L
With 1/4" Taper Tip
$1.00Each
66215A34
Devcon Dev-Pak Adhesive Cartridge #14345
Flex Welder, 1.7 Ounce (50 Ml)
$11.02 Each
74695A71
Duo-Pak Dispensing Cartridge Gun and Mixer
With 1:1 & 2:1 Ratio Plungers
$22.86 Each
----- Original Message -----
From: Bill Green
To: BDally6107@xxxxxxx ; swiftsolo@xxxxxxxxxxxx
Sent: Thursday, February 24, 2005 9:56 AM
Subject: Re: Tracks coming off
Try this, though it may not be any less expensive. Go buy the West Etching
kit. This is the stuff that allows you to epoxy metals. Follow the directions.
Use some of your leftover ProSet to bond the pieces together. It might possibly
help to saturate a piece of 2oz. glass matt and slide it in.
My guess is that when the mast bends, the track is forced to bend in a
slightly different arc. The original adhesive is neither strong enough to stay
glued (as Plexus would be) or pliable enough to allow a little play (as ProSet
should be).
I have not tried this on a mast, but I have used it to glue aluminum tubes to
glass that needs a pliable bond (i.e. epoxy with hardware bonder just cracks
off).
Bill
On Feb 24, 2005, at 7:41 AM, BDally6107@xxxxxxx wrote:
Good to hear from you Bob. Thanks for the tip and the info about the IC
masts.
The Plexus is expensive and nasty smelling. It's the same stuff that
dentists use to glue on crowns. 49er masts use it to glue on their tracks and
they avoid this problem. The great thing about it is that it is self etching
so no surface sanding is required (the old stuff will have to be cleaned off).
We are requiring all of our future masts from Forte to use it.
I'll take a piece of sail track, rough it up, and see how well epoxy sticks
to it. I'm a little suspicious because it look a lot like the reusable
stirring sticks that we use (the cured epoxy pops right off by simply bending
the stick).
We'll be at a couple of regattas at your club this spring and summer with
six Swifts. If you're interested, I'll bring one for you to sail in a regatta.
Let me know.
Best regards,
Bram
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