Thanks,

That's worth printing out. BTW the adhesive I used was $4.99, pretty
pricey but way below the cost of an OEM cup holder.

Dylan wrote this morning about using a plastic welder, but I don't
know how it would be used on tiny, barely-accessible parts like I
fixed yesterday. I did take apart my 90 carat's vacuum pump in the
cruise control system and found the plastic un-gluable upon
reassembly. So I went around the seam I cut with a dremel tool with a
soldering iron and fused it back together. While it made a good seal,
I don't think that "welded" repair would bear a lot of weight if
required to.

Jim

On Feb 7, 2007, at 12:24 PM, Max Wellhouse wrote:

> Jim and Listees:  I have posted anecdotally on several occasions
> about this strain of adhesives.  Although I'm not a chemical
> engineer, part of the confusion with this stuff is that people call
> anything with a two-part mixing step "epoxy", whether it comes in a
> black or clear syringe, two metal cans, or a block of putty you
> mush together to get it to kick..  The Plastic Welder series of
> adhesives are based on a compound call methyl-methacrolate and yes
> it does stink.  If you are unsure of whether you are buying a
> plastic welding glue or epoxy, read the fine print on the back of
> the placard in which the syringe is stored.  If it mentions Amines
> etc, it's more of an epoxy.  If it mentions, methacrolate or methyl-
> methacrolate, well.....
>
> The Plastic Welder Jim used so successfully is marketed by several
> different companies, but the most accessible is the Devcon Plastic
> Welder sold(and sometimes mis-stocked) at Wal mart.  to the casual
> observer/shopper at WM, these syringes pretty much look all the
> same.  More on that later.  The 50cc syringes are a whopping $2.27
> each!!  Napa/AutoZone/Checker/etal as  well as Walgreens etc. sell
> this stuff under various brand names, but charge considerably
> more.  This product claims to have a breaking strength of 3000#,
> 90% of which occurs  after 30 minutes of curing.  Full cure in 24
> hours.  Clamping/pressure/weighting the bond can improve the
> bonding strength for sure.  You have to work quickly with it,
> especially in hot weather, so mixing only what you will use in 5
> minutes is the key.  It doesn't hurt to sand slick surfaces and
> clean foreign material from the bonding surfaces as well.  My guess
> is that the methacrolate actually melts part of the bonding
> surfaces and that's where the "weld" part of the product
> description comes into play.  The super duper expensive version of
> this stuff is made by a company in New England and is called
> Plexus.  For those of you needing a color match on your repairs,
> the Plexus is a gray color, but not worth the extra cost for my
> needs.  I uasually travel with a syringe of the Devcon stuff even
> though it's so readily available.  My 50cal. metal ammo box holds
> all my other epoxy and kevlar repair stuff.
>
> At some point I intend to experiment with some resin colorants I
> have for my Gougeon Brothers epoxy by mixing them into the Plastic
> welder to see if coloring the adhesive weakens it's bond.  I pretty
> much know the answer to that before I do it, but my supplier says
> 1-2% by volume is all you should use with polyester/vinylester, and
> epoxy resin systems, and I have a feeling even mixing all 50cc of
> the Plastic Welder  even for a small repair, adding just .5 cc of
> resin colorant would be hard to measure and likely wouldn't change
> the color substantially anyway.  Black may be an exception. Really
> small amounts I would think to be impossible.
>
> I have successfully bonded 1.5"x4" polycarbonate plates (with 1.5"
> metal D-rings in the middle of them) to the vinyl interior skins of
> ABS and kevlar/fiberglass canoes.  In the years in which I
> outfitted whitewater boats for a second income, I never had one of
> these plates pull up and they took some serious stress(anchoring
> thigh straps) and taking major trauma when the boat struck rocks
> beneath the water's surface(hull flexing, not actually having the
> rings on the outside of the boat!!)..
>
> As for the other adhesives called epoxies, there are some caveats
> as well.  The "5 minute epoxies" set up quickly, but read the fine
> print on most of their packages, most of the quick setting epoxies
> are not waterproof.  Even my beloved Gougeon Brothers epoxy doesn't
> tolerate high temperatures.  I tried to repair a steam gun for a
> clothing shop once and the steam pretty much melted the epoxy
> down.  It was a plastic repair, but prior to me discovering the
> Plastic Welder stuff.  I would've loved to try the PW on the high
> temp application.  As a general rule, the epoxies and fiberglass
> resins you buy off the shelf have to compromise bonding strength
> for shelf life.  Polyester and vinylester resins require a really
> nasty catalyst called Methyl Ethyl Ketone Peroxide(MEKP).  Not only
> does the resin have an offensive odor, but the MEKP finds its way
> into your eyes, you can go blind.  The epoxies cost more, but
> usually bond better and most don't have the odor issues.  Without
> adequate ventilation, a respirator should be worn regardless of
> odor or not.  The Gougeon engineers test their resin for shelf life
> and have samples from 20 years ago that still have 90% bond
> strength, they just get more viscous with time and wetting out
> densely woven cloths becomes difficult getting all the air bubbles
> removed.  The hardeners tend to absorb moisture from the air and
> with time and change color, but their shelf life would still be
> adequate.  I have hardener that 5 years old and severely
> discolored, but still kicks when its supposed to.  If I have a
> repair that needs to be clear, I'll use fresh hardener.
>
> None of these adhesives will bond polyethylene, as it needs to be
> "welded" with a "hot air" plastic welder and I never got the hang
> of that.  Old Town Canoes sells both a "repair" kit and a "grunch
> pad" kit for its Discovery line of  cross-linked polyethylene
> canoes, but that urethane-based resin system is very expensive, has
> a very short shelf life, and kicks very quickly after mixing.  You
> also have to "polarize" the plastic surface to be bonded with the
> brief passing of the inner blue cone flame of a propane torch to
> get the urethane to bond to the poly.  I hated fixing those
> boats!!  Cheap to buy, but expensive to repair
>
> The last item I'd like to mention is that the polyester and
> vinylester resins are really difficult to tell when they're "over
> the hill". By that I mean their shelf life has come and gone.  I
> once used  old polyester to try to fix something and even though I
> used 4% MEKP, 6 hours later the repair is still gooey at 60 degrees
> F.  The point is, you can't look at it and tell whether it's still
> good or not and cleaning up all that gooey crap and starting over
> again just isn't worth it.  Hopefully you novice"bonders" out there
> know a little more about all this stuff now.
>
> .
>
> So much for that epistle.
>
> DM&FS
>
>
>
> 10:08 AM 2/7/2007, Jim Felder wrote:
>
>> For those of you who have tried to used epoxy to repair broken
>> plastic items, you've probably been underwhelmed at the results,
>> especially when gluing together chipped and broken pieces (bonding
>> one flat surface to another usually works fine, it's the pieces that
>> crack through and need repair that seldom hold).
>>
>> Yesterday, a four-legged passenger jumped into a front seat and
>> damaged an open cup holder. As much as the OEM holders cost, I
>> thought I'd pick up some epoxy and give it a try, but I didn't expect
>> much as I had not had good success in the past when the pivots broke
>> off of the lower part of the holder.
>>
>> One of my FLAPS had something called NAPA Plastic Welding Systems.
>> Don't use it in a room you're going to be breathing in! It REAALY
>> stinks. It is a 2-part epoxy, of course, and it dries a milky white,
>> so I used as little as possible on the black cup holder.
>>
>> In a couple of hours came the moment of truth... would the repair
>> withstand being forced over the protruding hinge pins? It did. I put
>> a little silicon lube in the joints and on the metal spring plates,
>> and the original "snap" came back the holder, all ready to go back in
>> today.
>>
>> For stuff like repairing heater vent covers and broken off heater
>> valve cover pins, where strength is required but not much bonding
>> surface is available, it looks to be the stuff.
>>
>> Jim
>>
>>
>>
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>
>
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