From: John De Armond
Newsgroups: rec.outdoors.rv-travel,alt.rv
Subject: Re: Converter upgrade finished, now I need an adhesive for 
	polypropylene
Date: Tue, 22 Aug 2000 17:19:06 -0400

go wrote:

> Now for the dilemma.  I would like to glue/seal the stacked boxes
> together (not the covers!), but they are constructed of polypropylene
> or polyethylene, and I can not find an adhesive which will work on
> these materials.  I will probably also add a couple of nylon bolts
> through the case sides for some extra strength, but I feel a proper
> adhesive or sealant would help to keep excessive water and dirt out of
> my boxes.  Any suggestions?

Loctite does make an industrial adhesive that will bond to these
plastics but they're expensive and require surface prep, normally by
electron beam bombardment.  For this application, I'd suggest simply
welding them together.  If you know someone in the auto body
business, he probably has a plastic welding setup.  Little more than
a fancy soldering iron with special bits.  Filler rods can be bought
from the local auto parts store that caters to body men.  You can
figure out what kind of plastic the box is by looking at the
recycling triangle on the bottom.  If you can't find a body shop,
you can do the welding yourself with a soldering iron and some means
to control the heat.  A light dimmer will do. It takes a little
practice to make a pretty joint but it's a LOT easier than welding
metal.  If you're really cheap, you can cut filler "rods" from the
scrap plastic where you trim the boxes to fit.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel,alt.rv
Subject: Re: Converter upgrade finished, now I need an adhesive for
Date: Tue, 22 Aug 2000 23:42:03 -0400

go wrote:

> Yeah I was afraid it might take some industrial and hard to obtain
> stuff.  I had hoped that since I had lots of surface area here, that I
> might be able to find something which would provide a decent bond.

The problem is, these plastics have such a low surface energy that
normal adhesives won't bond.  The electron beam adds energy sites
which provide bonding sites.  it is said that a propane torch can be
used in a pinch (the flame is ionizing to an extent) but reports
I've read say that the energy sites are not well implanted and go
away after awhile.

> >welding them together.  If you know someone in the auto body
> >business, he probably has a plastic welding setup.  Little more than
> >a fancy soldering iron with special bits.  Filler rods can be bought
> >from the local auto parts store that caters to body men.  You can
> >figure out what kind of plastic the box is by looking at the
> >recycling triangle on the bottom.  If you can't find a body shop,
>
> What are the recycling codes for the various plastics?  So far I've
> been going by the manufacturers description as to the type of plastic
> used.

Well, let's see,

1 is PETE (Polyethylene Terephthalate)
2 is HDPE (high density polyethylene), probably what your battery
box is.
3 is vinyl (what most clear beverage bottles are made of)
4 is LDPE (low density polyethylene
5 is PP (polypropylene)
6 is PS (polystyrene)
7 is "other", usually a layered product or an unrecyclable product
such as ABS or polycarb.

I got all that good info here:
http://www.recycle.net/recycle/Plastic/index.html


> >you can do the welding yourself with a soldering iron and some means
> >to control the heat.  A light dimmer will do. It takes a little
> >practice to make a pretty joint but it's a LOT easier than welding
> >metal.  If you're really cheap, you can cut filler "rods" from the
> >scrap plastic where you trim the boxes to fit.
>
> I've got various soldering irons, and even a variac which could be
> used to throttle them.  How difficult is this to do?  I'd need to melt
> the rods, but be careful not to melt a hole in the box.  Do they make
> these plastic filler rods for use in a standard hot glue gun?

Well, that's kinda like asking how hard is sex?  Pretty easy once
you get the hang of it :-) I watched a body man weld a plastic
bumper and picked it right up.  Easy enough to practice since
plastic is everywhere.  I doubt that a glue gun could get hot
enough.  Besides, this is true welding where the substrate is melted
and fused together with  the filler.

I'd take a cheap high wattage soldering iron and peen it down so
that it has an oval cross section about as thick as you want the
bead to be.  Then just put the iron between the pieces to weld,
melting the edge in the process.  Move the iron away as you feed the
filler in from behind. Since molten plastic is thick, it won't drop
out like metal will, plus it conducts heat poorly so the "puddle"
won't spread rapidly.  To me, this is one of those things that's
easier to do than to describe.

You might try dropping in a few body shops and see if you can find a
friendly guy who will show you his rig and maybe even how to use
it.  Or just jump in.  If you totally screw up a couple of boxes,
you've not spent any money to speak of, plus you now have copious
practice material :-)


> Thanks for the suggestion John.

Yer welcome.


John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Plastic repair
Date: Tue, 17 Aug 2004 03:10:14 -0400
Message-ID: <2hb3i0def90v9nqsqiam5dsln7keuho8lf@4ax.com>

The subject of plastic repair comes up often enough that I thought this site
might be of interest:

http://www.urethanesupply.com/

Despite the name, pretty much anything needed to repair any type of plastic
found in an automobile or RV.

I've mentioned plastic welding several times.  Here is an airless kit:

http://www.urethanesupply.com/5500ht.html

This is an airless welder.  The other type commonly used is a hot air welder.
Harbor Freight sells one that looks pretty nice.  I recently bought one (at a
flea market for a buck.  SMS supreme!!!!) but haven't used it yet.

When I recommend visiting a body shop to have this or that plastic welded, one
of the two types of welders is what he'll have.  Which is better?  Dunno.  I
have the hot air type so that's what I'm going with :-)

I just bought an electric car (1976 CitiCar) with fairly decrepid ABS body
panels so I'm going to find out how the welder works...

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Waste tank froze [and cracked] in Texas!
Date: Mon, 12 Dec 2005 14:42:13 -0500
Message-ID: <e2krp19fhd88g75fdlgs7njfgmgjqllco4@4ax.com>

On Sun, 11 Dec 2005 08:41:18 -0600, Bob Giddings <bobg@escapees.com>
wrote:

>On 11 Dec 2005 05:48:35 -0800, "alan" <alanspcs@isp.com> wrote:
>
>>Thanks, I was thinking I would pour some appropriately thinned "wet
>>patch" inside the tank [after removing the gate valve and plugging the
>>drain with a stopper].
>>
>>I'm thinking wet patch, because I'm a fulltimer and I can't sit around
>>and wait for it to dry out.  If you understand.
>>
>>The patch materials I've seen advertised are quite thick.  I'm hoping
>>someone might be able to recommend the appropriate thinner, so it would
>>pour and flow.  Just occurred to me that the manumacturer might have a
>>notion.  Old age is a killer!
>
>I think you are just going to make a mess.  Sometimes you just
>have to spend the money and get it done right.  If you don't,
>you're gonna end up in deep doo-doo.

I fully agree.  The patching crap won't stick to the tank materials.
All it'll do is make a mess.

The best way to fix the tank is to plastic weld it.  Harbor freight
has an inexpensive hot air welder.  Urethane Supply has everything you
need.

The only way you can fix it short of plastic welding is a mechanical
fix.  That is, some sort of material on the inside and outside held
together by fasteners through the plastic.  If the crack is on a flat
surface, a couple of pieces of Dow 5200 Urethane coated plywood, one
on each side, held together with galvanized sheet rock screws will do
the job.  This could be considered semi-permanent.

If you don't want to do the welding yourself, clean the tank well and
find a body shop that repairs plastic bumpers.  Your tank is either
ABS or polyethylene.  The bumper shop will be equipped to handle
either.

A method of temporary patching is to drill several small holes next to
the crack and then apply Rector-seal or equiv plumbing patch epoxy.
Apply it heavily enough that it extrudes through the holes and forms
mushroom heads on the inside.  The Rector-seal slightly expands as it
cures and will form a mechanical lock in each hole.  It won't stick to
the plastic tank but the mechanical lock should be enough to at least
get you to warmer weather.  It will eventually come loose, as the
plastic and epoxy expand at different rates but it will work for
awhile.

John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Which way is Arizona? Help!!
Date: Sat, 01 Dec 2007 19:56:02 -0500
Message-ID: <ehu3l3df1hnb13ock962gaujrkj0khqfvp@4ax.com>

On Sat, 1 Dec 2007 12:14:02 -0800 (PST), Yukon <Loyza3@gmail.com> wrote:


>> The other problem I've had relates to moisture.  My building is old and the floor is
>> a slab.  Apparently moisture comes up through the slab after rains.  I never noticed
>> a problem with carpet but this stuff has absorbed the moisture and curled up along
>> the edges.  Despite being made with some sort of plastic, it is NOT
>> moisture-resistant.  If your RV is absolutely water-tight, including seepage from
>> below, then it'll be fine.  If not then I'd certainly want to put down some sort of
>> vapor barrier under it.
>>
>The moisture issue is discussed pretty intensively in the instructions
>manual.  It does come with some vapor barrier or even sound barrier.
>Not sure if you can put down both.
>
>John,  you seem to have the reputation of  "do everything yourselfer"

*Blush*  Actually, I have to admit that I hired out the installation of that
flooring.  It looked like way too much knee time plus the guys who did it were happy
to be paid in BBQ :-)

>extraordinaire,  I'd like to pose a question to you: you mentioned
>this www.urethane.com company, and I haven't read it in detail yet.  I
>have been having problems with my sewer system as you might have read.
>After they re-fix my drain pipes and tanks,  do you think it might be
>a good idea to reinforce all the joints with this urethane material?
>(not sure if it's a tape or roll-on liquid of some sort, but I re-
>visit the website. Because I don't want to get under that trailer
>again any time soon. Thanks.   yukon

That's http://www.urethanesupply.com.  "urethane" is just part of their name - they
sell tools and supplies to weld all sorts of plastics.

Yes, it's certainly possible once you find the weak spots.  If your tank is ABS,
there are adhesives available that make bonds almost as strong as the base material.
That's likely how the fittings were attached to the tank.  It requires some pesky
surface prep ("activation") that involves ionizing the surface (usually done in the
field with a very hot torch flame applied very quickly) but it can be done that way.

If your tank is polypropylene or polyethylene then the only really practical method
out in the field, and the best method in any event, is welding.  Plastic welding
works just like metal welding.  The base material is melted and a plastic filler rod
is fed into the joint.

There are two basic methods, hot air and hot iron.  Hot air welding uses a source of
intensely hot air to fuse the plastic.  Something like this inexpensive kit from
Harbor Freight

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=41592

or the slightly more expensive

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96464

I have one of the first units and after I replaced the
stiff-as-a-16-year-old-pecker-on-prom-night cheap orange hose with some silicone
rubber hose, it made a fine unit.  I operate it using a lamp dimmer to control
temperature.

The iron method uses a heated iron similar to a soldering iron to melt the base
material and to feed in melted filler rod.  Here's a basic kit that Urethane offers

http://www.urethanesupply.com/5210.php

I decided that $60 was too much for a $10 soldering iron so I purchased a replacement
tip from Urethane and fitted it to a $10 Rat Shack soldering iron body.  Works great.

Two things of note that they mention on that page.  First is FiberFlex.  This is a
fiberglass-reinforced plastic filler rod that is much stronger than the base
material.  Basically, if the weld penetration is good, the joint is stronger than the
base material.  The other product is the stainless steel mesh.  This mesh is embedded
in the joint with the hot iron.  It makes the joint even stronger.

The iron is the cheaper tool and is necessary in some instances where heat damage to
adjacent structure is undesirable (the cosmetic finish of a plastic bumper, for
example) but IMO, the hot air system provides a far superior weld.  It takes a slight
bit more skill and the air gun won't fit into some tight spaces but those are
problems worth overcoming.

It seems to me that you have more serious problems than can be fixed by reinforcing
the plastic.  Two sets of failures that close together indicate to me that something
is woefully wrong with how those tanks are installed.  Perhaps something is out of
square or material is protruding into the tanks' spaces or the fittings are in a
strain or something.  It needs some qualified attention.  I think that I'd be on the
coach builder and demand that they pay someone competent to drop the tanks and find
out what is wrong.  Obviously the last outfit you used wasn't.  With failure
happening that rapidly, there has to be something fairly obvious wrong.

John