Hi just to give my 5 penenth.
Powder coating is good. Can last for years.
I know of one company that offers 15 year warranties.
However like everything its all in the prep. clean the substrate
properly, ie degrease and then etch any surface corrosion with a
phosphating acid. Follow with a pretreat of zinc phosphate (tricat) or
one of the new silane based processes and you have twenty years. The
right material will resist cracking, we use 16mm 180 degree bend back
without cracking on 1.6mm material. With the correct pretreatment
substrate creep is minimal, but it can happen.
Cleaning ready for powder coat is more than a rag soaked in thinners.
Next thought. What about Autophoretic (not sure about the spelling)
coating just like the new three wheeler. Inside and out by dip processing.
Dave
On 02/07/12 18:03, Owen Jenkins wrote:
Writing as one who teaches materials and corrosion science, these are
my thoughts.
1. Powder coating is fine until it gets damaged, when crevice
corrosion can occur underneath it. Once it does, you have to get it
all off, grit blast the rusted chassis and start again. Looks nice and
lets you clean the chassis, thus suited to concours types.
2. Galvanising works. Galvanising with Waxoyl on top works even better
at resisting corrosion. This is my preferred option and what my +8
has. By this means you have three barriers protecting the chassis: (1)
the Waxoyl, which is easily replenished, (2) the passive oxide film on
the zinc galvanising and (3) the zinc acting as a sacrificial anode to
protect the chassis cathodically.
3. Do not expect to repair a galvanised chassis. Two problems:
appallingly noxious welding fumes and possibly liquid metal
embrittlement of the steel by molten zinc, if the steel gets too hot.
A bent galvanised chassis is scrap. Been there. That's what insurance
is for.
4. If you are given to doing patch-welding of things, go for an
uncoated chassis and weld in new bits when it rusts. The thought of
this makes me shudder.
5. Have an uncoated chassis, make sure that it is grit blasted,
etch-primed and finished with high-build epoxy. This works well on
subsea equipment designed to stay on the bottom of the North Sea for
decades. Mind you, they have a cathodic protection system, too.
6. Have a traditional, steel chassis, grit blasted and painted, and
keep it well Waxoyled, with annual top-ups. This is what happens on my
4/4. This also works.
I suspect GEE don't like galvanised chassis because they are not
economically reparable and getting them galvanised is a pain for them,
as they will have to subcontract the work; not because of any inherent
advantage to you, the punter (unless you make a habit of bending
chassis). This is my guess, as an ageing and cynical freelance
engineer who has bent a chassis but hopes not to repeat the exercise.
Cheers,
Owen.
----- Original Message -----
*From:* Richard Jones <mailto:[email protected]>
*To:* mogtalk2 <mailto:[email protected]>
*Sent:* Monday, July 02, 2012 5:23 PM
*Subject:* Re: [mogtalk2] chassis at G.E.E.
I 'm certainly not a fan of powdercoating as once the surface gets
cracked water gets under and it bubbles - some of the surfaces on
my plus 8 that look to be powder coated like the scuttle and some
suspension parts are not good and once it goes you can only take
it off and paint it. At least you can touch up galvanizing with a
cold touch up - but don't know how effective that is. They must
have a good reason for not recommending it though - did think the
chassis fitted by the factory were galvanised. Have certainly had
a galvanised climbing frame in the garden for the past 20 years
and that is stiil as good as new, if not as bright and Alko
caravan chassis are all galvanised to good effect.
Richard M800RGN+8
*From:* "[email protected]" <[email protected]>
*To:* mogtalk2 <[email protected]>
*Sent:* Monday, 2 July 2012, 16:43
*Subject:* [mogtalk2] chassis at G.E.E.
Why do they not recommend galvanizing?
My 1973 4/4/4 was re-chassied 20+ years ago, and unlike the original
ungalvanized one was after about 18 years, is quite sound.
That original one had new box cross members fitted and repaired
and the
rearmost one re-plated.
TC
David.
-----Original Message-----
From: Paul Fileman [mailto:[email protected]
<mailto:[email protected]>]
Sent: 02 July 2012 15:44
To: mogtalk2
Subject: RE: [mogtalk2] 4/4 chassis on ebay
>> Which advert and which month's Miscellany are you referring to?
I meant the G.E.E. ad which I cannot find in the July issue. The
price list
on their web site refers:
http://www.geeltd.co.uk/index.php/chassis-prices.html - I have not
used
them so cannot comment on the accuracy of this information.
Best regards
Paul
-------------------------------------------
View posts on The Mail Archive
http://www.mail-archive.com/[email protected]/
[http://www.mail-archive.com/[email protected]/]
Modify Your Subscription:
https://www.listbox.com/member/?&;
86
Powered by Listbox: http://www.listbox.com/
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2012.0.2180 / Virus Database: 2437/5105 - Release Date:
07/01/12
-------------------------------------------
View posts on The Mail Archive
http://www.mail-archive.com/[email protected]/
[http://www.mail-archive.com/[email protected]/]
Modify Your Subscription: https://www.listbox.com/member/?&;
Powered by Listbox: http://www.listbox.com/
View posts on The Mail Archive
http://www.mail-archive.com/[email protected]/
Modify <https://www.listbox.com/member/?&;> Your Subscription
[Powered by Listbox] <http://www.listbox.com>
No virus found in this message.
Checked by AVG - www.avg.com <http://www.avg.com>
Version: 2012.0.2180 / Virus Database: 2437/5106 - Release Date:
07/02/12
View posts on The Mail Archive
http://www.mail-archive.com/[email protected]/
Modify
<https://www.listbox.com/member/?&;>
Your Subscription [Powered by Listbox] <http://www.listbox.com>
-------------------------------------------
View posts on The Mail Archive
http://www.mail-archive.com/[email protected]/
[http://www.mail-archive.com/[email protected]/]
Modify Your Subscription:
https://www.listbox.com/member/?member_id=22459785&id_secret=22459785-4a39ddf8
Powered by Listbox: http://www.listbox.com
