ex_hustler
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| posted on 30/7/07 at 11:54 AM |
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Galvanised rhs steel tubes
Hello people,
I decided to start building my locost after reading for a year this amazing site. I live in Greece so you will have to tolerate my efforts of
speaking proper English 
Well, as most fresh builders I have questions. One of my relatives ordered me at a low cost the steel rhs tubes (25*25mm * 1.6mm wall thickness). I
didn't gave him any special specifications. But he thought it would be best to get galvanised steel tubes so it won't get rusty and last
longer with less care... And so he did.
I read somewhere in the forum that the fumes are really unhealthy to breath. I will do all the welding outside my garage in the open.
To increase difficult I intend to use an Arc Welder. The primary reason is that MIG welders are REALLY expensive in Greece and secondary I already
have a really good (pocket size) inverter electronic arc welder.
Am I going to have a hard time in welding galvanised tubes?
Should I go on?
Thank you,
George
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smart51
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| posted on 30/7/07 at 12:14 PM |
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You could file the plating off the ends of the tube, say 30mm. The heat affected zone will not burn off the zinc.
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ex_hustler
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| posted on 30/7/07 at 12:21 PM |
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Okay, say I can do it for the outside of every tube. But unfortunately the zinc is also inside the tubes...
(I wonder if those galvanised tubes could be the answer to the nightmares from getting rust in the interior of tubes.... )
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907
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| posted on 30/7/07 at 12:23 PM |
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Sorry George, but IMHO the answer to your question, "Should I go on", is no.
Apart from the degree of difficulty, and the health issues, I cannot see the point of a galvanised chassis
if the weld areas have had the corrosion resistant coating burnt away.
It's like using a 10 tonne hook on a 2 tonne chain IMHO.
Sorry
Paul G
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ex_hustler
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| posted on 30/7/07 at 12:37 PM |
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quote:
Originally posted by 907
Sorry George, but IMHO the answer to your question, "Should I go on", is no.
Apart from the degree of difficulty, and the health issues, I cannot see the point of a galvanised chassis
if the weld areas have had the corrosion resistant coating burnt away.
It's like using a 10 tonne hook on a 2 tonne chain IMHO.
That is SO true... the coating will be burn because of the heat. I guess I will have to use one of those galvanise sprays at the welding areas.
Well, I forgot to mention that I have already "lost" 4 hours (last Sunday morning) cutting the tubes to book measurements with all that
weird angles at an engineer shop with precise cut tools...
What should I do having all those tubes already cut? I don't mind the money but the "lost" 4 hours that I could have been at the sea
with my wife...
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MikeR
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| posted on 30/7/07 at 12:39 PM |
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depends what you want - do you want the rust protection or do you want a chassis?
I you've got the steel, then use it. Whats the harm (ok, you know to take precautions when welding).
My biggest worry would be arc welding the chassis, not the steel. I've never done arc but i've heard comments that you'll have
difficulty on steel so thin.
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Peteff
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| posted on 30/7/07 at 12:56 PM |
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A DC inverter should arc weld your steel easily, they are very good on thin material. Just clean the galvanising from the weld area with an abrasive
wheel or flapwheel in your drill/grinder.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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iank
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| posted on 30/7/07 at 01:05 PM |
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Removed link as people wiser than the author believe it's a crock.
[Edited on 30/7/07 by iank]
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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ex_hustler
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| posted on 30/7/07 at 01:07 PM |
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quote:
Originally posted by Peteff
A DC inverter should arc weld your steel easily, they are very good on thin material. Just clean the galvanising from the weld area with an abrasive
wheel or flapwheel in your drill/grinder.
I was just told that I should use thin flux-coated rods and set the amperage very low at 20-25amps instead of 90-100 amps that usually can weld thick
solid steel.
Thank you all for the advices, I will write back as soon as I get welding the bottom of the chassis with the arc welder.
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907
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| posted on 30/7/07 at 01:13 PM |
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OK, so the best advice I can give before you get deeper into your project is, have a go.
With some of your off cuts, make up a test piece, say a 300mm square with a diagonal or two.
Weld it up and see what you think.
Better to waste an hour or two than end up giving in later on, possibly though ill health.
I suspect you will change your mind.
As a time served welder by trade the only way to make a galv chassis IMHO is to use oxy/act and bronze weld it.
Those galv sprays are no better than paint btw.
Paul G
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BenB
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| posted on 30/7/07 at 02:06 PM |
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If you've cut the metal to size I'd just use it. You'll need to grind back all the galvanising coating where you're going to
weld which'll be a pain..... And you'll still get some zinc fumes.
If you weld outside and put some fans to blow away the fumes you should be okay (which you'll probably need to keep cool anyway from what
I've heard about temperatures in your neck of the woods anyway). If you start getting muscle aches, headaches and feeling generally rubbish you
know you've absorbed too much zinc!!!
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907
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| posted on 30/7/07 at 02:15 PM |
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I have just re-read this thread, including my own posts, and have come to the conclusion
that I have not emphasized enough the hazards of zinc.
Zinc fume inflames the lining of the small intestine, the stomach, and the large intestine.
It is for this reason that the advice given is to drink milk, as this coats the walls of the said organs.
This is not a cure however. It just slows down the bodies adsorbsion rate.
It does nothing however to protect the lining of the lungs.
Zinc dust, from sanding or grinding, is more long term if breathed in.
This is adsorbed by the body over a much longer period.
Many trace elements are required by the human body, but in minute quantities.
For the link in a previous post to suggest that welding galv could be good for you is IMHO irresponsible.
AFAIK the active ingredient in wood preservative is zinc, and we know how long that lasts.
Sorry to get on my high horse but I believe that our health is our most treasured possession.
Paul G
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BenB
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| posted on 30/7/07 at 02:51 PM |
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For sure health's important.....
First of all you have to determine if the coating is 100% zinc. If not, you're looking at inhaling a whole load of nasties (bad news)....
Chromium poisoning, for example, is big bad mojo.... Trying to find out what's zinc and what isn't is tricky or impossible. Most people
hope it's just zinc 
If we're just talking about zinc oxide then the main risk is zinc metal fume fever. Most people recognise the symptoms, stop welding and
symptoms settle after 48hrs. As long as you recover from the short term symptoms there are no long term consequences to this. People with already
knackered lungs, however, have succumbed to the inflammation of the lung that can result from zinc oxide fumes... If, however, the exposure to zinc
oxide continues you get zinc poisoning. People have died as a result of this.....
IE
Welding galvanised sheet metal is potentially hazardous because of the metal fumes it produces. If you have any respiratory problems it's
certainly not a good thing to do.....
If it's definately zinc oxide being produced, you try to make sure you're not inhaling it, and you stop AS SOON as you notice possible
symptoms you should be fine.... If you carry on inhaling it despite developing flu like symptoms you're asking for trouble.... If in doubt,
don't weld it (or make sure you've got mighty fine life insurance)....
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iank
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| posted on 30/7/07 at 03:16 PM |
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I've removed the link, you're both quite right that if there's anything more than zinc around it's a bad idea full stop.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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MikeR
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| posted on 30/7/07 at 03:31 PM |
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ok, i've changed my mind after reading the above - don't do it!
If it was just a little bit - perhaps you'd be ok, but a full chassis is probalby not the wisest of things.
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907
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| posted on 30/7/07 at 04:12 PM |
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quote:
Originally posted by iank
I've removed the link, you're both quite right that if there's anything more than zinc around it's a bad idea full stop.
Hi iank.
I hope you were not offended by me referring to the link. That was not my intention.
I know you put it on here in good faith.
I just felt that it was wrong to refer to it's healthy properties, and the welding of galv in the same statement.
atb
Paul G
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iank
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| posted on 30/7/07 at 04:51 PM |
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quote:
Originally posted by 907
quote:
Originally posted by iank
I've removed enthe link, you're both quite right that if there's anything more than zinc around it's a bad idea full stop.
Hi iank.
I hope you were not offended by me referring to the link. That was not my intention.
I know you put it on here in good faith.
I just felt that it was wrong to refer to it's healthy properties, and the welding of galv in the same statement.
atb
Paul G
Not at all, but I certainly don't want to put up a link that might make someone sick. IIRC BenB is a (real) doctor who's experience
certainly trumps internet links
If the galv could contain more than zinc then you shouldn't be putting a welder anywhere near it.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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caber
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| posted on 30/7/07 at 06:23 PM |
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OK so it looks like you have lost 4 hours and some cash on galvanised steel. A couple of things that I would suggest before you carry on. Firstly you
can see if it is possible to use your inverter for TIG welding using a suitable torch and gas. If this is possible then this will be far better than
arc welding or MIG welding. Second next time you get steel DON'T cut it all to book lengths, the book is WRONG the Ron Champion one that is (
sorry Chris!) Get the McSorely plans from the web, google will find them, they are much better to work with and the cuts are more accurate. I still
would cut the pieces as you need them as it is possible that you will run out a few millimeters and it is better to cut to fit particularly if you
are TIG welding. There are a few pieces that are best not cut and welded until you start particularly bracing around the engine bay, this is best done
once you have test fitted the engine, manifolds etc. otherwise you will find yourself cutting tubes out and refitting to miss vital bits!
By the way you will inevitably lose a few more hours along the way, building a Locost is a learning exercise and there will be things that you have
done that you will see can be done better later on so you will make changes as you go and end up with a better car as a result.
Good luck and have good fun buildimng and running your car.
Caber
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ex_hustler
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| posted on 4/10/07 at 10:27 PM |
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Hello,
I want to add a comment about galvanized
steel tubes after 2 months using them for
the chassis. I had no experience on getting
ill or dizzy working with this material. But as
you see in the picture I work on top roof
and it is open and there is no lack of fresh
air. And also I haven't worked for many
hours in a row and also never did much
welding. I just tack-welded the
tubes so far.
Another thing about the welding
procedure is that I never angle ginded the
galvanising coating of the tubes before tack
welding them and I didn't experiencied any
problems with welding.
The only stupid thing I did all that time was
using rutil rods with normal polarity in the
inverter welder. I read somewhere that
when using rutil stick rods the welding
clamp should be attached to negative (-)
polarity of the welder and not to possitive
as in other flux coated rods.
I tried that reverse polarity and I was very
satisfied with the results.
In the picture you see both welding results.
The weld around the bracket was done
using negative polarity and rutil flux coated
rods. The poor welding between steel sheet
and the tube was done using positive
polarity. The difference is HUGE!
You can also see the progress in the chassis so
far here (it is posted in a greek
locostbuilders community forum):Progress so far
http://www.locostbuilders.gr/viewtopic.php?t=3
Latest photo of chassis :
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907
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| posted on 4/10/07 at 10:47 PM |
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I bet your neighbours love you.
Paul G
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ex_hustler
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| posted on 4/10/07 at 10:55 PM |
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Well, that's one reason of slow progress.
Generally I am trying not to annoy anyone working only morning hours till noon and then
about 3 hours at the evening. I can do all the
measuraments, calculations and tube trial fits
anytime but can't use angle grinder or a
hammer to chip of slag and spitting that arc
welder causes around welds. No-one complained for noice till now.
There is much work ahead to be done and I should get along well with neighbourhood...
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MikeR
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| posted on 6/10/07 at 09:14 AM |
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psst - make sure you can get the car from the roof to the road otherwise you'll only do VERY short journeys
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