zomg
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| posted on 30/12/09 at 05:55 AM |
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Anyone Oxy gas welded a chassis?
Hey all
I'm justing doing a bit of research before jumping into the locost game. My basic dilemma is I don't have access to a large enough work
space that has 3 phase power, this limits me in terms of what welders I can use. I currently have a basic 120AMP stick welding runner off a single
phase supply.
So my question is, is it practical to simply tack weld the chassis using a stick welder then finish it using oxy gas welding? My current experience
with gas welding has been on 4mm+ steel,. How well does the technique scale down to <2mm thick tubing?
My understanding is the main draw backs of gas welding is without shielding gas the weld will become contaminated, much higher work temperatures can
lead to warping and large HAZs. What other issue will I be facing?
Other than this the only route I can see is to purchase a single phase MIG (probably <160AMP) and hope thats enough or look into finding a new work
space with better facilities (this won't be easy).
Any advice is appreciated.
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nitram38
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| posted on 30/12/09 at 06:30 AM |
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Virtually everyone here has a single phase mig to build their cars. It is plenty big enough to weld our chassis up
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Mr Whippy
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| posted on 30/12/09 at 07:41 AM |
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all you need is a 130-150 amp mig and a 13 amp domestic supply.
I think most folk would be worried about heat distortion with gas welding especially as most locost chassis are built without heavy duty jigs.
Fame is when your old car is plastered all over the internet
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907
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| posted on 30/12/09 at 08:22 AM |
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Nitram & Whippy are spot on,
but if you do use the O/A then bronze welding is the way to go.
All the old Lotus 7's had bronze welded chassis.
Cheers
Paul G
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turbodisplay
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| posted on 30/12/09 at 08:39 AM |
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Its possible to go up to 170A with a 16A supply.
I used arc for my chassis, very hard to do, but does, if done propely, hive a stronger weld.
There is also more distortion, so i would say mig is the best route.
Darren
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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britishtrident
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| posted on 30/12/09 at 12:04 PM |
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If you want to use gas welding Bronze welding is the process to use --- usually called brazing but brazing is strictly speaking a different process
carried iut in furnace.
However MIG is the way to go for 1.5 or 1.6 mm rhs.
If you buy a single phase hobby MIG you will find the Clarke brand are the more reliable and produce more consistent results than some widely
available sub £200 welders .
I have a SIP and regret its purchase every time I use it.
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marcjagman
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| posted on 30/12/09 at 12:17 PM |
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7
Posts 2154
Registered 5/11/04
Location Essex / Suffolk border
Member Is Offline
Photo Archive
Building: Whatever pays the rent
posted on 30/12/09 at 08:22 AM
Nitram & Whippy are spot on,
but if you do use the O/A then bronze welding is the way to go.
All the old Lotus 7's had bronze welded chassis.
Cheers
Paul G
Not allowed to braize these days are you? surely thats why you have to weld a car for it's MOT and not braise.
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Confused but excited.
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| posted on 30/12/09 at 01:00 PM |
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quote:
Originally posted by britishtrident
but brazing is strictly speaking a different process carried iut in furnace.
Yep! That's how I do my lamb chops.
OK I'll get my coat.
Tell them about the bent treacle edges!
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Canada EH!
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| posted on 30/12/09 at 02:33 PM |
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We used a similar process to Lotus when building components for CanAm cars.
Nickel bronze rod with a liquid fluxer in the acytelene line. The fluxer looks like a small acytelene bottle, about 10" high filled with liquid
flux.
This provides a shielded flame much like a mig or tig welder.
We used it mostly on 4130 alloy to prevent heat cracks along the edge of the bead.
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skodaman
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| posted on 30/12/09 at 06:16 PM |
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I didn't think brazing was acceptable on cars anymore. My old mini failed its mot years ago because the sills had been brazed on. Would it
pass IVA if chassis was brazed together?
Your 120amp stick welder should be up to the job. It's the only welder I've got. Depends how good you are at welding. A mig welder
would be a lot easier though.
Skodaman
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David Jenkins
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| posted on 30/12/09 at 06:31 PM |
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There's ordinary brazing (with brass, an alloy of copper and zinc) and bronze brazing (an alloy of copper and tin).
Brass brazing is a no-no as the material is quite brittle. Bronze brazing is far stronger, but there is a special technique to its use (mostly to do
with the way that joints are prepared).
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iank
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| posted on 30/12/09 at 08:25 PM |
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quote:
Originally posted by skodaman
I didn't think brazing was acceptable on cars anymore. My old mini failed its mot years ago because the sills had been brazed on. Would it
pass IVA if chassis was brazed together?
Your 120amp stick welder should be up to the job. It's the only welder I've got. Depends how good you are at welding. A mig welder
would be a lot easier though.
Better tell caterham, all their chassis are bronze welded.
This has been discussed many times. The only real problem with bronze welding is the accuracy you need when cutting the steel as you have to be super
accurate - can't fill a big gap like mig can (though that's not a particularly good idea if you want a strong chassis).
Lots of good info in this thread on the subject (including a nice picture of a caterham chassis)
http://www.locostbuilders.co.uk/viewthread.php?tid=50872
I wouldn't try and stick weld a chassis unless you are a real expert with it as it's more suitable for much thicker material and
you'll be blowing holes if you aren't an expert.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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gazza285
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| posted on 30/12/09 at 09:20 PM |
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quote:
Originally posted by skodaman
I didn't think brazing was acceptable on cars anymore. My old mini failed its mot years ago because the sills had been brazed on.
Bronze weld fails the test because it will stick to rust, allowing you to bodge up say the sills on an old mini without having to do a proper repair.
DO NOT PUT ON KNOB OR BOLLOCKS!
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WIMMERA
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| posted on 2/1/10 at 09:02 AM |
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If you are considering building a car in Australia I would suggest you join Oz-Clubbies.com to get a handle on the local rules.
Cheers
Wimmera
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zomg
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| posted on 4/1/10 at 05:54 AM |
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Yeah I'm an Oz-clubbies member, I've been reading through all the regs and it's scary how much work I;ve got ahead of me. But
I'll get there in good time.
I think I'm going to be looking at something like this.
http://www.sydneytools.com.au/shopexd.asp?id=12354&bc=no
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TheGecko
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| posted on 4/1/10 at 07:06 AM |
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quote:
Originally posted by zomg
Yeah I'm an Oz-clubbies member, I've been reading through all the regs and it's scary how much work I;ve got ahead of me. But
I'll get there in good time.
I think I'm going to be looking at something like this.
http://www.sydneytools.com.au/shopexd.asp?id=12354&bc=no
Hey zomg, get yourself active on OzClubbies - they're generally a pretty friendly bunch and you'll get more specific answers to rego
questions etc. Where in Oz are you?
Re: the welder - that looks like pretty good value when I remember that I paid about $550 on sale for the unremarkable little SIP 150 gas/gasless MIG
I'm using. Knowing what I know now, I wish I'd found the extra dollars and bought a decent welder at teh time because it would actually
be easier for a novice like me to use (no fiddling with flaky wire feed etc).
Anyway, good luck with your build - hope to see you on OzClubbies.
Dominic
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