stutz
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| posted on 26/2/04 at 03:24 PM |
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Oxy Acetylene Welding
Hi,
I Started a night course in welding yesterday(I've welded a bit before, but am fussy and want a chassis I can trust), and the first module is
Oxy Acetylene Welding. After discussions with the teacher, and a few searches of this and other forums, I'm considering using this method to
build my chassis. I know it will make the job slower, but am more concerned with the overall finish and quality of the job. I'm looking at
buying an Oxy Acetylene kit and rang my local BOC dealer who quoted rental of the smallest capacity bottles (3ft Oxy and 2ft Acet) at £70 per year,
refill is £40. Sounds a bit expensive to me, has anyone got experience of what I should be paying.
Thanks,
Stephen
[Edited on 27/2/04 by stutz]
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blueshift
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| posted on 26/2/04 at 04:06 PM |
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iirc you get major heat distortion problems with oxyacetylene welding. This is enough of a problem with MIG for those of us fairly new to it.. and
besides the bottles you have to shell out 200-300 quid for the oxy equipment. Compare that to 150 ish to get set up on MIG..
It's horses for courses, if you were an experienced oxy welder then fair enough, but if you're new to it you might have problems with
distortion. Having a straight true chassis is very important for handling.
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ned
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| posted on 26/2/04 at 04:06 PM |
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oxy acetaline will be slower and may well distort the tubes more due to the duaration of higher temp when welding. I found it easier when i learnt to
weld but imho mig is the way to go. rental on a bottle of argoshield for mig is similar money. the alternative is the disposable bottles (for mig
welding that is)
i'm not a qualified welder, but am sure someone will be along shortly with more info/better arguements.
Ned.
beware, I've got yellow skin
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Alan B
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| posted on 26/2/04 at 04:46 PM |
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quote:
Originally posted by blueshift......It's horses for courses, if you were an experienced oxy welder then fair enough..........
I agree....MIG is cheaper, faster, easier....
not necessarily better...all methods of welding can do a good job if done right...
Just my 2p
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Dave J
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| posted on 26/2/04 at 04:59 PM |
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Hi Stephen,
Is that trade or retail? , per cylinder or for the lot?.Unless you can get a discount, I guess you will be stuck with it. We are paying slightly more
on the acetylene, but then it is a 4ft bottle (size F). The oxygen(5ft..size W) works out at £32.00/year rent .No idea what the refil costs.
We also have a MIG set that has a size X (3ft but smaller dia than oxy and acetylene) argoshield cylinder. The rent per year for this is £26.37 all
the above do not include Robbin Tax.
I'm just wondering what the difference in costs would be; MIG versus Oxy-acetylene.
Torch, nozzles, flashback arrestors 2 lots of gas etc. I would think that on those sizes of cylinder you may need a few refills (certainly on the
oxygen) with he best will in the world, you may have to redo a few welds.
You might think about delaying your decision until you've had a go at MIG welding on your course, then you will wonder why you ever considered
gas welding. MIG is sooo easy and quick and in no time at all you will be producing professional welds (Mig doesn't blow back at you either and
melt your barnet in a shower of sparks.)
On the safety aspect, personally, I wouldn't fancy storing Acetylene at my home (assuming that is where your build is) heaven forbid if the lot
went up, then your insurance Co might come over all awkward.
Best of luck.
Dave
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Alan_Thomas
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| posted on 26/2/04 at 06:05 PM |
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I used Oxy to weld all my chassis. Plus points are:
you don't need to pickup the grinder the welds are finished perfectly
also you see the weld pool progressing you know you have full penetration.
Minus points -
Its expensive
Its Dangerous, unless you know what you are doing (MIG never blew up anyone's house!)
It is slower (but warmer in winter )
Unless you are very careful you will get a lot of distortion
So unless you have experience (I had 20 years worth) my advice would be to stick to MIG
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Hugh Paterson
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| posted on 26/2/04 at 06:42 PM |
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Steven, + and - on both counts for neatness of welds, the oxy/acetylene wins hands down but as mentioned heat distortion will be a problem especially
on thin gauge metals, however if you have a cutting torch as well as the welding nozzles its a damn handy bit of kit for profile cutting lumps of
steel and helping stubborn bolts and things free. In a commmercial situation such a setup would be indespensable, in a one off build u can probally do
without it in favour of a good MIG setup. No matter what u choose avoid the small bottles of any gas works out more expensive in the long run,
(unless u know a nice person in the pub trade for Co2). Another thermal welding technique to consider is Tig, slower than Mig granted but with a bit
of practise well worth the effort. Setup costs similar to Mig, quality of welds far superior IMHO. Check with your lecturer to see if u can try a bit
of all of them and make your own mind up
Shug.
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stutz
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| posted on 26/2/04 at 06:58 PM |
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Thanks for all the replies. I will be going on to MIG and TIG, and wont make my descision until having tried them all. I have done some MIG and ARC
welding before, but found the gas welding on my first night far better than any other welding I had done.
Interestingly enough, the school (College of Norh West London) were quite persistant I did gas welding first, as they said it would greatly help my
electrical welding later on.
quote:
Is that trade or retail? , per cylinder or for the lot?.
Retail price for both bottles.
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Peteff
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| posted on 26/2/04 at 07:41 PM |
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You will also be hit with a handling or administration charge by BOC. This was £11 per transaction even if you fetched your own bottles from their
depot. This is for one or 100 bottles so if you only have one to fill it works out very expensive. I used a portapak kit which I still have but the
mig has rendered it unused for a long time now. It was very useful for seized parts though.
yours, Pete.
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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Stu16v
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| posted on 26/2/04 at 07:50 PM |
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quote:
It was very useful for seized parts though.
Ahh yes. The Red and Blue spanner....
I also had had access to MIG and gas (and more recently TIG), but I feel that MIG is probably best suited to the chassis construction, for the reasons
listed above.
Stutz, the tutor is on the ball (well, he should be really...). Once you have mastered gas, the rest will follow almost naturally. MIG is like drawing
slowly with a felt tip pen (subject to correct setting), and TIG is kinda like a mixture of the two skills. All have their strengths/weaknesses.
Dont just build it.....make it!
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Mark Allanson
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| posted on 26/2/04 at 10:16 PM |
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Hey, Guys, you are getting me all nostalgic, I love Sexy Ahotalene, The distortion problem is no real problem as, the same with MIG, you will be
welding both sides of the tube so the distortion should cancel themselves out.
Advantages are that if you do get a bit of distortion, you can just heat up the tube to either expand it or contract it using the cutting nozzle
without the trigger pulled. It is really useful for bending, unsiezing, making O/A baloon bombs, brazing, soldering, cutting..... it is good fun.
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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blueshift
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| posted on 27/2/04 at 02:34 AM |
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guh, mark, you're making me think about getting a set again just for funning around with. Stop it, please.
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ed_crouch
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| posted on 27/2/04 at 10:14 AM |
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quote:
On the safety aspect, personally, I wouldn't fancy storing Acetylene at my home (assuming that is where your build is) heaven forbid if the lot
went up, then your insurance Co might come over all awkward.
It wont matter about insurance. You will be VERY VERY VERY DEAD.
ed.
I-iii-iii-iii-ts ME!
Hurrah.
www.wings-and-wheels.net
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Staple balls
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| posted on 27/2/04 at 10:21 AM |
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rather than just
a little bit dead?
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Dave J
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| posted on 27/2/04 at 10:30 AM |
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From a purely practical point of view, oxy acetylene, whilst giving you good welds is awkward in that unless you have a safe custom built stand to
rest the torch when moving the tube to be welded about, then you will be forever turning off and relighting your torch.
No doubt like the rest of us, space is at a premium, therefore waving a lighted torch about might be a bit hazardous.
Assuming you have a safe stand to put the lighted torch on, then you have to think about all your expensive gas burning away while you are not
welding. At least with MIG the gas only flows when the trigger is activated.
Mind you the thought of having a nice hot welding torch at the moment is quite attractive, its brass monkies to say the least in my garage 
Cheers
Dave
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Dave J
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| posted on 27/2/04 at 11:03 AM |
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Assuming you are daft enough to stand around warming your hands on an increasingly heating acetylene cylinder, then yes I'd say you would be
pretty much dead.
If anybody does have the misfortune to have a heating cylinder, then provided it hasn't gone too far (too hot to touch), then call the fire
brigade, drag the cylinder outside, if you have a garden pond chuck it in. Failing that, hose the cylinder down to keep it cool, until the firebrigade
can take over. If it has gone too far, evacuate the area and leg it to a safe distance.......cause you got a potential bomb there.
I've always thought it would take nerves of steel to do this, so I go by the adage "Life before brickwork.......leg it!"
This is what flashback arrestors are for, to make sure this doesn't happen.
If you go for second hand kit, make sure you replace the arrestors with new. It's not worth the risk to do otherwise.
Don't get too alarmed, been doing gas welding for years, not had it happen yet (touch wood)
Cheers
Dave
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David Jenkins
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| posted on 27/2/04 at 11:20 AM |
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I must admit that I have fancied a portapac oxy-acetylene setup, but shied away from having these gases in a domestic environment (I consider oxygen a
dangerous gas in its own way - nice to breathe in small quantities, but hazardous in bulk!).
If I did have oxy-acet. I must admit that I would probably consider brazing rather than welding - much less chance of heat distortion as it's a
lower temp.
Can you use oxy-propane for brazing? I don't see why not, and it would be a lot safer than acetylene.
rgds,
David
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Hugh Paterson
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| posted on 27/2/04 at 11:28 AM |
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The propane is a bit dirty as gas goes but it would chuck out enough heat to braze with, better using it for burning only though in lieu of chucking
expensive actylene throw yer burning torch with the oxy. Good hint neat Oxy out a mask is a damn good hangover cure now how would I know that
Shug.
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Terrapin_racing
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| posted on 27/2/04 at 11:43 AM |
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Gas welding is fine - don't be put off by the fear mongers. If you are considering using OA then you need to consider the safety aspects. All
the information you need is freely available from BOC etc.
Follow the safety advice - use quality flame arrestors etc. I use a small set as mentioned earlier in the chain. Rental is about £80 per annum for the
bottles and refills are approx £40 a pair.
It does last a long time and is very flexible - brazing, welding - general heat applications etc.
[Edited on 27/2/04 by Terrapin_racing]
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Cousin Cleotis
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| posted on 27/2/04 at 02:15 PM |
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hugh, if you breathed just pure oxygen you will die.
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Hugh Paterson
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| posted on 27/2/04 at 02:33 PM |
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Silly I know that it was medicinal out of a "sick bay bottle", nice wee lift if u are hungover, then we all got caught
Shug.
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blueshift
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| posted on 27/2/04 at 03:18 PM |
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quote:
Originally posted by Cousin Cleotis
hugh, if you breathed just pure oxygen you will die.
I think this is untrue.
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Hugh Paterson
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| posted on 27/2/04 at 06:02 PM |
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Blue shift I suspect yer right but as I was having a whiff of it along with one of the sick bay Rangers on my ship, I thought in for a penny, doubt if
I would snort it out of a welding bottle har har
Shug
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flak monkey
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| posted on 27/2/04 at 06:09 PM |
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Yes you can breathe pure oxygen, but not recommended for long periods, see quote below;
Question - Could humans breath (survive) in at
atmosphere containing pure oxigen?
Yes they could...for a while and then they would begin suffering from oxygen
toxicity which causes a number of serious problems not the least which are
some pretty serious neurological damage.
PF
========================================================
Sure. At normal atmospheric pressure, it's fairly dangerous, as ordinary
substances such as clothing become extremely flammable under those
conditions. In the short term, the human body has no problems with a high
concentration of oxygen. In fact, exposure to elevated oxygen pressures is
sometimes even used as a treatment for some diseases, such as gangrene.
Over the long term, some tissues may suffer oxidative damage. I don't
really know what the long-term health effects are, though.
Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois
Give a good head rush apparently 
David
Sera
http://www.motosera.com
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Mark Allanson
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| posted on 27/2/04 at 06:57 PM |
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Bugger snifing it, just keep making the balloon bomgs
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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