Oxy-Acetylene welding
Posted By : Colin Wake, 30-Mar-2005, 09:54pm
All my welding used to be oxy-acetylene, and the results were reasonable, but it was all welding big lumps of metal together, not thin car body
panels.
You need to be very skilled to get it right and not get too much heat distortion.
I did car restoration evening classes and was re-educated into the ways of gas welding, and I still bottled out of welding a new lower lip onto my spit mk3 bootlid, the instructor did it and even he got some distortion.
Buy a MIG welder and get a pub CO2 cylinder, after a few days of 'pigeon-s***ing' you will get the hang of it and you won't get the distortion.
If you want to do a years training course then go the 'gas' route, as after the first couple of ruined panels, and the panel beating course (you will never satisfactorily get rid of the ripples, trust me!) you will wish you bought the MIG!!
Colin
You need to be very skilled to get it right and not get too much heat distortion.
I did car restoration evening classes and was re-educated into the ways of gas welding, and I still bottled out of welding a new lower lip onto my spit mk3 bootlid, the instructor did it and even he got some distortion.
Buy a MIG welder and get a pub CO2 cylinder, after a few days of 'pigeon-s***ing' you will get the hang of it and you won't get the distortion.
If you want to do a years training course then go the 'gas' route, as after the first couple of ruined panels, and the panel beating course (you will never satisfactorily get rid of the ripples, trust me!) you will wish you bought the MIG!!
Colin
-
Oxy-Acetylene welding
Posted By : David Fisher, 04-Apr-2005, 12:18pm
Thanks for the replies,
Renting the bottles was mentioned as being expensive, any ideas how much?
-
Oxy-Acetylene welding
Posted By : John Davies, 04-Apr-2005, 01:36pm
Argoshield sixe 'X' &163;40/yr
Refill about &163;9
Size X is the smallest cylinder, about a meter high and 14cms wide. Enough for most projects, short of a complete restoration. You need a suitable pressure regulating valve (not the one that comes with the welding set, for disposable cylinders) and a special square spanner for the cylinder tap.
JOhn-
Oxy-Acetylene welding
Posted By : Clive Speaks, 04-Apr-2005, 02:01pm
I learnt to gas weld years ago and came to MiG much later. I think you can achieve a much cleaner weld, weld dirty steel, cut and stretch metal with an acetylene set, the real crippler is that some councils insist on purpose built storage and work areas for gas sets.-
Oxy-Acetylene welding
Posted By : Colin Wake, 04-Apr-2005, 03:09pm
<snip>
the real crippler is that some councils insist on purpose built storage and work areas for gas sets
<snip>
Do they???
Mmmmmmm........
I used to keep mine in an integral garage that shared a wall with my neighbour.
She went through a period of trying to trace a 'gassy' smell in her lounge....... about the same time I was sold a leaky bottle by BOC...... very strange co-incidence. Thankfully she didn't smoke.....
Colin
p.s. anyone got a spare Acetylene cylinder knocking about, I have an oxygen one, but refuse to give BOC anymore money, I think I have kept them profitable in years gone by! -
Oxy-Acetylene welding
Posted By : David Fisher, 05-Apr-2005, 06:30am
Ahh, I was under the impression that gas bottles were attached to a wheeled trolley specifically so that they could be mobile.
How's about declaring a garage as a purpose built storage area then.
Is CO2 affected by the same rules?-
Oxy-Acetylene welding
Posted By : Philip Brammer, 05-Apr-2005, 09:21am
I am fairly sure that the fire brigade need to be informed about the storage of oxygen and acetylene at premises as they pose a significant risk in the event of a fire and need special handling. Acetylene is kept in a medium (like kapok) and can burn for a long time inside its bottle before exploding, which is why they are treated so carefully.
Using grease or oil on the threads of the oxygen connections can cause fire and explosions due to chemical reactions.
This is another reason why hiring the bottles from boc is so expensive. Not sure of the exact figure but many garages no longer use gas due to its cost when mig is so cheap.
Bottles are kept on trollys so they can be moved around the workshop as they are very heavy. Spare bottles are kept in chained racks in an approved storage area.
Co2 is an inert gas and can be stored anywhere, even in pubs
-
Oxy-Acetylene welding
Posted By : David Fisher, 05-Apr-2005, 12:28pm
Thanks for that, I think the gas route is prohibitive.
I'll look more closely into arc welding
Thanks-
Oxy-Acetylene welding
Posted By : Paul Bodiam, 05-Apr-2005, 04:41pm
Careful: don't confuse MIG (Metal Inert Gas) with arc welding.
Yes, they both use an electrical arc struck between the weld medium and the workpiece to provide the heat, but MIG uses a fine wire surrounded by a inert gas shield whereas arc welding uses a thick weld rod surrounded by a sacrificial coating that melts and provides a combined flux and shield. Once the arc weld has cooled, you have to chip-off the solidified shield to expose the welded joint.
I would not want to try body restoration with an arc welder - it is a very clumsy medium, best suited for repairing farm implements.
As another contributer put it: MIG is the only way to go.
cheers
Paul-
Oxy-Acetylene welding
Posted By : Adrian Lee, 05-Apr-2005, 05:31pm
"it is a very clumsy medium, best suited for repairing farm implements..."...wonder how we all managed before Migs then?
Depends on ability and skill with an arc welder.
-
Oxy-Acetylene welding
Posted By : Paul Bodiam, 05-Apr-2005, 05:43pm
Fair comment
I learned to arc weld while working on a farm as a teenager and so I tend to think of it in that context. I find MIG welding much friendlier to work with - unless you're attempting to do it outside on a breezy day
cheers
Paul-
Oxy-Acetylene welding
Posted By : Adrian Lee, 05-Apr-2005, 06:37pm
Farmers don't you just love 'em...................my favourite story of working as an agricultural/plant fitter..............Farmer phones up 06:30... "My tractors front axle has snapped can you mend it",off i tootles to said farm,"where is it then?" says i upon my arrival.........."over there in the slurry pit i was stirring it up"............wanders over,4 foot of very wet slurry....."sorry mate no can do"........he says "why?"......."its kinda difficult welding anything thats under the level of your shite!"
-
-
-
-
-
-
-
-
-
Oxy-Acetylene welding
Posted By : Philip Brammer, 30-Mar-2005, 10:06pm
Oxy-Acetylene is pretty much history now for body repairs I'm afraid. Its also very expensive to hire the bottles from BoC. Very basically you open the
acetylene valve on the torch (no 6 nozzle maybe) and light. Turn down the pressure until it burns without the black smoke. Open the oxygen until it
burns with a nice hiss and a bright blue/yellow point. melt the metal to a pool of liquid and add the welding rod to fill as you move the pool forward.
Easier with Mig! Only thing you cannot do with Mig is to braize and anneal (I am happy to be corrected tho') Of the two I would go for Mig as it is
possible to weld onto much thinner metal than with oxy-acetylene. Mig also creates much less heat and therefore much less risk of distortion and fire.
-
Oxy-Acetylene welding
Posted By : Duncan Banks, 31-Mar-2005, 11:15pm
Totaly agree, MIG is the only way to go for versatility and ease of use.
I sugest using 0.6mm wire (most hobby machines won't use any bigger anyway).
CO2 pub bottles if available are a perfect compromise for casual user.
MIG welding in industry usualy uses Argo shield (cougar) with a mix of 5% argon to CO2.
The use of pub CO2 in practical terms merely means a little more spatter, but nothing detramental.
Start off on piece of scrap with virtualy no gas on and just add a little until a smooth cleen bead is achieved. Too much gas can do odd things to the arc and is very wasteful.
You will find a pub bottle used like this will last a long time.
Metal Inert Gas everytime