Gimme a tip on O/A welding thin-wall tubing, please

Joel_BC · #1 01/16/10, 05:39 PM

I've been running a very fine line... Trying to weld fairly thin-walled mild steel square tubing (using oxy-acetylene, which is all I've got). The tubing is 1" cross-section, with .105"-thick walls.

Problem, as you may imagine, is that getting the steel of the tubing to flow in the puddle before dabbing the rod in is finicky, as sometimes it tends to burn through. I've been using a fairly small tip (Victor #1) with pressures set at: 4-5 lbs, acetylene; 5-6 lbs oxygen. At the torch, I try to keep the flame neutral, and not an oxidizing flame (as I know that would burn through). I'm mostly self-taught as a welder, so I could use advice.

I know I can repair any holes, but it is a nuisance and slows things down.

I've thought about using a slightly larger (Victor #2) tip with a 'softer' flame... might this help? Thanks.

idahodave · #2 01/16/10, 05:55 PM

Did you consider brazing?

agmantoo · #3 01/16/10, 06:06 PM

What are you using as a filler rod?

Old Vet · #4 01/16/10, 06:16 PM

On thin walled I find it easier to melt a piece of rod then get it to puddle. What I do is to put the rod on the piece and melt it all together. It may not be the way to do it but it worked for me.

ace admirer · #5 01/16/10, 07:11 PM

.105 wall?,,,,thats kinda thick as far as tube goes....how is your fit....it helps if the fit of the parts is tight with no gap...as someone has already said...it helps to "bridge" the gap by heating the rod and kinda blobing some metal in the gap to connect the two...which means the heat is shared between the two making controling the heat much easier.

i also think you might be correct....i think your pressures may be high for a beginner, and a softer flame (easier to control heat) my help. above all take it easy ...dont loose your cool....once you get the hang of it.....its kinda fun.

Joel_BC · #6 01/16/10, 08:49 PM

Okay, well two of you have given an opinion about going the same route (or very similar) - namely, cutting or blobbing some of the filler rod onto the joint and proceeding with the weld. But how do you avoid "cold lapping" if you di it this way?

agmantoo · #7 01/16/10, 09:59 PM

Joel_BC

Can you braze? The process is very similar but you must concentrate the heat more on the filler rod and at the same time keep the material being fused elevated. Once you get the knack of how to do it the task is rather simple. With the joint properly heated and the filler rod approaching melt point the filler rod will cease to glob and will puddle and dispense onto the material being worked as the filler rod is further heated. What material will you be using as a filler rod? Have you tried a steel coat hanger?

Windy in Kansas · #8 01/16/10, 10:48 PM

When I learned back in high school we were required to learn to push a puddle around before we were allowed to be taught welding. Learn to manipulate a puddle on some scrap and then learn to start adding some rod to the puddle. Then you simple introduce a second piece of metal into the equation.

Once you get the hang of it you won't forget and then arc welding will be a breeze as well.

Joel_BC · #9 01/16/10, 11:43 PM

Quote:

Originally Posted by Windy in Kansas

When I learned back in high school we were required to learn to push a puddle around before we were allowed to be taught welding. Learn to manipulate a puddle on some scrap and then learn to start adding some rod to the puddle. Then you simple introduce a second piece of metal into the equation.

Yeah... well, I have no trouble welding thicker metal, and did spend a lot of time learning puddle control with thicker stock. My trouble is burning a hole (only sometimes) in thin stock! And the solution of placing a piece of rod or dripping a molten blob onto the joint (as recommended before) sounded like it might be conductive to cold lap, and a weak "weld".

Yes, I do know how to braze and have done a fair bit of it. But, while brazes are strong in terms of an ordinary bond, I tend to think of brazed joints as less strong if the joint has to stand up to shock stress, or vibrating stress over the long haul.

Old Vet · #10 01/17/10, 12:16 AM

What I meant was to put the rod down on the piece and heat it and the piece to a puddle. That way you have more to work with than melting a puddle on the piece and then aiding rod. Having a softer flame also helps with this not a oxidizing flame but a soft flame. Do not open the valve on your acetylene or oxygen all the way just get a good flame that is blue.

ace admirer · #11 01/17/10, 07:43 AM

ok, yeah, i agree, about the learning process. take some of the tube you will be using and just form a puddle on it an inch or so from an end. learn to push the puddle around with the flame. when you get confidant with that, try the welding...

the cold lap caused by "bridging " can me minimized by welding back into the cold start.

i would not down play brazing for strength. a proper (close fit) brazed joint has a bearing strength of over 60.000 psi.

Joel_BC · #12 01/17/10, 08:18 AM

Thanks, guys... I do apprecite it.

Bearfootfarm · #13 01/17/10, 09:59 AM

Are you using any flux?

Joel_BC · #14 01/17/10, 10:23 AM

Quote:

Originally Posted by Bearfootfarm

Are you using any flux?

I use fluxes for brazing and soldering. I don't know anything about the use of flux for O/A welding. But if this is something new - and helpful - please tell me the basics of how it works (and what the fluxes are called and how you find them at the local retail level). Thanks.

Bearfootfarm · #15 01/17/10, 03:41 PM

You use the same flux you would for brazing.
Boric acid works good with steel, and just helps the metal flow a little smoother.
You can put it on the joint, or just dip your filler rod

Blu3duk · #16 01/18/10, 08:04 AM

Before I even opened the thread up I was thinking "thin wall tube, #2 tip"

William
Idaho

Joel_BC · #17 01/18/10, 09:59 AM

Quote:

Originally Posted by ace admirer

ok, yeah, i agree, about the learning process. take some of the tube you will be using and just form a puddle on it an inch or so from an end. learn to push the puddle around with the flame. when you get confidant with that, try the welding...

Yes, thanks Ace. I did a session like you suggest here, yesterday. I'll do more of it too - practicing on scrap with situations that "don't count" but will build up my feel for puddling with thin-wall.

ace admirer · #18 01/18/10, 12:34 PM

well fusion welding is science and skill. its thinking about a dozen things at one time and trying to control all those things with two hands.....the more things that are natural to you (through practice) the easier the craft is....

i think thats the problem with craftsmens perception to other people, they make their craft look too easy, and sometimes loose money or worth because of this perception.

it would help if you have a fellow craftsman to just spend a few minutes with you in the beginning stage....but reguardless, you will get the hang of it.

Windy in Kansas · #19 01/18/10, 03:34 PM

Quote:

Originally Posted by ace admirer

the more things that are natural to you (through practice) the easier the craft is....

i think thats the problem with craftsmens perception to other people, they make their craft look too easy, and sometimes loose money or worth because of this perception.

But if we (they) didn't make it look easy the untrained wouldn't buy tools, get frustrated at the difficulty with them, and then sell them to us cheaply.

ace admirer · #20 01/18/10, 09:21 PM

Quote:

Originally Posted by Windy in Kansas

But if we (they) didn't make it look easy the untrained wouldn't buy tools, get frustrated at the difficulty with them, and then sell them to us cheaply.

Good One! and True....