From: laforce@xenon.arc.nasa.gov (Soren LaForce)
Newsgroups: rec.crafts.metalworking
Subject: Re: Oxy/Acet welding problems
Date: 26 Jan 93 17:03:00 GMT
Organization: NASA Ames Res. Ctr. Mtn Vw CA 94035
News-Software: VAX/VMS VNEWS 1.41

In article <C1GsAw.7GE@dartvax.dartmouth.edu>, Charles.K.Scott@dartmouth.edu (Charles K. Scott) writes...
>I'm into a long term building project that involves many different
>skills; woodworking, welding, engine building, cable stringing and
>fabric.  

stuff deleted


>asking.  Specifically, the material I'm welding is 4130 sheet steel
>..080" thick.  I finally decided to go to the local welding supply shop
>to make sure I was using the correct tip and they called a Smith
>dealership.  The dealership was happy to sell me a new tip which
>appears to be the smallest they make.  There is no way this tip works
>for metal this thick, I can't imagine what was going through their
>minds to recommend so small a tip.  I wonder if it's even going to work
>on the thinwall tubing that's .035".

I'm not familiar with the smith equipt.  My torch is a victor (with
airco gauges).  An 00 tip seems like it would be about right 
for .080 steel.  I usually use about 4psi and 8psi for that size tip.


>pressures.  My friend always used 5psi (Acet) and 20 (oxy).  I've had
>difficulty using these pressures.  In desperation I finally just start
>fiddling with the regulators and now have about 8 and 15 respectively.

Sounds too high, this is about what I use for a #3 tip. (10 & 20 actually)

> 
>Here's the question: Is there a specific pressure to set the requlators
>for  welding?  I know what to set for cutting, that's not a problem. 
>Cutting is easy, welding requires delicacy and skill.  When welding
>aircraft parts, good enough isn't good enough.  It must pass inspection
>or it can't be used.
> 
>The welding I'm doing requires me to weld one piece to another at a 90
>degree angle.  I have to bend a piece into a U shape and weld the U to
>a plate.  

Keep practicing, that's the only way anyone gets good.  I'm not that
good a welder (pretty poor actually).  Make some practice welds on 2
flat plates, just butt jointed together.  Put one plate in a vise and
bend the weld.  The weld should not fail much (if any) sooner than
the surrounding steel.  When you can do that, go on to more (geometrically)
complicated welds.

>I've discovered that welding into the angle isn't easy and I
>must be missing something in the set up.  I haven't been happy with the
>bead yet and my friend, who has built several aircraft confirms that
>they are not satisfactory.  What would be recommended to place the work
>on so that the heat isn't wicked off.  Would firebrick be a good base?

Yes!

> 
>I'm also using a 1/16" rod which my friend also says is incorrect, he
>feels 3/32 would be better.  1/8" is too big.

Don't know, 1/16 sounds pretty good; 1/8 sounds too big.

> 
>It appears to me that a lot of things have to come together to make a
>satisfactory weld.  The books I've read on aircraft welding say that
>the rod is dipped into the puddle and kept there and the puddle and rod
>and tip are all moved down the area to be welded in one fluid motion. 
>Easier said than done, I haven't achieved this ideal yet.  One of the
>problems, among the many, is that I have to use so much heat to get
>things molten that the hand holding the rod gets too hot and makes me
>jumpy which doesn't do any good for my steadiness.

WEAR GLOVES!!!

> 
>Man, this is getting involved, sorry.  Let's just start one thing at a
>time. Is there a specific pressure setting for the regulators and does
>it vary according to the thickness or type of metal being welded?

Yes.  I tend to run the pressure too low.  You know the pressure is 
too low when your torch blows out!  I've run a #00 tip as low as 
2 and 4 psi.  The largest tip I generally use is a #3, which I run
around 10 and 20 psi (8 and 15 tended to blow out)  all pressures 
are acetelene then oxy.

I think the pressure is more determined by the tip than the work, the
tip (of course) is then determined by the work.

> 
>I'll deal with the rest of the stuff as the discussion evolves.
> 
>Thanks anyone who can assist.
> 
>Corky Scott
Newsgroups: rec.crafts.metalworking