Arc welding - What am I doing wrong?

I've recently bought an arc welder (SIP Turboweld 8 - 190 amp) and have been trying to use it to weld some scrap car parts (wings) that I'm using in a sculpture I'm making. I eventually got so frustrated with it that I gave up and bolted them together.

I'm doing an evening course at the moment where I'm learning on a similar machine, but I haven't tried to weld anything this thin before.

I've tried using different sizes of electrodes (1.6, 2.0 and 2.5), and altering the current, but it just doesn't seem to work for me. I find it incredibly difficult to strike an arc, and while I can do test runs okay, as soon as I try a butt or lap joint, it just becomes a horrible mess of blobs and holes.

Has anyone got any suggestions as to where I might be going wrong? Or is it just that I need more practise?

Before you buy.

Try posting this question at rec.crafts.metalworking too. There are lots of welding experts there.

Instruction. Practice, Practice, and Practice. Finally, you need to be pretty good to arc weld sheet less 16 gauge. OA torch is the better tool for thinner metal like your welding.

Why don't you try using a mig welder much better for welding thin metal with and more control I learn't to use one at night school regards Martin Evans

As to MIG vs. OA torch: I guess I'm old fashioned. I think one should get a good mastery of torch and arc welding before using MIG. But, yes, of course a MIG is easy to use. Although, when she eventually needs to weld heavier stuff, she probably won't understand the concept of penetration.

JDK

heavier stuff,

I think the question right now is regarding light material, but mig will weld heavier material also.

The concept of penetration applies to mig, and any welding. Actually, I believe you are going to learn to control penetration better on the thin stuff. Too much is bad, and I believe that's the problem being encountered by attempting to stick weld the auto body.

Before you buy.

I disagree entirely. You will learn TIG more easily by experience with torch and stick beforehand, but MIG technique is sufficiently distinct to not benefit appreciably from either of them.

General principles of joint formation, preparation and weld design apply to all forms of welding, but you can learn those as easily on MIG initially as on any other.

True enough in theory, but this presupposes some instruction rather than the process of autodidaction, which apparently we have here since she is looking on the internet for advice about welding techniques!

I didn't mean to suggest that a MIG could not weld heavier stuff. But a recommendation to use a MIG for a new welder usually results in using a low-end one with flux core wire.

I'm of the opinion that when first learning 'blowing throw' is better. You can learn to back off, but moving the other direction in skill is harder if bad habits are developed.

I think the essential points are

1. Good instruction 2. lots of practice, and 3. for the kind of thinner metal she is now using (and given her apparent lack of experience) arc welding is inappropriate (and in my opinion, she she learn to use an OA torch).

One technique that might work is a spot weld at intervals instead of a continuous bead. If you setup for minimum heat and the smallest electrode, then only hold the arc for a second or so you should be able to produce a decent joint. It might require epoxy filler to make the rest of the joint what you want, but that's the way an auto bodyshop usually does it. Also, remember that a short arc is cooler than a long one, so by keeping the electrode pushed down almost touching the work less heat is generated to burn through. All of it takes practice, and tons of it.