[Highschoolwelder]

Hi all,

I am a senior in high school and I convinced my teacher to let me get our Lincoln Idealarc 250 ARC/TIG out and get it up running as it hasn't been used in years. I've TIG welded once before but I don't even think you could qualify it because it was only for about half an hour and that was before I could even use filler; however since then though I've been practicing oxy-fuel and have gotten pretty much gotten that down and just last week I got to fire up the TIG welder and run some aluminum and some stainless. The stainless went pretty alright, I'm still getting down the foot pedal and my speed compared to oxy-fuel but it still didn't quite look like I've seen on say Jody's videos...not that I'm saying I'm going to be that good right off the bat but I was just wondering if I could get some tips on what I could do to make my beads look nice and shiny and pretty. Also I brought some aluminum from home and tried that for the first time. The aluminum got better after about an hour of practice but anything more than just a flat bead is still somewhat of a challenge but that's because I'm not used to it melting through so easily. I ventured off and tried a lap weld but that didn't exactly turn out so hot. But my main wonder is what is the best way to eliminate the craters. It's not as bad on stainless mainly just on the aluminum. I don't know if I need to taper off towards the end of the weld since it heats up more towards the end of the bead, or dip it a couple extra times before I take my foot off the pedal. Any input would be great and I'll post some pictures when I can.

[Otto Nobedder]

Yep,

Always do a dip as you taper off on stainless (like buttoning off a MIG weld), and do it twice (or fat) on aluminum (it shrinks more as it cools).

Post up some pics, and you'll get better advice.

Steve S

[Wes917]

Double dip at the end on aluminum, circle around the puddle while tapering. Stainless, dip and circle while tapering down.

You can also taper down and come back onto the weld bead

[Highschoolwelder]

Thanks for the input guys. I'll try and post pictures as soon as possible but I was also wondering why some of my welds with aluminum are pretty shiny and some are gray and dull am I not running enough gas pressure or is my metal just not clean enough or what? I'm using 3/32nd tungsten and a pretty small cup so I'm usually using about 22-25 psi.

[Antorcha]

Thanks for the input guys. I'll try and post pictures as soon as possible but I was also wondering why some of my welds with aluminum are pretty shiny and some are gray and dull am I not running enough gas pressure or is my metal just not clean enough or what? I'm using 3/32nd tungsten and a pretty small cup so I'm usually using about 22-25 psi.

If you have to ask if it's not clean enough, it's not clean enough. AL needs to be surgically clean to get the hotdog results you see in pics and videos.

[Superiorwelding]

Highschoolwelder,
I wish I started welding in high school! Here is a video from Jody doing some lag joints that I think will help you.
http://www.weldingtipsandtricks.com/alu ... lding.html
If you are just practicing you will be fine just using a SS wire brush to remove the oxidation. You don't need it surgically clean to just practice. You can adjust your AC balance to get a little more cleaning action as well, if you do not have a wire brush. It sounds like your base metal is just getting to hot. I assume that the welds start to flatten out and turn grey the more beads you run on your base metal. Let your pieces cool down a little between passes or switch between two pieces and you will be fine. Although a hot piece will teach you amperage control as well. I cant wait to see your pictures.
-Jonathan

[Wes917]

Highschoolwelder,
I wish I started welding in high school! Here is a video from Jody doing some lag joints that I think will help you.
http://www.weldingtipsandtricks.com/alu ... lding.html
If you are just practicing you will be fine just using a SS wire brush to remove the oxidation. You don't need it surgically clean to just practice. You can adjust your AC balance to get a little more cleaning action as well, if you do not have a wire brush. It sounds like your base metal is just getting to hot. I assume that the welds start to flatten out and turn grey the more beads you run on your base metal. Let your pieces cool down a little between passes or switch between two pieces and you will be fine. Although a hot piece will teach you amperage control as well. I cant wait to see your pictures.
-Jonathan

While I get what you mean I have to disagree with just the wire brush. You play how you practice, and prep is a huge part of what we do.

[Arizona SA200]

One of my best friends has been an automotive painter since we were in high school together and I have helped him with projects. That little finger sanding in the door jambs and blocking the car out complete with 600 grit sand paper. I did all that with him and once asked why. His reply was, you can give the best painter in the world a paint gun to spray a show quality paint job but if the prep is crap the paint job is crap. He brought me some aluminum years back to weld and i gave him a stainless wire brush and said its all about prep work.

[Superiorwelding]

Wes and Arizona,
I appreciate you two pointing the prep we do out. Prep work is very important to our work, however, you must learn to crawl before you can walk. If a beginning welder focuses on learning the art of actually welding first and then learn how to prep he will be good. Although I can't argue the fact that the sooner one learns to prep correctly, the better off they will be. When my teacher taught me years ago, he began by setting Alum on the table and taught the basics to me first. I had a tough enough time learning that, let alone the prep work.
I guess sometimes I forget things I take for granted, like the prep work. I have done my fair share of painting and I always tell others that prep is 90% and trigger time 10% of the time. Same with welding. A good portion of our time is spent prepping for the weld that only takes a few minutes.
-Jonathan

[Arizona SA200]

Back when i was in school for welding, prep was stressed as the biggest factor in the appearance of a weld when tig welding. If prep is taught from the get go it eliminates some of the problems with the learning curve. A student must however learn when material has not been prepped correctly. I guess its one of those here's the right way but this is what happens if its wrong, kinda deals. And actually it doesn't matter what process is used all welds should be prepped. It is just more noticeable with tig.

[Highschoolwelder]

When I've been prepping I've been either taking a wire brush and cleaning it down to shiny raw aluminum or cleaning it off with a wire wheel down to shiny aluminum. I have no issue with doing as much prep as I can because I want to learn it all right the first time so that I know I'm making good welds, but what should I do to prep my material with both stainless and aluminum? Also the machine I have access to doesn't have AC balance, frequency, pulse, background current or any special goodies like that. It's a nice big older machine so it's pretty much got AC/DC, post flow, and a foot pedal with 3 different amperage settings on the machine.

[Wes917]

Wes and Arizona,
I appreciate you two pointing the prep we do out. Prep work is very important to our work, however, you must learn to crawl before you can walk. If a beginning welder focuses on learning the art of actually welding first and then learn how to prep he will be good. Although I can't argue the fact that the sooner one learns to prep correctly, the better off they will be. When my teacher taught me years ago, he began by setting Alum on the table and taught the basics to me first. I had a tough enough time learning that, let alone the prep work.
I guess sometimes I forget things I take for granted, like the prep work. I have done my fair share of painting and I always tell others that prep is 90% and trigger time 10% of the time. Same with welding. A good portion of our time is spent prepping for the weld that only takes a few minutes.
-Jonathan

I guess that where our difference of opinion comes from. I believe the prep is the crawl before the walk. On a poorly prepped piece problems can occur and then you could be blaming something else when the problem is the prep. Also when first starting you will develop bad habits that will transfer over to your work when you start

[Superiorwelding]

When I've been prepping I've been either taking a wire brush and cleaning it down to shiny raw aluminum or cleaning it off with a wire wheel down to shiny aluminum. I have no issue with doing as much prep as I can because I want to learn it all right the first time so that I know I'm making good welds, but what should I do to prep my material with both stainless and aluminum? Also the machine I have access to doesn't have AC balance, frequency, pulse, background current or any special goodies like that. It's a nice big older machine so it's pretty much got AC/DC, post flow, and a foot pedal with 3 different amperage settings on the machine.

There are many ways to prep your SS and Alum. You can wipe them down with acetone to get any deposits off the surface. A SS wire brush or SS wire wheel will work for both the SS and alum. I pulled up some of Jody's videos to give you a few ideas for practice.
http://www.youtube.com/watch?feature=pl ... wB4PESPAlI
http://www.youtube.com/watch?annotation ... WNZioJ_FOc
-Jonathan

[Arizona SA200]

I prep with a SS hand brush and have several, one for AL one for SS one for mild steel and so on. This prevents cross contamination. I also use acetone after brushing. Products like alumakleen (i think thats how its spelled) work good for the really dirty stuff.

[NYWELDERJim]

For really grungy, painted or rusted parts I "sand blast" them with aluminum oxide grit followed by brushing with a SS brush then a wipe down with acetone.

Jim

[Arizona SA200]

For really grungy, painted or rusted parts I "sand blast" them with aluminum oxide grit followed by brushing with a SS brush then a wipe down with acetone.

Jim

Good call Jim. I do not recommend doing this with silica media. Use the aluminum oxide like Jim mentioned.

[NYWELDERJim]

I only use either aluminum oxide or garnet grit in our blasters. We have not used a sand or silica based material in over 25 years. For less agressive cleaning of aluminum and steel parts such as cleaning carbon deposits off of steel valves and the combustion chambers in cylinder heads, I use glass beads. The blasted parts are then put through an ultrasonic cleaning tank with a detergent solution then rinse with water and dried.

[Highschoolwelder]

At home I've got my own media blaster but unfortunately not at school. We are on quite a low budget with lots of shotty equipment and our teacher is also (not to offend anyone) an engineer/architect and honestly does not know how to weld, light a torch, or run a lathe or mill. So pretty much in my 3 years with our previous shop teacher I learned almost everything I know about welding and machining, in addition to what I've learned on my own, but now I have to teach the teacher sadly enough. Also we don't have acetone, alcohol, a specified grinding wheel for tungsten, or specified stainless steel brushes for aluminum. So pretty much I just work with what I've got and do the best I can with the equipment and resources that we can afford. Most likely I am going to end up going and buying some acetone to bring though because it seems like a semi-essential part of the process.

[Otto Nobedder]

I weld on a variety of applications, some under strict guidelines and QC, and usually something in liquid hydrogen or liquid oxygen service (sometimes liquid nitrogen or argon), and I RARELY use solvents in the prep. At most, I use solvents to degrease/clean metal before I begin the "real" weld prep so I don't carry grease and dirt into the prep from adjacent metal.

I will, when needed, use solvents and rags to clean two inches on either side of the joint. Then, I'll dress to shiny one inch either side with a flap disk. Then, the weld is prepped (bevel and land) with a grinding disk specific to the metal (ferrous or aluminum). The backside is dressed at this time, with a 20000 RPM flap-wheel for pipe as one example. Then time to tack. Then feather the tacks with a grinder, and a dressing with a SS wire wheel dedicated to that metal.

That's it for prep, for stainless or aluminum, even in my most carefully coded work.

Steve S