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T Joint practice

Posted: Sun Oct 30, 2016 1:43 pm
by PaterNovem
So I hit the remnant pile again at the junk yard / metal supply place. Got some 2x1x.125 square tubing and 1x.125 flat bar. All 6061. I cut the flat bar into 2" tabs on went to practicing. Once I get going I seem to go ok. So this little set up gave me some tacking and starting practice. My problem on this has been that I get the tab too hot and melt through. I am having more success by changing the torch angle such that I am more on the base piece than the attached tab. Once I get the base to puddle the tab is ready to go.

Using 1/16 2% lanth electrode, 1/16 4043 filler, 150 amps on foot peddle but only using half to 2/3 once I get a puddle. 250hz, no pulse. I tried some different pulse settings without much improvement.

The setup is giving me good practice. I still melt out the edges... gotta keep working on that...

Re: T Joint practice

Posted: Sun Oct 30, 2016 1:56 pm
by RamboBaby
That looks pretty good but I'm having a hard time understanding how you're pumping 150amps through a 1/16" electrode without having it drip off into the puddle.
Once you get good and comfortable with what you're doing here, try going back and welding the backside of your joints. You'll be out of poition as a mofo, regardless of how you try and position your part. Its really good practice but frustrating as hell the first couple of times that you try it. The tighter the spacing between the tabs, the harder it gets. This will lead to the understanding of why flex head torches were invented. Sticking to a torch with a fixed head while learning will make you a much better weldor.
I find that Tjoints are the most difficult type for me to weld unless I'm doing them vertically because they put my wrist in a really awkward position.

Re: T Joint practice

Posted: Sun Oct 30, 2016 2:40 pm
by entity-unknown
Try 100-120Hz and I'd probably up your electrode to 3/32 2% Lan. You're doing great in regards to not dipping your tungsten too! I see you only did it a few times. Looks like you might wanna clean your metal a bit better. Try using a sharpie and making a a few lines across the plane you want to weld. Clean it with a sander or I guess a rubber cork thing works good I've heard... Once those sharpie lines are gone, it's clean! After you acetone wipe it but honestly I cheat on that a lot and the chances are quite frequent where you'll have a black halo to start with if you do cheat here but you CAN carry it on and it seems to clear up which I think you might have found out....

150A should be good and it sounds like you're riding out the pedal right from the gate to near the end if you're mashed to almost mashed to start, and begin pumpin that pedal like you are. Once you're near the end with that length, you'll likely need to be around 1/3-1/2 your pedal, and taper off as much as you can at the very edge and fill it as fast as you can with the filler to make that last lil bead sit right. Taper off for about 2-3 seconds till it's just a tiny lil spark and then let go and you're done!

1/16 filler and your thickness of material seems to be great for everything except Al. Al is very thirsty and takes a lot of filler. The fun part here is you have to be a good judge because Al will take as much filler as you can give it; total gluttony. So you measure your bead and if it looks good, dip n roll! With 1/16 you're also going to be spending more time and energy filling/feeding which will cause fatigue and you'll see it in your weld.
I'd recommend 3/32, 1/8 would actually be almost too much but very doable and the least amount of feed effort. Still 3/32 with your thickness will be very comfy with the least amount of failure.
Lastly.... Make sure you got a very good grind on that tungsten. Besides knowing the basic fundamentals I've found your tungsten grind is about the most important thing you can do for prep and very necessary for a beautiful weld using an inverter. It's also the one thing besides the basics, that has the most significant effect on your welding. I think it's even more important when it comes to Al since you're on AC, not DC and with a bad/poor/ok grind, you'll have a lot to a fair amount of arc wander. If you get a good/perfect grind, your arc will be stable, and almost as predictable/reasonable as a DC arc.

Re: T Joint practice

Posted: Sun Oct 30, 2016 6:53 pm
by MosquitoMoto
Looks to me like you are doing great.

Short runs beginning and ending at edges are a challenge. What works for me is to get my filler 'dab' rhythm going but always remember that it ends with a 'push'. When you approach the edge - not when you get there, but a dab or two before, back off the pedal a bit, then end your run with a push of filler rather than just a dab. Even if you haven't already backed off quite enough, the extra filler acts as a heat sink and helps stop melt through.

Keep at it. Funny, it seems I did so much aluminium practise running long beads, yet now that I'm actually building stuff, my runs seem never to be for more than a couple of inches. Short run practise like yours pays dividends!


Kym

Re: T Joint practice

Posted: Sun Oct 30, 2016 7:01 pm
by entity-unknown
I'm with Kym on the long vs. the short. I haven't needed more than 1.5 inches in almost all my welds except a finger press from Swag Offroad but even then you only wanted to go about 3in at most with a lot of tacks to make sure the thing didn't warp at all. Had I made a long run like my practice welds, it surely would have warped and when you want something flush at a perfect 45/45 degree angle, you want to be as patient as possible i.e. small runs. Cheers to the great work!