[Cammo]

Hi,

We have been mucking around in the shed welding up a storm, and I was wondering if you guys could have a look at the video and let me know what you think we are doing wrong and right? Your help would be much appreciated.

http://www.youtube.com/watch?v=4naw88cM7is

Cheers

Cammo

[Otto Nobedder]

You seem to have the technique down nicely. I watched it without audio for now, as my wife is watching "Pride and Prejudice" about 5 feet from me. , so if any of this is covered in the audio, I apologize. I'll play it with sound when her movie's over.

Three gentle critiques:

It's not "tungsten carbide," as stated in the text. It's either pure elemental tungsten (which it appears to be, by the nice ball it forms), or a rare-earth alloy.

You do not need to "point" a tungsten for HFAC. For pure tungsten, you can break it off cleanly and round the end. (It's going to form a ball; Pointing it only provides some very thin material to melt completely and drip into your weld, making an inclusion.) For alloys, such as lanthanated, you can taper it and square the end.

When restarting a weld, it's wise to wire-brush the start point and the heat-affected zone in the direction of the weld, as the heat from the previous weld accelerates oxidation and can give you a "skin" that requires extra heat to break through when restarting.

(Bear in mind I've welded aluminum pipe in critical applications that were x-rayed for quality control. Your results speak for themselves; you appear to do just fine. My first critique is just an edit. The other two may simplify keeping your quality consistent. Your mileage may vary...)

Oh, and, nice camera work!

Steve S

[nova_70_383]

im not familiar with that machine, but it appears to me you have too much ac balance. with an inverter machine the idea is to keep a pointed tungsten.

[Otto Nobedder]

im not familiar with that machine, but it appears to me you have too much ac balance. with an inverter machine the idea is to keep a pointed tungsten.

Pointed?

No.

With an inverter AND an alloyed tungsten, a tapered and BLUNTED tungsten. You will not keep a point on HFAC, regardless of the machine. The reverse cycle of the AC will round your tungsten regardless. Even if you're welding beer cans with 1/8 inch, the tip will round.

With pure tungsten, as they appear to be using, there's no "point" even tapering the tungsten. Rounding will do.

[fisher]

Yeah it looked like it was all going well. I too just blunt end the tungsten and slightly bevel the corners with that type of butt joint, but with lanthanated electrodes I will do a half point if welding anything I want more focused heat and less current.

I was a bit concerned watching you sharpen the tungsten that way with the point towards the grinder. I too did that in the past until I had a bit of an accident when the wheel caught the tungsten and shot it back into my hand, a bit nasty and quick when it happened, never do that again, always hold the tungsten above the wheel so that the direction is opposite to what you were doing and you are grinding away from the tungsten's tip.

[Otto Nobedder]

Good catch, fisher,

I didn't notice. I sharpen tungsten like that often, but I use a pin vice, so my hands are beside the tungsten, and with the extra control, I've never had one catch. I'll have to rethink that, and consider what would happen if it did catch, because doing it that way gives me a great point, and great visibility when I sharpen.

Steve S

[weldin mike 27]

Hey,
A very special Supervisor (read POS) told me one that there was no way in hell a tungsten could be grabbed and ejected by a bench grinder..... ......ah, thanks. Yeah right, I'll still be very carefull thanks. (idiot). Rant over.

Mick

[Otto Nobedder]

Yeah, I know of someone it happened to. He sharpened both ends, so he drove a "needle" deep into his hand. I always assumed the pin vice gave me some protection, but I'm going to give it some "failure mode analysis". With the vice, there's little danger of driving anything into my hand, but the tungsten is more likely to shatter when slammed into the steady-rest,and the pointy end is going somewhere...

[weldin mike 27]

Hey,

We now have a dedicated tungsten sharpener, so the risk is decreased. However when you are a decent walk away from it and under the hammer, the bench grinder still gets used. Including one 15 inch one thats about 60 years old. Good machine, but not for Tungsten sharpening.

Mick

[Otto Nobedder]

Best thing I ever sharpened tungsten on, was a 3" vertical stationary belt sander with 120 grit. Fast, accurate, and safe.

I've never had the opportunity to use a dedicated sharpener, but I'll have to look into them, and start selling the idea to the boss...

Steve S

[weldin mike 27]

Hey,

I beleive ours went for around 3 grand. Its a serious unit. I think in your work otto it would give excellent repeatable results. This one has a diamond wheel with a coolant system. Its also traps the grinding dust/sludge. Hijack again lol.

Mick