Welding Tips and Tricks

Hello, we are having a bit of a issue welding some aluminum tube (about 1/4 wall, to some .500 thick plate, bead has to be perfect on this particular weld

The welder is a syncrowave (1994 model I think) 351 no pulser option, using a WP18 water cooled torch, foot pedal. using argon (no mix)
Tubing had been turned in a lathe dry,, plate was new, we removed the film and have cleaned with acetone, using a 8 cup with 1/8 tungsten, We have never welded this thick of plate on my machine before,

does anyone have experience with the 351 of that era here? I'm wondering just how much effect the HF setting has on this? it has always been used at a very low setting such as 20, and what settings have worked for you, , and , or if possibly im having some issue with the machine in some way, it is hard to keep the bead nice and uniform,
(edited) let me add, I just checked the spark gap and although it was out, it was only .011 spec calls for .008 which I adjusted, tips seem to be pretty clean
any help is appreciated
thank you
tom

The manual recommends using the lowest setting possible on the HF intensity control (This is more to limit radio frequency interference than anything else). Unless you're welding in your garage in a residential neighborhood, you can turn it up.

I doubt this will have much effect on your welds, though. For aluminum that heavy, a good pre-heat is in order, focused more on the .500 plate. You'll also benefit (both in bead appearance and ability to reach/maintain welding temperatures) from using a 50/50 He/Ar mix. Since I have ready access to helium at work, I've experimented quite a bit with different proportions through a mixing valve, and find great benefit to approx. 40-50% helium, not much more improvement above 50%, and a falling-off of arc stability and ease of starting above about 70% in HFAC welding.

Check with your gas supplier. Sometimes custom mixes are relatively inexpensive (helium's not cheap anywhere) if they can mix it on site. Sometimes, it's more economical to get a bottle of helium, and use 2 flowmeters and a tee fitting, and set your own mix. Just be aware that while an argon flowmeter will work on a helium bottle, the flow numbers are a lot different. 10 CFH helium will "just" lift the ball of an argon flowmeter, about half a ball-diameter.

A side note: If you need perfect beads, even if you stick with straight argon, emphasize to your supplier the need for a dry bottle. For economy, not all gas suppliers evecuated their bottles every time or for long enough. You can also install a dessicant dryer in-line between the flowmeter and machine, for cheap insurance.

Steve S

Definitely going to need preheat because 250 amps (AC) is going to be the minimum for getting solid tacks on that material and you will be waiting for a bit until it gets hot enough. If I recall correctly, 250A is the top of that torch's AC rating. I'd like to have a heavier rated torch and at least around 270A for tacks and getting the heat up on the parts. All of this also depends on how 'big' the parts are relative to that thickness. Larger plates and such, I could see myself tacking in the 300A range if I am to make any time at all and the additional punch for restarts.