Rule of 33 for TIG welding 

One of the techniques for improving weld quality and reducing defects is the rule of 33 for tig welding with high speed pulse settings.

But first, lets talk about slow pulse settings for a minute.

Low pulse rates of .7 to 2 pulses per second have a purpose in controlling heat and work great for things like thin sheet metal outsider corner joints on stainless steel.

By alternating between a low amperage and a higher amperage, heat input can be lessened and when you combine that with using chill bars, or chill blocks, distortion can be lessened a lot.

But then what about high speed pulse settings? What are they good for?

A high pulse rate of say 100 or higher pps really helps to focus the arc and is useful for jobs like tool and die and mold repair.

Pulse rates of around 33pps also seem to help agitate the puddle while also focussing the arc somewhat and can help to prevent micro cracking on nickel alloys like inconel 718 castings. The agitation of the puddle along with near perfect argon shielding from a large cup like the furick BBW, allow the normally sluggish puddle of inconel 718 or other nickel alloys to flow at a lower amperage...and that can translate to lower overall heat input.

Pulse tig settings between 3 and 30 are very difficult to watch and give me a headache so personally, I just avoid those pulse settings.

But once you get up around 33 pulses per second, the pulse is fast enough so that it is not difficult to watch at all... you get used to it pretty quickly.

In fact, it sounds almost like TIG welding aluminum on ac except much quieter.

I coined a phrase years ago for pulse tig settings called “the rule of 33” where you set all pulse settings to 33. 

The "rule of 33 for tig welding" is easy to remember and it works very well for filling gaps on thin wall tubing as well as for welding on or near an edge.

What is this Rule of 33 for TIG welding?

Using the rule of 33 is as simple as 1, 2, 3

1. Just set pulse rate to 33 pps,
2. background current to 33%,
3. and pulse width to 33.

33 is not carved in stone but is just a way to remember a great starting point for using higher speed pulse rates.

For example, I remember developing a welding procedure for HIP cast inconel 718 where 39 pulses per second, 33 background, and 33% pulse width aka pulse on time gave much better results on micro cracks than without pulse.

I have used the rule of 33 for filling gaps on thin wall tubing, tig brazing with silicon bronze, titanium test welds, and build up on the edge of stainless.

It works especially well for tig welding on an edge or near an edge.

Dont be afraid to experiment with the pulse rate, background, and pulse width. 

Every situation is different when it comes to what pulse settings will work best for high speed pulse tig settings.

But you will probably remember the "rule of 33" for tig welding pulse settings better than 39, 33, and 33.

But what if your machine does not have all 3 pulse settings?

In fact, Some tig welding machines don't have all 3 pulse adjustments and have the pulse width fixed at 50%. ( my CK mt200 pulse width is fixed at around 50%)

No worries, you can achieve almost the exact same results as the rule of 33 just by lowering the background current down to around 20%.

Is it really necessary to use tig pulse settings?

In my own experience, I would say nearly everything that can be done using pulse, can also be done without pulse. But pulse sometimes makes things a bit easier.

For automated applications like orbital welding stainless tubing, thats a different story.

But pulse tig settings can make things a little more foolproof and a little less tedious.

Can you hold your speed to 70 mph on the highway without cruise control?

Absolutely! but cruise control makes it just a little easier.

TIG welding something as thin as box cutter blades can be done without pulse settings but can be easier with the right pulse settings.

TIG brazing silicon bronze overlay in a thinly worn area on a hydraulic tube can be done without pulse settings but using the rule of 33 makes if flow like honey and might just prevent blowing a hole.

Give the rule of 33 a try.