Very thought provoking video. Great job

It all depends on the age of the aluminium, if it's over 40 it won't be able to hear the higher frequencies, so the higher the frequency the less it will notice.

TIG with TOT should be a series

Hey This Old Tony, tangent thing I wasn't sure you knew: I noticed your cracked nail in the video. Get some CA Glue, put a droplet on you nail and then put a tissue (facial) on the drop. Let it dry. Remove excess tissue and then get your wife's nail file or one of those lathe files you've mentioned and sand the patch smooth. It's kinda like fixing fibre glass. Source: my Mum was a nail technician for more than forty years and I suck at hammers.

You know it's TOT's video when you hit the like button before it even starts! Thanks Tony

The skin effect actually does appear at pretty low frequencies [1]. The skin effect at 200 Hz is as low as 4-5 mm in a plasma. With square waves there will be higher harmonics and the depth will be even smaller. Higher frequency will cause power to concentrate in the outside of the arc cone. That extra heat on the outside will dissipate a lot more before getting into the metal, and indirectly widen the arc very slightly as heat on the outside will generate a little extra plasma from the surrounding cool gas. Say you're running at 2000 Hz with a square wave and your overall skin depth is 1 mm. If the arc is 4 mm wide, the power in the center is 20x lower than the power on the very edge of the arc. At that point it might as well be off. At 200 Hz the difference will probably be closer to ~20%, but that's still a huge difference and the overall heat into the weld will be reduced a lot as well. Since power is concentrated on the outside of the cone it doesn't have an insulating later between it and outside air and it radiates faster. The reason skin effect is usually neglected at low frequencies is that the overall power dissipation doesn't change much until higher frequencies, and wires are much thinner than a GTAW arc. Electrical engineers don't care much if a wire has 10% more resistance than expected, but when you're welding a 10% change in settings can be a big problem.

Two videos in as many days? I must be dreaming.

I do a lot of pipe welding with an extended land bevel which is similar to the grooves you welded in. I always go high frequency on the root to prevent the puddle from spilling outside the bevel, then I go low frequency on my fill and cover pass.

the machine is most likely not producing a perfect square wave, there is a slight ramp in the cycle switch, the slower frequency allows for a longer time at max amperage while the higher frequency spends more of the overall duty cycle in the transition between positive and negative

Hey Tony! Electronic Engineer here - I think your statement at 8:35 ish might be off. I doubt it's a square wave. Probably more of a trapezoid shaped wave, with a set rise time based on the voltage you're running, humidity, quality of grounding and so on. That rise time will be the same at 20Hz and 200Hz. And probaly takes a few milliseconds. Therefore at higher frequencies instead of hitting the flat at the top of the trapezoid, it's either sloping up halfway, before sloping down again, or just spending less time at the top, so the integral yields less energy to the work. Great video as usual!

Tony, I am new to Tig welding, don't even have a tig welder but want to start. I am so appreciative of your documentation because you have managed to explain AC frequency to a chef! Damn bro, I love your style. Keep up the good work

Hi Tony. In my work as a EE my experience has been that the skin effect at the frequencies you speak of is negligible. While I am no expert I believe that it is indeed the cone width that is controlling the energy density of the plasma and thereby producing a wider or more narrow weld bead. The reason the two cones looked the same in your video, regardless of the discharge frequency used, is because you are looking at the photons emitted when the electrons supplied by the welder recombine with the argon ions. However, I don't think that those photons are actually representative of the energy flow/density within the plasma beam. What you need in order to see energy flow in the plasma beam is a camera that can see electrons, or better yet heat. If you don't have either try googling "energy density in AC discharge induced plasma flows". The results of that search should have a few such heat pictures of plasma beams. What you will see is that inner cones (that can't be visually isolated based only on the light they give off) do change and that as a result the heat signature of the plasma flow changes drastically as well. The smoking gun in your experiments was not what the plasma flow looked like on the camera, but rather the characteristics of those little pits in the base metal. They were more spread out in the case of the lower frequency sample. That's because those multiple "cathode sites" formed based on the energy density of the beam. They are the tell tail sign of where the beam was the hottest, and how close or far apart they are seams to correlate well with the frequency of the plasma discharge that produced them. I have no idea if I am correct or not, so please consider my theory as just another possible explanation. Ohh, and please keep making videos! I love them, and they are very uplifting whenever I enter a bout of depression. I watch them, and then struggle out to the shop to build something and then I start to feel better. So thanks for that gift!!!!

Tony you spoil us with frequent videos

Unlike everyone else commenting....I have no idea what you (or they) are talking about....but it held my attention for 13:13

You're an epic teacher Tony. I've had trouble with aluminum boxes. I'll give this a try!

Holy Toledo that was the quickest 13 minutes ever! Thanks Bud that was awesome!

Good stuff Tony, very helpful....would like to see more...thumbs up from me...excellent explanation. 6061 his welding is the Mona lisa of welding....he turns his welds into an art form.

4:17 Couldn't have said it better myself. The AC frequency adjustment is highly overrated.

Great blog @This Old Tony. informative and entertaining!!!

Hay tony, I started watching your videos only the other month. The ones about making a chainsaw go cart and now I'm bloody hooked! They are just so enjoyably good! Keep making them and I'll keep watching thanks!

Tony, excellent work on this one...helps a lot

wow, 2 videos in 1 week. Love it! Thank you for sharing this info.

I’m teaching myself how to tig right now (literally I’m at the bench) and I found this video very helpful!

@8:00 it clicked in my head. As I'm listening to your description, i'm thinking about my experiences with high power audio. Low frequency sound penetrates walls, while high frequencies reflect off the surface of the wall. Eureka! Of course this principal would extend to the frequency of the AC current, and it's ability to penetrate through or reflect off the skin of our materials. Great video as always! Thanks.

Love the explanations you give!

oh oh oh oh,TOT's released a new video, clicked, liked sat back and enjoyed :)

An excellent practical demo of the HF effect.

Jody is pretty awesome. Welding tips and tricks has a Lot of good videos

Hi Tony! Nice explanation on the differences in the AC frequency

So many videos! Marvelous!

Pictures, draw a picture. Then my head doesn't hurt quite so much. Great video. Keep it up.

Just want say I agree with your experience. When I was welding aluminum regularly at my old job we would bump up the frequency to get the best penetration we could into the roots of our corner joints and more control on edges.

Useful to understand this, I'm a pictures over words guy, allows me to have a useful way to tweak the knobs and pretend I know enough to be dangerous! Thanks Tony

Great video - I really appreciate the upfront honesty. I really learned something: Not to trust people who seem too confident in their non-explainable beliefs about welding especially. I never understood people who are just learning stuff by heart but have no clue why or how they are working. It's like remembering every single outcome of every single equation without ever doing actual calculations. That just feels wrong and dumb to me.

Experience has told me that FREQUENCY has more to do with how much energy you get into the metal. A higher frequency will take longer to heat the metal and the puddle will freeze somewhat faster. The lower the frequency, the more energy is put into the metal and the puddle is somewhat slower to freeze. The frequency is tuned to fine adjust the amount of energy put into the weld puddle. Again, this is just *my* personal experience with welding Aluminum.

Soooo...like the lower frequency gives u a wider puddle with less penetration down and slightly lower crown, but more penetration sideways (cause of the wider puddle/arc); while a higher frequency gives you a tighter puddle and more penetration down with a slightly higher crown. In simple terms one might even just say that a lower frequency gives you a wider arc, while a higher frequency gives you a tighter arc...like you know...99% of all welding videos on KZfaq regarding AC aluminum welding. I love TOT, but this was 😆🤣 Though I gotta say, some of the best actual puddle footage on KZfaq, something so many can’t get right. I loved the previous video on general Tig advice, that slow-mo footage of the puddle moving around while the torch was still, and pointing straight down, was priceless.

I also remember things better when I understand them better.

this is the perfect video to fall asleep too at night

Great video tony 🙌🏻🙌🏻

Interesting I always have used higher frequency settings, I'll have to try turning it down, excellent video.

3 videos in 1 week ? Could live with that 😁

i have no clue what u do there BUT i love ur videos ... i keep telling tomyself: maybe i learn something which i could use sometimes

Ok Tony, this is great stuff and definitely helps me when thinking about AC frequency. Now, its time to add pulse settings to the mix :)

Didn't see anyone else mention this so thought I would chime in with a thought: electric pixies aside, if you apply an oscillatory heat source to an object, the extent to which that heat penetrates the material will depend on the frequency. Think of it as a thermal-skin effect. For flat plates this decay goes as exp(-d * sqrt(pi*f/a)) where d is the distance from the surface, f is frequency, and a is the thermal diffusivity. I'm getting skin depths on the order of a few mm so I think this makes sense. The key here is that it matches intuition, higher frequencies, smaller boundary effect. Not saying there aren't other physics, but I bet this is a piece of it. *Correction* I think this is complimenting Sharky's explanation

Me and my Bar Z bash welder thank you for the help their Tony

Thank you, I'm just learning so that was very informative

interesting as always. I eagerly await the responses.

6:25 Distance from workpiece also changes the focal area of the arc.

Two videos in two day Awesome, and your jokes are getting better.

Thank you, Great explanation!

Thanks, I’m glad you got that off your chest.

Very interesting. I haven't done any tig welding with my powermts welder yet and have always wondered what that setting was all about.

Bam!!!! Mind blow. NAILED IT TONY!!!!

I love these videos

Tony this is a awesome video thanks guy your the man and off topic of this video your old welder I had one similar to it and was having the same issue with it and went through it driving myself crazy like you and a welder friend of mine that is a paid welder man they really make some good money sometimes it can be well over a hundred an hour anyway wow almost forgot what the heck all he did was put a high end grounds on it and Walla works perfectly I was happy happy joy joy that it worked but hmmmm I didn't like him for a minute cause it was that easy for him SO he double grounded it he tells me to put one at each end or ground my table and the part so I never heard of this before but I did it and surprisingly it does well so give it a try maybe it's a video love your channel keep teaching me stuff like to learn can't wait for your boy's projects I bet he's thinking already

OMG. 2 days in a row?? I must be dreaming ! Haha

Electrical Engineer here, with experience in RF, high voltage, and power transmission. Induction heaters for very large pieces of metal often are run down into the audio range, 1kHz or even less, to get sufficiently deep penetration of the work piece. There very well may be some merit to the skin effect theory, or at least should definitely not be ruled out on account of the low frequency. The shape of the electrode tip will strongly impact the electric field gradient, causing breakdown at lower voltage for sharper tips, and probably impacts the way current circulates within the plasma. What this means in practical terms, I have no idea. I'm not a welder :-)

So... reading through the comments, my brain shit its pants! I guess i should have doped up on adderall while i was in school to stay focused. Instead, my pubescent mind would just wonder anywhere in from what my buddy ate for dinner based on the smell of expelled gasses from his mud vein, to what circus act I'll perform with my unpredictable yogurt slinger before the parents get home. I always thought welding much like i do... IT WAS PORK CHOPS!! Really though, great videos! Getting smart and giggling like a girl! Much appreciation to your knowledge, willingness to share, and knee slappers TOT! You help guys like me figure out a way to make it through a conundrum!

Hmmmmmm Yeeeeeees...............i did not hear a word you said,after that cool looking CK water cooled torch and leather cover was on screen.But it was another awesome video with cool arc shots.

Very interesting thanks for sharing.

Great video I’m looking to purchase my first TIG welder DYI hobbyist of course looking at the cheaper Chinese under $1000 range

i was always under the understanding that higher frequency allows to run your tungsten sharper without it balling up thus creating a more precise and controlled arc. my welder does not have adjustable frequency, would like to try one. good video!

Always enjoy your videos... I want to put my 2 cents in it's about your cup set up nothing wrong running a screen but in my time I really don't use them on aluminum. a stander diffuser #4 or #5 cup. there are time I have used a screen or larger cup but not often. In your test I would use the #4 it does have an effect on the etching zone. also you can run less gas 10 CFH. there are many variables in AC welding. wave form, AC balance, frequency and independent amperage. all play a roll ( causing complete Chaos ) ;-) Cheers

There was a comment made in the video that really resonated with me. "if 'I don´t know why, I`ll never remember it". I´ve been aware of that "feature" of my personality for many years, and it´s caused me a lot of headache in learning-environments. It seems at though learning in school never really is a matter of understanding.-It´s more a matter of remembering and being able to recite something for an exam, and then forget about it. But i like understanding. It´s the reason why i later in life learned so much about all things in life (like why AC frequency does what it does). I just wish teachers would recognize that some people really need a level of understanding instead of just remembering, and that the two might be causally linked.

Come for the shop tips and education and stay for the Dad Jokes. I heartily pressed the picture of the clenched fist with thumb extending upward, indicating my approval.

Think of it as a very fast stitch weld setup. If your MIG has stitch settings, you can duplicate the results. The longer the on time, the hotter the individual event. That happens because you are putting heat in faster than it is carried away. Because of this, longer on time results in higher local temperatures and larger puddle size. As the frequency goes up the shorter heating period no longer 'gets ahead' of the cooling period (as far, and eventually, not at all). Also the arc kernel is what generates the heat, not material resistance, so the surface shape and size effects heat flow (both in and out) My 2 cents. Thanks for all your videos, great insight - always learning, and having fun too.

I do know that you're absolutely correct about the shape of the tip part. Electrical charge likes to collect to a point. Perhaps it's something like this: The higher the frequency, the less time each pulse has to travel through the material. So it doesn't heat it as deeply on a higher frequency.

Nice work Tony! ATB, Tony

Great video! Under the same exact conditions, such a small change in frequency should have little effect on arc. When you start getting into orders of magnitude of frequency change then you will start to see a small difference but at that point you have a device that will not pass rf noise emission standards for certain communications bands. From an emag perspective, changing the sharpness of the tip will have a significant impact on arc width. In terms of power delivered at different frequencies, again, a change in frequency should have no effect. I and most of your commenters agree that your output wave will have more distortion at higher frequencies but there are probably other non-ideal components within your machine causing less power delivery. This is kind of difficult to measure because you would have to measure the power close to the tip. Just the tip, and only for a minute, mind. However, because the currents we are dealing with are relatively high, electromagnetic effects come into play and so the current "paths" through the material after the arc can be significantly different at higher frequencies.

"If I don't know why I'll never remember it" - that totally was my whole high school career in a nut shell

He's a witch! Or a practical genius. Best explanation I've ever heard.

Fantastic! Thank you!

i want to try tig welding... i am an old guy and have been welding smaw, gmaw, fcmaw, dual shielded fcmaw, old school oxy acetylene welding and brazing and even just plain old soldering with a torch or an iron for years, when you referenced Jody from welding tips and tricks.. had to subscribe... kudos dude.. btw Jody rocks and so does weld.com

This video makes me want to fire up my welder and do some tests of my own. Inside corners are always the biggest problem areas when welding.

I did the same video on the HTP invertig 221 with the freq changing only before you did this and I had the same results as you. This is less of a gimmick then the wave forms at least. The wave forms don’t do anything at all it’s a scam. This was spot on with frequency great info.

Hi Tony, great video. It would have been interesting to show the plasma cone with a fixed set-up over the centre of the slots. This might show the effect of geometry on the cone shape compared to a flat surface. Best regards.

Tony, I'll take a stab at this. I'm going to guess puddle width is driven by the amount of time the AC freq is in the negative or positive position. At 20 Hz, the 'wave' cycle time is 1/20 of a sec, or .05 sec. The neg or pos duration would be half of that, so .025 sec. Electron and Ion travel direction are driven by the polarity of the electrode. So when using 20 Hz, the Electron/Ions are being 'pushed' (or pulled if you prefer) for ~.025 seconds in one direction before the polarity changes and reverses the direction. For 200 Hz, the wave/cycle during is 1/200 of a sec (10 times shorter) thus the electrons/ions are pushed (pulled) away (towards) from the electrode 1/10th the amount of time as with 20 Hz. This decreased time is witnessed with your (TOT's) test as the Higher Freq (200 Hz) bead profile is obviously a lot narrower due to the shorter amount of time that electrons/ions can 'fan out' from the shortest/direct path to the work piece. I'd try to explain myself better here but i'm probably already too wordy so i'll leave it at that. Tony, thanks for all your efforts and great videos!

Before going wild with physics theory... I would use a clamp Amps meter and see if the current is really the same in each frequency. I would do the welds again with someone watching the meter telling me where I'm at when at full pedal. Then if the results are different I would do it again trying to match the current by controlling with the foot pedal. If I had a welder I would be testing this right now. Very interesting. Thank you for all the great work.

Skin depth is a completely reasonable explanation for heat penetration with thicker materials like your test sample. Skin depth in aluminum at 20Hz (sine wave) is about 18mm and at 200Hz is about 6mm. it should be noted that a square wave (or a squarish wave) has frequency components on every odd harmonic above the base frequency that account for maybe a 10th or so of the total power of the signal which would tend to flow shallower.

Tony, I think your explanation is spot on. You probably know this by now, or someone else mentioned it in the comments below, but just in case, here is what I found... The skin depth at lower frequencies is negligible for small conductors at these frequencies, (20 to 200hz). But, for large conductors it is very relevant. See: en.wikipedia.org/wiki/Skin_effect#Examples According to the graph there, the skin depth @ 200hz is 6mm, while @ 20hz it's 11mm. That's a big difference in the depth of current flow. The more resistive a material is, the larger the skin depth. As always, thanks for the videos!

Proof is in the puddles! Great job!

I never welded anything in my live and I didn't understand a thing. But nevertheless I watched the whole dam video just because it is sooooo fucking funny and well made. Props to you mate.

Great video, as always. I've gotta knock off a couple points for you not doing your welds on the rotary table, though.

Tony could you make a video explaining the first steps about how to use a metal lathe? Like a tutorial for young machinists?

interesting video, thanks!

As a electrician (is that spelled right? Well iam ELEKTRIKER) higher frequency forced the current to run more towards the surface (because the changing current is inducing a magnetic field). Thou your right and thats what iam seeing as well. You get more heat INTO the area that you are welding. Maybe towards higher frequencies the current travels off of your weldpuddle into the surrounding... Just a theory here :) You can touch the arcs of powerfull teslacoils (with like more than a few mA output) and dont get killed because the current is just running over your skin (because of kHz to Mhz of frequency!) This video is older and maybe nobody reads this but HEY thanks for your very good videos, YOU LIVE MY DREAM. Id like to have that kind of equiptment ;)

My new 325 amp TIG machine will go up to 300HZ. I stay at 130HZ. I control the arc by shaping the electrode. Blunt for wide arc, sharp for narrow arc. If I increase the HZ it requires a higher amp setting. If I pulse, it needs the amps increased with increasing the pulses per second. Raising the frequency out of site is only for entertainment. I love that high whine 😛

"people have been welding with 60 hz since the beginning of time" !! Classic! This needs to be on the front page of a world history text. Excellent.

I think it the difference in bead profile between the 20hz vs 200hz has to do with the oxide layer and the thermoconductivity of aluminum itself. It will also depend on the balance. But I think of it like this. The more switching from the hertz allows the oxide layer to retain a certain (dare I say surface tension) for lack of a better term. Which in turn reduces the bead profile and the wetting in the toes of the weld. The actual plasma cone shape really depends on how you dress your tungsten. Would love to see what 6061 thinks!!! Great video!!!

thanks for noticing.. I have been working out

With some divices you can also variate your zero line of the sinus. The minus cleans the material and the plus makes it burn into the material/puts in the heat. So if your material is dirty, or highly oxidated, you pull the sinus down, so that minus curve is longer and lower/deeper. With a low frequency you stretch out your sinus and with a high frequency you compress your sinus.

Brilliant welding :)

thanks I have been working out.

You're really good welder. Kudos from amateur.

Hi old Tony. I was wondering what kind of camera and lenses do you use. Your video quality is so clean.

Your critique of other Tubers' weld comparisons was almost "fightin' words" until you called out Jody in particular for not being full of ish. He's the one who really pulled me into welding as a hobby.

Idk but I would think of the freq like a pulse. The higher the frequency the less time spent on the penitration side of the cycle. So if I was pulsing in DC on say carbon. The higher the pulse the higher the amperage required to penitrate the same as no pulse. Thanks for the videos. Always good stuff.

I can't weld worth a Tinker's D*m#, and I don't own a TIG welder, but I still love your videos even when I can't relate to them! :)

I found similar results. The higher frequency tends to have a tighter and taller bead. The lower frequency flattens out and penetrates more at the same amperage. Guess I will try and up the amps when running higher frequencies.

Another thing to take into consideration, your welder vs another in maintaining a perfect sign wave at high current vs low current may differ from another welder. Not saying your wrong but it would be kind of useful to see the wave form. If you could do that then I think the debate would be settled. In any case thanks for another fantastic video.