TIG welding with the pulser

left = no pulser, right two = pulser. Basically, i stink using the pulser!!

My history in welding: I first learned to weld around 2004 from a friend with a MIG welder that specialized in hand-railings and other endeavors for work. I asked for a quick lesson so that I could attach an old snowplow to my huge steel bumper of my ’67 Dodge Powerwagon. After trying to sign up for the Ti, then Steel, TIG UBI framebuilding classes 2 separate times 5 years apart and having to bail out at the last minute both times because of a new job (yes, TWICE!), I missed out on getting an earlier start down this framebuilding path.  So around 2005, I was able to take a short after-work welding class at CU Boulder in their machine shop. It was mostly MIG and gas-welding, we had a full 30 seconds on the TIG machine — no joke.  Not until 2010 did I get to take a class from a framebuilder in Denver who taught me how to TIG weld, or at least started me on the path to learning to TIG weld.  If I had to do it all over again, I’d have told my first future boss that I WILL be gone for two weeks immediately after being hired, so I could have taken that UBI course back in 2001. But I likely wouldn’t have gotten the job…

Anyways, so now what? I’m still struggling with the TIG torch but feel like i kinda know what I’m doing now.  For some reason, my first teacher had a prejudice about using the pulser function to TIG weld bike frames.  He taught me that if you use the pulser, you are supposed to dab the rod at the peak amps as you move the torch along the joint – not lay the rod in there so that the torch eats it up as you move it along. So at 1Hz, this was not too hard, but at 2Hz it was extremely hard (and still is) not to get the rod stuck in the puddle once the cycle went to the base amps. Furthermore, I was taught it was basically ‘cheating’ and easier than not using the pulser to make a smooth stack of dimes bead.  He recommended that I learn to weld the real way first, then if I felt I needed to, then start using the pulser.  So, I thought (ignorantly) that nobody used the pulser to weld bike frames and if they did they were taking the easy way out.  Oh my, how wrong was I!?

The pulser helps many framebuilders achieve that perfect, consistent, even-width and seamless looking stack of dimes weld.  It’s likely that if you peruse the YouTube’s of your favorite builder (if they have any) you’ll see the on/off flashing of the TIG welder instead of a steady glow of light coming from the tube joint.  There’s really too much to talk about why one is better or worse than the other, but I am starting to believe that the pulser is a superior method of TIG welding, especially on thin-walled bike tubing.  There are many professional sites out there to tell you the same including the Miller website and other pro framebuilders on the message forums.  The main gist of the reasoning is that using the pulser gives a flash of high amps followed by a cooling period where the metal can fuse but not overheat in the same way or as easily as when not using the pulser.  The settings one uses are extremely important obviously, but in general, when using the pulser you should get a more consistently homogenous fusion of the two tubes, less possibility of the bead itself being a stress riser, and less tube distortion. [Let me say that you can obviously weld bikes just fine without the pulser and they’ll last a very long time. I doubt there’s any long term studies showing a comparison, and I’m doubtful that if you’re a good welder without the pulser that it’ll significantly (or at all?) reduce the longevity of your frames.]

What i do: What I have done on my bikes is NOT use the pulser since that’s how I learned and how I can actually get a good bead as of yet.  But if and when I needed to do a second pass to fix a poor looking (poor penetration weld) I’d turn on the pulser and not only make the bead look better but pull the tube in the direction of the weld I just passed. However, I would not use more filler rod and just pass the torch over the bead. It’s not a good practice to continue, but if you don’t starve the weld (lack of filler rod) on the 1st pass, you should be OK with a quick second pass to pull the tube (and frame) more into alignment.  This is not just my hot air, but was said on a framebuilding forum by the same person that I got a quick TIG welding lesson from last week when I picked up my new frame fixture. (I’m not sure he said it’s OK to not use additional filler rod though when using this “technique”.)

What I learned from Don: I hope he doesn’t mind me paraphrasing his advice, but please take this as just that: advice from a pro to me. Realize that I may have heard it in a different way then it was intended, or just plain incorrectly.  I told Don that I don’t use the pulser and he suggested I should since I have been getting some head tube and BB ovalization when welding my frames.  Nothing probably out of the ordinary but I have nobody to help me determine that either way.  I know warpage from laying a TIG bead is common, and the extent depends on how tight your miters are, how thin the tubes are, and how hot you are laying down the bead.  Anyways, here’s what he recommended I do for using the pulser (keeping in mind this may be nothing earth-shattering or even new for most of you that learned how to weld in a better way than I).

1.) You want to PUSH the filler rod into the tube joint by rolling the rod between your fingers.  The thumb simultaneously pushes the rod forward into the puddle as well as twists against your index finger while the other fingers are holding the rod straight.  This keeps a constant tension and movement of the rod into the puddle as you move the torch foreward. This is pretty standard filler rod hand technique but it is something I never learned to do and therefore don’t do.  I just have been dabbing the rod into the puddle as I move the puddle along the joint, whether I foot-pulse or keep a steady amperage.  Since the tube passes aren’t very long, I haven’t felt the need to learn the above technique since I’m not going through a ton of rod.

Believe it or not, this was the biggest eye-opener for me. I have never moved the torch over the tubes and even just laid the filler rod there for the tungsten to melt along-the-way since I was taught that was bad form. Having someone that gets such perfect welds (Don) tell me to use the pulser and PUSH the filler rod into the joint (and puddle)…well, that was totally counter to my current way of thinking.

2.) Keep moving the torch at a constant, and relatively quick, pace along the joint.  The stack of dimes happens naturally when the pulse cools the puddle each cycle.  When not using the pulser, the stack happens when you add filler at a given interval along the joint and the puddle cools as you move along.  I have also paused when dabbing the filler rod into the puddle while moving the torch (pausing only for a milisecond) to get a certain rhythm going and get a nicer stack of dimes.  Anyways, this isn’t anything new but part of the whole picture — move the torch steadily along ‘eating’ up that filler rod along the way.

3.) Don’t let the filler rod cool outside of your gas lens (outside of the argon shielding gas).  I have always removed the rod to let the puddle cool and let the argon get its full access to the work, but you should keep the rod under the cup  protected from contamination.  Some leave the rod in the puddle but it would seem to me that that doesn’t work for bike frames when you’re laying 4-6 separate/opposite passes on one tube joint.  Proper welding sequence is not to go all the way around the tube at one continuous pass in one direction, but to do something like 12-3, 6-9, 3-6, 9-12, or the like.  The welds will then put more equal tension on the tube and keep it in better alignment assuming equal heat control and miter quality.

The other things he said were mostly just confirming stuff I already knew so I don’t remember them as well as the above 3 things.  But the pulser settings are something of an enigma for me and I think most new welders.  I’ll just come out and say that I have dinked around with the settings a LOT and still haven’t found anything that works really well.  Having said that, I usually use something like this:
80 peak amps, 12 base amps, 45% of peak, and at a rate of 2HZ.

Each TIG machine has it’s own way of saying the same thing for these settings so what mine are may have to be translated into what your machine says…i don’t know.  But for thicker-walled tubing, I go higher on the peak amps (90-100) and raise the base amps a few too.  For 0.6mm walled tubing, I’ll go colder.  But again, I just truly stink at using the pulser as you’ll see from the above photo.  The left-most weld is my normal way of doing it (no pulser) and the right two practice welds are using the pulser after tacking it in place.

If I’m going to switch to using the pulser full time, I have a LONG way to go! I couldn’t get the pushing the rod into the puddle thing…it’s so counter to what I usually do that I was slowing my pace and overheating the metal and also starving the puddle at other times.  Then it’d blob up on the rod and add too much rod the next pulse.  UGH…

8 Responses

  1. Good stuff! My take away is to “lay wire” while pulsing and keep pressure on the filler rod in the puddle while finger feeding (not dabbing in and out of the puddle). I use this method on straight/flat-ish joints (disc tabs) and pulse the foot pedal since I don’t have a pulse option on my old machine. I typically work every other joint just like your used to; constant amps and dab, dab, dab…
    Rolling the filler between the fingers is something I’ve never tried, usually just feed the rod in between my index and middle finger. Will have to try that one.

    You mention the filler rod balling outside of the puddle when trying to lay wire. I often encounter this issue with dabbing at constant amps when things get too hot, or the puddle hasn’t formed well enough to accept the filler. Whenever I can, I’ll lay wire as a way to avoid the problem since the filler is already in the puddle with pressure applied.

    • Thanks Andy! I appreciate you adding your comments and experience to the mix. I hope to add to this post with the comments I’m getting from other builders too in the comments over the next few days. I’ve already received more site visits for this post than any other individual post (101 en-counting) so I know this is a topic many are interested in learning about! The Framebuilders Google Group has some comments that I’ll post up soon just in case people that read me aren’t on that list.

      I do think laying the wire in there will do the trick and may help bridge the learning gap for now of not being able to roll the rod in the filler-rod hand while maintaining all the other things going on with your foot, torch hand, brain, work, etc. I’ll have to give that a try. I also agree with your thoughts on why the wire balls up sometimes. I know that I get over-excited to add filler when I’ve had too much espresso! It’s like my left-hand with the filler wire has its own mind and can’t stop punching the puddle before it’s up to temp!

  2. I found your blog to be very helpful and informative. I am new to frame building as a retirement hobby and decided to go the TIG way as my primary method. I was taught with pulsed welders and have been getting pretty good at it but was taught to use the dabbing method. I can see how the constant feed would be better. Can’t wait to give it a try. Being new, I do not have to worry about changing my old ways.

    Thanks for the great ariticle. Anymore tips for the newbie would be appreciated.

    Regards

    • Thanks Carl, I’m happy to help the novice since I was in your shoes not too long ago! I hope my blog can be a resource for the beginning framebuilder. I still am no expert, please realize, and I feel like I’ll be learning for many years to come.

      I’ve copied/pasted some comments below that are from the Framebuilders Google Group that resulted from another builder posting a link to this post on my blog:

      Brent Steelman:
      The best welder I have ever known does not use a pulser. But many use a
      pulser to achieve excellent results. What makes a skilled welder is
      patience, practice, common sense, good hand-eye-foot coordination, and
      an ability to focus on the moment.

      —————————————————————————

      John of User Bikes:
      I think some people get caught up in the ‘stack of dimes’ look, thinking that is what makes a good weld.
      If one is hung up on stacking beads, one needs to be sure there is proper penetration in the joint, not stacking beads for the sake of the look as obviously you begin to approach a cold weld.
      I learned gas welding in aviation in the early 1990s. I can promise you there is no stacking of dimes going on there….especially with the torch movement. I weld without pulsing, and certainly don’t have that stack when working with steel.
      I do agree pulsing can help mitigate some warping and feel pulsing is the smarter way to work (taking advantage of technology advances in welding), just hard to change the past twenty years!
      While stacking is pretty, it’s not necessary. For whatever reason, there has been borne the assumption one needs that look…..
      And please correct me if working, but the term really is an aluminum thing.

      —————————————————-
      Dave Bohm:
      I agree with John here.
      The stack of dimes look does not necessarily in and of itself indicate the quality of a weld. Although the opposite is true as well. A poor looking weld is usually a poor weld. Welding inspectors can fail a weld just on looks alone but we (bicycle makers) kind of take the even puddle thing a bit too far at times.

      The idea of a pulser has been discussed here and is generally right but if you are pulsing your work at a very low pulse rate (1-5 hertz per second) then you really are not taking advantage of what the pulser has to offer. Many great welders can do this very same thing with their foot/hand. The real benefit is in the higher pulse rates. Ever wonder why a machine even comes with 300, 500 or 1000 hz? No they are not doing it just to compete with one another. The higher pulse rates reduce distortion, agitate the weld puddle to reduce porosity and can affect the penetration of the filler material without increasing heat input. Really these things should be run way up there above 50 Hz. That means you should not use the pulser like a metronome to help with pace. That still has to come with all the standard hand/eye/foot skills that TIG welding entails.

      • Appreciate the additional information. I am working with 1mm 4130 chromoly tubing. With your settings, what gas flow rate do you find best. Do you recommend 1/16th or 3/32 filler rod and tungsten? I have been playing with both and want to know if there is a better choice. Thank you.

      • I use 15-20cfh, and 3/32 rod ground to a fine point. I tried 1/16th shortly but had some trouble getting used to it. I heard that 3/32 is better but I can’t remember who said that and why. I think it depends on the amps you weld at — higher range with 3/32.
        Also remember to keep everything really clean and the room draft free.

        That 4130 comes pretty dirty so use emery cloth or a wire wheel on the outside to clean and if you have one a flap-wheel or flexible cylinder hone to get the inside. Then wash well, it should look shiny like bike tubing when done.

        There are lots of variables but one I found to be neglecting at the start was the careful ramp up and amp control with the foot pedal. As soon as the puddle forms you stop upping the amps, hold steady, and push the puddle while adding filler in a smooth steady fashion. When your pass is done slowly back off the amps and hold the torch still so to not disturb the argon flow while letting the post-purge run its time (10 sec is plenty, some use less, a few use more).

        Sorry if that’s stuff you already knew, just thought I’d cover it here to be sure!

  3. […] I do not know other than seeing his signature on message board posts, linked to my last post on Pulsed Tig-welding in the Framebuilders Google group and it received more views than I’ve ever gotten on one […]

  4. Thank you very much for sharing your findings and experience.
    It´s great and refreshing to see the “new wave” and the “new ways”.
    Really inspiring.
    Greetings from Madrid.

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