Conchfish AL 17.6T build

[kmorin]

Carl,
found some images to help w my remarks.


just a bunch of pony pipe clamps will give you a set of nearly infinite hand supports for TIG work in general.  This old image was during a discussion of making fitted pipe joints while on the bench- But I hope the idea conveys the versatility of pipe clamps as hand positioning welding fixtures?


Here's an image of the tungsten (w/o gas cup) and filler trying to show the amount of movement between puddles can be less or more depending on your travel and the 'swing' angle of the torch 'aiming' the arc cone.  In your examples above, I'd suggested you might make this movement less than you're showing as the welds' "puddles" are more elongated than might be ?


I hope this shows a weld that has less distance between 'dips'/dimes/puddles and you can see the edges of the weld is more uniform-less serrated and the bead's overall shape is a bit more uniform with less high and low to the individual dips/pauses/puddles?



Same idea, trying to show a little less distinction between puddles/dimes/pauses and more overall uniformity and that is from less travel per pause, less volume surge and more filler volume uniformity that comes from dipping more often but w less filler.

TIG welds with larger rounded depth then valleys between puddles tend to leave a more ragged edge and that usually results in more tearing along the HAZ in a bend break test- and is more vibration susceptible to edge cracking in a high strain area.

Carl, hope these old images will help make better sense of my post above?  I've tried to explain why I make these suggestions but if I'm not coming through clearly I'll trust you'll speak up?

Cheers,
Kevin Morin
Kenai, AK
 

[m32825]

Hi Kevin

Very helpful, thank you. You have a gift for teaching, time will tell how much aptitude I have for learning!

Bonus points on the welding support suggestion because I already have pipe and clamps. I was wondering what I was going to do with extra pipe, now I know.

I can see that I'm making progress with the stringer beads on plate exercise. The puddle issue I mentioned earlier was because I didn't have enough heat. When I added more heat my puddle flowed better (until the end when it got away from me) and i got a shinier bead.

Those are beautiful beads you posted. I'll try to tighten mine up while I work on uniformity. How much should my filler metal stick up above the base plate for stringer beads?

-- Carl
 

[kmorin]

Carl,
Padding beads don't need to stand very much proud of the plate. What is more of a learning exercise is to keep that profile uniform from start to finish, along w the bead width.

As you light up, and get the initial puddle, and add your first filler dip- you'll create the size of crown of that weld. IF you have the amperage up high (?) the filler will more fully melt into the parent metal, where the same length/volume of dip would crown up much more if the amperage/wattage were lower.  Higher amperage and lower profile or crown is fine, as is a slightly taller or more rounded compared to a 'sliver of an almond'- uniformity is the goal.

The crown ht. is not the key focus of padding beads. Not that the profile should be vertical edged at the 'toe and top'/right and left edges of the bead, the uniformity should be the primary focus.

As a side note: TIG power supplies are designed to monitor the arc and adjust for a Constant Current; unlike MIG power supplies trying to maintain a Constant Voltage. IF the formula is Voltage Equals Current Times Resistance (V=IR) then; if you pull the tungsten up- elongating the arc- you'd increase the Resistance of the arc. When the TIG control circuit 'sees' this change of Resistance due to a longer arc length it will adjust the Voltage upward to keep the Current the same.... but the result is still an overall increase in wattage (V*I) or 'net heat input'. 

All that means- if your pedal or finger control is left at any given setting and you pull up the tungsten while welding; you will effectively increase the 'heat' just as though you'd pushed more on the pedal or the finger control. It's important, for uniformity, that you're aware of this effect on 'flattening' the puddle profile.  More heat/wattage/voltage will resulting in more melting of the parent metal and that will allow any given volume or filler rod to be less built-up and lower the bead's profile.

Also, as you weld along a fixed sized plate a practice piece that can soak up only "so much" heat/welding arc/wattage before the entire plate gets hot.  Therefore, less amperage/wattage/power/heat is needed to get the parent metal to melt and eventually the metal will just 'drop out' of the puddle since the heat cannot be dissipated rapidly enough to 'freeze'/re-solidify and allow the parent metal to retain its original shape.

IMO, you need to keep in mind that after a few inches of welding you'll need to slowly and constantly reduce the pedal/heat/amperage otherwise the heat will build up too high for the (limited size) test plate to 'hold' a uniform bead.

In other words; high heat to begin/initiate the puddle, then reduce to continue welding at a given cross section/profile and finally, continue to manually slowly cool the arc wattage in the last 2/3 or even 3/4 of the practice weld if the plate is small enough?  This statement is extremely important if you're practicing on 3"x4" plates and less important if you're practicing on 12" x 20" plates.

I'd suggest getting half dozen min. 6"x6" plates and rotate them so they don't get hotter and hotter- if the conditions of your practice continue to change- while you're trying to get uniformity (!!) then practice can be pretty frustrating. By rotating the test plates, letting them cool to room temp between beads, you'd provide yourself a more uniform practice environment.

When you go to boat welding; the overall hull, even of a small skiff, will be huge compared to test plates.

Hope this helps tune your practice a bit more finely as you get your "TIG hand in"?

Cheers,
Kevin Morin
Kenai, AK 
 

[m32825]

Great guidance Kevin, I will work on it during practice this weekend. Thanks!

    -- Carl

[kmorin]

Carl,

I had a few different trades mentors, one in several trades and one of them used to say that "Practice Makes Perfect : ONLY IF you're practicing for perfection."  If you practice the wrong thing or the trade crafts' skills improperly, coarsely or without very specific mental images (sight picture in shooting sports) then; you'll end up creating poor habits that have to be overcome to actually advance in your skills.

The 'aim small- miss small' admonition to the younger shooters applies to most trade work. I believe the closer to exact your mental imagery of your goals with your hands are during practice- the faster you'll become better/good by keeping an exact set of ideas/goals as focus of your intentions as you practice.

So, while I've given lots of details, if you can imagine the beads as shown, and as described? It's my contention you'd advance your skills more rapidly than just repeating (unknowing) errors and having that negative feedback cause confusion and wandering around w/o much benefit to the practice sessions.

If it were January, I'd envy your ambient temperatures, but now that it's warm here (50F) I'll just wish you well tolerating those working conditions.

Cheers,
Kevin Morin
Kenai, AK

 

[m32825]

You guys are a great source of information and encouragement. I've still got work to do but am seeing improvement. Heck, "seeing" is the biggest change. I'm getting to the point where I can better critique my work, and I'm starting to be able to pay attention to different things while welding.

Sample of this week's practice below. These are 1/8" plates  3x6 inches in size. The weld lanes are scribed just under 1/4" wide. Each row of a plate starts with a single weld button on the ends and in the middle. The idea is to connect the buttons, allowing me to practice continuing and ending on something other than flat plate. I do a row then switch plates, then let everything cool before the next row on the first plate.

I am still too cold at the beginning and too hot at the end, and my consistency needs work, but at least I'm starting to see what's going on.

Shop temps have been ranging from the lower 80s to 100 or so lately. My enthusiasm flags in the upper 80s, but things will improve in another month or so when cloud cover increases and our afternoon thundershower pattern starts.

    -- Carl

IMG_20240512_174150750_copy_1600x1582.jpg (51.95 KiB) Viewed 134 times

 

IMG_20240512_174340839_copy_1600x833.jpg (39.7 KiB) Viewed 134 times

 
 

[kmorin]

Carl, you're showing very good progress for someone that's just coming to alum. TIG. 

Couple remarks to follow up.  Yes some of the starts are too cold, but... by just pausing before you leave that initial puddle/"start up point" & making sure you have the entire width between your guidelines 'wetted' - you'd have starts like the lowest bead on each plate- which are very much better than the upper beads' starts.

Next is to keep your eyes bouncing between 12:00 & 6:00 or the two edges of the puddle, if they're reasonably uniform to your guide lines then you can skip watching the arc.  If the leading edges of the C shaped puddle begin to 'pull back' form the guides ? Then lift the torch just very slightly; OR, add just a little more pedal/slider/amperage; OR slow your dip and travel rate to allow a small fraction of time more before dipping so the puddles are able to flood out to the (now increased) edges of the wetted area.

And on that subject- some of the beads seem to be skewed to one side- more "slanted U's" than evenly concentric " C's " inline. This can come from keeping the torch grip to short- the angle of the arc would then be from the side of the bead, leading to the filled puddle being inclined instead of uniform.   I'd consider in those instances a little longer torch head sticking our to your grip (move your hand back on the handle) so the tungsten is 90.00 Deg over the bead, still leading or leaned back but not leaning back AND to one side.

Next beads on these plates are to use one side of those previous welds as one side of your guide line, and add a bead along side with another single scribed line 1/4" or even 7/16" to 3/8" away from the 'toe' of an existing weld.  This will give a little different overall thickness- as the previous weld above each new bead will have a little different parent metal mass since there's a weld already added and you're tying into that existing weld as part of the newer beads. 

This is how padding plates work and its good practice to tie in to other beads - sometimes at the very 'toe' of the original bead, other times at 1/2 up the side and still in other cases fully to the top center of the previous bead.  All are good exercises and represent different welds in different fillets you might encounter in future weld joints.

Last are the stops.  You know from the course work that when you stop the Alum. arc that the arc core is molten but then left to freeze instantly.  When this happens you'll almost always leave a little crater and that is the most common beginning of weld failure cracks.  The reason is that arc core is hotter than the rest of the puddle and more expanded than the outer edges of the puddle- so it contracts more when cooling.  Cooling with some 'top puddle' to fill down is good practice.

IF, when stopping  you get to the end of the weld and immediately drop the welding current by 50%, but keep a small weld puddle going/molten ..... then, continue to lower the welding current until the puddle freezes at the top; you can avoid all cratering at the end. 

While tapering the power, if you add a small bit of filler, not a full puddle's worth of length, while the smaller end puddle is still lit- that molten metal will then fill downward into the chilling/freezing/solidifying aluminum where the arc core is.  BY allowing a still molten source pool of metal above the cooling arc core the cooling metal below will 'pull' or fill the arc core from the bottom up with cooled not super heated metal thereby avoiding a crater in the end pool/puddle/bead.  You did this successfully in a couple of the beads you show, but not all. So its clear you're tuned to the need to close out/end a bead w/o a crater. 

TIG becomes a series of 3 stages; starts, run & ends.  Each has a series of methods to master to become proficient and it looks to me like you're well on the road to being good at this welding method.

Surely do NOT envy sauna-like temps for working in the shop! Keep up the good work, your boat will look great.

Cheers,
Kevin Morin
Kenai, AK