Conchfish AL 17.6T build

[Vesselmech]

Really impressed that you all are putting in the work to get the welding procedure, and technique dialed in. You will certainly see a difference in the quality and longevity of the hull. I am a welding instructor and CWI in Gainesville Fl. My background is in pressure vessels and aluminum is certainly not my strong suit, but I would be happy to help out a little with the welding of this hull for a little insight into the project as I consider starting one myself. Carl I sent you a PM with my contact info. Keep up the great collaboration and work!


 

[m32825]

Nice chatting with you Vesselmech, you are welcome to come check it out.

[m32825]

What's with these holes I got? They showed up after I did a restart, not a problem in the first segment...

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[kmorin]

Carl,
almost all holes like this are from escaping gases- heated on the surface of the parent metal then rising into the puddle and if large enough- not given time to escape the molten metal before the puddle freezes.  The arc comes along and vaporizes/converts from liquid to gas some contamination in the weld zone and the contaminant begins to 'gas-out'. 

As you're moving along the weld, these contaminants/gases expand and bubble to the surface of the weld.  If you're not cleaning adequately OR if the cover gas is at an inadequate flow rate you can see pits of frozen gas bubble's sides as you weld.

Is the T fillet clean?  Is the lower edge of the T (vertical) material clean to the point of sanded & or Vixen filed & are both pc.s acetone wiped w clean cloth/rag/wipe?  Is the surface of the weld zone cleaned w/acetone or another de-greaser?  Have you used a steel or bronze/brass brush on thee metal?  If a part is cut in the band saw or with a jig saw, the resulting saw toothed edge has to be sanded/filed/dressed to reduce the entrapped contamination along those sawed edges.

Is your torch angle too steep, allowing the argon to 'pull' or 'draft' atmosphere onto the puddle introducing oxygen that could then combine with contaminants that are being lifted by the arc to the top of the puddle's surface?  Leaning the torch too far 'back' or leading the puddle too far will allow the flow of argon to create a venturi that pulls atmosphere over the puddle and bubbles form due to the reaction of vaporizing contaminants with increased oxygen.  These can form bubbles.

Is your tungsten clean?  Sometimes poor weld quality arises from aluminum on the tungsten, but not usually bubbles- more often that results in a blackened, smutty, weld with other puddle deformities.

Bubbles (shown) have a series of causes but most commonly they're the result of surface contaminants not cleaned adequately prior to welding.

Cheers,
Kevin Morin
Kenai, AK
 

[m32825]

Yep, contamination is the cause. Last weekend I grabbed a couple coupons and thought, "wonder how this would weld if I skip acetone and just wire brush it?" It did okay, but there was this one hole that appeared. I set it aside and forgot about that. I picked it up Friday and welded the back side. The first half went fine, when I restarted I noticed a lot of soot until the puddle got wetted out, then the holes appeared. The holes are on the opposite side of the plate from last weekend's hole.

Now I know what that looks like, so good learning experience. Does it need to be fixed? How would I fix it?

[Vesselmech]

Carl,

Kevin has provided you with a very thorough explanation of what could be causing your porosity. Another issue I have seen in our region is a general decline in the quality control of our compressed gasses. If you ever start to experience porosity or poor shielding in general and you have just changed out your shielding gas it could be the problem. Some aluminum fabricators in our area have started to purchase high purity Argon because this issue has become so common.

I look forward to seeing your project sometime this summer!

Ryan
Gainesville, Fl

[gandrfab]

I'm seeing 2 issues red looks like a motion control issue and yellow a contamination issue?

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[kmorin]

Carl,
To repair a hole like this is a TIG weld only needs to 'float' the hole closed in most instances.  The hole looks to be clean sided so by floating the weld before, on and past the hole usually you'll allow the gas in the hole to expand as the hole's sides become molten and the expanding gas will float to the surface of the puddle and the puddle will fill the previous void. This method simply allows the weld area to clean from bottom to top like it might have before during the original weld if the travel speed were (much) slower.

This doesn't always require any filler but.... even if such repairs don't always require filler you would watch the surface of the puddle as you move over it with the arc and if the surface collapses below the previous and following puddles' face levels; the gas bubble below the surface is greater than shown on top so you'll need filler to top off the weld now made pure metal instead of Swiss Cheese.

Other methods are to gouge out the weld in front of the hole, at the hole and after the hole and re-weld the area.  In the case of the holes you show - close together, nearly adjacent to one another; I'd remove the entire weld with a saw blade, carbide burr, router bit and re-apply a weld the entire area.

As Vesselmech mentions you might have bad gas but.... if that's the case(?) I'd expect the entire weld and those done before and after to show soot and darkened surface with little or no side cleaning zones at the toe and top of the welds.  I don't see bad gas as creating bubbles inside the molten weld then rising up (gas expanding & floating in the molten aluminum) like the images seem to show?  I"d expect bad gas to show over the entire weld's surface where 'hot argon cleaning action' was degraded by contamination of the argon.

G&R notes there is contamination showing at the Salt & Pepper surface grit at the beginning of the weld, near the toe.  I think this could indicate the weld zone wasn't clean enough- but this can also come from not acetone wiping filler rod that you've handled bare-handed -in sweaty shop temperatures- as the oil film left on filler will take this form in many cases.  Using acetone on filler rod and the weld area can help reduce this S&P surface grit, burned oil/hydrocarbon particles, to wash off in the hot cover gas.

As to positional/gas cup issues causing the holes?  I'd expect to see an area of the weld affected on the surface- if the gas cover were too diffuse due to the torch being too high to cover the weld? Then I'd expect to see a smutty, sooty, darkened area where the gas shows it didn't cover the weld?  Here the cleaning action is pretty consistent along the toe and top of the weld- but there's still holes. 

If the cup were aimed too high or too low, then the clean zone would seem to show that?  From the videos and still images it looks like the gas coverage is pretty well controlled. 

I still think I've seen this most commonly occur when something like a bit of trapped mill scale is concentrated by a bandsaw blade cut, or cut lube is left on the edge of the work piece. Also, a grinding wheel can deposit phenolic resin (glue for lots of hard grinding wheels) onto/into the parent metal.  Then, as the area around this high heat melting-point particle becomes molten; it begins to heat up and either vaporize/gas-off or float in the molten metal as it gases off.  When particles that are pencil tip sized heat up there's plenty of gas released and if the weld travel speed is 'normal' lots of time these will leave bubble's frozen/chilled edges as a hole or gas pockets.

Don't know for a fact what caused the bubble but if you continue to practice and renew the de-greasing and cleaning up to required standards (?) and don't have further bubbles you'll know at least one element that was contributing to those bubble holes you show.   If you continue to have holes then I'd agree that checking the gas bottle history is worthwhile as would be a cover gas caution by using an larger cup size and perhaps increasing gas flow along with the bigger cup??

Cheers,
Kevin Morin
Kenai, AK

 
 

[m32825]

I cleaned up some new coupons and got good results, see below. Then I went back and tried to close the holes, more kept popping up! After a few passes they stopped, but by that point I had cooked things really well. Good exercise on the consequences of not cleaning.

I'm going to switch over to the spool gun.

-- Carl

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[Vesselmech]

Looking good, your practice is paying off!

[m32825]

Speaking of practice...

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[gandrfab]

Very nice, how about off hand? lefty if righty or righty if lefty.

All those T's can become

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[m32825]

gandrfab: I'm in the denial stage of coming to grips with off-hand welding, but I know I'll have to face it eventually. Good suggestion on repurposing some of my practice pile!

I switched over to spool gun and tried a few stringer beads, then inside corner, which I kept leaving too cold at the beginning. Remembering how well outside corner went with tig I decided to try that. Got my brace set and sparked up. My guide hand got a little "stuck" at the beginning, leading to overfill, but things improved once I was moving smoothly. I think I do my practice moves fluidly but subconsciously put more weight on my guide hand when it's time for the real deal.

-- Carl

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[kmorin]

Carl,
couple thoughts on MIG practice.
Like working to improve your pistol grip and shooting results, a slight pressure BETWEEN your hands will help to provide a stability to your MIG welds.

I realize that sounds counter-intuitive but have practiced this for 50 plus years and it helps me.  May not contribute to your own practice and MIG bead but I'll review my impression of this technique.

When you're moving the bead in a long smooth movement... Unlike TIG where you're stepping ahead and pausing, then repeating those movements.... MIG in the style you're showing requires a steady even drag of the hands (carrying the torch) over the weld zone.

By adding a small or light pressure between your hands- pressing one arm/hand into the other and having the torch hand reply by pressing back toward the guiding hand- you learn to increase your stability even at higher speeds of travel.

This does require practice as it's more natural or intuitive to leave one hand or the other as the main control of movement.  Say your strong hand is left, and you have the torch in that hand.  Then its most intuitive for your left hand to actually set the pace, guide the torch so it has to be steady to get the even bead.

On the other hand, (no pun intended) if you provide a slight resistance in the right hand as you move both hands along the weld track (?) you can achieve a more even/steady/stable movement of both hands. This technique isn't widely discussed even by those who practice it without realizing they've acquired the habit?

Just a thought about working to acquire a nice tight, even, MIG bead on the joints ahead in your build.

Also a few thoughts on the weld coupons you've accumulated.  I usually bandsaw them on wooden blocks to support the 'leg' of each coupon and remove the weld beads as close to the weld as possible. Then run the edges of the cut coupons on a belt sander to flatten and clean that edge.

This way you get 4-8 more welds of the types you've shown - inside OR outside corners and fillets for the same original metal.  If you don't want to keep buying stock to test/practice and want to keep using what you've got until you're down to the 'nibbins', then; sawing out the welds and sanding back to smaller coupons is a handy way to keep those materials re-cycling as more of the same weld types. 

I keep these to run a few seconds of tests before doing 'the next' weld just to be sure of my settings, how my hands are behaving (sometimes arthritic hands don't behave as we expect!!) and confirming what bead type and profile I'm expecting. 

Your beads show great progress, and good understanding of scale/proportionality of the bead size which are very often missed; by even long-term, experienced welders.

Cheers,
Kevin Morin
Kenai, AK

 
 

[m32825]

Kevin,

I wish I had a band saw, but all I have to work with is a table saw. Cutting plate with the table saw works, but it is a glitter factory. If I use it I am committing to making a big mess and subsequent clean up, so I'm a little reluctant to fire it up.

I see what you're saying about pressure from both hands stabilizing things. It seems like you are making a triangle between your body and the gun, bracing against the core of your body. When I slide along my guide any variations in smoothness cause variations in speed when I'm using a light touch. With both hands working a little against each other I would not be as sensitive to those imperfections. I will practice that.

Today I worked on improving my guide setup. I've seen pictures of yofish's hog trough, and I get the idea, but it doesn't work as well with a small plate, there's nothing to land the trough on. So I clamped some tee bar to my hydraulic press frame and slit a piece of PVC to slide over it. Works pretty good but the spacing and angles are fiddly to get right.

I also took a shot at video. It's more challenging with a spool gun, I can see why there's a lot more tig footage. Options for camera placement are limited, and it wants to be where you need to go. I ended up welding over and behind the camera. I had the camera tucked under and behind my guide, which worked well, as that placement provides some protection from the fireworks. I need to use more filter next time, the weld puddle was too bright to see details.

-- Carl

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 Spool gun video - open corner
 

[kmorin]

Carl, Yes the idea is to create a triangular frame of the arms, chest and gun at the apex of the triangle in order to offer more stability. Note the travel speed of TIG allows the hands OR hand to brace individually and move along the weld. However, with the much increased speed of MIG (drag type beads not whipped as much) making smooth sweeping movements along the weld is key to uniformity as travel and deposit volume are directly related.

I think the outside corner MIG bead looks good, and I do understand the guide's surface can impact travel consistency.   

I’m not sure if this will help (?) but I’ll go "a little farther into the weeds" about what’s happening with my old carcass when I’m welding MIG alum. I tense the lat’s- that is the main muscles of the back that support the shoulder regions are flexed, not hard just flexed and that helps me in the previously described triangle’s rigidity. Also, by having the entire pectoral girdle (as I believe it is called?) tensed/flexed slightly my reliance on the guide-hand support pressure on the guide surface is reduced; so any drag on the guide surface has less impact on my overall movement. I try to keep the guide as light pressure not fully supporting the movement of both hands holding the torch. 

NOW for the key movement idea of what took me the longest to master. DON’T turn at the waist. I found that when I welded long MIG beads I’d turn at the waist to keep the shoulders to arms shape a steady triangle. Later I realized this was actually hurting my bead. 

If the gun is rotated in an arc, the stickout and travel angle will change. Long at first, then short as at the 'top' of the arc and finally long, again, toward the end of the arc of travel.  The wire stickout and travel angle (lead) should not change. SO; that implies the best long MIG bead will happen when you avoid rotating at your waist and move so the shoulders/arms are steady at the same angle to the weld zone as the weld goes from beginning to end. Don't make an arc of the torch to the weld - make them as parallel as possible to keep the weld's settings as uniform as possible.

Constant Voltage (MIG) power supplies are constantly varying the Current to keep the Voltage as uniform as possible; so, changing the contact tip to work distance (arcing torch travel) should be avoided or you're "FIGHTING" the power supply's circuitry.

To do this you need to add the knees. By leaning over the left (you’re left handed) slightly flexed knee when you begin the weld, and slowly transferring your wt. from left to right and moving at your knees NOT your waist, you’ll be able to keep the torch (shoulder/arm/gun triangle) at the beginning angle to the weld for 10-14”. I realize that’s a long weld compared to your coupons. 

IF your weight is evenly transferred between slightly bent knees as you move from beginning to end of bead (?) then you can move/slide/glide the base (knees, hips, waist) under your shoulders and keep them moving evenly. As this stance also requires the elbows to flex in conjunction to the transfer of weight from left to right leg (knees flexed) you can see what practice is needed to acquire a clean, foot long bead that has the same torch angle? 

I realize this is a pretty refined movement description but if practiced you’ll find you MIG bead is greatly improved. By keeping a firm (bent knee/flexed legs) foundation below your lightly tensed shoulders and moving in a clean sweep along the weld zone- you’re avoiding most of the flaws in other methods of handling an aluminum MIG drag style bead. 

I practiced this for hours without the torch, just my gloves and hood on before it worked for me. I was suggested the idea for this movement by a martial artist who watched me weld 45 years ago. He was working for me and suggested the types of movements I was misunderstanding. I was rotating (knees fixed not bent and flexed) not sliding evenly side to side. I tried his ideas (he wasn’t a welder) and found that I could put down a longer more controlled bead using his methods of movement.

Not everyone that MIG welds will even inquire about this level of planning, practice or preference. However, I’ve seen some others who do this - I think it was intuitive for them(?) but I had to learn by repetitive practice.

I did my practice on guide pipes similar to what you show, similar to Yofish's Hog Trough weld guide, and on furniture clamp pipes as I’ve referred above. I also use the following exercise myself and found it was very helpful for newbie welders when I had employees. 

I ask them to put on their hood, gloves and sleeves and practice standing at a plywood sheet with paper taped to the surface. Taking a pencil in the torch hand, and guided by the off-hand, bent at the wrist, with the back of the off-hand, gloved (wrist) sliding on the paper.  Draw lines, do various e’s and c’s all to practice the MIG bead w/o the torch. This employs the knees and shoulder movement ideas we’ve discussed and helps to give the tip of the pencil concentration w/o the distraction of arc, splatter or burning embers flying.

On hull welds, especially in thin materials like your hull, long narrow uniform beads are one of the keys to even contraction and reduced wrinkling or ‘hungry sides’. To obtain those welds I practiced until I had decent uniformity. I had a crew of more than a dozen guys cutting, fitting and tacking up- and used to weld for all of them: but it did take 10 hours in 12-16 hr days to keep up and get those skiffs out the door. 

After I got the movements in decent control - my beads became more uniform and were put down longer and in less time than I’d been able to do before. I found this both profitable and a gain in quality.  Experiments in this direction will help you to find a stance and body position that is best suited to you as you plan welding out your skiff.

By taking a 'knife fighter's'/martial artist's stance and moving through the weld (cold) before each pass, you'll find the bead improves as you're able to glide your torch along the weld with reference, not dependence for support, on your guide hand (back of the bent gloved hand at the wrist) and surface irregularities will have less impact on bead uniformity.

Hope this isn't too much zen movement theory to be useful?

Yes your video's filter was a little light and the arc was therefore too bright.... but the steadiness/variability of the travel was shown, and that's where my remarks are focused. 

Cheers,
Kevin Morin
Kenai, AK 
 
 
 

[m32825]

Kevin,

Your description of the proper form has similarities to spraying paint with an airless sprayer. The goal is to keep it the same angle and distance relative to the surface and maintain a constant speed. You have to consider body geometry and move side to side to evenly cover large surfaces.

Everyone learns differently. I like all the detail, time will tell how well it sinks in! The pencil/paper exercise is great because I can do it anywhere and it doesn't smoke up the garage!

I want to circle back and work on fillets and inside corners. Is that where I use e's and c's? 

-- Carl
 

[gandrfab]

Your link wasn't the easiest to spot.
https://www.youtube.com/watch?v=En5q4KuFUZA
 

[gandrfab]

Side note.
Take a walk through a production boat building shop, take pictures of a bunch of welds.

The camera is not kind to welds.

[m32825]

Is there a better way to provide a link to a video? I am open to suggestions. Here's a new attempt at settings, you can see the filler and even a couple drops, but everything else is dark.

video
 

[starbright55]

Kevin, thanks for all the guidance. As I said in another thread, I am about to start a build too. I'm taking a different approach to Carl - I haven't tacked up my hull yet but instead am trying to fabricate the little, non-structural parts. Lots of coupons in a pile, just like Carl!

[kmorin]

starbright55,
You're surely welcome to a discussion of the countless mistakes I've made learning to build welded aluminum boats since I started in the 70's.  If anyone can save a bit of learning from scratch and avoid the boat wrinkling mistakes I've made over hundreds of hulls, big and small, then our host welder's purpose for putting up the site here at AAB.com Forum is partly achieved.

I already knew how to weld steel from oil field work before I first welded aluminum. But the conversion to aluminum- especially with the older fixed frequency power supplies was quite the education and physical workout.

Glad to have helped, hope you'll feel free to post any questions you have about your build (with pictures if possible?) if you think I might have a useful opinion about some method to get over that hurdle? Can't hurt to try?  "The only 'dumb' question is the one not asked".

I know what you mean about welding coupon scrap, but by sawing close to the weld toe or top and stripping out the welded parts you can most often reuse coupons several times.  I like 8" or longer test pieces so I can test long MIG beads, to see how they look and then cut out of the ends an inch or so for bending or polishing edges (like Jody Collier shows on WeldingTipsandTricks.com) and etching to see how I'm doing with penetration; given the settings.

I've mentioned several times, and will repeat that most of the boats I see are 'over' welded in that the beads are too large, wide and the welds' strength comes from the two legs of the weld beads' triangle onto the outer surface of a T-fillet.  I have consistently gotten better weld quality in smaller size with less distortion and print-through by beveling the edges of T-fillets.

Therefore; in the process of building your skiff you can predict the weld locations of all the interior framing both stitch welded and continuous. Because of this you can test bevels, percentage of bevel/chamfer in different thicknesses and mark and bevel your parts and bulkheads prior to tack up.  This also gives the added advantage of being able to tack just inside or "at the ends of the bevels" in order to frame the eventual welds.

Few, if any, builders bother with this level of build prep.... but those who do, in conjunction with weld tests of the different joints' geometry, end up with a cleaner build and this goes for the main manufacturers' boats as well.  Draw or use an existing Body Plan Section and note all the longitudinals both inside and outside the hull, all of those are usually stitched and all of them represent some or another weld pattern that allows you to plan to create weld zones cut into the longs to accommodate better welding.

Feel free to post pics of your welds and test coupons, and the work you're doing on sub-assemblies.  I have a fairly in depth tank building thread on Glen-L Boats Forum that I did a few year ago that might help if you're not done with tanks yet?

Cheers,
Kevin Morin
Kenai, AK
 

[m32825]

I worked on fillet welds with the spool gun this week. I found my self covering some of the same ground as when I started fillet welds with tig: beginnings too cold, voids, and lack of consistency. I am seeing improvement. Here's the best of the lot, it was hard to get a good picture, so I did a video fly over as well.

    -- Carl 

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 video
 
 

[kmorin]

Carl,
The edges of the MIG bead above shows lots of overspray.  I'd say too much. This implies that in order to get the puddle wetted (wattage sufficient to melt the parent metal) you're going to a longer arc?  When the MIG arc it too long, the cone where it hits the metal is wider- and that's shown by the overspray or lots of droplets of wire along the sides of the bead. These droplets/overspray are not contributing to the weld in anyway.

You may want to move up one wire size?  If I recall (haven't reread the thread) you're using 0.030" wire? Probably move up to 0.035" to carry a little more wattage in the arc and 'burn' the wire's tip closer to the parent metal to keep the spray cone's foot print on the weld zone tighter.

Each wire size (dia.) has a range of wattages (volts x amps) of power it will conduct and at each of the ends of these ranges the wire's welding performance changes.  So a very small wire (0.023") will only carry so much power before it burns back- regardless of how fast you feed the wire into the arc.  On much larger wire (0.045") you can carry more than double the wattage and still only have the wire feeding at 1/2 max WFpM while keeping a very tight arc to the puddle.

I'd encourage you to experiment with the next larger wire- IF you're seeing this much overspray.  The exception is that you're not using the max WFpM rate and you could increase that feed speed to shorten the arc with the wire size you're using.  

So if you've got the wire turned up to max? move up to the next wire size.  IF you don't have the wire feed speed already against the 'stops'- turn in up to get a shorter arc length and keep the spray cone foot print on the puddle tighter.  The images seem to show a nice small puddle- and good travel speed so I suspect the wire size increase would require you to increase you travel speed NOT wire feed speed, in order to keep the small tight puddle and have less overspray but still have good fusion.

As to starts and stops there are two general categories in hull welding. First is the stitch/chain/intermittent weld and Second is the case of major hull welds; continuous welds. In the first case you'd practice the 'race course' pattern for starts and stops. In the second case you'll be cutting out/gouging out starts and stops (unless you 'wipe-out' the endings?) so they're not very critical to good welds except the last puddle in the final course of seam welding sequences.

Race Course pattern refers to an (semi)oval pattern of the MIG puddle's travel. To begin the weld, you put the wire one or two puddles into the final weld area, in your left hand case- welding from left to right- you'd begin to the right of the beginning of the weld. Then pull the trigger and move immediately to the left to the first puddle's location and pause for part of a second while the weld fills, and then continue to the right.  This is the first 'end' of the Race Course pattern.  You'd done a U turn in the first puddle by staring where you will fill the next two puddles and whipping the arc to the beginning of the weld.

When you come to the end of a stitch weld you reverse again, and move the last puddle over the top of the next to last puddle so the crater is not left full depth at the end of your weld bead.  You're doing two 'U-turns' one at the beginning to keep the cold start in an area which will get burned out as the full power weld comes by over this arc initiation, and at the end you leave the shallow puddle on the top of the next to last bead where avoid the arc core chilling upwards from a full depth weld and forming a crater crack.

On long hull seams you don't have quite the same problem as you will cut out/gouge/carbide burr grind-out the starts and stops to make sure the tie-in passes have clean weld metal to tie into.  There is still the question of how to end a pass or sequence layer of hull seam welds and this following techniques saves lots of work in weld end prep.

Just as you release the torch's trigger, whip the gun out of the weld zone.  This wipes the final arc along the base of the weld zone, does not leave a slowed down double layer puddle and makes cleaning the seam weld end very easy with just a wire brush- usually.  I understand this 'wipe-out' ending isn't very intuitive but I will assure you, once practiced it will cut your hull seam prep time down a lot while not impacting the weld quality at all.  Since the tie-in, ending of beginning of the tie-in welds, will have a very low mass, very hollow and not filled weld zone; normal welding settings will create a full depth fusion of these 'wipe-out' ends of the previous sequence when doing long hull seams.

My weld method remarks don't apply as well if you have a 'crater fill' (weld ending) program sequence on your welder.  My Lincoln MP350 Power MIG does have such a setting.  IF your power supply has this then my remarks about ending welds aren't very helpful.

Hope that's not too much verbiage to get these relationships?

Cheers,
Kevin Morin
Kenai, AK
 

[m32825]

Hi Kevin,

Great explanation. It's helping me build a mental model of how different variables interact.

I was running.030 wire at 420ipm. Maxed it out at 480ipm and things improved, but I'm still getting that cold start look and overspray at the beginning. I'll do passes with .035 tomorrow and post pictures.

I picked up some 12" x 2" coupons to do longer runs on.

-- Carl