So, You want to buy a welding machine...?

Steel and aluminum boatbuilding. See: "Boatbuilding Methods", in left-hand column of the Home page, for information about alloys.

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Re: So, You want to buy a welding machine...?

Postby Kevin Morin » Wed Jun 29, 2016 2:22 pm

bumping an older thread to make some more welding remarks for those who pay attention to such details?

Most hull seams in welded steel or aluminum boats would be welded by MIG (metal inert gas or wire feed) because the speed of deposition is faster than TIG; unless the TIG is motorized in some way. Faster welds, take less time and since all the time of the welding process an arc is used to melt the parent metal parts; it stands to reason the less time of a weld the less Net Heat is added to the parts being welded- And.... therefore less expansion and contraction happen as the result of faster, cooler (net heat) welds of the boats' hull and frames.

I recently saw a newly built boat that was not welded too well. The welding was done with a newer power supply, with many extremely advanced controls that may have been a problem for the owner/builder? Sort of like having a drag racer to drive to the grocery store- most of us couldn't even get a fueled rig running! Let alone pilot a rail frame 'car' on the streets or even shift gears off a stop light! What I saw was an owner's work that had welding flaws too many to mention. So, for anyone considering a new (to them) welding power supply (MIG in this post) I'd be cautious of falling for the sales pitch about the great benefits of all these exotic features to control the arc. Pulse, Pulse-with-Pulse, Pulse On Pulse, and all sorts of other terms are 'sold' to buyers as the 'end all' the 'solution' to a newer welder coming to MIG welding- that is not really completely accurate.

What I see in some of the newer builder's work is a failure to take the welding skill step by step- building on the previous step, once its mastered, to add another layer or skill and knowledge- but not before the previous skill is actually learned well enough to rely on those muscle memories to provide a decent weld.

I'd encourage anyone considering a metal boat build to be realistic about the time they'll take to practice welding BeforE they weld on their own boat!!!! Can't stress that enough. I know its expensive to practice with gas and wire and electricity to run all that- but what is the value of taking perfectly good metal and making a poor job of your boat build because you didn't practice enough to get a decent weld?

Just because you buy a fully featured electric guitar doesn't mean you can sound like a professional musician using that guitar- regardless of the bells and whistles available- they're really only fully useful in the hands of someone who knows how to use those features- and that is someone who has held and played those instruments for hundreds or thousands of hours.

I'm not saying the advanced arc controls are not potentially beneficial to both new and more experienced welders; I'm simply noting that I've recently seen another example of the fact that there is no short cut to welding proficiency. All readers should be realistic about the time to learn welding, and that realism should include time to practice for many hours. Otherwise, your build could suffer in quality- that will show in the welds, that could (will) affect resale potentiall, and that means you can't recover your own time and materials (even your costs) unless you take time to learn the basics, practice and apply them and TheN and OnlY then is is wise to weld on your boats' hull.

Older power supplies without all the bells and whistles still represent a very good value for the costs- and they'd force you to learn the basics since they don't, for the most part, have the digital controls that give all the fancy sounding weld terms that seem to confuse newer welders.

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Kevin Morin
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Re: So, You want to buy a welding machine...?

Postby billy c » Thu Jun 30, 2016 4:40 am

Kevin-
is there a short list brand/model for selecting an older power supply MIG that would be a good fit for us building a metal boat?
(insert Witty phrase here)
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Re: So, You want to buy a welding machine...?

Postby Kevin Morin » Thu Jun 30, 2016 9:18 am

Bill, not really a short list because some of the power supplies have lasted forever! Power supplies seem to last much longer than wire feeders- so the weak link in the chain of older welding systems (MIG) is the wire feeder. With their motors and drive rollers and contact tips not being made any longer- they are what seems to fail. Most of the Lincoln and Miller power supplies lasted for decades- but not all the older wire feeder have.

Miller and Airco both made good, long lasting 1 lb. guns (push only- wire in the handle/case style) guns that have lasted well- Miller's 30 E is still seen. There is actually some support for the older systems here ( http://www.weldmart.com/store/millerdirect.htm but as I understand they're not as helpful for aluminum applications and try to sell newer push only steel guns?

Not many push-pull guns have lasted as durably (more to go wrong) but almost wire feeders by MK Products ( http://www.mkprod.com/ ) were/are durable and some may still have parts available if not running. MK built and sold both push and push-pull wire feeders or guns.

http://www.ebay.com/itm/HOBART-RC-300-R ... SwbYZXctyA here is an example of a potential deal- or disaster where you're buying scrap? The only realistic way to know if this old system is worth a look it so know if it will still weld and if the wire feed will feed wire? To do that, in any used system you'd have to be there with the system- and run it. OR, you could find a welder in the area of the sale who knows about the system to have him evaluate the value?

I'd say buying this without knowing it runs was pure foolishness. On the other hand- if it sold for a few hundred dollars and it did run, could have some of the older parts on the gun replace (MK Cobramatic- like the wire feed liner, and some case parts??) then, (and only then) it represents 1,000's of $ of value purchased new. some of these systems were run hard, not maintained and "put up wet"- so they're not worth scrap. The same appearance may be a gem that has low hours, little use and was stored 80% of its life- with one owner?

So, as to a list, not really , but the value is only shown if you're close enough to be able to see or weld with the system. But you can do some research on the MIller, Airco and MK guns- to see if anyone specializes in supporting and rebuilding the, (#1)? and two if there is a life in the power supply- you should see an arc and be able to weld with it. If you're half a continent away- don't have any knowledge of the equipment and can't find a representative to act in your behalf" IT's Not a Deal!

Forgot to mention earlier, many community colleges or local college campuses in some states offer 'night classes' in different skills and welding classes taken in that setting is a potentially low cost means of learning if you're going to spend the time to learn to weld - well enough to build a boat? The cost of a few hundred for a course that gave your a couple dozen hours of beginning welding is worth the money in my view. You don't buy any equipment- some gas, wire and welding booth time (rental more than purchasing) so you can walk away and not have expensive investment in tools you won't master.

As I've mentioned on the other threads; its better to know you're not going to do the welding on your own boat- and plan from the beginning to hire that work done with carefully researched other people doing the work- than to do a poor job of that critical step of the build. I have a friend who's bead is not what he wants to put down on his projects. So he "hires" me to come to his shop, using his welder(s) to do his welding for him. He's happier getting a more uniform bead on his work, and he's skipped the hours required to get his own skills up to the level he wants- sometimes he won't even tack the work up- preferring to have all pieces ready and we tack up together then I weld out. (Its) Not for everyone but it does work for his (mostly steel frame) projects.

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Kevin Morin
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Re: So, You want to buy a welding machine...?

Postby Kevin Morin » Thu Jun 30, 2016 2:43 pm

I'm not sure if this older topic is still very actively read? but I do have more to add to the subject- learning to weld. Not just on welding systems- power supplies or wire feed gun or TIG torches (or stick electrodes and holders ) but on the generic topic of physically performing the weld itself.

The other posts in the Metal section here, talk about various aspects of fitting, cutting, preparing and even welding beads but in this post I'd like to suggest that many MAny, most, lots and too ManY training methods don't result in learning the skill in a reasonably short time- for too many people. The result of long training time is that fewer people are able to afford the time in their year(s?) and maybe won't want to spend the money to get that time welding - and that translates to fewer people being interested enough or confident enough to learn to weld - so they don't.

What I'm posting here, is a brief review of some aspects of welding that are not thought about - typically. At least not by new welders in my experience. However, having talked to many welders of all sorts of skill levels and hours of work in the trade, its surprising how many of these ideas I'll mention below would help a new welder. The surprise is- as much as these facts would help a new welder-99% of all welding training I've heard about does not take any of these facts into the training process!!

Welding is a physical skill - admittedly guided by the mind like all skills - but it requires a body able to perform the required actions.
Welding is a related rate of combined physical acts and actions that can only be done when all the various elements are tuned within narrow tolerances- one of the biggest is guided by the physical acts of the welders' hands.
Welding requires a combination of the two main types of muscles in the body- fast twitch and slow twitch- in fact: welding requires a coordination between these sets of muscles.

All the above descriptions are focusing on the body movement or physical aspects of welding- I'm not discussing the adjustments of amperage, voltage, arc length, travel speed, arc shape or joint type; all that is being explored in this post is the body movements and the skills required to move in a certain way or movement in a certain level of control of the, arms, hands and fingers' motions.

If anyone is familiar with sports training they know that most sports require a combination of musculature training? For example baseball practice is not all catching, not all throwing or not all batting, sliding or any other single act of playing the game. We've all seen practice in each of these individual skills and that applies to golf, football, and other widely played sports.

Each sport has available accepted practice exercises for different muscle groups doing different tasks- the golf swing wind up- base sliding running and drop to slide.... tennis the serve or even the serve toss up overhead ..... Equivalent isolation training exercises are almost totally absent from welding training!

When we weld we're wearing PPE (Personal Protective Equipment) that includes heavy gloves, boots not canvas shoes, heavier clothing and even a leather jacket or at least leather sleeves to keep the hot Beebees from burning our clothes and our hide underneath. We're often wearing hearing protection a hat on to cover our hair (and the ear toward the weld) a welding hood to protect our skin and eyes and in many cases an air purifying respirator! That is a lot of equipment- almost like wearing full pads in hockey or football?

Now, after putting on all the gear (PPE) and taking up the torch/gun/stinger we begin to learn to weld? 90% of the people are so distracted by their PPE they can't concentrate or move well enough to do the job! how is that a surprise?

What to do? If you're serious about learning to weld- get the PPE, and put it on. Stand (don't sit) in front of a sheet of plywood with paper taped to the plywood and hold the torch -DO nOT turn it On! Just tape a pencil to the torch and draw lines- then draw lines and make little 'e's and 'o's uniformly along the lines you drew with a straight edge. What are you doing? Well- you're getting used to seeing out of small hole in a plastic helmet while you're wearing 25lb of extra cloths with big gloves on your (at least left ) hands. If you'll do exercises like this- for an hour a day (you legs will make you quit way before that) drawing slow lines up, down, side to side and above your head- for a week or so- when you get ready to 'light up' you'll be working on seeing the weld not on reducing your "shakes".

VERY, very Very few people can stand in front of a plywood paper panel and draw decent lines in slow motion without their hands dragging on the paper- (that's what I have to do) but that is what welding requires. Why light the torch before you can even expect to hold it steady enough to weld?

What is being asked of the body to do a weld? First the legs and hips must be steady enough that they hold the body up- the core or belly & back have to hold the ribs and shoulders steady enough to allow the arms to do the main movement control. If you can't do that- well there's not going to be much welding happening. OF course we can use our off hand (not holding the torch) to steady our torch hand- and most of us do that. But... even that requires you to be able to coordinate the movement of both hands being slowly evenly and with out twitching - moved over a surface other wise the melted metal that is deposited is uneven, won't melt both pieces being welded evenly and the weld may be weak and will be unattractive.

Do this same exercise with the knees bent 10 degrees! Add this entire exercise on you knees (use a foam kneeling or work pad!!). Don't allow yourself to work "just between the shirt pockets" work at arm's length both left and right, observe that when you rotate your core- you chaNGe the angle of the gun to the work!!! (very big deal)

By wearing all the PPE, getting used to the wt, the limits to vision and touch by working to get a muscle movement that works for the job- before you try to learn to hold the arc steady- you'll shorten your time to learn to weld drastically. Interestingly- 99.98% of all who read this will not do the exercises and then will say " welding is hard to learn!" And if its taken all at one time (like trying to be the lead guitarist in a stadium playing rock band without hundreds and thousands of hours of preparation....) welding is hard to learn. Mainly hard because almost everyone refuses to break down the entire skill into simple, trainable, repeatable, exercises that would allow the skill to be learned in a sequence- only moving ahead to the next stage when you'd prepared some basis to take the next step!

Steadiness is a matter of being able to move one set of muscles in coordination (some would say 'anti-coordination') with another set of muscles. Learning steadiness and even movement that is required of manual welding can be reduced to series of exercises - like most other physical activities- if people would just take the time to practice in sequential steps instead of trying to all 24 movements with new PPE and a hot spattering, blinding arc - all at once.

When you learned to drive you'd ridden in a car- but 90% of new welders have hardly seen an arc! When you learned to drive did you try to shift gears (speed up slow down) turn on the blinker and turn to the left in traffic, change the radio station, CD, air conditioner/heater and talk on your cell phone all at one time? Not many people can say that was how they learned- but many of us might drive like that now- because we're familiar with the various aspects of information coming into our eyes and ears all at once. Welding is very similar, once you're used to all the sights, sounds and heat of the arc, dealing with it is much less information overload. So I'm advocating getting your body ready to hold a steady arc length by exercising with the welding gear on... before even lighting the torch.

I've trained lots of young people to weld, and more than a few adults. I typically train young people in 10th or less time of adults- the young people don't interfere with the learning process compared with the adults- who almost all refuse the learning process due their involuntary interference with the information coming into their minds that is new or different from their preconceptions. Breaking down skills to exercises will shorten the time required to learn the skill by allowing the learner to concentrate on simpler background muscle memory learning before having to combine all the body skills and information together.

You could say this is why a piano teacher starts with scales before moving to Mozart's concertos.

Cheers,
Kevin Morin
Kenai, AK
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Re: So, You want to buy a welding machine...?

Postby Kevin Morin » Thu Jul 07, 2016 11:03 am

Received an email from someone asking about the order of learning to weld for boat building? Essentially the question looks obvious to answer but I'm taking time here to post this reader's question because of my experience teaching welding to past employees and friends.

Remember that welding is a muscle memory skill? So learning sequentially or step by step can be very helpful to isolate each given step and allow rapid overall improvement compared to learning all the steps at one time or simultaneously.

What is not said in that post (above) and left questions is which process is best to learn first? TIG and Stick are usually slower paced welding processes and MIG is usually considered a faster paced welding process. So if we're doing exercises to learn a set of muscle memories- it seems to follow the slower processes should be learned first? That is, unfortunately not always the best practice.

If you learn to move in slow motion compared to the 'real speed' of a movement - for example the first few times you swing a bat, golf club, or tennis racket- you may want to move slowly, carefully in order to get the best 'form' for that sport's swing? However if all your practice was at the enforced slow speed, (then) none of the practice would help you play that game well. Eventually you'll have to spend much more time at full speed to get proficient.

Let's compare that to welding. If you spend hundreds of hours with stick electrode welding as you're learning (??), say in a college night course at the local community college burning rod on a padding plate, then you've spent lots of time learning to hold a bead at stick welding conditions. That is about the slowest welding speed widely in use. This practice would concentrate on steadiness, uniformity of your bead(s), even tracking and width, and generally becoming used to watching the bead through the welding lens filter glass. All good and necessary in learning to weld.

What is not desirable, and can be a limit to moving on to MIG (especially aluminum MIG) is that everything is done in slow motion, all your muscle memory is being created at very slow speeds. The problem only comes to light when you try to pick up a MIG gun and 'keep up' with the needed speed of travel- your reflexes will have been created in slow motion and you will have to work to overcome that early practices' impact on your movements.

So, to answer my email question, if you plan to learn to wire weld aluminum, I'd suggest you consider getting access to that type of welding equipment very soon in the practice time line. The reason is that while working slow with stick is #1 lowest cost electric welding, #2 slow paced and easily repeatable, #3 helps to work at slow speeds to train your eyes "separately" from your hands, #4 slower movements to begin allow more time to correct and adjust the bead- allowing better quality at the earlier stages of learning.

However, the reasons to move to higher speed MIG as soon as possible are: #1 Becoming used to moving through the welds faster -before you've become habitually slow motion oriented, #2 Moving to MIG early in training allows you to associate the body isolation and steadiness exercises to faster weld travel while you're still without "muscle habits". #3 Becoming used to "highway driving" so you are not shocked when you are exposed to aluminum MIG speed requirements later, #4 Learning to move faster, earlier, requires you to perform the steadiness exercises at a higher and more difficult level- you can always slow down- but speeding up if your training has All been slower- is much harder. #5 if you've done exercises to prepare, and gotten used to wearing PPE while exercising - the higher speed welds are easiest to learn to do well when you have not welded as long- fewer habits to "unlearn" in order to progress.

All that was to say; many welding courses seem to teach a set of skills without isolating them and I think that can be improved? Do you learn to play golf at Augusta National? or do you learn at the local course working with the Pro on isolated aspects of your movements? When you learn to swing a bat, the first few swings may be just to introduce the form of a good swing, including all the body parts' movements relative to the swing. However, most of the time batting practice is done at full pitched speeds, because that is the most challenging of all conditions. So, I hope to have shown (that my opinion is) MIG aluminum should be practiced as early in the actual welding practice (as can be afforded) so that you compare your own progress to what will be the highest speed reflexes you'll need in building a welded aluminum boat.

Cheers,
Kevin Morin
Kenai, AK
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Re: So, You want to buy a welding machine...?

Postby Pullie » Thu Jul 07, 2016 11:38 pm

Great work Kevin,

One thing I would like to add to this thread is the welding quality. I work as a QA manager in welding and NDT and it suprises me how often I see welding that is clearly unacceptable and they hire me to explain the obvious.

Fillet welding is in my opinion one of the most critical welding where a slight deviation of a parameter can results in a massive welding failure, If you look closely at fillet welds you will notice that the penetration depth is minimal at best. therefor the throat profile and leg lengths are very important.

Visual inspection of fillet welds is easy. you just have to know what to look for. In de link is a nice easy to understand article on the most common defects and how they look.

http://www.derivativesinvesting.net/art ... -remedies/

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Re: So, You want to buy a welding machine...?

Postby Kevin Morin » Fri Jul 08, 2016 9:25 am

Pullie, glad you're looking over the thread's content, we could use some welding inspectors' input.

While focusing on the newer welder, where QA usually comes as corrective(s) father along the learning curve, I do agree that a fillet weld in aluminum has almost no penetration unless the T of the fillet has been beveled to allow some increase in the root face area and a re-orientation of the actual weld root legs' under the vertical piece of parent material.

Even in the instances of a stitched/chained/intermittent weld pattern like a longitudinal to the hull panel weld- or non-water tight transverse frame (bar or bulkhead) to the hull or topsides - all T type fillets; gain from having a weld bevel cut onto the edge of the butted parent metal edge. This is often not done, and we may even say - most often not done, but that doesn't mean the idea of beveling in the way of a T fillet weld is not best practice.

Next is to note for the new welder the difference in penetration between steel and aluminum MIG welding processes. The nature of the ARC and polarity result in (more of) a gouging effect on steel which is not (as) present in aluminum- using the same process. (we're not discussing stick welding as that is rare in aluminum) The illustrations in the link do show some surface penetration of the parent metal by the puddle- but in aluminum, even a well tuned MIG weld can result in almost no penetration of the parent metal- When Compared to Steel's arc properties. All the more reason in my view to find mechanical means of increasing the penetration by gouging, beveling, or other joint prep steps- especially in fillets.

Last, as a new welder progresses along the learning path to proficiency- break bending their own welds should become 2nd nature and a common practice. The reason to do this is that the surface of the weld may not reveal the flaws you've buried in the bottom of the welds? Aluminum MIG happens at about 4 to 10X the speed of steel MIG welding, that means the wire is fed through the contact tip at a higher rate, is vaporized into the arc cone and deposited on the parent metal in the weld puddle/pool at faster/higher/greater rates of both weld travel and deposit rate of the weld.

Greater travel speeds means less molten metal time. Less time molten means there is less time for naturally occurring gas bubbles to float to the top of the molten metal (weld puddle) where the hot cover gas can flood them off the weld. Aluminum also has a higher rate of transfer of heat than steel- about 7x as high. So, a 1/4" piece of aluminum 'cools' or chills the molten metal of a weld 7x faster than the same 1/4" thick steel piece cools its weld.

All this contributes to a retention of impurities inside the aluminum MIG puddle when compared to steel! So learning to weld in aluminum must include acquiring the habit of breaking the welds as self-tests to observe what the root fusion and gas inclusion looks like. Settings like amperage, voltage, wire feed speed, gas flow are all important contributors to quality welding but... so are gas cup and contact tip clearance from the work, gas cup angle to the work (weld area), rate of travel, steadiness or uniformity of gas cup gap to work (weld gas coverage).

My remarks were intended to focus on the reader who was considering buying a welding system and learning to weld to be able to build their own plate aluminum boat. We've discussed power supplies, gun systems (wire feeders and other torches), learning steps that might speed the overall skill acquisition, exercises to isolate muscle memory based skill improvement, and now - introduced the idea of making QA a routine part of anyone's welding work.

On other threads, near this one, I've tried to explain with text and images what to consider in either doing or supervising different welds in aluminum. Hopefully, we're expanding the knowledge of readers who may decided to take on a plate boat for themselves, and our remarks can help guide new welders shortening their time to acquire reliable welding skills?

Cheers,
Kevin Morin
Kenai, AK
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Re: So, You want to buy a welding machine...?

Postby jim8014 » Sat Jul 23, 2016 11:58 am

I need to weld with some 5356 filler wire, with a Miller 211. Since the wire is stiffer than 4043 and the length of the gun cable is 12 ft, will that wire work with the standard Mig gun?
Thanks

Jim Collins

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Re: So, You want to buy a welding machine...?

Postby Kevin Morin » Sat Jul 23, 2016 12:42 pm

jim, generally you'd need to use a spool gun ("1lb. gun") or a push-pull type but not the Push-Only steel type MIG torch for aluminum wire.

Here are the reasons.
#1 while 5356 is stiffer than 4043 its still aluminum it will not feed in a push-only system smoothly for 12'; instead it will surge or slow down while welding.
#2 coiling slightly inside the liner (which has steel contamination in most cases) the softer aluminum wire will slow down by gathering inside the liner and that can (and very often does) lead to burn back where the wire fuses to the tip because the slow-up of the coiling wire in the liner allows the arc to 'run' up the wire to the tip.
#3 then, when bunched inside the liner, 5356 will usually surge out the tip faster than the arc (at the IPS and wattage settings will burn it) consumes the wire - so - the wire hits the puddle, lifts the gun and pulls the gas coverage off the weld, only to slow down again and risk burning back when the CV power supply ramps up the amperage to keep the Voltage flat when the Resistance of lifting the wire and contact tip goes haywire in the surge! (rodeo)
#4 repeat.
#5 even well tuned, with the liner held almost straight the weld is usually not uniform.

If the gun is kept almost perfectly straight, and if the tip is sized correctly for the wire/wattage/weld (tuning if very difficult with steel equip.) then... some people will accept the welds in aluminum MIG from a push only welding torch. However, any of the various problems mentioned will then create lumps, cold starts or cold lap stops, and other weld defects using this torch's weakness for feeding aluminum wires.

While some people do use this process, no one that welds aluminum for a living, or who's responsible for critical welds will accept the quality defects that regularly come with this wire applied using the steel wire, push-only torch.

There are more discussions of this combination on various welding sites as well.

Cheers,
Kevin Morin
Kenai, AK
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Re: So, You want to buy a welding machine...?

Postby jim8014 » Mon Jul 25, 2016 11:06 pm

Kevin,
Thank you so much. I think I will sell the 211 and get a Lincoln 350P with a spool gun. I really need a bigger welder anyway.

Jim

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Re: So, You want to buy a welding machine...?

Postby Kevin Morin » Tue Jul 26, 2016 8:42 am

Jim,
both the Miller 350P and the Lincoln 350MP are powerful welders, and both come with the "one pound gun" torch options; where the filler wire is in the handle of the torch body in a small push-only roll. The Miller has fewer variables & settings than the Lincoln in my experience, so it is easier to learn to adjust with fewer arc controls. I have the Lincoln 350MP but have welded with the Miller equivalent power supply a few times, so I'm pretty sure there are different learning curves with the two systems.

This is quite a step up in MIG power supplies and I advise that you consider welding with both power supplies (if that is possible ?) before deciding on one or the other? Not all suppliers keep demonstration welding systems to help with sales? However, if there's any way possible to find both systems to weld it is worth your time especially given their high costs.

cheers,
Kevin Morin
Kenai, AK
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Re: So, You want to buy a welding machine...?

Postby jim8014 » Tue Jul 26, 2016 6:42 pm

I am sure my welding supply house, Northwest Gas and Welding can get me access to both machines. Even though I am a little guy, they treat me like a big customer.

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Re: So, You want to buy a welding machine...?

Postby Kevin Morin » Wed Jul 27, 2016 2:42 pm

Jim that's great to hear that you'd get that level of service. It will allow you to get some sort of idea or 'feel' for the two systems controls, torches and welding beads.

If you're not going to be working on a whole boat (or more) where the many enhanced and advanced features of the Lincoln would be used (?) I think you'll find the Miller controls are simpler to learn? Not saying that's the result you'll find but that's what I've seen in the past.

Don't hesitate to let me know if there are any questions you think I could help answer?

Cheers,
Kevin Morin
Kenai, AK
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Re: So, You want to buy a welding machine...?

Postby Kevin Morin » Fri May 12, 2017 8:27 pm

Leaving posts littered around the web for years does bring an email or two trying to get clarification of an opinion posted years ago- at least it has for me.

I've tried to make points in different threads spread over a few sites about the "first welded aluminum boat" - usually remarking about the size, scantlings and the implications of welding that material. My usual remark is something to the effect "smaller, thinner is not easier; the first boat should be >16' LOA and 1/8" or heavier material".

I have tried in many posts to make the point about proportional welds, boat size (displacement or LOA) and scantlings as that affects welding aluminum but I'm going to tie that into to welding processes and power supplies, at least partially, in this post.

A small 10 or 12' skiff, dinghy, punt is hard to image weighing 100's of pounds! Can you see you or the kids, grand-kids, smaller people trying to row a 200lb or 300lb 12' long skiff? What about trying to beach that weight?

Boat scantlings (thickness and dimensions of the materials of the boats' construction) need to be in proportion to the boat's design. We don't expect to have 1/2" plate bottom panels in a 14' run-about- and we shouldn't expect to see the bottom of a 22' offshore power boat of 0.060" sheet.

Small boats would be more proportionally built of thinner material than larger boats. But too many new builders in welded aluminum seem to ignore the fact that welding aluminum both thick and thin is more work than welding the middle thicknesses. Thin aluminum is thinner than 0.125" or 1/8" and thick aluminum is thicker than 0.250" or 1/4" aluminum. Welding the three or four thicknesses in between is easy compared to welding thicker or thinner.

Welding thinner aluminum is harder and harder as the material thins. I've welded for a long time, & welded quite a bit of marine alloy aluminum; I'd estimate that welding 0.090", 0.080", 0.060", 0.040" gets harder each thinner step taken downward in thickness.

In fact I'd say it was twice as hard to weld each few thousandths thinner the metal gets. If an 18'er is 1/8" thick hull- what is the proportional thickness of a 12' punt? 0.08" ??

But in proportion to a boat's LOA or displacement- as you get shorter and lighter- the proportional scantlings become as thin as listed above.

One very significant fact of welding aluminum that ignored by even some of the most widely known builders is that any weld larger than 1.2 or 1.3 Times the thickness is out of proportion to the metal being welded. So, if we look at the weld sizes for thin scantlings, which are in proportion to the smaller boat(?) some of the welds would be VERY, very small.

Welding equipment (MIG & TIG) is much harder to control and operate below 1/8" compared to the ease of that same equipment welding from 1/8" to 1/4". If you consider MIG welding of 1/8" using 0.035" wire (perhaps 0.030") that is roughly proportional and works well. However using the same wire for 0.080" or 0.060" is an extremely difficult skill to master using MIG. This comparison continues to become disparate- the smallest MIG wire is 0.023" but even that is extremely hard to use welding 0.040" sheet.

So the lower end- proportionally thinner due to the small LOA and displacement of little boats- of aluminum welding is many more times difficult to learn and the results are so limited: most short LOA, smaller displacement aluminum boats are riveted!

Welding thin material is so difficult to do effectively that most manufacturers simply skip welding and rivet, lap seam and glue their small thin boats together.

TIG welding is more controllable because it is much slower paced than MIG in most cases. A small capacity/amperage TIG power supply and a small wattage hand torch would seem to be the solution to welding thin aluminum for small boats. There is another problem in this combination- the slow pace of the welds, the very small cross section still leaves a large amount of heat of expansion in the metal- making the boat hard to form cleanly; even with TIG.

So, if you're reading this article on buying a welding power supply with the goal of building a welded aluminum boat (?) AND the first boat you have in mind is a "start small- build bigger" tiny skiff- please let me caution you that unless you're willing to build a very heavy - but still short LOA skiff? stay with a 16 or 18' skiff of at least 1/8" thickness.

This way you can buy a quality used welder, even a transformer power supply, with a spool gun/one pound gun/pistol style wire feeder and end up with a good quality skiff. If you confuse small. thin, short skiff and "a good beginning" related to welded aluminum boats- I'm pretty sure you'll find the limits of aluminum welding systems will make your project frustrating.

Not all older power supplies will carry a constant arc for 0.030 or 0.023" wire. Most TIG power supplies that output AC (most commonly used for aluminum) will provide small amperage/voltage/wattage arcs that will create good quality puddles in thinner aluminum.......But... few new welders will be able to TIG weld effectively with a 0.045" or 0.060" filler wire being hand fed! So while the MIG power supply may have circuit control problems- the welder themselves may have finger control problems in thinner material due to the very fine filler needed to create a proportional TIG weld in thin material.

By staying with 1/8" and thicker metal, 16' to 20' and middle range MIG or TIG welding, you'll have a much better project than trying to acquire the skills needed to weld thinner, proportional metal for a smaller skiff. A Scrambler or a Slither in the 17' range will be lots less work than trying to build a proportionally thinner MiniMaxed or a PeeWee in welded aluminum to start your metal boat work!! If you're buying a welding power supply and torch system to weld aluminum please consider staying in the mid-size range in both power supply AND boat project until you've got a few under your belt.

If these statements are confusing, or you'd like to ask a specific question please feel free, I'd be happy to try to explain these points of view for any reader of the Forum. AS a complete welded aluminum boat fan- the last thing I want to do is to discourage new builders- but I'd also like them to be aware of this misconception about smaller boats being easier to build.

Cheers,
Kevin Morin
Kenai,AK
Kevin Morin

Kevin Morin
Posts: 697
Joined: Thu Jan 24, 2008 11:36 am
Location: Kenai, Alaska

Re: So, You want to buy a welding machine...?

Postby Kevin Morin » Sun Aug 13, 2017 10:51 am

Tsts22, yes a single power supply that does all three types of welding could be nice! but is not available, that I am aware, that includes AC. DC TIG and MIG in power power supply are out there, and most TIG power supplies will burn rod all in DC. Most dedicated TIG power supplies come in both DC+, DC- and AC but don't include MIG.

But aluminum TIG is done with AC and that is what's not offered in the combo power supplies, that I know about. So most of us end up with an AC TIG set up and DC MIG w/wire feeder. For smaller boats (>25') a 250 Amp power supply should be enough for both MIG and TIG but if your design has a thick keel bar(?) you may need to both preheat and add some helium to the argon cover gas to get a full fusion weld using only 250A.

If there will more boats- not just one- then moving up to the 300-350A range is very common for most full time builders.

Cheers,
Kevin Morin
Kenai, AK
Kevin Morin


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