Glen-L.com

Good evening all
I'm putting out a question to all the alloy welders out there.
I'm planing to build a 23' aluminium boat, I wont go into to many details here but I am after some information on the mig set-up.
I own a mig which I bought new back in the eighties, good large machine which has had not much work, I doubt any of you would of heard of the brand as they were made in Australia back then.
Its a CIGWELD Transmig 195. 240v 15amp, rating 180amp at 30% duty.
Now I realise there must be much better machines out there for alloy welding, but this is what I have and its mine.
What I would really like to know, what is going to be the best set-up for the Mig for welding this boat together, work on the fact I have have to weld sections from 1/8" thick to 1/4", Im certain in one place there's a 1/2" plate but maybe I can bolt and weld, Will cross that bridge later.
Now I have been reading about Spoolguns, I can also get Teflon liners to use the original torch with alloy tips, I don't really know were to go from here, as I don't know enough about it.
recommendations would be appreciated.
Thanks
Katoh

Katoh, three types of MIG; all will weld steel; two will weld aluminum.

Spool gun and push-pull guns will weld aluminum [reliably] but not the 'Tweco' style push from the cabinet gun most used on steel. Aluminum wire flexes too much in the conduit then surges and stops at the tip: burn back, lots of blue, sailor-like language in the shop air and you end up bald.

Go with a spool gun but the power and controls adapters could be a challenge as the circuit values of controls and relays may not be simple to match. I'd make a list of the controls; contactor, wire feed motor transformer or direct?, gas valve in gun or solenoid?, and either remote or panel mount voltage then try to see if anyone's spool gun is close. Otherwise the power for the wire feed motor may have to come from a separate and added-on power supply to match new gun motor to older power supply.

Cheers,

_________________
Kevin Morin

Hi Kevin
Great to here from you.
You said there's three different types of mig, how do you determine which is which? Excuse me if this sounds like a silly question, Maybe I have the wrong mig? If I do I wont waste my time looking for bits for it.
You have definitely convinced me to buy a spool gun
I have come across a universal spool gun adaptor http://www.weldingdirect.com/spgunswkiun.html
They have told me this should work with my mig and then its just a matter of buying a universal gun. The majority of guns I see work with 0.035" wire is this heavy enough for our plate alloy boat, welding up to 1/4" thick or do you need something larger?
What are your thoughts?, or am I going about this the wrong way.
thanks
Katoh

Sorry Kevin I think I misunderstood your first statement, about the 3 different types of migs, I thought when I read that there is typical difference in the machine itself but your talking about the torches, Ok now I understand a mig is a mig its the wire and gas deliverance that's different. Please excuse my first question.

I have used a CIGWELD machine in the past and it was a very good machine. However I do not think a 180amp 30% duty cycle is going to give you enough energy to get adequate penetration and fusion on the 1/4" plate. One thing you can do to help out is use a Heluim/Argon mix gas. W/O getting into the tech talk, it basically gives more energy to the weld puddle. Generally speaking you can usually weld with about 20-30amps less than with straight argon gas on 1/4"plate.

A word of advice. You are going to spend several 1000 $ in material to build this boat. You can look around and find a good used Lincoln or Miller in the 250amp range with a spool gun for 1500-2000. I think it would be money well spent. Even a CIGWELD machine in the higher amperage range will give you a lot better performance. If you can find a used MIller spool gun, buy it over any other. Any electric shop can make you an amphenol plug to fit it to any machine. Unless you are going to spend the money on cobra gun you will not find a better gun than the Miller. I used one on my Lincoln 255 until I upgraded to a push pull system.

Hi mcmbuilder.
Again great info, the majority of the vessel is 4 and 5mm alloy with some 3mm stuff on top, only down in the hull I have some 5mm plate to get welded on some 6mm bar, which will be welded on both sides to the 5mm plate, do you think I might get away with it with the Cigweld? I think I'm looking for excuses not to spend another couple of grand, as we all do it times, but If you really think that it wont do the job than I will have to look at getting something else.
thanks
Katoh

On the 3mm stuff you should be alright. I really have doubts as to being able to the 4&5mm stuff. The heluim/argon mix will help. I currently use a Lincoln Power Mig 350 with the push/pull system. I usaully run about 22volts and 400ipm which translates to 195-210amps with .035 5356 wire. That is with 100% argon. With the mix I am closer to 160-175amps. So you can see you will be pushing the limits. Welding on both sides will definitely help, but if you have total cooling of the metal between the time you weld each side it will actually be harder to get good tie in due to the increase of the thickness of the weld joint.

Before I would actually try to make welds on the boat I would cut some large scrap pieces, at least 1'X2' and see how your penetration goes. You could use a teflon liner for this, just keep everything very straight and it will feed good enough for this simple test. No way you will be able to weld your boat with that because of all the twist you will have in the gun lead as you make the position welds.

Don't take this as an insult, but depending on your skill and experience with aluminum you may want to take the welded pieces to a certified welding inspector and let him visually check the welds for suffficent toe bead penetration. It is very easy to make a visually nice looking weld but has no tie in on the edges if you don't have enough energy to make the welds. If there is not a CWI nearby, you can also buy some die penetrate and test it yourself.

The reason for the larger pieces is it will give you more of a feel welding the larger panels on the boat. A smaller piece will quickly heat up and even with low energy the bead will start to tie in as you move down the plate. That will not happen with the larger pieces.

If it does not fuse like it should then you know you will have to get a bigger machine. Hope all this helps.

I don't take offence to advise given to me by someone with more experience and knowledge than myself, that's why I ask the question.
I have had a bit of luck, a good friend friend of mine has offered me his mig to use, and his is a lot bigger than mine, his is a 250 (not certain on brand Lincon?), so now I have two machines at my disposal. I am going to look into a universal spool gun around the 300amp range and then I can utilise it on both machines.
That is very interesting about the heat when welding both sides of a plate, I was going to do that everywhere I could, So correct me if I'm wrong I should weld one side say 4-5" of weld then immediately do the other side, then vice versa.
Before I even attempt to weld any part of the vessel, I was planning on doing lots of practice on scrap, I want also to make some racking for my truck, This should give me a feel for things.
I have plenty of time and in no rush to finish.
Thanks
Katoh

Katoh; One thing that I have found over my years of building, money spent on tools is not wasted.
When I build my 34' steel sailboat I bought a new Beta Mig 250 mig welder for around $1800 ( no spool gun as I was using it on steel ) I used it and kept it for 6 years (covered with clear "shelf plastic") and sold it for $1500 cash to a metal shop I dealt with. It's still in daily use 14 years later.
I bought a Milwaukee HD nibbler for $1100 ( a beautifull tool that allowed me to make cuts to panels on the boat and get perfect weld fits ) and sold it 6 years later for $800.
So this is something to keep in mind. You're really "renting " a good tool at an excellent rate and making your job and the project better and easier.
Doug

You will not have to swap sides that often. If I was welding a long panel in your situation I would weld for 5mins on one side then do the other if that is possible. Just don't let it cool down to the air temp. Yo will be amazed at much better it weld if the metal is even 125-150 degrees compared to just "room temp".

As for the mig gun, just remember you will get what you pay for. This is from someone who bleeds Lincoln red too, there is not a better spool gun on the market than the Miller XR series gun. Even the prior generation model, I think it was the spoolamatic 1 & 3 series are better than anything else. CObra is also now in the spool gun business and they don't build any junk. If you go with generiac type guns just make sure of the availability of tips, nozzles, etc... and don't get one there is not a good source of parts for.

Good Luck and keep posting about your progress.

G'Day Slug
I know what you mean, you cant loose with good tools , you always get your money back. My problem here when I buy something I'm always reluctant to sell it, Its hard to explain but I'm not the sort of person who can buy something use it and sell it after, its stupid but I tend to get attached to things and have difficulty parting with them. I must of got this of my father whose the same, still drives around in his 1964 truck he bought new back then, still uses his carpentry tools that Noah gave him as boy. Just reading this it really sounds like a psychological problem.
mcmbuilder
Again invaluable advise, I have seen a few spoolmatics on Ebay, I will keep my eyes open.
Just going back to welding both sides, could you not preheat the opposite side weld with a torch before welding if you did let it cool? Would there be an advantage to preheat all the joints first then weld . I'm not talking about oxy but with a propane torch. I could just leave it in the Aussie sun, guaranteed to get over 100degC.
Cheers
Katoh

Katoh,

I should have written more clearly, yes the MIG I was referring to was not a constant voltage (CV) power supply, often called a welding machine, my reference was to the three general types of wire feed system.

The pistol grip style with a roll of wire mounted to the back and carried on the welder's wrist is called a "one pound gun" for the roll's location and rough size of wire spool- so also called a spool gun. Spool gun/1lb. gun/pistol style gun/whatever we call them are the most cost effective for short term one-off projects because they deliver a reliable wire feed and therefore weld bead with the lowest cost for that reliability.

I agree fully with mcmbuilder doubting you will weld much 4 or 5mm plate with that small a constant voltage power supply. The low value of 180A at the very low duty cycle of 30% means the machine was designed to weld 0.025" steel hard wire on very thin sheet metal. 0.035" wire will weld that thickness but 0.045-0.47" wire is more proportional to those scantlings and will produce better fusion. Your power supply won't burn 0.045"-0.047" aluminum wire.

I also agree a mixed gas will help improve aluminum performance but his final advice is the best; the tools he lists are much more suited to your task.

One final detail- which likely is not important now- the issues I addressed in regards the spool gun connections to the older power supply were not addressed by the hardware you show. The issues are not even approached by the switch shown in the link. If your vendor will come to your site and 'make your gun weld' with his product- then; buy it. IF NOT? well let the buyer beware. I'm willing to wager large volumes of fermented hops beverages they won't come to make their claims good.

I assure you that if you or the vendor believes the issues I raised are addressed (?) then both of you may have an education before you!! If you do find a spool/1lb.gun you should make sure you know the motor voltage, control type (contact or powered switch) and other circuit details or you will pay more for that education than reading someone's post online! The electrical connections aren't the critical issue if both sides of the circuit aren't doing the 'same job'.

Some welding power supplies have wire gun feed motor transformers in them others don't. Some mfg's use one voltage for one purpose others use a different value. Some use DC some AC for control circuits, some have contactors (power relays) with one voltage coil and others have another, if the coil for the contactor uses a voltage from an interposing relay whose coil is in turn powered by the gun's trigger and you connect that contactor coil voltage to the gun's trigger- direct? well, the list goes on.

I've rigged a few dozen brand mixes from Miller to Lincoln using power supplies and wire feeders from different dates of manufacture and just these two have plenty to choose from. Mix in products, power supplies OR wire feeders, from other mfg.s(?) it would be helpful to pay attention to what each circuit does to avoid problems.

Since the materials for a 24' welded hull will cost at least 7-10K$US [min.] depending on design- it seems reasonable to spend enough on the correct tools to join that pile of money so you don't compromise the material investment? Weld integrity is the most critical welded hull factor that you can control, unless you milled the metal and built to your own design? That being true, a more adequately matched power supply with a matching wire delivery system seems minimal investment regardless of that number?

Sorry for making my first reply vague.

After reading the other posts, I think these gentlemen are guiding you in the most effective direction. I happen to be an MK Welding Products fan myself, they make the Cobramatic push-pull, the Python push-pull and several very nice spool guns. In fact I have the same power supply and wire feed as mcmbuilder. I also have the older Cobramatic (three) the new MK Cobramatic SX (mini wire 0.025") and several other MK products; I don't think you can go wrong with their equipment, and neither does Lincoln or Miller as they bought those series of wire feed systems from MK and relabeled them for years.

Regarding preheating alloy prior to welding- there is product designed to help control that exact process it is called a temperature crayon. These sticks of mixed waxes melt at exact temperatures so you can touch the metal being heated with the crayon and know its temperature if you don't have a portable laser based temp probe which are not used more commonly- and are relatively inexpensive. I've used temp. crayons when welding heavier section material in a cool shop before I got the (old) King Cobra that would run 1/16" dia wire.

If you heat (propane is good because you can 'see' the dew or condensate "run off") to 185-200F the fusion heat of even 0.035" wire would be adequate to weld 4-5mm plate, and once you begin welding you're adding quite a lot of temp to the parent metal so unless the shop is quite drafty the boat won't cool enough to 'chill' [curl under without fusion] the top and toe of your bead.

When preheating the focus is not on the joints alone or you could cause some uneven expansion, I'd preheat the entire surface of the boat to be welded. This uniform heat of expansion will mean the temperature differential between the weld zone and the neighboring material is lower and that will translate into less contraction/expansion distortion from seams to hull panels. The temperature gradient or difference in temp is a contributing factor to the rate of transfer of heat, where the entire hull is warmed to 100 F or 125 F the rate of expansion or contraction is less than if the weld zone is 200 F and the panel is 50 F.

Working in Alaska, when we built full time, it was not unusual to put a space heater (diesel open flame blower type) under the hull as prep for the days work to warm the entire hull in order to reduce the HAZ/weld seams to panel heat differential.

cheers,

_________________
Kevin Morin

Good evening Gentlemen
Its been a while, but I have taken on board the advise of all and have purchased parts and equipment. Firstly i purchased a spool gun from from NZ, a 250amp spool gun users miller parts but has a duty cycle of 60% at 200amps, secondly I purchased the big brother of my original mig a transmig 275. looks identical to my machine but is a 415v mig with a 40% duty at 240amps, suits me as the feed roller and torch had problem's but i removed them as I am using the spool gun. I also fixed up my original Mig to use the gun as well and have been practising with that on some 1/8" scrap materiel which is giving me some very positive results, as well as giving me some practice. I will practice some more and then make some racking for my truck then look at maybe starting to weld the boat.
One last thing I will ask is what size wire do you recommend to use, I am having lots of conflicting reports to what dia is best. I have spoken to one boat builder/welder who advises to use 0.035" and nothing else and stated do not go larger, others recommended 0.04", others say if you can apply it smaller the better use 0.03". I have read smaller more penetration, but not really certain which is best, and want to go buying all different dias and sit there with testing, be good experience but I can get the same information from those with the experience.
Thanks to All
Cheers
Katoh

Katoh glad to hear your project is progressing.

For aluminum sheet 0.060" up to 0.100" thick, use 0.025" or 0.030" wire diameter. You can get 0.035" wire down that thin but it is more work and less in proportion. From 0.125" to 0.187" thick material 0.035" wire will work fine but many experienced welders prefer 0.045" wire diameter for this size material in order to get higher travel speeds.

I'd say, starting out, 0.035" wire for 1/8" to 3/16" plate was good practice. From 0.187" (3/16") and up use 0.045" wire and if you want to single pass 3/8" or heavier I'd move up to 1/16" wire but that will take another wire feeder and power supply.

Hull seams on a welded boat are longer and more continuous welds than a truck rack frame, I'd prefer to use TIG for short bar or angle or square stock frame assemblies the MIG starts and stops make those very short welds more effort, one solution is to use 'run-on' and -'run-off' blocks so the welds initiate and terminate off the frame's narrow material.

Cheers,

_________________
Kevin Morin

Hi Kevin
Thanks again very valuable information, I don't have a tig or have access to one, I thought the truck racks would just be more practise for, and there for my truck to be removed and used when carrying long lengths so they don't need to look real pretty.
One last thing Ill ask concerning wire size, is tip size. I received a lot of .031" and .039" tips and nothing else, can I drill some of them to .05 to use the larger .045 wire?
Thanks
Katoh

If the spool gun is a miller type gun then it has the long contact tips. Do not try and drill those out. They have a slight bend to them to ensure a constant current pickup. If you are successful in drilling them the point at where your wire picks up the current may move and inch or more during a weld which will result in tremendous amperage flucuations.
Not sure about down under but a package of 5 .045 tips will cost less than $10 here in the states.

Glad to see you upgraded the machine, you will not regret that. I agree with Kevin about welding the short runs on angles or tubing. With aluminum mig it will usually take 1/2" for the weld to get hot enough to start fusing in.