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Welding SteelChoosing a Welder for Your ShopIf your looking to buy a welder for your shop, do not ask a welder! Ask an average guy that has tried both and consider your application.
Choosing the welder is all about what and where you will be welding. We are building a 74 foot boat from 1/4 inch steel for the hull and 3/16" aluminum for the pilot house and 1/4" aluminum for the tender. We started out with a used Hobart 210 Ironman with a Spoolmate 185 gun for aluminum and both have served us well for years. The Spoolmate will be pressed beyond it's limits to weld 1/4 aluminum so if we can get a system that will do aluminum too then all the better. We could get a better spool gun but another solution is a wire feeder with a push-pull gun. Push-pull guns have drive motors and feed wheels in the gun, just like a spool gun, but instead of a 1 pound spool of wire on the gun they help pull wire that is being pushed from the wire feeder. On a Boat and In the WaterFor us the welder will go on the boat as part of the shop, so we want something that is easy to move, power efficient and will run of a single phase 220 volt AC generator. The more expensive Inverter type welders fit the bill for light weight and power efficient and they also DC which is nice because underwater welding is in our future too. Inverters also output constant voltage or CV so they can power most any wire feeder. Getting a welder with circuit board that is potted or can be potted to protect it from salt water damage is a good idea too. Duty CycleDuty cycle correlates to how long you can weld in a 10 minute interval before the welder or gun get too hot. A 60% duty cycle at 200 amps, means you can weld for 6 minutes at 200 amps and then you need to let it cool down for the next 4 minutes. To weld 1/4 steel requires 290 amps, DC, running .045 gas shielded, flux core wire. We want 100% duty cycle . Because engineers exaggerate, the marketing department exaggerates more, and neither work outside in the summer in Oklahoma. Portability - Stick is Best
Putting a 74 foot boat together requires a lot of moving around for simple tack welds and while stick welding is a slower than wire welding, it is very easy to just drag one cable around. We ended up with a used Lincoln Invertec V300-Pro, inverter type welder for $1500, it's a lot more than you need if you just want to stick weld. You can in a pinch an old 150 amp alternator tuned by a 5 HP gas engine or electric motor will get you by, or you can step up to a brand new 120 amp arc welder from Harbor Frieght for $120. You'll just need some 1/0 cable to get the ground connected and get the stinger were you need to reach. But stick will definitely be the most portable.
A Suitcase makes MIG welding portable and it's faster than StickOnce things are held together with some stick tack welds and you want to weld faster and cleaner then nothing beats a MIG suitecase wire feeder. I simply love our Miller X-Treme 12VS wire feeder. It takes a 44 pound spool of wire so there is no stopping to change a stick every 2 inches, it has never bird nested the .045 wire, it has a 400 amp Profax gun with a 15 foot umbilical so I can reach everything in a 25 feet diameter before I need to move the feeder, and when I do move the feeder it's tough enough that I can drag it but only 80 pounds with a full spool of wire so not horrible to carry. It gets the power for the wire feed motor by drawing it off the power cable, so the only thing connecting to the suitcase is the 1/0 cable from the Lincoln Invertec and a 1/4" air hose that connects back to a CO2 gas bottle. Both the Lincoln Invertec and the CO2 gas bottle stay over 100 feet away. We have selected wire that is both flux core and shielded with CO2 gas for best quality, but you could also run flux core only wire and eliminate the gas hose. But you pay for the advantage. We purchased our Miller X-Treme from Red-D-Arc. They rent welders, but they will sell them too and prorate the price bases on the number of hours on the specific unit. So my best welder is the most beat up looking thing you've ever seen and it cost us $1300 with the ProFax 400 amp air cool gun with the 15 foot whip. Think twice about getting athe 20 foot umbilical between the gun and the feeder, especially if you might use a wire that is less than .045 inch. If your sold on a Miller X-Treme then be aware that they make a smaller, lighter and cheaper 8VS unit, but it does not take the larger 44 pound spools of wire and the smaller spools for some wire types can be twice the cost per pound so you can end up spending a lot more money than you saved on the feeder. There are a number of portable suitcase type wire feeders, but
the Miller in our opinion is the best:
Portable? No! - But a Good Shop Floor WelderThe least portable welder you can get is a something like our Hobart Ironman 210 MIG wire welder. We can move it out of the shop too, but we need a very heavy 100 foot long 220 volt extension cord, plus the CO2 gas hose, plus a 110 extension cord to run the water cooler for the Spoolmate gun if we are welding Aluminum. The wheels are only good on paved surfaces and it weighs well over 180 pounds with a full spool of wire. It's a durable welder and only cost us $600 used, but it stays in the shop and normally has smaller .023 wire for small part fabrication. sed flux-core wire can be moved in to perform the finish welding. A suitcase wire feeder is can be powered off the stick welder box. We will set the Inverter power supply out of the way and carry around the 80 pound wire feeder on the end of a 100 foot long power cord that runs back to the Inverter. From the wire feeder box to the gun is another 15 to 50 foot set of cables including; power, the welding wire, control wires for telling the wire feeder when to start pushing and how fast, a hose for shielding gas if required, and possibly a couple of water hoses if the gun is water cooled.
Rebuilding a Cobramatic Water Cooled Push-Pull feeder.Three cheers for the support people at Cobra welders; www.mkprod.com, for finding the original documentation for this welder. Documentation: Cobramatic Manual, Gun Consumables The gun also came with liners for aluminum wire even though they were using it with steel wire. Which is a on the Do Not Do List, because steel wire wears through the aluminum wire liner and shorts. This has happened with my gun. You'll know it because the nozzle will have power too, not just the wire tip. The folks at www.mkprod.com will help you find the right part numbers for your gun and you can order them through AirGas and other supply houses. Part Nubers for our older Cobra Gold gun are: (1) Carefully heat the case around the gun and it can be bent back into shape. Then coat it with epoxy to patch up the holes and fill in the gaps. Heat form an acrylic view port to cover the rollers, warp it up with electric tape and it's looking good on the outside. Inside required some solder and epoxy to add a new water connection port. Originally one water line was inside the power cable which is a cleaver idea for keeping the power cable cool. Unfortunately that power cable had been replace with a standard cable, so I cut and soldered on copper tube to give the head two hose connections. The orange hose is 1/4 inch air line that will now deliver and return the coolant. (2) The feeder got two new switches soldered onto the control board and a third switch added so I can power the coolant pump on and off. You can also wire the pump into a 110 AC circuit that is live while the gun is running, but I wanted to give it more time to cool after the gun is switched off. (3) The two water coolant lines now pass through the box and to an aluminum coolant tank. There is a small garden fountain pump in the bottom of the tank. An acrylic cover let you see the coolant level and seal the tank. A plug is treaded into the top to allow for coolant to be added easily. (4) Using vinyl and Velcro salvaged from our school bus, Kay
sewed up a really nice cable cover. See:
Canvas Work for more. Hot Slag Warning
You have to balance the amount of protective clothing against the chance of passing out on a hot day. My brother Pat dropped in to celebrate July 4th. He picked up the welder and put together some beams to support our shade over the build site and demonstrated how quickly you can pick up on wire welding. He also demonstrated what happens if a chunk of hot slag gets inside your shoe. Most of the time you just get a little weld splatter that stings and quickly cools off. The problem is that can't tell the difference between a little weld splatter and a big chunk of molten slag until it is too late. His solution was to stand a piece of cardboard on the ground and lean it up against his legs to deflect the incendiary devices. Boot work too, but who wants to wear boots in July in Oklahoma. I prefer sandals because the slag is easily shaken off. : ) Lincoln Invertec V300 TipsCV FCAW This setting has been optimized for Innershield and
Outershield flux-cored. ARC or Stick Welding - Stick SelectionWe don't plan on doing much stick welding while building the
boat. It will only be used when a few short welds are needed
and it's not worth moving the wire feeder. We'll have 6011 rod
for welding in the flat down positions, 6013 for general
all-position welding and maybe some 7014 for thin materials and poor
fit materials. Wire or MIG Welding - Wire SelectionLets start with the fact that a Wire Feed Welding machine can be
used with 3 kinds of wire.
The most common type used on small to medium sized machines indoors
is solid steel wire, usually ER70S-6.
This wire requires a gas shield, which can be pure CO2, or a
Argon/CO2 mix.
Solid wire means you are MIG welding.
MIG rules the light gauge fabrication world.
Light gauge is steel under 1/4" thick. For sheet
metal work a good starting point is
.023” The wires that use a gas shield can be used with pure CO2 or
Argon/CO2 mixes.
Pure CO2 is very hot and very cheap, but it does make a lot of
spatter, which makes for a lot of clean up afterwards
Argon added to CO2 makes the arc smoother and cleaner. Innershield - Lincoln's brand name for flux core wire. It
needs no shielding gas in moderate wind. Gas SelectionMIG welding can be done with both mix gas, which is a mixture of CO2 and Argon, normally 75% CO2 and 25% Argon and sometimes 80/20 or you can use CO2 only which will save you some money. CO2 only requires that you short weld instead of spray weld, it welds a little cooler so you'll need to turn the power up and you will get a larger heat effected zone. My 150 cubic foot tank cost $55.50 to fill with 75/25 which is about 37 cents per cubic foot. I traded that in for a 50 pound CO2 cylinder, about twice the size, and the refill cost is $60.55, but 1 pound of liquid CO2 will expand to just over 8 cubic feet of gas, so my 50 pound cylinder has 50 x 8 = 400 cubic feet of gas which comes to 15.1 cents per cubic foot, or less than half the cost. And if we turn the cylinder upside down, it makes a great fire extinguisher for the engine room, and can make fizzy mixed drinks. :) Our Choice for Welding the HullWe tested 1/16" Lincoln Innershield NR233 and .045" Lincoln Outershield 71M. Both are flux core, but the Outershield 71M also uses 100% CO2 shielding gas. We actually buy Frontiarc 711 which is a knock off of Lincoln Outershield 71M
Innershield NR233
Recommendations for .045 are 175 to 200 amps at 375 to 400 ipm for flat and 150 to 175 amps at 300 to 325 ipm for vertical. We tested at 245 amps and 350 ipm in flat down. Shielding gas is 100% CO2 at 40-50 CFH. Lead is DC+
Working to Limit Weld Distortion
Resources: Job knowledge for welders - Distortion - Prevention by pre-setting, pre-bending or use of restraint
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ProFax Parts for 400 Amp gun on Miller V12
Tweco
24A62 Nozzle $2.47
Resources
www.weldingtipsandtricks.com
http://groups.yahoo.com/group/welding_group