Adding a Spool Gun to a Mig Welder for Welding Aluminum

In this video I show how I installed a spool gun for welding aluminum on my Yes Welder Mig-250 Pro, my first test welds with it, and cutting/acid etching the welds to check penetration. This wiring diagram can also be applied to some other kinds of Mig welders as well, the important thing is that the feed motor and spool gun motor are the same voltage. Mine are 24 volts. I hope this video/instructable helps you, if it does please like, comment, or subscribe. If you would like to purchase this welder or a different one use the coupon code "MattTheMaker" for a 10 percent discount at YesWelder's website or click the link and the savings should be automatically added to your cart. https://yeswelder.com/discount/MattTheMaker

Thanks!

Materials You Will Need:

• Wire crimp connectors
• Red and black primary wire
• A sturdy connector for two wires to plug into each other (I used a old RC car battery connector)
• A Spool gun that matches the existing welding lead connector (Euro Style in my case)
• Tesa Loom Tape if your'e a cool guy, otherwise electrical tape will do
• A six pin rocker switch
• Solder stuff is optional, I soldered my primary wire to the rocker switch pins since I didn't have the right size connectors and couldn't wait
• Argon tank for welding aluminum: While this will work on a lot of different welders the shielding gas used for steel welding will not work. I am using my Tig welding bottle which is 100 percent argon.
• 1 or 2 hours of time

Tools You Will Need:

• Wire crimper/stripper/cutter
• Drill
• Drill bits sized to make a hole that fits your switch
• Metal Deburring tool (Optional but recommended)
• Phillips screw driver or 7mm nut driver for unscrewing the case
• Marker or pencil

First you will need to take the outer cover off of your welder and inspect the motor to check the voltage.

• Mine was fastened on with two phillips screws to hold the handle on and several screws with phillips/7mm hex head around the left and right sides.

• The case nests into the front housing, wiggle it back then up and out. Don't force it, check for a overlooked screw if it doesn't come out easy

• Inspect your drive feed motor to check its voltage. Mine was 24 volts so I ordered a 24 volt spool gun.

• I was a little concerned since the multimeter read under 12 volts when I tested the leads going to motor and was feeding wire at the fastest speed but it works fine.

• The motherboard that powers the drive feed motor is separate from the board that powers the welding current, I'm told this is a good thing to look for when looking at mig welder internals. Im not so sure of the advantages other than making repairing easier to swap boards but I could see where it would provide more consistent feed than if it was on the same board with lots of intense power spikes.

• Make a harness with a rocker switch that has 6 leads. Two are for input and 4 are for output, two outputs are activated with each position. I added the following things to my harness to make life easier.
  • Blue electrical connectors. I added these because I needed a way to connect the wired inside the welder to the switch. I didn't have the right connectors for the tabs on my switch and had to solder the wires directly, I didn't want to chance soldering the switch in position and get splatter on the mother boards.
  • A old RC car battery connector. This will be how I connect the two extra wires coming out of the spool gun lead to my welder. There are better connectors out there I'm sure and I could have used the blue connectors but this is a little stronger.

• Cut the black and red wires that feed the DC feed motor. Make sure you leave enough room to trim the insulation and add connectors.
  • The lines you just cut that connect to the motherboard are your inputs for the new rocker switch.
  • Connect the wires coming off the motor to one side of the rocker switches outputs.
  • Connect the wires that lead to the spool gun switch to the remaining outputs on the rocker switch.

• I ran a bench test with the cover off to make sure my wiring was correct and that it would work before I drilled a hole into my welder.

• With 3 red and 3 black wires it may be helpful to label your wires with tape. I like to use multiple colors of making tap, that way I never need to use a pen.

• There are two extra wires that should be sticking out of your welding lead end, these go to the switch in the spool gun. I connected the other side of the RC car plug end to these wires.

• Normally these wires run out the backend of the plastic tube on the end of the lead. I cut a hole so they could come out the front and reduce the chance of them getting pulled/damaged. This was not the best since my extra wiring caused the plastic tube to sit cocked. It doesn't affect functionality and I may clean it up later.

• I have a Euro style welding plug on my machine so I ordered that kind of spool gun. There are other types of plugs to connect to the welding machines so get the right one for you.

• I drilled a hole in the side of the cover for my switch to fit
  • Choose your hole location carefully so there are no clearance issues once the switch is installed.
  • Deburring the hole since it is a good habit to get into to reduce injuries, plus it will be less likely to damage the wires on install.

• Carefully feed the wires/switch through the hole and screw the switch in place with the large plastic nut they come with.

• I fed my spool gun switch connector through the front of the grill and connected the wires according to how I had them when I did the wiring test.

• Replacing the cover is the same as it was removed.
  • At first I used less than half the screws because I was so excited to try and weld with it. Don't worry I got around to it and didn't loose one.

I ran some welding test on some scrap that I had laying around. Ive owned a tig welder for 5 years but just got this setup and I haven't really mig welded since trade school. For the first session on the new rig I was pleasantly surprised. During the testing I remembered that by adding a spool gun I was adding two aluminum welding processes, short circuit transfer and spray transfer.

Short Circuit: It is what it sounds like, a controlled short circuit where the wire is melted as its fed into the grounded object. By coming into contact with the grounded object the filler wire completes the circuit and "shorts out".

• The fourth picture shows my best short circuit weld on the 1/16 inch wall thick tubing. I couldn't get spray transfer to work without blowing out the thin walled tubing.

Spray Transfer: This is when the wire that is being fed melts mid air and the flow of the current pulls it into the puddle. This is something I never used till now but it rules. The voltage needs to be cranked up for it to melt mid air and your wire stick out is much farther than short circuit.

• The last picture shows the best looking spray transfer weld I got.

Shielding Gas: I am using 100 percent argon for these welds, a normal bottle of mig shielding gas for steel will not work.

• I cut the welds with my mini horizontal bandsaw. It folds out from under the table and is a real treat to use (Maybe I'll do a instructable on that or do a shop tour sometime).

• I put rust cleaner on the welds to etch them then doused them in baking soda and washed well. I think you could use a safer acid like vinegar and have it on there for longer. If anyone knows let me know, I'll eventually end up trying it.
  • The darker grey area on the cut surface was revealed by the etching. This dark grey nugget shows us the weld penetration.

• The second picture is my best looking weld from the outside but the test says otherwise. The inner most two welds in the next picture were the ones that looked so good. It was on 1/8 wall 1x1 square tubing.
  • You can see there is some holes in the nugget that are porosity likely caused from not cleaning the aluminum or my torch angle being wrong so the shielding gas didn't keep out the contaminants.

• The fourth and fifth pictures show my 1/4 fillet test.The weld wasn't nearly as pretty but the aluminum was cleaner.
  • Cutting in some cherry picked spots revealed a nice nugget!

• I have a lot to learn technique wise but but I think this machine can handle 1/4 inch aluminum in a single pass.

This modification went far better than I could have expected. I got to get better at using it but I know the gear is capable. This is basically the only way I could see myself having a 250 amp mig setup for aluminum and steel that was in the budget. I am at less than 500 dollars for the whole rig.

• Welder: 400 on sale
• Spool gun: 86 off ebay
• Switches, wires, connectors: Already had but that cost is trivial compared to the rest.

I hope this helps someone upgrade there workshop! Please like, comment and subscribe! If you would like to purchase this welder or a different one use the coupon code "MattTheMaker" for a 10 percent discount at YesWelder's website or click the link and the savings should be automatically added to your cart. https://yeswelder.com/discount/MattTheMaker