This is very much a work in progress.

Tools needed:

• One (1) 1/8“ wrench (open-end) (Available in the maint cart)
• Two (2) 1/2” wrenches for work on the MIG gun

Always have two people to change out cylinders; it's useful to have extra muscle, or a spotter.

Cylinders (both full and empty) are stored against the cages behind the metal lathe.

Cylinders in storage must be secured with a chain or ratchet strap.

Cylinders in storage:

• 100% argon
• MIG Mix (25% CO2, 75% Ar)

Cylinders are labeled with their contents. Make sure you are getting the correct bottle.

Do not move cylinders without a cap on the cylinder, securing the valve.

Close the valve on top of the gas cylinder.

If the indicator dials on the regulator show pressure in the system, we must purge the lines.

With the welder unit powered on:

1. Turn down the wire speed and voltage as far as possible
2. Hold the gun far away from the ground clamp
3. Pull the trigger until the dials register no pressure in the regulator.

Cut off extruded wire, coil the gun tube, and stow the gun.

Note: if you have a large amount of excess wire, put it in the box in the powder coat area. The wire is useful for hanging workpieces while powder coating or curing.

With the cylinder valve closed and the lines purged:

1. Find a cylinder cap. (There should be a cap next to the base of the cylinder, but it may have migrated to another part of the welding area.)
2. Loosen the compression fitting on the regulator. (Use the 1 1/8“ wrench.)
3. Remove the regulator. (Move the regulator and the hose out of the way.)
4. Put the cylinder cap on the cylinder.
5. Undo the chain holding the cylinder to the welder.
6. Lift the cylinder off of the welder and onto the floor.
7. Spin the cylinder to a dolly.
8. Bring the empty cylinder to cylinder storage.
9. Secure the empty cylinder in storage with a chain or a ratchet strap.

1. Transport new cylinder from storage to the MIG Welder.
2. Lift the cylinder onto the cylinder shelf.
3. Secure the cylinder to the welder with the chain.
4. Remove the cylinder cap. (Place the cylinder cap on the shelf at the base of the cylinder.)
5. Attach the regulator. (When hand-tightening the compression fitting, keep the regulator supported.)
6. Tighten the compression fitting with the 1 1/8” wrench. (DO NOT OVER TIGHTEN. Use the wrench to tighten the fitting about a quarter turn past finger-tight.)
7. Spray soapy water on the fittings.
8. Open the cylinder valve fully to charge the cylinder. (Use the gray valve handle; it will indicate for the next user that the valve is turned open: red is open, gray is closed.)
9. Inspect the fittings for any leaks. (The soapy water will noticeably bubble in the presence of leaks.)

TODO: add/film a demonstration of soapy water showing a leak?

If you are changing out a spool that still has wire on it, make sure to keep tension on the wire at all times so that the wire does not spool out and birds nest. Hold the wire end firmly, or use a piece of tape to keep the spool from loosening.

1. Secure the end of any wire left on the spool.
2. Flip the black lever knob down to take pressure off the rollers.
3. Flip the upper roller assembly up to get access to the wire track.
4. Pull any remaining wire our of the roller assembly and gun tube.
5. Take off wire spool cap.
6. Remove old wire spool.

Install the new spool in the welder on the spindle.

Replace spindle cap to secure the spool in place.

Check the wire size. We usually use 30 thou wire (30/1000 of an inch). The guide rollers installed in the MIG welder are sized for 30 thou wire. If you are swapping out to a different gauge of wire, you may need to change the roller guides for best results.

1. Detach new wire end from spool (maintain tension!)
2. Feed wire end through collar in roller assembly.
3. Feed wire over lower roller guide.
4. Check the wire's progress through the eyelet in the roller assembly.
5. Lower upper roller assembly.
6. Pull lever knob up to lock the roller assembly.
7. Straighten the gun hose as much as possible.
8. Turn on welder.
9. Pull gun trigger to feed wire down the length of the hose.

Turn the lever knob to adjust pressure on the wire in the roller assmebly.

1. Secure the end of any wire left on the spool.
2. Flip the black lever knob down to take pressure off the rollers.
3. Flip the upper roller assembly up to get access to the wire track.
4. Undo the gun tube thumbscrew (store it in the threaded hole next to the the gun tube thumbscrew hole)
5. Pull the gun tube (friction fit only)
6. Pull any remaining wire our of the roller assembly and gun tube.
7. Replace gun tube in welder.
8. Secure the gun tube with the thumbscrew (thumbscrew should mate through to the copper ring in the gun rube)
9. Feed new wire through the rollers and up the gun tube.

Before servicing the MIG gun, unplug the welder.

1. Loosen the lower locking ring a quarter turn, and then pull it downward off the gun onto the hose.
2. Loosen the upper locking ring a quarter turn, and then pull it upward off of the gun and over the nozzle. Put the upper locking right in a safe place.
3. Gently pry apart the halves of the gun casing (friction fit).

Inspect the copper stranded cable at the base of the gun for any damage.

Use two 1/2“ wrenches to loosen the brass sheath assembly.

1. Gently but firmly press the halves of the gun casing together (friction fit)
   • Make sure the trigger is properly fitted to the casing.
   • Make sure the trigger is correctly oriented with the nozzle.
2. Slide the lower locking ring up the hose, line up the tabs and slots, pull the ring up onto the gun casing and tighten a quarter turn.
3. Slide the upper locking ring down over the nozzle, line up the tabs and slots, push the ring down onto the gun casing and tighten a quarter turn.