Suitcase Welder

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I know, I know, it's not exactly a Miller but what the hey. It's "ho-made".  I'd say it's better than a Chinese welder but every part in a Microwave Oven says "Made in China". It's putting out 42 volts, a little better than I hoped for. I don't have a way to measure the amps.   Started with 6013 1/16th rods because I figured that would be about all it would do but it burns 'em right up so I'm going to try 3/32 today. The weld pic is it's first run and the first stick weld my son has ever done. We'll get better at it. Main thing is we had fun doing this and it cost just about nothing thanks to our throw away society. Thanks for the idea Llamafur. Attached Images
Reply:He-he, that's VERY KEWL! I'm glad to see the magnetron tube is not around. You wouldn't last long yourself if it was. Maybe you should add a statement like, "Do not try this at home, we are professionals." SteveLast edited by rookie_steve; 05-21-2009 at 09:23 AM.JunkYard Tools .com
Reply:Ha ha ha... I'd like to see that get passed airport security as a carry-on! That's a good one!Congratulations on your build, thanks for posting it.Good Luck
Reply:"Yes, Officer, I weld for a living.  No, all those wires and transformers in my suitcase are NOT a bomb - it's my welding machine.  Why do I have to come along with you? .......... Could you get this dog to stop sniffing at my crotch?"Great work.  Llamafur, your Instructables homemade welder strikes again!
Reply:nice job
Reply:thats cooool,  bout how much does it weigh?
Reply:Tried 3/32 rods with the suitcase this afternoon and I think I found it's sweet spot. The 1/16 were just too small. But now on to the next problem. The damn thing really lays down a nice bead.Someone gave me one of those Matco made in Italy mig only welders some time ago. The gun is no good and the plastic drive mechanism is broken. It's not worth repairing. On the other hand it has a transformer about five times bigger than a microwave. I'm thinking this might make a pretty good DC stick welder. If it is DC. I guess that's my first question.My little Miller Sidekick Mig is DC so I assume this one would be too.Looking at it, it seems that if I disconnect the mig electrical parts what I'm left with is an on/off switch, a four position tap and a transformer. Nothing much else in there. I thought about just connecting my electrode holder and ground clamp to the secondary winding and go. That's about all that is involved with the suitcase deal.  I'm a little reluctant though  because I don't want to tear up the transformer. I figure you guys will know if this welder is DC or not, and if I'm just being stupid.  I know you can buy a tombstone AC cheap enough but this is good father and son stuff. Feel free to make fun of me.
Reply:Wonderful, 42 volts is also great too. whats going to be your first project?
Reply:Thanks Llamafur. We don't have a thing to do with it right now. Something will come up though. What do you think about the Matco transformer idea? I read on the Instructibles page that there was nothing wrong with using a bigger transformer if you had one.
Reply:the output from the transformer is AC, it gets rectified to DC by a full wave bridge then smoothed out by a big capacitor.
Reply:Originally Posted by hvwI'm thinking this might make a pretty good DC stick welder. If it is DC. I guess that's my first question.My little Miller Sidekick Mig is DC so I assume this one would be too.
Reply:lets see some pic of the weld with the 3/32 rod
Reply:Originally Posted by rookie_steveI haven't seen a schematic but.... it sounds to me that you are tapped into the secondary of the transformer, meaning that it is an AC welder. If you add some diodes and capacitors from the transformer secondary winding before going to the electrode then you would likely have a DC welder. And again, nice project. Steve
Reply:Most MIG process I'm aware of is DC.   There may very well be a rectifyer in the little MIG case.    Lots of the self shielding MIG wire run DC- as opposed to DC+.    Doesn't matter for a DC stick machine just wire out to a couple lugs so you can switch the work & stinger leads around for either.Be really nice if you can incorporate the amperage adjustment in the works.If the Matco will still fire up really all you should need to do is connect a stinger to where the mig gun hooked up.  Jumper the MIG gun trigger wires together inside the case & go welding.  You might also want to unhook, remove entirely, to lighten the unit, the feed motor.IF IT WORKS, DON'T FIX IT2 Lincoln CV-300 / LN-7 GMALinde-VI 253,400 & 450 w/MIG35 feedersCNC Table with Oxweld O/A & Hypertherm 1250G3Lincoln Ranger GXT 250Hobart-MicroWire 300ESAB Heliarc 161ESAB-Mobilemaster 2 CC/CV Feeders& more
Reply:This is a photo of the Matco. I've removed the mig gun and wire feed control. The windings on this machine are aluminum rather than copper like the suitcase. Even though the Matco transformer is much larger it gets much hotter. Suitcase really doesn't heat up.The welds in pic 2 are from the suitcase. I'd like to make the Matco a DC if it isn't already since I really don't need two homemade AC welders. We undid the two large secondary wires and wired the stinger and ground directly to them. I don't know if the gizmo they're attached to in the photo is some kind of DC deal or not. I guarantee you everyone on this board knows more about welding than me so any thoughts will be appreciated. Attached Images
Reply:Originally Posted by llamafurhere is a rectifier, it just needs a capacitor across the dc output.
Reply:Originally Posted by hvwWe undid the two large secondary wires and wired the stinger and ground directly to them. I don't know if the gizmo they're attached to in the photo is some kind of DC deal or not. I guarantee you everyone on this board knows more about welding than me so any thoughts will be appreciated.
Reply:Yikes! All that is probably going to mean it'll just stay AC. Way beyond my grasp.
Reply:Those aluminum plates sure look like heat sinks for diodes. post a picture showing the stuff bolted to the plates better-- fredLincoln 180C MIG
Reply:MIG is DC, so somewhere 'downstream' of the transformer in the Matco should be the rectifier part of the machine.I'll guess that the rectifier (diodes) are probably on the large flat aluminum plates above the air vent in your picture.But unless you rewind the Matco transformer, the output voltage is probably going to be too low for stick welding.  Also, please be safe with all the experimenting and such.  Your totally open machine does have potentially lethal electrical levels out in the open there, and having a cloth suitcase next to a sparking/spattering stick weld is possibly a way to have a flaming suitcase.  There's a reason why welding machines are typically made with metal cases.  It protects the machine and the user.Have fun, but be safe.  The best laid schemes ... Gang oft agley ...
Reply:Originally Posted by MoonRiseI'll guess that the rectifier (diodes) are probably on the large flat aluminum plates above the air vent in your picture.
Reply:what about caps for a stereo system? they are big and handle lots of current.  Don't know on the voltage though 20-24v or higher maybe?  I guess I don't know what voltage is needed for stick.
Reply:I love it!"Do you have a suitcase welder I can borrow?""Of course, here!"  *hands over suitcase*"The hell?!"
Reply:THATIS........SPARTAAAAAAAHHHH
Reply:That is a nice little suitcase you built... The Matco has a full wave bridge rectifier mounted on the back and has an induction coil on top of the transformer. This is common in the cheaper mig welders and stick welders. The induction coil acts as an arc stabilizer and there are no smoothing caps. These work very well in my opinion if you can't find any capacitors which can cost as much as a cheap welder! You can use the Matco as a stick welder with no problem with just the bridge rectifier and induction coil, they work just fine. The caps defiantly help but are not necessary for a decent stable DC arc. The cap or caps would have to be either one 47,000 mfd 50v or more, or a bank of 2, 3 or 4 making up the same value in parallel.Last edited by J0K3R-X; 05-22-2009 at 09:31 PM.Lincoln 3200HD MIGMiller Thunderbolt XL 225/150 AC/DC Old Craftsman 35-230 ARC modified with DC RectifierHarbor Freight 80amp InverterHarbor Freight Easy MIG 100 ModifiedA couple MOT ARC weldersHHO Torch in progressThanks JOK. I think you nailed the Matco set up. The aluminum plates include several diodes adn the secondary winding has the attachment you described. I think you can see them in the photo. It now looks like we would connect our two leads to the secondary winding where it bolts to the aluminum plate. My concern is that Moonrise is correct in saying that this little welder just won't produce enough power to be worth fooling with. It doesn't put out near the voltage the suitcase did. I know this Matco is not a Miller or Lincoln but Jeez is it cheaply built. Plastic everywhere. And I'll bet someone paid a fortune for it off a Matco truck because of the financing. It's the same as Snap-on's Blue point welder.Meanwhile, we suffered a significant setback with the suitcase welder when my wife realized it was mounted in her deceased mother's suitcase. WTF? We had to give it back. You'd think I was cleaning engine parts in the dishwasher or something. Anyway it's now mounted on the Matco's former welding cart.  The donor microwave in the background is on its way back to the dump today, its job being done. Attached Images
Reply:man that thing is WAY too cool! like the brady bunch suitcase. i bought a few from that era at a garage sale a few years ago. very slick man. wanna sell it? lol
Reply:re: voltage levelsCommon small MIG machine running GMAW (solid wire and gas) in short circuit transfer mode or small FCAW-S wire (Innershield NR211-MP or similar) will have a voltage typically less than 20V at welding current.Stick weld will have a voltage closer to 30V at welding current.The MIG machine's transformer just isn't made or designed for the same voltage level that a stick needs.And please put some sheet metal over the top of the 'machine'.  The best laid schemes ... Gang oft agley ...
Reply:Yeah, I suspected that. The label on the back is very sparse. It says:O.C.V. (Min - Max)  20-30  ( I don't know what O.C.V. means)Under that it says:[email protected]   110A@17VHolding the multimeter leads to the ends of the secondary winding we measured voltage at the four tap settings as follows, beginning with lowest:1. 25V2. 28V3. 32V4. 35V I'll be putting a metal housing around the suitcase. It is a work in progress. Had a pretty good one that was taken away!
Reply:Get one of those steel-lined Samsonites.  You could drop a truck on one of those ......
Reply:O.C.V. = Open Circuit Voltage, which is the voltage that is there when NOT welding (the circuit is open, ie no complete connection).Once the welding circuit is complete (ie you are actually welding and have an arc going), the voltage is lower than the previous OCV.How much lower?  It depends on the machine, but a small MIG machine might have an OCV of 30-33 volts and the actual voltage while welding would be more like 15-18 volts (short circuit transfer, spray transfer has a higher voltage but the typical small MIG can't get the voltage high enough while welding to get into spray transfer mode).A stick machine might have an OCV of 80 volts (which is enough to shock you pretty well!) and a voltage while welding of about 30 volts.  The best laid schemes ... Gang oft agley ...