arc welder/spot welder? Answered

Can an old small arc welder be used to make a spot welder? It's a 60 yr. old Grindl. A stamping on it says input amps 20, sec. amps rated .80- 80, welding volts 20, max open cir volts 80.

Question by hjones47222222   |  last reply


Backpack Welder

Check out this awesome backpack welder; I saw it in a Farm Show magazine.  It would be fun if someone made an Instructable of one of these.

Topic by robbtoberfest   |  last reply


Can a ARC WELDER be converted to a SPOT WELDER?

I have this ARC welder which puts out 50 AMPS, flip the switch gives you 80 AMPS. I would like to spot weld thin metals for a project i am working on, and by all accounts on what iI have seen on the INSTRUCTABLES all I would need is the copper tips attached to the clamp device

Question by yeagerxp   |  last reply


Home made welder?

I have a transfomer that appears to be wound with an aluminum winding. Is  this aluminum and will it be safe to make a welder out of?

Question by DWA   |  last reply


cheapest welder for aluminum?

I need to weld 3/16" sheet aluminum for a boat i'm making and want to do it at the cheapest cost. this welder (http://www.harborfreight.com/90-amp-flux-wire-welder-68887.html) says it won't do aluminum (and i'm not sure 90 amps would be enough anyway). Is that true? What if i bought the 180 amp model? Any suggestions for other welders?

Question by ridecruz88   |  last reply


MOT spot welder?

I want to build an MOT spot welder and ive already cut the wiring out of the transformer but i noticed while doing so i scraped off what seems to be the coloring off the primary.  Will this affect it in any way? Also, i can really tell the power of this transformer? can anyone help?

Question by dask13   |  last reply


Diy Spot Welder

Hello, this is my first post here at Instructables. I will get straight to the point. I plan to build a diy spot welder. However, in most of the diy spot welder projects I have looked at, including Hack a Day and Instructables, a MOT (Microwave Oven Transformer) is used. The secondary is rewound with thicker wire, and the transformer is used to step down voltage and step up current. I have heard that these transformers can supply as much as a kiloamp at very low voltages. However, I do not own a MOT, they are too costly to buy, and I do not want to retrieve one from a microwave because- A) Nobody happens to be throwing away a microwave in my area. B)The guys who own the scrap metal and thrown away appliances will only give me a microwave oven at a hefty price. C)I would prefer to live a very long life, and do not want to gt myself electrocuted poking around the innards of a microwave. SO, I did a thorough search, and found that some people made a welder from a stereo amp transformer. Again, I did not own one, but what I did own was an ultrasound generator that was supposed to drive away rats. After making  bloody inroads into it`s innards, I found a transformer quite a bit larger than the regular step downs. It is 5 cm long, 4 cm wide and 1.7 cm tall.  Input voltage is 220 volt AC from the mains, at 60 hertz. Output is 12 volt AC at a maximum of 300 MA. Speaking from experience would anybody please tell me whether this is suitable for a spot welder? Please ask me for additional information, including pictures, if required. Thank you.

Topic by TheLightningConductor   |  last reply


Will this capacitive discharge welder design work?

I am planning to build a capacitve discharge welder so that I can tab weld my battery packs, and I have no intention of paying 2K plus.  I recently came across a fairly simple design, and was using it to design my own.  If anyone that has built one of these, or knows how to, can look at this design in detail, and inform me if I have the right componants, and in the right order, it would be greatly appreciated  *** Please, I know the dangers and risks to what I plan on building so please do not express your concerns here.  Everything has risks, but without risks their can be no reward.*** UPDATE I added a new diagrahm with the opto-iso and relay that you two recommended, not sure if its right yet, but its a work in progress

Question by supramp   |  last reply


I have a hobby mig welder. How do I fix it ?

I have a hobby mig welder it seems feed wire fine and the gas flow is good but when the arc is struck it sputters as if the power source is low. How do I fix it ?

Question by chs247   |  last reply


Re wiring the secondary transformer I could not give it 20 turns. I ran out of space.? Answered

I am trying to build a welder from microwave transfomers. I started using 10 gage solid wire but I could not fit 20 turns as suggested. If I use the stranded wire will I be able to fit the 20 turns? Do bigger transformers come with larger holes or they are the same size? Any suggestions and/or answers are appreciated.

Question by taino1   |  last reply


Is there a way to convert a generator into a arc welder? Answered

Is there a way to convert a generator into a arc welder?

Question by stevnmilr   |  last reply


has anybody build a stitch welder?

 i want to replace the batteries of my power tool and stitch the batteries together.

Question by rickyt   |  last reply


small hobby resistance/spot welder?

I want to weld small steel wires (the size of guitar strings - +/_ .035) to make small sculptures. Solder works, but is not fast or strong enough. Can I make a welder to run on 115VAC?

Question by Dweevil 


can you turn your wirefeed welder into a plasma cutter.

Can you turn your wirefeed welder into a plasma cutter.  if you replace your gas line with an air line  and connect the cables to the  ,- terminals?

Question by smackit   |  last reply


i have a 6200 (running) watt generator for back up power. how can i make it a welder also?

How do i make my generator a welder?

Question by marknor   |  last reply


one transformer wire that i rap melted, the welder was working fine until this happenned what went wrong?

Welder was working fine then i seen smoke coming from one of the transformers, the insulation melted off the wire that i rapped, what did i do wrong????

Question by boomer75_75   |  last reply


Welding Transformers in series. How close can they get to one another?

Building the microwave transformer welder. Is there a distance that they need to be from one another? One site said they need to be 5" from each other. Some youtube vid said they can't be aligned in the same direction and has to be 90 degrees turned.

Topic by eric m 


how can i but a foot petal a tig wielder that did not come out with one?

The wielder is a chicago weiding system 240 volt ark/tig inverter welder and tig welding torch modal 66787. 10 to 130 amps.as I said it did not come out with pedal is there anyway to wire one in to it?

Question by bikerdad   |  last reply


What is the duty cycle of a welder? Answered

Is a 6% duty cycle good? Bad? Terrible? Worth blowing up?

Question by bowmaster   |  last reply


Modding a cheap MIG welder?

I recently bought a cheap mig gasless mig welder and I was doing some online reading about it. So I found out a mig welder should be DC, with gasless having the clamp at + and the torch at - . However when I looked at the schematic (in the images) and inside the welder to confirm it, and it was AC. So it turned out really cheap welders are ac. So my I want to try mod it to be DC. My question was, what diodes should I use? What Capacitors and capacitance do I need? And how do I design a Choke? I was looking at getting this diode: http://www.ebay.com.au/itm/MBRP400100CT-400A-100V-SBD-Schottky-Barrier-Rectifier-Diode-Module-/160930207205?pt=AU_B_I_Electrical_Test_Equipment&hash;=item25783015e5&_uhb=1  And then putting two of them together to make a full wave bridge. Would a Schotty diode Work? Or do I need a stud diode? And about what capacitance do I need? Would lots of 2200uF 50v capacitors in parallel work? Could I put in a variable ballast? and where would it go, on the 240v side or the output? Lastly, could I also add a modded microwave oven transformer for low voltage high current in parallel to boost the power? I guess I would have to wind it to have a similar voltage. Thanks

Question by makincoolstuff   |  last reply


Making a better spot welder....

I am in the process of building a proper spot welder from scratch. Proper more in terms of the electrical and electronics part but not so much in looks ;) My problem now is to find useful info on what power levels are required for certain tasks. I realise that welding thin sheet metal won't need as much time and amps as welding a 3mm stainless steel rod - but what is a "good" power level? I watched a bunch of Youtube videos showing various approaches but for many it seems the producer had no clue about the difference between creating a short with burn marks and a weld... Especially when it comes to creating battery packs with a capacitor bank as the main power provider you can clearly see the device burns holes but does not really create a welded spot. On the other hand there are a few videos showing spot welder made from a MOT that seem to produce a proper melted and welded connection. When I used a proper spot welder at work it had timing settings, power levels and even a feature to adjust how the current rises.... Not to mention a gauge that checks the pressure and only activates the welder once the set point is reached... There is a ton of info out there that after a thausand words still tells you nothing you need to know :( So is there anyone here who can shed some light on the actual process of spot welding in easy words for everyone to follow? I am aiming for a max output of around 400A @ 1.5 -2.5V with an adjustable shunt in the transformer core to avoid oversaturating the core. In a later stage I will add power control over the primary side but until then it is only time control, from a few ms to a max of 5sec if the damn controller arrives one day. Big questions: 1. Is a power control really required or is it possible to cater from thin to thick just by using different timing settings? 2. Since a MOT is used for the power supply: Is it better to leave the shunts out to fully avoid saturation by adding an inductor in line with the primary or is it still better to adjust the shunts under load to get the maximum power possible? 3. Aluminium and other materials benefit from using AC but would be good to have a DC output too, if so then what materials really need DC? 4. All I could find is that copper is used for the electrodes, due to resistance and heat transfer - are there other options apart from using copper? 5. Tricky one: I would prefer to use the secondary winding as the new primary to avoid core saturation and to lower the load on the power outlet. Where can I find very thin copper bar material that I can coil up and insulate as I would quite a few more turns to get at least 1.5V out of it? Just don't like the idea of spending days rolling a copper bar thin enough.... For the advanced model at a much later stage: Of course I would like to be able to use a proper power control instead of a motor dimmer or similar. For obvious reasons an inverter microwave jumps to mind. But after checking one I noticed one big problem: there are not really that many windings on the primary of the transformer at all! Same way our modern switchmode power supplies only use a few turns these things do exactly the same. After some quick and dirty initial tests I realised that even a single turn of thick wire already results in over 20V on the secondary. Wasted a lot of wire and time making one coil with 5 turns less and one with 10 turns less but the system would not even start with it. Seems these things need a fixed inductivity on the primary that matches the frequency used, in my case 36kHz. Would love to overcome this problem so I can at least go down to a single turn to get under 5V on the output side as space is non existing on these inverters. Can I cheat? Do I need to change the circuit to match the new primary coil? Am I thinking in the wrong direction altogether here? And added bonus would be to be able to adjust the power from around 15% to 100%, so far the electronics don't allow anything below 45%. Is it possible to drive these inverters in resonance? (Ok, off topic as I would like to use this for a beefy HV supply) Last thoughts: I know people already used Arduinos and Raspberries with displays and all but so far I have not found anything that shows how to do it properly. Seems all that counts is to create connection one way or the other and to call it a spot weld even if it is just a burn hole from discharging a capacitor bank through a needle like electrode.... For obvious reasons I don't want to create just another spot welder that makes a professional pee himself laughing about it. IMHO nothing beats personal experience with something but I don't really like wasting my time by trying what other people alread did a long time ago. So if YOU already built a MOT based spot welder and used for more than a few spots I would love to hear from you! Let me know what type you used, what problems or shortcomings you noticed or where you feel it just does not work out the way you expected it. From simple things like always getting bad sparks or arcing, over how easy or hard it is to get consistand results to whatever really annoys you while using your homemade spot welder. I hope that your feedback here will help me to write an Instructable on building a spot welder that does what you expect it to do, not once or twice, but everytime you use it. Mechanics might vary the same way the electrode style does but the weld should always be a proper weld that won't tear apart ;)

Topic by Downunder35m 


robotic arm arc welder

Is it a robotic arm capable of arc welding feasible for a diyselfer ? I spotted some robot arms for cheaper than 200 $ over the web . Vantages for the operator would be no weld fumes breathing , no uv rays and such ..

Topic by gabdab   |  last reply


How to limit welder current (heat)? Answered

Hi All, I admit to being electrically dumb, well one step above dumb, I'm a software engineer not electrical engineer, but I don't even know enough enough to be dangerous yet:) I'm going to be converting an ac welder to dc. It's a harbor freight 90 amp flux wire job, comes from the factory as AC for some unknown reason, but should be DCEN for FCAW welding. There are several walk throughs availabile online. I don't know the rules for linking to other forums, so I won't post a link, but you can google 90 amp welder dcen conversion if you want details. I attached an image of the circuit I got from a post by bluecatfish onweldingweb. I'll be taking the transformer output, running through a full bridge rectifier to convert to rippled DC, using capacitors to remove ripple, and lastly running through a torroid inductor. Another problem with this welder is it only comes with high/low power settings. The low is still too hot and burns through thinner metals.  I want a way limit current further, but maintain voltage for a stable arc. I'll be adding a bleeder resistor to drain the caps, which gave me an idea. At first I thought to use several more resistors in parallel with the bleeder to reduce current. I imagine this might work but be horribly inefficient. It would still use all available power from the supply, just converting some of it to heat, leaving less power for the arc. I've read that adding resistance in series will reduce current, but won't that drop voltage available for the arc? Then I was thinking, I have a motor speed control for a router. I believe this is a pwm. Could it be used to chop the mains input (120v 20a) to the transformer and reduce overall output without effecting voltage(I've read this is 38v 80a in the factory state before my mods)? since I'm adding capacitors downstream, will they just discharge too fast leaving me with ripple/pulsing? If so, how would I slow the discharge rate? (I'm looking at 3x or 4x caps 22,000uF @65v in parallel on a bus bar, so 66,000 or 88,000uF total). Sorry if in not making sense, as I said in the intro, I have a lot to learn, and right now, the more I read, the more confused I get. Edit:  After more research, and to hopefully use correct terminology, I think I'm talking about using a current divider when referring to multiple resistors in parallel to the welding leads. I think I'm referring to a switching regulator when I suggested using a pwm to chop the transformer input. Can either of these work like I'm hoping? Is there a better way, that is relatively simple?  Thanks in advance for your patience and help. 

Question by DonaldF9   |  last reply



how do i wire a dual altenator in a 91 jeep wranglr for a onboard welder?

I already installed the second alternator i have a dual battery setup with one battery taking care of the jeep and the second battery powering a winch and air compressor i want the second alt to run the second battery and the welder but i dont know how to wire it up i have a ultima externaly regulated alternator help would be appreciated

Question by chikenjojo   |  last reply


Can a stick welder Weld aluminium ??

My dad has a mig welder and i dont want to buy a gas kit for that so ive been thinking of buying a cheap stick welder WIll it be able to weld aluminium angle or box aluminium

Question by stephenniall   |  last reply


Wireless TIG welder foot pedal?

Has anybody ever heard of or created a cordless foot pedal (remote) for tig welding? I hate having to buy new foot pedals for our Miller Synchrowave TIG/ Stick when the power cable gets cut or burned through. Thought about "bluetooth" signal.

Question by bobhdus   |  last reply



How can I build a 220V welder using 220V microwave oven transformers? Answered

I read TimAnderson's Instructable on building a homemade welder from microwave oven transformers, but that instructable is for a 110V setup, what should I change to make it work using 220V transformers on 220V. (I already gathered all the materials...)https://www.instructables.com/id/Build-a-Microwave-Transformer-Homemade-Welder/ ....Link to TimAnderson's homemade welder?

Question by inserbot   |  last reply


can i make a mini electric welder out of a disposable camera? Answered

Only for small joints not to be used, just as an experiment

Question by sharlston   |  last reply


Large electrolytic cost/size "sweet spot"?

I'm in the process of sourcing components to build a capacitive discharge battery tab welder - there are a few designs out there on the internet from this one: http://www.philpem.me.uk/elec/welder/ which I like because it's nice and simple, to this one, http://www.youtube.com/watch?v=hxWo8ko2k2A which is gorgeous but complicated. So anyway, first off I want to find some large capacitors. I'm wary of using car audio stiffening capacitors as it looks like they don't last very long for this purpose, although they can be obtained relatively cheaply, and I can't afford large standard type electrolytics which cost an arm and a leg. I did have the idea that there must be a "sweet spot" in terms of cost/size where I can build a bank of capacitors without breaking the other sort of bank - it looks like probably being around the 20 x 47,000uF (like this design uses: http://www.pittnerovi.com/jiri/hobby/electronics/welder/index.html ) mark, but I wonder if anyone with more recent component purchasing experience than me can provide some pointers? The voltage rating needs to be in the 20 to 30 volt range. Oh, and when I've finally built one, I'll post an instructable, I promise! My version is likely to be rather more analogue though as I don't know anything about microcontrollers.....

Question by throbscottle   |  last reply




i have a mig welder and my welds form in balls, i have to grind them down for ages, how can i make them pool?

Please could any EXPERIENCED WELDER advise me?

Question by l96470fps   |  last reply



how do plasma cutter power supplies work? Answered

I built a small stick welder, now i plan to build a plasma cutter i am going to buy the torch head because it seems it would be hard to make one(if anyone has an easy way to make a torch please tell me) but what i need to know is what goes into a plasma cutter power supply, right now i have 2 transformers (20 volts, about 30 amps) i know for plasma cutting i need DC current. how much voltage and current is needed. i don't plan on cutting any really thick metal this is just a little experiment i want to try. so can you please provide a schematic of a power supply and explain to me what the required outputs are

Question by twenglish1   |  last reply



DIY generator

I'm new to this forum. I just got my welders certificate. I've seen on the web some projects that convert an auto alternator to a 300 amp welder. I live in an apt. and don't have 220V. I have a new mig welder and it works super for thin and medieum guage metal. My buzz box needs alot of power, about 15 KW, and even used generators are out of my range. Can anyone help?

Topic by CraigLam   |  last reply



Where to find old UPSs welders and power line transformers?

I am trying to make money by salvaging copper from old junk like tranformers. I wanted to know where I could find the following items for salvaging: UPSs. Uninteruptable power supplies have really nice power transformers with lots of copper. Old welders. These have lots of copper in the windings and cables. Power Line Transformers. I have read these have about a hundred dollars worth of copper in them. I would like to get these for free or very cheap. Thanks.

Question by nurdee1   |  last reply


Need help with wiring a KJD17 switch for homemade stick welder!

Hello everybody! So, I finally got around and made a stick welder, and it wa surprisingly easy! Now it's just up to make the box it will live in, cooling and on-off-switches and the like. I have a KJD17-switch which I'd really would like to use, it has automatic safety protection against power outages and restarts, which sounds nice enough, considering that this again is an electric appliane that I made myself, meaning more protection is always good! Now the problem is the safety protection, as I do not know how to wire it! Where am I supposed to connect the A1-pin? To pin 14, maybe? I'm afraid I'll destroy this nice switch by connecting it wrong, so if anyone has a clue, please let me know. The datasheet for the switch can be found here. On the datasheet there is the same shematics as on my switch. Best regards Elmo

Topic by Kaljakaaleppi   |  last reply


rectify electricity before transformer?

Can you rectify the US mains (120vac, 60hz) as it, and used the pulsed dc to feed into a transformer and get a dc voltage out of the transformer? I'm asking this because it would be much much more efficient for high current situations. Here's my specific situation:I want to build a capacitive spot welder and a capacitive discharge cutter in an all in one device. To charge the enormous capacitor rapidly (1.5 farads in my case), I need a very high current power supply. I'm using a modified microwave transformer that was rated at 1kw, and it is now modified so that it outputs 12 volts AC at around 80 amps (probably less because of losses). This must be rectified to charge the capacitor.Assuming a perfect transformer (for arguement), it would have:120volt, 8.34 amp input12volt, 83.34 amp outputthe following is with full bridge rectifiers, assumed voltage drop: 1.4vIf the power was rectified before the primary, the loss on the bridge rectifier would be: 11.67 wattsIf the power was rectified after the secondary, the loss on the bridge rectifier would be: 116 wattshuge differenceso once again, the final question is: Does rectified input of a transformer = rectified output? Does the 120hz pulsed dc (as opposed 60hz ac) matter? Could this setup charge a capacitor?

Question by guyfrom7up   |  last reply


diy welding mahine cable size?

Hi guys i wanna make a welder. i checked https://www.instructables.com/id/Making-an-ARC-Welder-Part-1-of-2/ there the king uses 8 awg copper cables for the winding of the transformers.  here (namibia) they seem to have only 6 or 10 sqare mm cables. can i use 1 of those?

Topic by kefflon   |  last reply


Where have all the EE's gone; long time passing......

I'm trying to upgrade the control circuit on my cheap TIG welder. The existing control is a 10k ohm potentiometer, mounted on the welder. It's wired up such that the voltage drop across the pot is proportional to the welders output. Instead of having one knob that controls the output, I want one knob on the welder's panel that selects the maximum output, and another knob ( to be mounted in a foot pedal control) that allows me to select output power from zero up to the maximum value that is set on the panel knob. Seems to me that there should be a relatively simple, elegant solution that gets covered in the second year of an electrical engineering course. Or am I just insane to think that such a thing should be simple? I've tapped out my own social network, and I can't find anyone who will admit to being an electrical engineer. Thanks.

Topic by CTroyer   |  last reply


why do we receive AC power in our homes if mostly everything converts it to DC?

*except lightbulbs and welders. maybe water heaters?

Question by k_man93   |  last reply


I'm trying to build a welder from microwave transformers, but I got this weird looking transformers instead.

I recently got two old microwaves from a junk yard and wanted to build an arc welder with its transformers by connecting both in series and getting an output of around 40V all together. But when I open the microwave instead finding the big chunky laminated iron core transformer as shown by many youtube videos, i found a small weird looking transformers instead. ( as shown in the pictures) I read somewhere stating that the primary coil should at least have 1 turn per volt. However, this transformer only had around 17 turns in the primary. The core was also not laminated and it had a copper wire holding it in place. The primary coil was made of a thick litz wire and the secondary was a very thin wire. Anyhow, I still continued the project and I experimented with one first. I use the same primary and made my own copper wire for the secondary. I made the secondary by using thick copper wire which I found in some antenna wire and I stacked it up and twisted it and put a heat shrink tube on it. Base on a few tutorials i saw i need an output of 20V from each transformer coming from an input of 240V AC. So with 17 turns in the primary i need around 1.5 turns in the secondary. When i finished everything and connected it to the power supply, it vibrated for awhile and then blew the 13A fuse in the plug. So i added a light bulb in series hoping to increase the resistance and reduce the current but this time nothing happen and it didn't even vibrate but the bulb did light up. I think its because the primary coil has a resistance around 5 ohm and the bulb have resistance of 100 ohm so the potential differences is very low on the primary coil. I am not sure why isn't it working. Please help me as i can't find any tutorials on how to make a welder with this form of transformer. There were no other transformer in the microwave so this was definitely the main transformer. Is the problem because it has too little turns in the primary coil or it has too low resistance? I don't know please help me. Thank you!!

Question by KhayhenS   |  last reply


Microwave Oven Transformer arcs too small- about half a millimeter

I have two microwave oven transformers (MOTs) that I am currently working on, and I have taken one of them apart to make sure of the wiring of the coils. I am fairly confident in the wiring of the whole system. I have the original primary and secondary coils, both made of copper. The transformer is one of the larger ones I have seen, and its wattage at about 1000W. I know it is not popping the breaker because the hum is always on. I have read through many of the instructables out there about MOT's, so I understand it pretty thoroughly, but the arcs on the instructables I've seen are several inches long, and my arcs are about half a millimeter. I really wouldn't call it an arc at all.  I have the common wall output of 110 VAC, 60 Hz going into the primary coil, and the ground is attached to the MOT block itself. One of the secondary output wires is connected to a capacitor bank of 3 MOC's in series, and I have the other output on the end of a PVC pipe which I touch to the opposite end of the capacitor bank. What am I doing wrong? 

Question by Technicolor   |  last reply


How do I use new chip-style microwave oven transformers ?

I'm working on a microwave oven transformer based AC welder. Newer microwaves don't use classic steel and copper transformers but rather something much lighter with a few beefy electronics that look like transistors. My question is how does one manipulate these new-style electronic trasformers (if that's what they're called)? Imagine all the wonderful things one could to with such a light-weight but powerful circuit. Maybe it could run a laser, welder, or do voltage boosting for renewable electricity systems with long cable runs...

Question by snotty   |  last reply


Where can I find 4 AWG wire? Answered

I got my microwave, and now I want to make a spot welder. Any recommendations for where to find 4 AWG wire, or something similar?

Question by CameronSS   |  last reply


small plasma cutter?

I got a asmall plasma cutter 110volt. is it possible to make it cut thicker material?? or do i have to use bigger transformers and stuff?? i dont no much about the plasma cutters. was also wondering if i could some how hook it to a lincon 225 stick welder? thanks for any help

Question by monster30   |  last reply