I Made a Battery Spot Welder from an Old Microwave and Excessive Mahogany 

''Honey where is our microwave?'' ''Funny you mention that, actually...''

shout out for making something that so perfectly gives off that vibe of "i found this in my grandpas old shop and have no idea what it is but it seems scary"

What you want for your welder's cables is funnily enough called Welding Cable. It uses much finer strands then typical wire and EPDM or neoprene insulation for greatly improved flexibility. FYI it is also great for use in high power rv dc power systems because it's much easier to route and work with in confined spaces.

We are so here for this kind of fabricobbling content! It's always a joy to watch. Seeing you comment about security Torx fasteners gives many of us AvE vibes. 😁👍

"Transformers are electromancy" *Proceeds to build and program a solid state arduino controlled curcuit capable of handling a massive amount of current supplied by a basic single phase step-down transformer that works on the very first try*

Hey Robert, I have looked through your arduino code and I think it might be worth adding a safety feature to it. Currently, you're checking if the button is pressed on every loop of the program and activating the relay if that is the case. So if you hold the button pressed in all the time, the relay will activate again and again on every loop of the program. As a result, if you set the activation time low enough and/or don't release the button quickly enough, the relay will activate multiple times. You might want to add some code, to check if the button had been released and pressed in again, so it would only activate the relay once for every button press. Might save you from burning up the connections you want to spot weld and save you from a fire, in case the button gets stuck pressed in. Anyway, great project, you might have convinced me to try it myself. There have been times when I wished I had a battery spot welder, but not often enough to go out and actually buy one and I've been hesitant to make it myself.

5:30 - You learned tolerances! Hurray! The worst part about taking your beautiful CAD model and bringing it into the real world.

With how fancy of a box Robert made for his spot welder, I cant wait to see the box that he makes for his batteries!

"How do you get people to stop using your tools?" Dude I almost spit out my coffee! Nicely done

I get the feeling we're going to see a ton more 3D printing in the future. "When all you have is a hammer, everything starts to look like a nail"

The channel might be called Under Dunn, but I'd say that spot welder might be Over Dunn. Makes me want to make one now, even though I have no use for one.

*Easy to assemble **Fastly.Cool*

"Have you seen the microwave Robert?" **Zap** 'No'

Until 9:15 I was wondering where the mahogany in the title was going to be used. Awesome spot welder! Amazing how we now typically use Arduinos where we used to use a simple 555 timer or even a single transistor with an r-c circuit to time it. But then, it wouldn't have worked the first time.

"Excessive Mahogany" - it's interesting to see the different region RU-vidrs with their different locally available excessive species. In the vague hope that you'll see this - I just thought I should mention that your regular channel is not featured on this channel! I actually came for the woodworking content and now suddenly I'm watching a guy deconstruct a bus, but it took me months until the algorithm told me about the other channel!

Another Channel where RU-vid recommendations algorithm was eerily spot-on. Enjoyed the info and delivery.

Just FYI: if you can, it's better to remove the secondary without cutting the transformer open (you can for example cut the winding in half and punch it out) because if you break the core you'll never weld it together perfectly and it's gonna change both the inductance of the primary and in general increase the loss of the transformer. You can see this in the video when the transformer vibrates really loudly and draws a lot of current even with no load

Building cool stuff while exercising self deprecation at the highest level. Awesomeness

Hi Robert, I found your channel through the Hackaday blog, super happy they linked it! Having a blast going through your videos, love 'em!

I really love how over-under-over-engineered this project is!

Your edit on cutting the box joints is my favourite part.

Best "how to" on these DIY welders I've seen.

The audio edit about 4 minutes in, with the sound of it being on only stopping when you touched the transformer, but you had it unplugged the entire time, is pure genius. Thank you for being you and trusting us enough sharing it.

I see you're flaunting your RU-vidr wealth with all that copper! As others have mentioned, we're here for the fabricobbling!

I like you, you're hilarious. This video was brilliant, thank you. I more-than-half expected the finger-joint cutting montage to turn into a song.

I made one a year ago and used it to cobble a 18V 18650 bosch battery for dirt cheap. Almost the exact same setup as yours just it featured a foot switch which i also made from microwave relay from doors lol

Love the way you approach things and your sense of humour!!

This is a masterpiece and I loved the humour involved in it's making, but I particularly liked the unintentional Teckno music effect when making the box joints.

Cool, I've used a wine bottle box and instead of cutting the core I've sawed off one end of high voltage coin and pushed it out. For the switch I've used a "wall mounted" 230V spring loaded light/doorbell switch bolted to a plank so that I can operate it with a foot.... Although I've never made a spot welder head, instead I've used it to heat wire to cut Styrofoam. And for melting stuff :)

With a program like VCarve or Aspire, you can easily CNC parts from 3D printer models. There is no reason your handle or button grip should not be a matching wood for your case.

*I'M GLAD I FOUND THIS CHANNEL!!*

This guy's the best. Best sense of humor too.

The best part of your videos is just how fearless you are! Thanks for sharing.

Any time I hear microwave transformer, I get incredibly nervous! Looks like you did a great job, and didn't hurt yourself (at least that you've shown on video!)

The joy of making useful tools, I also enjoy making tools by myself instead of buying them if I can make that happen, so thanks to you for that, I have all the necessary parts and going to start as soon.

We used to say that the most dangerous thing in the world is a programmer with a soldering iron… and that was before people started tearing apart microwave ovens. Nice job!

I think that it's great that you show your mistakes, makes your videos more enjoyable to watch knowing you're human like most of us! Plus I learn best from making mistakes! Keep up the good work!

Nice methods and solutions on the box. I can see I am going to have to watch more of your videos.

First “safe” one of these I’ve seen. Nice job

I'm getting some real Mattias Wandel vibes from the woodworking, I love it.

RE ripping that board vertically on the bandsaw, well done & hilarious! hahahaha

Make that switch button into a foot switch! You'll really like having a free hand. 13:37 - You will desire!

Cutting out the box joints reminded me of the song Doubt by Delphic Also, brushed vacuum headers for CNC machines don't last all that long and don't look nice for most of their life cycle. When they get all messed up just replace them with stiff enough silicone sheets spliced near the bottom - works perfectly and stays decent for years.

I had no idea you were a professional level wood worker. Fantastic work!

Oh man, this is giving me flashbacks. I used to work at Batteries Plus store, and we would rebuild battery packs for customers. Most of the time it was things like odd drill pack batteries which are just a bunch of Sub-C's spot welded together. Our machine had a foot lever lever that that would lower the probe and trigger it; I swear it had a bicycle pedal on it. I don't know why, but there was some finesse to it, if you pressed down too hard you would "pop" the weld. You're set up with the trigger looks much easier!

Your Dad has an awesome garage.

Do NOT open a microwave over unless you know what you are doing. Lots of angry pixies in there even when it's unplugged.

I love your bench mounted bandsaw

No comment. Just a +1. But a real, a heartfelt +1 .... lovely.

Thank you for the code. Love the clever wit.

If you had half as much fun doing it as we had viewing it, you had a lot of fun indeed!

If you want to go Super Fancy with your power cords, you can get IEC power cord (think "computer power cord") receptacles off of a bunch of different things, and the hole shape is cad file is easy to find.

Man, Can you believe his patience and attention to detail. Incredible. truly Incredible.

Great content. I specially liked the notice at the end saying that the most important thing is the spot welder itself, and not the fancy box and all the tools needed to build it. People often do not make difference between a RU-vid channel and real life.

Mad scientist woodworking!

An awesome spot welder project, LOVE IT Rob!

I don't know if I've watched too much of these, but my first reaction when I saw the box-joint jig was a "did he mess this up". I know this is pure torture, but I'd like you to know that "twas was for naught" as some twisted person half-way around the got a hefty chuckle out of this and the first smile of the day :D I short, a humble thank you!

I forgot you mentioned this channel. I only found it on this video when watching videos on batteries. Now I get to hear you talk about more stuff. I don't know why but I enjoy your style of videos.

I guess that "modern man" has forgotten the special digits that form a magical number: 555 All that hardware and programming, for a simple pulse? A potentiometer, with a dial that you calibrate, two capacitors, a couple of resistors, a potentiometer, and a 555...

thx for talking about the simplification of it like not needing arduino and stuff

You are absolutely correct having it work the first time is an amazing feeling. Nicely done!

Magnificent. The first test energized me.

Congrats on being featured by HAD!

Segfaults... That is one seriously nerdy shirt. Respect.

People who can create both software and hardware will rule the future world.

some youtube videos I can walk away and listen while I go grab something from another room. here, as soon as I do that, there's a childish giggle and i have to finish what I'm doing, come back, and rewind to see Robert knock half a transformer off with a chisel.

Super super nice episode !! Here you get different elements, such as electronics, some data coding, welding current, and wood work. Stop saying you're an idiot, because you are not. I look forward to more such episodes, it's fun and you are very skilled, and now I have to work on my own projects... .. and as before, fantastic video editing!

Nice. I didn’t see a fuse in there. Hope ya got one! I’d feel bad if I didn’t say anything

You’ll need a fan in there! Will get mighty hot over a day working! 🔥

This was an epic video because the first part is ripping apart appliances, then we learn about Transformers/magnetism/induction theory(sort of), then we learn programming/electronics and finally we get to do custom wood working 😂😂 You've basically described my garage in a nutshell. 😊😊👍👍

Making things that make things are my favourite things to make.

Safety note about solid state relays. They always pass voltage! Not an issue with 2v, but when I used one to control the heater on an electric hot tub I was introduced to 240vac several times. Mind you it's in the single digit milliamps but still not fun.

This isn't as dangerous as it seems. I don't see any comments *thoroughly* explaining this, so I'll try my best. First, I'd like to discuss the misnomer that it's not the voltage that kills but the current. This is technically correct, but not the full story. It boils down to Ohm's law, which says Current = Voltage ÷ Resistance. These three values are always tied by this relationship. And there are some consequences to this: 1. An open circuit (no connection) will have an infinite resistance. No current will flow and a power supply will be at its max voltage. Here we see 2V. 2. A short circuit will have no resistance. Therefore infinite current will flow in theory. Metal is an approximation of a short circuit due to having low resistance. If the power supply cannot keep up, it's voltage will drop to maintain Ohm's law. 3. Due to consequence 2, Robert should have actually measured current while welding. (A short circuit) Not while open. The 10A is probably just due to losses. The real current might be much higher than 600A through metal. 4. The human body is pretty resistive. The exact number will depend on what two points of the body you measure through. But even two points close together on the skin has a high resistance. As such, at 2V, the current is very low. Nowhere near enough to hurt you. At 120V, you can flow enough current to kill depending on where through the body it flows. (Particularly the heart) 5. Due to that, the output is actually less dangerous then the input to that transformer after modification. (NOT before) 6. Still, it makes the metal hot. If you touch it while it's welding or shortly after, you will hurt yourself. Be careful nonetheless! Hopefully this has been educational. Electricity is truly fascinating, and I'm all too happy to spread my knowledge!

CNC, 3D printing. This is getting fancy! Have fun with the welder!

Fabulous. You are a creative genius and so much fun to watch. My mood has been duly lifted. 😊✔

You should have made the arduino play some short annoying tune every time it has produced a welding pulse. It helps in remembering that tune for the rest of your life when seeing a battery pack.

I like how it's called the 'Zip-Zap' yet looks like a professional modern but tasteful well made box haha.

LOL Heirloom spot welder. omg, that's amazing.

Well, if you hadn't gone that fancy with the woodworking, then you couldn't have posted it to your woodworking channel! I love it, what a great device you made and you survived to upload the tale!

Your explanation was really nice

I hope you still have the remains of that microwave. There are a couple of pretty good magnets in there that you can salvage.

"I made a Battery Spot Welder..." - How big of a battery is needed to run a spot welde.... oh, nevermind. That makes more sense!

Now you need to update that 7-segment display to a venerable ssd1306 blue OLED display with 128x64 pixels. Otherwise how are you going to customize the font, add scrolling effects, and add all sorts of absolutely pointless yet essential eye candy?

I love watching you build and make things, and especially happy for you having success early on. You've made a nice workshop and some great creations come out of it. Absolutely love your attitude and personality. Nice job on the spot welder and good luck for the next stage :)

This must be one of the most terrifying things I've ever seen you do! :) ++applause++

This is so cool, unfortunately I always get hopelessly lost when electrical projects are intertwined with electronics because I do not understand or know anything about electronics, electronic parts and components, circuit boards, electronic wiring or how to make any of it work in conjunction with electrical hardware. It is a very nice knowledge to possess and it sure does turn your electrical tools into very safe, controllable and refined tools. Wish I understood any of it.

i built a microwave oven transformer power supply a few years ago. i went a little crazy with my wire and used some 0ga wire. got ~2.2v and dead short, measure out at 1360 amps. just used it a couple weeks ago to weld up some tabs on some 18650's to make a battery pack. best FREE.99 i ever spent.

Well done. Fun to watch project.

this man deserves so much more love!! These videos on both channels are so amazing

I'm so glad he didn't over engineer the case or anything else in his build! xD Glad it worked and that his wife got a new microwave.

Can't wait to hear you merge CNC router, the router table, drill, and brad nailer into a rhythmic symphony. Great job!

I don't even care about what you are building, I'm here for the famous commentary!!

I understood about 1% of this project but i loved the video all the same! Keep it up man!

"and this other box" *proceeds to lay down a sick beat*

This was fun to watch. Don’t know why. My medication may need adjustments.

The entire video was excellent. Great and entertaining editing, and a cool useful project. Subscribed, can't wait to see your channel explode.

Nicely Dunn, sir. ;) And your code is fine. Simple, reliable, and not over Dunn.

You should link your second channel....I didn't know about it....All that time that I was waiting for you to post new videos......... AWESOME project man.

I built a much less fancy version of yours a few months ago. To anyone wanting to make a much worse but still functional version, I used 1/8 copper rod with points ground on it for the electrodes and used only an arduino and a push button switch. To adjust the timing, I make changes in the arduino code. It’s much worse but for my purposes the timing can pretty much be set and forgot. Another tip is if you don’t want to (or in my case couldn’t) disassemble the transformer, you have another option. I used a saws all to carefully cut each end of the secondary winding flush with the iron body of the transformer and then used a 3/8 drill bit to drill out as much as I could. With the majority of the material removed, it was easy to punch out the rest with a flathead screwdriver. Also if you mostly work on cars and small electronics, remember to switch your meter to ac before checking the transformer. That took me an embarrassingly long time to figure out.

I want you to take this as a compliment, I think you might be a mad genius 🤪