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

for an upcoming project on my other channel aging wheels i'm going to be converting this huge box of loose battery cells into a battery pack but in order to do that i need a battery spot welder which i do not currently possess now i could buy one or i could buy a conventional spot welder and convert it to use with batteries which would be pretty simple but instead i thought it'd be more entertaining if i built one spot welders aren't all that complex after all and assuming i don't encounter any hospital bills it'll be cheaper now the main components i need for this build are an old microwave this 3 8 inch solid square offcut of copper this stuff was surprisingly expensive they should make money out of this more copper this time in insulated six gauge wire form and an arduino a solid state relay and some other component tree to control the timing let's see how this project goes hopefully i don't get electrocuted ah they got the security torx picks on these but that's only going to slow me down there's what i'm looking for and all this can go in the trash this is the transformer out of my microwave this bottom coil here is where the line voltage goes into this is the primary coil it's made of a slightly thicker gauge of wire than the secondary coil unfortunately you can't see the wiring in the secondary coil because it's covered in epoxy and paper and all this jazz here but it's a substantially thinner gauge of wire the job of the transformer is to step up the line voltage the 120 volts that comes into the transformer into whatever the microwave uses i can't see the wires to count the number of turns or anything like that but if i had to guess i'd say that this transformer is stepping up to at least a kilovolt probably even more and in the process of doing that it also steps down to the current i would tell you how the transformer steps up the voltage but frankly i don't know transformers work by a combination of wizardry and magic maybe electroboom understands how they work but i don't but for spot welding i don't need high voltage low amperage i need the other way around i need high amperage low voltage so i need this transformer to step down the line voltage that comes into it and significantly ramp up the current now you may think that i could just wire this transformer in reverse to step down the voltage plug the line voltage into the upper coil here and have it output to the lower coil and that would step down the voltage but unfortunately the gauge of wire in this upper coil here is too thin and it would just melt if i plugged it into line voltage so i'm going to take this transformer apart remove this thinner coil entirely and replace it with my own coil made of this stuff it will only be a couple of turns and it will significantly increase the amperage and what is now the primary coil will remain the primary coil [Music] laughs i've got the output of my new and improved transformer hooked up to a voltmeter over there so let's plug in the primary coil to line voltage and see how much my new and improved transformer drops the voltage down to 2 volts 2 volts that's a significant drop this transformer is stepping down the line voltage of about 120 down to about 2.2 over there which is a factor of about 55 which means it's increasing the current by that same factor and since it's drawing almost 11 amps from the wall that means the output current is almost 600 amps whether or not it's actually close to that doesn't matter that's a lot that should be plenty for spot welding and killing someone all right that's the main component of the barbecue taser sorted now i need to make a little thing to focus all of this raw power down to two little pinpoints [Applause] [Music] now to hold these two probey bits in place i modeled infusion 360 a handle and then 3d printed it i printed it in petg i was afraid to use pla because i was afraid that these probey bits might get a little bit hot and the pla would get a little bit mushy this is actually the second print that i made the first one failed because i made the holes on the inside of here the exact same width as these probes and they didn't fit so i had to model it again making these holes a hundredth of an inch oversized now they fit just fine so now i can slide them in to their new permanent home now i don't think i'm going to need to epoxy these in place they're plenty stuck as they are and there we go one spot welder probe that i can hold in my hand here's a top tip for you how do you get people to stop using your tools you make your tools look incredibly dangerous for the points in the end of my spot welder gun i just used little bits of 12 gauge copper wire out of this little bit of romex here ground a point onto it and shoved them into the end i was going to hold them into the tips with little set screws but they're so well held in place as it is that i don't see that as necessary now timing circuitry to control just how long this spot welder pulse is i threw together this little circuit powered by an arduino i've got an arduino uno a rotary potentiometer a big satisfying depress red button some resistors for this seven segment display four digits seven segment display and a solid state relay for switching ac line voltage the way this works is you can use the rotary potentiometer to set the value on this 7 segment display it has a range from 0 to 1 000 in increments of 50. this number is the time in milliseconds that the relay will be pulsed for when you hit the big red button so right now it's set it i'm trying to read it upside down 300 milliseconds it will pulse for that time when i hit the big red button you can see the led here that's all it does it's a pretty simple circuit as for the code running this arduino i'll have a link in the description so you can check that out if you want to please be gentle i know how you programmer types can be relentless and judgmental i wouldn't have written it that way well you didn't write it did you i think i have some mild software engineer ptsd now let's make this circuit a little more permanent by unbreadboarding and soldering it to something oh and i made a little 3d printed mount for my button here i'm liking 3d printing then after what seemed like an endless amount of soldering i ended up with this mess here frankly i think the breadboard looked better i found a couple scraps of pcb that i soldered some pin headers onto and stuck down into the arduino these are theoretically removable although i'm going to leave them there for now and i soldered all the connections based off of these boards right here i've got some various wires going to my four-digit seven segment display soldered onto this bizarre semi-permanent breadboard thing it's whatever i found at micro center i've got two wires here going to my relay which switches power on and off to the transformer i've got another two wires twisted up going to my go button here to power the arduino i took apart a dc power supply basically just a plastic housing off of it so i could solder it straight into the plug that i stole off the microwave and i've got my rotary potentiometer right here now for an extra bit of added safety i did wire everything through this switch here so that the arduino and the transformer none of it is live as soon as i plug this thing into the wall now what do you say we give it its first ever test run i've got an icad battery right here and a strip of nickel let's try spot welding this onto that set for 300 milliseconds no idea if this will be enough no idea if this will work at all go oh oh did it work oh my god i've made a spot welder test number two i've turned the time down a little bit go oh that's so cool i made a spot welder look at that that's awesome i'm energized now making stuff especially stuff that i'm going to use and that i need is always fun but when it works the first time there's hardly anything that beats that feeling anyway now that i know that this setup works time to make an enclosure for it so you know it's not just this random collection of crap strewn all over my workbench every time he gives it [Music] [Music] so [Applause] [Music] [Applause] [Music] time for box joints here's my jig and i've dialed it in by making this box and this other box [Music] and just like that we have box joints that fit perfectly on the second attempt the first attempt i messed up big time and cut all the box joint fingers in the same place which doesn't work so i had to do everything all over again but at least now i have very nicely fitting box joints now to add features to one side of my box i'm going to use my new toy stepcraft sent me an m1000 cnc router oh whoops a little problem there i may have bumped it into the clamp totally my fault and for some reason my instinct was to turn off the camera instead of the cnc router because i'm an idiot [Music] [Music] [Music] i'll be making the lid of this box from these two bits of offcut that i glued up while you weren't looking and to keep the wood movement of this lid to a minimum i'm going to be gluing that on top of a bit of quarter inch plywood hopefully that will work to stabilize it so [Music] i think what i've done here is i've unintentionally made an heirloom spot welder did i need to make the enclosure for this thing a solid mahogany box jointed box no but my spot welder is pretty now makes these 3d printed handles look like complete crap in comparison the guts of this spot welder barely fit into this box so i'm glad i didn't make the box any smaller than i did and by the way i secured most of the components inside with tiny brass screws because fancy for future removability i attached the lid on this spot welder box using screws brass screws no less and like i said before hopefully wood movement isn't a problem on this lid because i glued it to a substrate of plywood i added three new holes to the back of the box here this recessed hole is for the switch it's an on off switch that cuts power to everything in the box hole for the power cord this power cord i stole from the microwave the zip ties just to keep it from going in and out of the box and i replaced the hardwired button wire with this rca jack so i can quickly plug and unplug the button handle and replace it with a foot switch if i so desire on the front of the box you can see the screen in place and i carved a knob out of mahogany for it on the step craft and the cables come out of the middle here i think i would like to replace these cables because they're really really stiff like to replace them with maybe jumper cables or something a little more pliable as for ventilation of this box there isn't any and i'm pretty sure that'll be just fine before i stuffed it into the box i tested out the transformer by having it on continuously for several minutes at a time and it only just got a little bit warm as a spot welder it's only going to be pulsed on for a fraction of a second at a time so i think it'll be just fine tucked away in this box and that's it if you want to build one of these for yourself i did not come up with this idea i got this idea from an instructable that was written several years ago and i'll link to that in the video description below also in the video description will be a link to the arduino sketch file that i wrote and it'll have in the sketch file the list of all the exact components i used as well as an arduino pin out so you can replicate the circuit that i'm using here and i'll have other relevant links in the video description as well such as the solid state relay that i'm using etc now you don't have to go as fancy as i did with a spot welder build like this you don't have to go anywhere near as fancy as a matter of fact you don't have to make a fancy enclosure for it you don't have to make an enclosure at all if you don't want to mess with arduinos or programming or any of that stuff you don't really have to you could wire this transformer up to just a button that you pulse manually sure you're not going to get anywhere near as finite of control as you would with an arduino but it's an option if you don't want to go down the arduino or programming route and if you don't have a welder you can reattach your transformer using epoxy none of this has to be complicated i just made it complicated because i had fun doing it and making something that looks very nice and is functional anyway thanks for watching you'll be seeing me use this in future videos on both of my channels

Channel: Under Dunn

Views: 298,258

Keywords: Arduino, PETG, Copper, Spot, Weld, 18650, 26650, nickel, Solder, Ni-Cd

Id: 6w9dFNRtqlg

Length: 15min 40sec (940 seconds)

Published: Thu Sep 09 2021