For a physics project (im in high school), i would like to build a spot welder, similar to this video.
https://www.youtube.com/watch?v=GCrqLlz8Ee0
I have little experience working with very high currents, but if i take proper safety precautions, such as wearing thick gloves, proper welding goggles, etc. would it be advisable for me to attempt to build this?
>>909759
i made one, there are videos on making a jig for a spot welder. its not hard, the hardest part for me was making the coil. i got a microwave from a thrift store and removed the transformer. 10g wire from lowes was like 12$ for 50 feet.
>> inb4 underage b&
Before you waste too much time, ask your teacher first if it is allowed, safety etc.
you really only have to protect yourself from the 120V primary, coz the secondary is just a couple of volts. so, if you cover the 120V terminals with heat-shrink or tape, the rest is relatively safe, unless you nicked the primary wires, exposing the copper.
as for welding goggles, you dont need them. it shouldnt be any brighter than birthday sparklers.
>>909763
I wound some 8mm copper bar as a secondary. The amperages are huge so you need thick wires! I soldered some very thick wire to the secondary but the solder melts... I need to revisit this some day, it's just lying around now...
I'm up to my armpits in repairing a tig welder right now. The transformers im finding are beasts, current loads that would just kill you dead, remember it's not the voltage that kills you...
>>909835
>if you cover the 120V terminals with heat-shrink or tape,
Don't use tape, that is not what tape is for. Use wire nuts and heat shrink.
>>909873
>wire nuts
>>909862
Yes. it. is. the. voltage. that. kills. you.
I=V/R, your resistance is fixed, so the only thing that determines current through you is the voltage.
Doesn't matter whether your 12v supply can deliver 0.00001A or 100000A across a short: it's the "12v" that determines what it can deliver across a human.
>>909882
Wire nuts are better then most connectors, and they're reusable. Fuck off with your bandwagon bullshit.
>>909889
It is only the amps that kill you. That is why you don't die from touching the batshit insane electric arcs from Tesla coils, and die when getting zapped from an arc welder which has far lower voltages.
Resistance is the main factor for low voltages only when if comes to skin resistance. Which is why a spot welder can't shock you. It's voltage is too low. If you jab electrodes into your skin, the same volts that normally won't shock you, because of skin resistance, can then deliver the amps which can kill you.
You can die from a 9 volt battery if you are tarded enough.
>>909889
yeah but a circuit that can only deliver .00001A @ 12V isn't going to do shit to you. I'm sure most of us have been shocked by thousands of volts from something as simple as static to spark generators or a broken lighter. That doesn't really do much damage.
>>909759
With as many secondary windings as shown in that image the voltage on the secondary will be around 1.8 to 2 volts for a single MOT transformer. You can safely touch these with wet hands and not get shocked. You can volt meter them to be sure.
Wear safety goggles. These sparks can sometimes be bits of metal, not just a birthday sparkler. Catching an abnormally large spark in the eye is no joke.
The main problem from spot welders can be smoke. It really depends on what you are doing. There won't be smoke like from an arc welder, but there is usually some smoke. Don't breath it. Work in a ventilated place. Or, like me, use a ventilated helmet or flow hood. I love my flow hood for ring welding.
With all things electrical that can kill you, always keep one hand behind your back at all times.
To get an amp reading for the secondary side, just use a clamp meter on the primary side when the welder is being used. Get the voltage on the primary side. Then do some easy math for the watts. Then use the primary side watts and secondary side volts to math out the secondary side watts. Don't try to measure the secondary side amps or you'll fry out your meter or get a reading too high for the clamp meter. Depending on your setup, you can get anywhere from 1,800 watts to 3,600 watts (120v or 240v).
Here's pics of my latest one from a while ago (reposted). They are in series so the voltage on the secondary side is doubled. I did that to power through less than optimal surfaces and oxides. As you can see the sparks are quite something. Though it is welding zinc-coated rods together. (3.72V 491A 1826watts) I found that the shorter the secondary cables the better the results. 6 feet long cables sucked compared to 10 inch cables. Thicker cables are also better than thinner cables.
>>909783
It is no more dangerous than making a normal 120v lamp in shop class.
>>909899
Dumbass....
Spot welder so vary in power from 5 to 500 kVA.
All use a capacitor bank charged by the transformer.
A high school age child has no business attempting anything like this.
I call bullshit on OP as no teacher would agree to anything like this as a project, the liability is too great for the school, town, and teacher to assume.
>>909895
Any and all circuits that deliver a regulated 12v can't kill you.
This is why you don't need PPE to handle laptop batteries.
>>909899
Here's another one I made in action. (1.85V 1427A 2640 Watts) I use it as the ring welder in a flow hood.
>>909910
We are talking about MOT spot welders. Specifically using a single MOT or at most 2 MOTs. They don't use capacitors. Making a MOT spot welder is a common teen project. They may look dangerous, but they are no more dangerous than anything you make that is powered by a 120V wall outlet or whatever wall voltage your country uses.
>>909889
Show your workings and source please.
>>909957
God fucking damnit. All you retards.
Amps are what technically kills you because amps are the measure of charge passing through your body, so of course it's the amps that kill you .
But amps do not move without enough voltage to push them through whatever resistor we're talking about. Sufficiently high volts allow amps to move. The volts needed to allow a deadly amount of amps changes with where they are sticking you, and that can be lower depending at what frequency the electricity is. 12v is enough to kill you if you're stabbed into the wet bits of your body (300-1000ohm). you wouldn't even be able to feel 12v across your skin (1000ohm-100,000ohm0)
12/300 = 40ma
12/1000 = 12ma
12ma is barely a sensation.
40ma DC would be enough to cause an uncontrollable muscular contraction which could translate to fibrillation or inability to breathe depending where the current is going. (Blood and heart is always a good path)
>>909969
So the voltage is irrelevant. It's the Amps that kill you.
Same reason a 20,000v shock can either kill you or be harmless. One is what's in a local electrical transformer, the other is what's crackling on your hands while you take off a polyester sweater. Both are 20kV but one is carrying a LOT more amps than the other.
>>910016
Are you really comparing static electricity with a pole pig.
baka
>>910016
... No. The voltage is not irrelevant. It is exacty what I said.
The voltage is required to drive amps.
I could stick my tongue on 1V behind a power supply that could deliver infinite amps because my tongue is such a high resistor that a perfect flow of current through it would only be 3ma. I might have a tingle. Even if the power supply for it was a nuclear reactor dedicated to making that 1 Volt. NO MORE THAN 3 MA WILL FLOW THROUGH MY 300 OHM TONGUE NO MATTTER WHAT IT IS LIMITED BY THE VOLTAGE AND RESISTANCE OF THE CIRCUIT, SO THE AMPS CAN NEVER KILL ME.
Now yes, if it's a pole pig or whatever, 20,000v fused at no relevant amp limit. Yeah, that could literally vaporize part of my body.
>>910024
>I might have a tingle.
No, it will taste oddly metallic, that's about it. It takes somewhere around 5v to start to tingle. 9v is full tingle and taste.
When I got my first gold cap on a tooth it was weird as hell. I could "taste" the electric being made from it and the non-gold filling. I was able to measure around 4 volts being produce (couldn't get a reading on amps at all. 0.00mA) I was a bit worried but after a month it finally stopped or I got used to it. I'm probably being poisoned...
>>910169
>lrn2 ohms law
>0:58 in the video he states it is true but goes on to asspull as much as he can because he doesn't understand what he's talking about
>in fact everything he said reinforces the shit he's trying to bust
Typical bullshit from a mythbuster fan.
Jesus Christ, have none of you taken a class on electronics? Are you all middle schoolers??
>>910184
>>0:58 in the video he states it is true but goes on to asspull as much as he can because he doesn't understand what he's talking about
Actually he says it has SOME truth to it.
More importantly, he pointed our that it's not the amps, or the volts that kill you, its the total energy in joules (or watts) that kills you.
Also important is that the amperage is directly determined by the voltage and resistance. Without sufficient current, there is a voltage drop, thus the total energy through your body decreases.
Next time pay attention before you dismiss via confirmation bias.
>>910190
Amps kill, not volts. It needs to be repeated. It is a fact.
>>910193
While it is true that amps are what kills you in the end, that doesn't mean you should throw out total power, skin resistance, and voltage too.
The issue with saying "It's not the amps that kill you, it's the volts" is the fact that, while yes, amps are what actually will cause the muscle paralysis that kills you, that's not the whole story.
This leads people to think that just because a power supply is 'limited' to a certain current, that it can only deliver less than or equal too that current, which is rarely the case. It completely ignores capacitance, inductance, possible energy delivery, and skin resistance. There are too many variables that could determine if a current source is lethal or not.
This is why anything over 30V (with dry skin mind you) is considered dangerous.
The statement is technically correct, but not practically. I'll give it that.
>>909895
a circuit that can only deliver 1uA @12V won't do shit to you for two reasons:
-12Vdc isn't enough for a significant current to pass.
-at higher voltages but if it's only capable of such small amperage, it will drop voltage before any more current can be drawn. note that voltage goes down.
>>910200
has the right idea. Current is proportional to impedance and voltage. Let's also not forget frequency has a role in how much current flows through a human body.
>>910193
then go touch a 1nF capacitor charged to 30kV. See how harmful a tiny charge at high voltage can be.
>>909910
As a sophomore in high school, I personally loved microwave transformers, especially the 2000 volt secondary. I did eventually remove it for a high current one as well.
It can be safe if you're smart about shit.
>>910239
> As a sophomore in high school
Or you can re-word it to avoid a ban
> When I was a sophomore
Or
> I am currently an 18+ year old in the 10th grade
>>910204
Its not the electricity that kills you, its the brain death caused by heart failure.
>>911213
there was an old joke about a lazy mortician once. "in the end, all causes of death are heart failure."
>>911169
Thanks for the page 9 save.
>>911169
>As a sophomore in high school
>I personally loved
>loved
>ed
Grammar's not your strong point, huh? The past-perfect is the second tense you learn in pretty-much every language, right after the present.
This would be because the concept of "something that did happen, but now is not happening" is such a useful one, it's near-universal.
>>909862
Voltage doesn't kill you but you need voltage to pierce through your resistant skin so the amperage can do the killing
Neither volts nor amps are measurements of power. The total amount of power delivered to your body "is what will kill you." You can hold two bare wires in separate hands that are capable of delivering 100kA, but nothing will happen if the voltage across the wires is only 12V, because the power dissipated across your body is 12V ^2 divided by the resistance of your body. Likewise when you get a static shock, the voltage is usually upwards of a few kV, but the total amount of current flow is very very little, because it was just a static charge.
>>910234
There are languages which have only past, present and future. Those are the better ones, without bullshit.
>>914022
This is the only answer which could be considered correct in this thread.
>>914022
>Neither volts nor amps are measurements of power.
>power is the rate of doing work. It is equivalent to an amount of energy consumed per unit time
>the unit of power is the joule per second (J/s), known as the watt in honour of James Watt,
>>914068
I'm not sure what you think you're on about, but you don't seem to have a point.
He's right; neither volts nor amps are measurements of power. You can combine them and use the PRODUCT as a measurement of power (in the form of watts, which is simply "joules per second"), but calling either alone a measurement of power is outright wrong.
>Remember it's not the voltage that kills you...
I swear to god, I don't know how I still get so mad after hearing this shit so many times.
>>914088
>+r
HHHHHHHMMMMMMMMMMMMMMMMmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm
>>914112
?
>>914112
if you are aware of the internal resistance of the source you will realise that it is capable of delivering a finite current.
>>914022
But wait.
Your static shock example, and I think you saw it yourself because you chose not to include the calculation, has a human sinking several megawatts.
Could it be that it's in fact not power, but energy that's important?
>>914040
I call bullshit. Name one.
>>914178
Death is caused either by fibrillation (which can occur if current passes through your heart) or by actual organ/tissue damage (burn).
The first takes a couple of mA, and the second a fair amount of current over a considerable amount of time.
Static shocks cannot deliver nearly as much current for nearly as much time needed for either case.
>>914082
>everything posted must be contradictive
Calm down. Eat something. Relax. Everything is going to be alright.
Why are the majority of people here so ignorant when it comes to electricity?
A couple minutes spent with a good book would solve that right away, you know? That "it's not the volts that kill you" bullshit will end up getting someone killed, I tell you.
>>910016
what if i told you you need both voltage and amperage to kill someone? 9500v diode bridge? i let it shock my tounge. hurt like a bitch. but i can zap any part of my body and be fine.
a MOT spot welder? i could hold both leads with my hands, wouldnt get shocked... if i add a few more turns, and i have arround 16-18v... i would be dead.
>>914568
>Why are the majority of people here so ignorant when it comes to electricity?
Because nearly ever teacher uses water analogies to describe electricity. Which is completely incorrect. Their basic knowledge is grounded in misinformation.
I too am making a welder from transformers. I'm following Grant Thompson's how to videohttps://m.youtube.com/watch?v=r6oDCbcmtWw&feature=youtu.be but I'm stuck at 1:22 where I cut the transformer with a grinder and chisel it open. I believe it may be because my transformer is made of a bunch of sheet metals glued together. https://m.youtube.com/watch?v=NMxeWvui_mI Should I just do what these hillbillies are doing and just chisel off the unwanted coils?
>>914745
I'd tell you you were full of shit, because V=IR.
>>914794
Water analogies are fine.
>>914794
because frameworks are taught as truth. but they are simply that, frameworks for modelling. this is why its so hard for most people to accomplish simple novel tasks because they can't into modelling. of course its not hard to understand why when the level of education most teachers have achieved allows them to read womens magazines and harry potter. remember how these were the only things they got you to read in high school? the few books harder than this I failed my assignments on because the teachers watched the movie instead of reading the book so my papers made no sense to them. I still can't really talk to normies.
I've made the same welder. it will work either way, but you won't be able to get 20 turns 8 gauge of nylon insulated wire into core if you thread it through
>>915241
No, they are not.
>>915256
lol All that wood makes me want to strap mine to a wood sound box for extra growl when I fire it up.
>>915253
Perfectly valid point.
Unless it's a BB gun, in which case you get to watch a moronic friend blow a hole through his nutsack because hey, it's only CO2.
>>909889
>Yes. it. is. the. voltage. that. kills. you.
Spotted the autist.
>>915767
>Spotted the autist.
Pretty sure you have that backwards, champ.
Put it this way:
Say I, or anybody half-competent with electronics, is working on some live circuit that runs at, say, 60V or less. I'm going to take care not to short anything out, but I'm going to otherwise poke and prod it as I please.
If I, or anybody half-competent with electronics, is working on some live circuit that runs at, say, 600V or more, I'm going to be real fuckin' careful about what I'm touching.
>>915767
Its the energy, in the right place, at the right frequency, for tissue penetration that causes defibrillation, the main cause of serious electricity injuries. This is part of the 50hz master race argument. Beyond that, a good hard punch of human toasting electrical burn is required.
I hate all the misinfornation about heart attacks. All sparkies have had one. And they get cocky because they survive. Heart attacks are rarely fatal. Pacemakers for example, are installed in people who have more than daily heart attacjs. Its just that with each one, when it lasts for a few minutes, you get hypoxia of the organs so you get diffuse organ damage. Brain, heart, liver, lungs, everywhere. But manly alpha faggots and foremen will tell you to just walk it off
>>915233
Guys, need some help here please.
>>915233
>>917152
You just need to remove the secondary coil of wire, that is the one with the fine wire. Just slip some cardboard between it and the thick wire primary coil then use a hacksaw to cut through the secondary coil. The cardboard will help protect the primary wire from scratches when cutting. You can also tape up the primary coil so bits of metal don't get in it.
After that you use something to hammer the secondary coil out. It can be a chore to do this because of all the glue some of these have. Just be patient. It is the method I use because it is more of a pain getting the I-E frame back together sometimes.
Just make sure to protect the primary coil. If you happen to scratch it, but the wires are not broken through you can use nail polish or epoxy to fix the scratches. Once everything is working properly you can use epoxy to secure your new secondary cable to prevent unwanted vibrations. Vibration can wear off the insulation over time and short out the transformer.
>>917168
I only have one of transformer, do I really need 2 transformers like Grant Thompson did in the video? Can I make another transformer out of the welder I made, some metal, and copper wire?
>>917168
Also, how bad have I done goofed? Can it be fixed? Does it need to be?
>>915773
>>909889
>>915253
The reason WHY volts are used to measure danger as opposed to amps is because of the simple fact that, unless you built the damn thing, and even then, you don't know how much potential current it can deliver.
Just because a power supply says 600V 10mA doesn't mean that it can't deliver more in a surge current, that it just it's CONTINUOUS rating.
Many power supplies have output capacitors, and simply going by the "volts don't kill you, amps do" motif, ignores that, and inductive loads, wire capacitance, body capacitance, and various other properties of electronics.
This is what is effectively stated in the video from >>910169
For example, the output capacitors of a power supply, lets say 12V 3A. Safe right? Not because of the amp rating, but the Voltage.
Now another at 12KV @ 5mA. Should be safe because the supply would need 2 more mA directly to the heart to kill you right? Maybe, but what if it's not. What if the output capacitors in this supply are capable of delivering a few KJ of power? At 12KV and a skin resistance of say, 12Kohm, that's 1A of current flow.
The "it's not volts but amps" logic will get you killed if you don't understand that it only refers to the final current delivery across the heart. It is used to teach physics with ideals (a rather bad way) in highschool, NOT to determine whether a circuit is safe to make contact with or not.
Very few circuits are inherently current limiting. Even fewer are capable of preventing current surges. Even then you should never assume a circuit is an ideal model, because an ideal model is impossible.
This is why voltage is used to determine level of safety, not the other way around.
>>917188
>For example, the output capacitors of a power supply, lets say 12V 3A. Safe right? Not because of the amp rating, but the Voltage.
Try sticking it into your skin then. Bam, dead.
>>917191
12V 3A is the rating of the supply not the capacitor, as capacity in capacitors is not measured in amps., my mistake for not clarifying this on both power supply models. 4chan has a word limit.
However, a capacitor charged up to 12V is hardly enough voltage to conduct through skin, and even then at 12V (assuming our model human has a skin resistance of 12Kohm) can only deliver something like 1mA if it were to make a circuit.
Unless you thought that 12V was 12KV.
>>917199
a 9v battery can kill you.
>>917326
Only if you jab the electrodes into your body. Your exterior skin is a pretty fair insulator.
>>917326
By that logic, yes anything can kill you. Even air. Hell, walking can kill you if you do it right.
I'm talking about levels of safety here, not what can or can't kill you. Your point has nothing to do with what I'm saying. I never said 12V couldn't kill you. Just that it's safe. Based on it's VOLTAGE.
Very few people are going to purposely jab electrodes into their skin whilst live.
And if you know what you're doing you would be hard pressed to do it by accident.
Either way Voltage is how we judge how "safe" a circuit is.
>>917345
>By that logic, yes anything can kill you.
Logical fallacy.
Amps kill, not volts.
>>917413
That's nice
>>917413
>Logical fallacy.
I don't see where I've committed a logical fallacy here.
>Amps kill, not volts.
Well if you actually read my posts you'd know that I don't deny that.
The fact that you purposely didn't read them or ignored that show that you're either A.) Bait or B.) Being as autistic as I am about this, except for some reason think I'm denying that final current delivery is what technically "kills" you.
I'm simply saying the "Amps not Volts" statement is often used to gauge safety, which is very wrong and not what it is taught for, and deeming things safe based on this is a good way to get killed.
>>917425
>I don't see where I've committed a logical fallacy here.
>By that logic, yes anything can kill you.
https://yourlogicalfallacyis.com/
>>917445
not him. if anything, I thought this thread was long dead, but since I'm seeing it on the front page again, I'll engage.
The issue with that saying, is that it's reduced to a dichotomy which is entirely not true. The dangerous aspect when dealing with any electric charge is not just one of the two properties people appear not to have an understanding of.
It's a combination of both, and the constants of the human body. A current through a vital nervous system will be lethal, but no current would be present without the voltage. A high voltage device capable only of low amperage won't be lethal, but as several have tried to explain, the voltage of the output drops, limiting the current that flows, essentially rendering a lower voltage supply.
A high voltage high amperage (even if it stays this way for a few seconds) source will kill you.
A High voltage low current is harmless assuming that the maximum current is never exceeded. in essence, current regulation is instantaneous. All it would take is a capacitor or inductor to turn this into a harmful source.
A low voltage high amperage source is harmless to your nervous system, as an insignificant current will flow due a low voltage. It may set other shit on fire, though.
In reality it's a combination of both that present the real danger, although it wouldn't take much to turn a high voltage source into something dangerous to a human. The reason several people hate that saying is it creates a false sense of security among those that don't know any better, then get themselves hurt on a CRT, PSU, disposable camera cap, etc. thinking they're high voltage devices just not capable of high current.
Keep in mind that I'm not taking into account the body's capacitive properties, which make a clusterfuck of us at high frequencies.
Can we lay this to rest?
Less is more.
>>917445
That's the first time I've seen a shill in troll form on /diy/
>>917706
>pointing out logical fallacies is shilling
u wot?
>>917326
No, no it can not.
>>914178
power is energy per time. If you get shocked by an absolutely massive potential for an extremely short amount of time, you won't get hurt, because the total amount of energy you received is still low. That's exactly what happens in a static shock; the potential difference is huge, but the actual amount of accumulated charge (and thus the amount of energy you receive) is small; so it hurts, but you don't get fried.
>>917709
>https://yourlogicalfallacyis.com/
Well for one he didn't point out what the fallacy was. He was just using it as an ad hominem in the guise of logic.
'9v battery can kill you' is pretty stupid to say under normal circumstances. 9v is perfectly safe to rub all over your skin. So is 12v. It is only dangerous if you have open wound on opposite side of your body so you have a chance to fibrillate the heart (which is very good because your blood stream is the best path), or you need to have them stabbed in and leave them there like you're being tortured and can't remove them yourself because even 9 or 12v stabbed into your wet and conductive bits won't cook you instantly, you will have plenty of time to rip the probes out so long as you aren't restrained.
Saying '9v can kill' is this context is dumb as saying 'Drowning in a teaspoon of water is a real danger we all need to watch out for at work.' Yes it is possible, no it is not likely enough to worry about.
>>917709
>Replies to anon claiming he committed a fallacy
>anon doesn't understand what fallacy or where
>Instead of pointing out which fallacy, posts URL to website who's homepage want's like $20 for a poster.
If anon did commit a fallacy, it's likely the person claiming this would say which.
Nice job tho, You almost had me too.
6/10, might visit shills site again.
>>909835
Not welding goggles, but normal (transparent) goggles, spot welding tend to throw molten droplets around if you don't apply enough force to the electrodes.
"It's the bullets that kill you".
>>917715
>you need to have them stabbed in and leave them there like you're being tortured and can't remove them yourself
...and even then, when Chile did that to people on purpose, no-one died and they ended up having to dug them and fling them out a plane.
https://en.m.wikipedia.org/wiki/Parrilla_(torture)
>>918135
That isn't the same thing it is for torture not death.
http://www.darwinawards.com/darwin/darwin1999-50.html
>>918125
This is just as bad as that shitty water analogy people use for explaining electricity.
