Answer to a frequent question: output voltage is 2.5V open circuit. Max. current is 5000A. The input voltage is about 240V 60A. It can operate on a 50A breaker as the duration of the current is short.
The density of useful content in these videos should shame 99.9% of RUclips "content creators". Some people are happy to watch a guy screw around in a lab, other people actually want to get shit done. I'm in the latter category and I need more of this.
first of all, thanks for sharing this videos with us. If i´m not mistaken, you said in the video that you made the spot welder yourself, would it be possible to explain a little bit more how you made it ?, i think yours is a piece of art and to know more would give us ideas for making better our own spot welder projects :)
It is quite simple: find yourself a 10 to 15KVA transformer with a 220-240V primary. Remove secondary and measure, using a piece of electrical wire, how many turns you need to get about 2.5-3V, typically 2-3 turns. Bend an anealed 1/2"x2" or 1/2"x1.5" copper bar into a secondary winding. Dismantle transformer lamination to install secondary. Transformer is switched by a 400V/75A solid state relay and timer (0.03-3 seconds). Secondary is coupled to moving electrode by a flexible cable or laminated copper cable with about 1" square cross section. If you find these instruction are not sufficient you should not attempt to build one, just get a used one or Chinese made one.
mawitonik Clamping is just an air cylinder activated (first) by same foot switch that turns the weld current on. The meter uses a current transformer, which is a toroid core with the primary being just the straight wire connecting the transformer to lower electrode (or a regular 50A AC ammmeter on the primary, cheap on EBay).
Thank you very much , this is a project that i've been wanting to make for a long time and i'm gonna give it a go again, i have a hundred more questions but i've taken enough of tour time, thanks so much, if i succed i'll try to post muy results.
powaybob You need a more powerful machine, ideally a capacitive discharge machine with a very short pulse so the heat does not dissipate. Not for beginners.
Dan, In your video, you mentioned that you did not use the power variator circuit. If I wanted to use the power variator, how does it work, and If I don't have one, do I need a current meter circuit?
Like, wow. After a quick check its a wonder he bothered to do these videos at all. It shows the humility and just downright goodness of the bloke to put these out to help others possibly go from idea to a sucessful prototype.
Dan, I learned more in 30 minutes about spot welding then I have in my entire life. Fantastic video. Thanks for taking the time to do this production. Dale Derry
This spot welder is amazing Dan! If you ever get inspired an "under the hood" video on it would be super interesting. Or any new videos from you for that sake. Thank you for takinging time and sharing this amazing video series with everyone.
The timer just counts cycles and controls a Solid State Relay. Current meter uses a current transformer, rectifier and holding circuit to hold reading or 60 seconds.
+Dan Gelbart Hi, Dan. Very impressive series of videos, and equally impressive homebuilt spot welder. Couple of questions on that unit if you don't mind... First, could you perhaps describe the circuit you're using to count cycles a bit more? The thumbwheels on your controller look like those on a typical timer relay but those are generally limited to triggering based on counts of 1/100ths, 1/10ths, etc. Haven't seen one of those that counts cycles. Second, do you do anything to detect that the electrodes have contacted the work before you initiate the weld? Seems to me you can't use a switch on the pneumatic stroke since you don't know how far down it'll go. So either you just assume that after a particular delay it must have contacted and clamped, or else you're doing one of: (a) monitoring air pressure to see that it's stabilized or (b) detecting closure of a circuit across the electrodes and using one of those to trigger the weld phase. Thanks! -Ben
+Benjamin Mitchell Weld power simply applied after a short delay. You can use a regular timer. When connected to a Solid State Relay in will only switch at the start of a cycle.
+Dan Gelbart Thanks for the speedy reply! Delay sounds like a much simpler approach to starting the weld so I'm glad that's the answer. Good to know on the timer. I'm thinking I may do the controls via arduino instead of a regular timer since it gives a bit more flexibility, but we'll see. Step one at this point is to find a big enough transformer to modify...
Hi Mr Gelbart, I have learned so much from you Dan, I can’t thank you enough. I’m almost certain that a man of your experience will know, but it is possible to spot weld two pieces of aluminum with a spot welder like yours, if you place two steel pieces between the aluminum parts and copper electrodes. See the following RUclips video from ‘Lazze’. The link is ‘ruclips.net/video/gcgC3V3mkcw/видео.html’. His RUclips name is ‘lazzemetalshaping’. I’m sure you know this trick already, but your viewers may find it useful. The steel generates the heat required as it will resist the flow of current. This then heats the aluminum. I don’t think the aluminum gets as hot as the steel, but the melting point of the aluminum metal (not the aluminum oxide) is lower. What do you think of this method Dan? Good idea, bad idea? :-)
Dear Dan! When I watched the first 5 minutes of the waterjet video, I could not stop until I watched them all. They were the best teaching course I’ve ever seen. In my entire life! They are so valuable for DIYers like me! I could spend decades experimenting and never invent such a laser pointer drill press centering jig!!! Or a webcam on a lathe!!!!! You are absolutely the genius! And I dream to ask you one question. In the spot welding video you count the welding exposure in “cycles”. What kind of a timer or a counter did you use to count AC cycles? All timers/time relays I was able to find online count seconds and decimal fractions of seconds. I did not find a single “cycle counter” which would be able to start counting from the zero crossing and have the complete AC cycles as a unit of counting. I think, this is important to minimize the welder’s interference to the power circuitry of a building and other negative effects. How such a device (AC cycle counter) is called correctly and where can I find it? Or all I wrote is a bullshit and I should not worry about this cycle counting when I build a spot welder? Thank you so-so much!
+Spock First, thanks for the kind words. Re cycle based timer: you are right, when I built it, over 40 years ago, the reason was to minimize interference. A counter was counting cycles and triggering a triac. Since it was built, solid state relays (SSRs) appeared and are inexpensive. Those relays are designed only to switch as the zero crossing of the AC line (again, to minimize interference) so you can use any timer to control them. A good range for the timer is 0-25 second in 0.01 sec intervalas. Most welds are done in under 0.1 seconds (3-5 cycles).
+Dan Gelbart Dear Dan, I could never dream of so quick answer, you really keep your finger on a pulse! The 0.01 second precise timer + solid state relay was my plan, but I was not sure how good they may work together until you told me. But still, did the cycle based timers exist 40 years ago before SSRs came, and disappeared nowadays because of no demand? Or you designed your timer yourself? (History is also very interesting, not only modern trends :) ). Thank you very much once again!
+Spock Designed my own as I had no money to buy anything those days. The spot welder was built from a 1/2" x4" CRS bar, the cover was already spot welded with the half finished welder.
+Dan Gelbart Dear Dan! I thought so, I thought so! :) You made my day month! Now I know enough to build my own welder (first prototype actually welded already). Yes, your welder is a piece of art as mawitonik said! Just THANK you!!!
I love practical engineers. This guy Dan Gelbert knows it's stuff, it speaks for itself. Not just theory but applied practice and experience. That, to me, is science square.
Wow so much good info in this video! I’m amazed at the way you can explain subjects in such an easy to understand manner. We may all benefit from your immense wealth of knowledge and hands-on experience, thankyou Dan
Not only have I not come across another video on spot welding which is half as informative about how to use it for a multitude of useful tasks, but I've yet to come across a spot welder build video that produces such a useful tool as you built yourself fifty years ago. The pneumatic closure and interchangeable tips take it to another level of useability. I'd love to build one for our hackspace, and the sheet metal bender you made around the same time would be very cool too.
Dan, thank You very much for taking the time to share Your knowledge! I learned more in 30 minutes about spot welding than I ever knew before. I am not a master machinist like You are, just an electronic engineer making my own prototypes for my line of work. Never figured a spot welder could be this versatile and useful for prototyping. It is now definitely on the WTB list for my shop. I really like Your design, I may try to copy it. I did once build a small capacitor based spotwelder for welding small wires for use under a microscope. The pulse was initially to fast causing gassing of the metal in the weld so the wire would not fuse to the base material well. In some cases I think You get a better result slowing down the current pulse a bit, there seems to be an optimum, but that is for much faster pulses than 50/60 Hz cycles of course. Best regards and thank You again, Erik
One problem for us was that contact pressure was limited due to the substrate being a rather soft circuit board that could not take very high forces . The wires were round and just a few 1/100 of a mm and usually tungsten or similar material very different from the substrate. Welding times i think was rather on the order of microseconds. My guess on why to fastest pulses did not work is that above a certain di/dt the thin wire seems to act similar to a EBW exploding bridgewire detonator type device and plasma pressure pushes the contacts apart. The result is just a spark, no fusion and also some undesirable metal plating on the surrounding structures. It did work when inductively limiting di/dt but the sweet spot was not so easy to find. I have also read about the double pulse method for capacitive welders where the first pulse creates a larger contact area and the second pulse fuses the weld, I guess to alleviate similar concerns. I do not know if that is practical for microscopic stuff due to the extremely short pulses required. Best regards and thank You again for Your excellent videos!
Hi! how you made the current limiter ? do you use a circuit ? I have 4 capsule diode 200v 6000A to make the rectifier and ceramic tube adjustable rheostat resistor 30x220 ohm 470 but how I can setting the current ?
hello Mr Gelbart thank you very much for sharing your knowledge, i would like to ask you at what voltage you spot welder operates and the reason for making the arms (what appears to me) out of solid copper bar. thanks again. Peter
The spot welder generates 2.5VAC at 5000A, so it can operate from a domestic 240V 50A outlet. If you have more power available I would go to 3.5VAC. You need the heavy copper bars to carry the current without losses.
thank you for taking your time to answer my question. i have 220 and think the circuit of my shop would handle 50 A max so i`ll have to downsize a bit. you say you would go to 3.5 vac, what would be the advantage over 2.5 vac. i`m planning to go as much as 14ga (2,1mm) but seeing you welding the balls have opened a big door for design. do you think i would still need the 5000A for this?
thebrokenbone In your case stay with 2.5V, as 3.5V will draw about 75A from your outlet. Max thickness you can weld will be a combined thickness of 5mm in steel and 6mm in stainless.
Dan Gelbart The answer can be use some large industrial capacitors to collect energy, and push really large current you need. The disadvantages as cost of this caps (I mean something this like www.energy-t.ru/media/zez2/compVN.jpg) and time waiting charge before each spot
The rating marked on circuit breakers is the *continuous* current. Brief pulses of higher current -- such as occur every time an electric motor are switched on (think about a refrigerator cycling on and off for decades) -- are fine and will not trip the breaker. There are limits; a direct line short should trip the breaker immediately. Circuit breakers and wire specifications are primarily intended to prevent fire and wire damage from overheating, and respond to the average heat dissipation. Wires are strung through the walls of houses; if not protected then they could become igniters. *Brief* pulses of high current simply do not have time to heat up the wires significantly. They are not a hazard, provided they are not so frequent as to push the average load above safe limits. If they *are* that frequent, the breaker will trip. Don't try to take this too far; use heavy wire, doesn't entirely apply to switches, etc. If you trip the breaker a lot, you have to start thinking about its contacts and what happens if the breaker fails shorted.
what type of solid state relay can you use to switch 5000A? My second question is what are the transformer specs? (Input Voltage, Phases Used, Output Voltage) thanks for your videos they are so great learned a lot so far.
The SSR is o the input side of the transformer, switching only 50-100A. The transformer is 240V primary, 2.5V secondary, 50A primary current. SSR needs to be rated higher because of transients.
sir you told the power of spot welding mch is15kva then the basic rating of the powertransformer is2.5v /6000A then my questation is how i can accomodate cu wire on the smaller size of the trans core crosssection my questation is can you give an guideline for the transformer design because the design is differ from conventional transformer.
The transformer is in intermittent use, which reduces heating constraints and allows use of smaller conductors than would be required for a continuous-duty transformer. Too small of conductors will however increase the secondary resistance and reduce the current capability.
Hi Dan, I love all the videos! Amazingly informative! I am building a welder and have designed a number of mechanisms for the linear motion... From looking at the fastener locations, none of them seem to match. This is a pretty basic question, but if you are willing, I am super curious about your design. Thank you!
@@dgelbart Thanks for the fast reply! From what I can tell there are two vertical plates bolted to the back of the front-sliding plate that engages the back of the front-fixed plate. That takes up all the clamping force. If this is correct, I'm wondering where the seating-force comes from that holds the sliding plate against the chassis when the jaws are open. I know there are many viable solutions here including off the shelf linear slides. I'm mostly asking because all of the solutions I have come up with don't seem to match yours and I'm sure yours is quite simple and clever.
This seems to be a doable build, and I am also interested in building a capacitive discharge welder. I can use regular 5amp outlet to charge it slowly and discharge through an scr across 2 sheets. weld more thickness by adding more capacitors. Can do Aluminum as well. But relatively, there's very little information on the net for sheet metal welding purpose. I think a 5 Farad 10v cap should do. but what kind of scr would this require? Is there anything else I require to know before building this? Thanks for the videos. I watched them all, now reading all comments in all videos. U are the best teacher I've had.
Spot welding is awesome. I bought a spot welder for a project basically because of this video, and it has been extremely useful for many things. I even used it to fix a broken sensor on my car, saved me $296 - pretty much paid for itself just with that.
Gosh that was so much information packed into a short video! I've just purchased an older type micro welder (made by Hirst in the UK) and am in at the deep end with it. This video has helped me no end to get the machine restored, tested and back into operation. I make metal flowers and the possibilities of such a machine are endless. Thanks for sharing this with us.
Hi... I am struggling with Ni-sheet welding.. since 2-3 months... I have 0.5 mm Ni-sheet. I want to spot weld it with another sheet of same size. But my electrode is getting melting ... arcing... oxidized joined... Please give me some idea...how I can achieve clean and strong welding
+Dan Gelbart Thanks for replying.... I am giving you detail of my work.. I am using Unitek -250 Welding Machine with following options: 1. Pulse set option : 1 to 3 pulse 2. Polarity : Straight/ reverse 3. Manual heat options 4. Switch up to 250 WS manual Presently I am using electrode of OFHC copper/ copper with tip dia 1.5-2 mm and want to weld two Ni--222 sheets of thickness 0.5-0.7 mm each. Up to 75 WS it is fine but above 75 to 250 WS it starts arching/ melting of electrode/ puncture of job/ oxidized welding area. So please suggest a solution. What are you general comments about surface roughness of the faces to be welded etc?
Dan Gelbart I should have asked a bit differently. Have you pressure tested any of the joints you have created with the silicon+spot weld technique? If so, what were your results? Thanks again!
Skyler Olsen I only leak tested, not pressure tested, the joints. I believe the pressure limit will be tearing out the welds and not the silicone rubber seal, as the seal is loaded in shear mode and has a large area. If you really worried about pressure better to TIG weld the edges.
Dan Gelbart Thanks again for the reply. Yea, TIG welding is the go to if this method doesn't work, just always have to worry about warping with larger panels. It sure would be great if your technique worked up to around 3 bar! I'll run some tests and report my findings.
What a great job! A couple (or a little more...) of questions: - when you say "cycle", do you mean a full 60 Hz cycle (16.7 ms), half of it (8.3 ms), or something else? - When you say 15 kVA, do you mean the size of the transformer used? - What are the open-circuit / full-load voltages of the secondary winding? - Is there anything between the secondary and the electrodes? Thanks in advance!
Cycle is a full 60Hz cycle, 15KVA is the size of the transformer, open circuit about 3V, more for a larger transformer. One side of secondary connected to moving electrode by flexible link made of many thin hard-rolled copper strips, about 5cm2 cross-section.
+Dan Gelbart Hey - can I ask you how you designed the 'clamping' mechanism? I am looking at using an offset crank-slider quick return type of design but am struggling a little with the details, such as how to make the motor stop at a predetermined pressure, then reverse itself to bring the arm back up.
Place the aluminum sheets between two pieces of stainless steel sheet. The heat from the stainless will melt the aluminum. This was a tip from one of the viewers!
I've never heard anyone say that glasses are good enough. No idea if that's true, but wearing safety glasses over regular glasses is an awful experience.
Try different safety glasses to find a better fit. Prescription safety glasses are available, $$$ though. Try (vented!) goggles. Much cheaper to replace and keep e.g. sawdust out of the eyes. Get glasses with big polycarbonate lenses, and there are side-shields that slip on.
2:47 I recall some time back someone spot welded aluminium sheets together by sandwiching the aluminium sheets between steel sheets. The heat generated by the electricity passing through the steel conducted to the aluminium and made the al sheets fuse together.
What is the diameter of the electrodes you are using? Also, I can't seem to find the copper alloy used for the tips on McMaster Carr. Thank you! Great video!
I just chose 12.7mm as electrode diameter. The inserted copper-chrome tips are 6.35mm (1/4"). McMaster carries the material under "copper alloy 182 rods".
Is there a good reference on spot welding ? I can find guidance on car panel welding and the largely automatic battery welders, but I have a device intended for precision welding at fairly low current (1000A) and it has a huge number of adjustments (pulse length, number of pulses, energy per pulse etc) that I have no idea how to optimise.
@@dgelbart Hi Dan, How did you insulate the horizontal Cu bars from the chassis of the spot welder? It appears the sliding mechanism is not electrically conductive, or there is a different way to hold the bars without completing the circuit.
The copper rods are insulated from the steel parts by thin fiberglass washers and sleeves. One rod is wired to the transformer with a flat copper bar, the moving one is connected via a flexible bar made by laminating many thin sheets.
@@dgelbart OK, thanks. I don't think I have room inside my project for anything that big though (TIG). And laser welding is most likely beyond what I could do at home, I think. Can you point me to design information on DIY pinch/spot welders anyway? I'd like to build a _SAFE_ small spot welder for my workshop -- I've heard too many bad things about the microwave PSU unit-based spot welders.
I already bought 1 on Ebay, too low powered. I have been looking for a more powerful model but not the huge industrial ones, with this model i could redesign the electrode holders and it would be perfect. I am interested in the component design of model.
Dan, if I can call you for your first name, I'm a native spanish speaker and maybe I did not understand all your technical specs about the machine, so I get to ask you, and I know you have been interrogated múltiple times bout it by people like me, interested in learning from you. What do you think about making a little spot welder powered by two twin microwave oven transformers of 1500 Watts each one, with their secondary coils rewinded with heavy copper wire? you stated the power in KVA, but the only thing I know about them is their consumption in Watts. Thanks in advance if you get the time to answer me, and sorry for my poor english.
+Gerónimo LEVRERO These are way too small transformers. Better to find a large one, at least 5KW (or KVA) and remove the secondary. KW and KVA rating are the same thing if the load is resistive. A 5KW transformer can easily supply 10KW for the short duration of the weld, which is under a second.
+Dan Gelbart Thank you so much for your fast answer to my message, I'll try to get a transformer from an Arc welder to make it. Of course, you're right about KW and KVA, just got a little confused when you said inductance increases as the electrodes lenght increases too, but a quick look at my notebooks clarified it for me. Sir, I must congratulate you for your excellent serie of vídeos, as an engineering student and enthusiastic "machinist", I find them way instructive and understandable.Many people gets benefits from your experience. Greetings from Uruguay and good luck!
+Dan Gelbart you are right again, I did not consider the movable Core, I will look for a common big monophase 220v transformer and rewind the secondary coil. I have 15 mm copper rods for the electrodes and I can machine them with my old Atlas 618. I think I heard 500A, but what should be the approximate voltage between terminals being the transformer without any charge? I mean in a machine like yours, I will not weld things thicker than 1/8"
+Dan Gelbart you are right again, I did not consider the movable Core, I will look for a common big monophase 220v transformer and rewind the secondary coil. I have 15 mm copper rods for the electrodes and I can machine them with my old Atlas 618. I think I heard 500A, but what should be the approximate voltage between terminals being the transformer without any charge? I mean in a machine like yours, I will not weld things thicker than 1/8"
Answer to a frequent question: output voltage is 2.5V open circuit. Max. current is 5000A. The input voltage is about 240V 60A. It can operate on a 50A breaker as the duration of the current is short.
The density of useful content in these videos should shame 99.9% of RUclips "content creators". Some people are happy to watch a guy screw around in a lab, other people actually want to get shit done. I'm in the latter category and I need more of this.
Yeah how many other billionaires would make something like this freely available?
@@daa3417 what are you talking about ? Who's the billionaire ?
@@TheNefastor Dan Gelbert is a self made billionaire.
You have an amazing mind Dan, a beautiful mind.
Fantastic knowledge you chare with us that still are interested in scients
first of all, thanks for sharing this videos with us. If i´m not mistaken, you said in the video that you made the spot welder yourself, would it be possible to explain a little bit more how you made it ?, i think yours is a piece of art and to know more would give us ideas for making better our own spot welder projects :)
It is quite simple: find yourself a 10 to 15KVA transformer with a 220-240V primary. Remove secondary and measure, using a piece of electrical wire, how many turns you need to get about 2.5-3V, typically 2-3 turns. Bend an anealed 1/2"x2" or 1/2"x1.5" copper bar into a secondary winding. Dismantle transformer lamination to install secondary. Transformer is switched by a 400V/75A solid state relay and timer (0.03-3 seconds). Secondary is coupled to moving electrode by a flexible cable or laminated copper cable with about 1" square cross section. If you find these instruction are not sufficient you should not attempt to build one, just get a used one or Chinese made one.
Thanks a lot for your awnser, how did you make the automatic mechanical clampling and meters? Your help is much appreciated.
mawitonik Clamping is just an air cylinder activated (first) by same foot switch that turns the weld current on. The meter uses a current transformer, which is a toroid core with the primary being just the straight wire connecting the transformer to lower electrode (or a regular 50A AC ammmeter on the primary, cheap on EBay).
Thank you very much , this is a project that i've been wanting to make for a long time and i'm gonna give it a go again, i have a hundred more questions but i've taken enough of tour time, thanks so much, if i succed i'll try to post muy results.
Dan Gelbart those are just great idea, i've never touht of using flat stock copper for the secondary of a spot welder.
What is the input voltage and current for this awesome spot welder?
Your videos are great! Thanks. The sheet metal shop at HP routinely spot welded aluminum. Were they using a different type of machine?
powaybob You need a more powerful machine, ideally a capacitive discharge machine with a very short pulse so the heat does not dissipate. Not for beginners.
Mentioned in other posts: sandwich the aluminum between 'heater' pieces of higher resistance material such as steel.
Dan, In your video, you mentioned that you did not use the power variator circuit. If I wanted to use the power variator, how does it work, and If I don't have one, do I need a current meter circuit?
+John Leech Works just like a light dimmer but with high power triac (50-100A rating). Believe me, you'll never use it.
Your microphone battery is going flat .
These videos are solid gold. There should be some award for such channels. Thank you.
After a short investigation, guess mr.Gelbart wouldn't care much about more awards :D
visnevskiscom You aren’t kidding!
Like, wow.
After a quick check its a wonder he bothered to do these videos at all. It shows the humility and just downright goodness of the bloke to put these out to help others possibly go from idea to a sucessful prototype.
The man sold one of his companies for a billion dollars 40 years ago.
Dan, I learned more in 30 minutes about spot welding then I have in my entire life. Fantastic video. Thanks for taking the time to do this production.
Dale Derry
This spot welder is amazing Dan! If you ever get inspired an "under the hood" video on it would be super interesting. Or any new videos from you for that sake. Thank you for takinging time and sharing this amazing video series with everyone.
The timer just counts cycles and controls a Solid State Relay. Current meter uses a current transformer, rectifier and holding circuit to hold reading or 60 seconds.
+Dan Gelbart Hi, Dan. Very impressive series of videos, and equally impressive homebuilt spot welder. Couple of questions on that unit if you don't mind...
First, could you perhaps describe the circuit you're using to count cycles a bit more? The thumbwheels on your controller look like those on a typical timer relay but those are generally limited to triggering based on counts of 1/100ths, 1/10ths, etc. Haven't seen one of those that counts cycles.
Second, do you do anything to detect that the electrodes have contacted the work before you initiate the weld? Seems to me you can't use a switch on the pneumatic stroke since you don't know how far down it'll go. So either you just assume that after a particular delay it must have contacted and clamped, or else you're doing one of: (a) monitoring air pressure to see that it's stabilized or (b) detecting closure of a circuit across the electrodes and using one of those to trigger the weld phase.
Thanks!
-Ben
+Benjamin Mitchell Weld power simply applied after a short delay. You can use a regular timer. When connected to a Solid State Relay in will only switch at the start of a cycle.
+Dan Gelbart Thanks for the speedy reply! Delay sounds like a much simpler approach to starting the weld so I'm glad that's the answer. Good to know on the timer. I'm thinking I may do the controls via arduino instead of a regular timer since it gives a bit more flexibility, but we'll see. Step one at this point is to find a big enough transformer to modify...
Hi Mr Gelbart,
I have learned so much from you Dan, I can’t thank you enough. I’m almost certain that a man of your experience will know, but it is possible to spot weld two pieces of aluminum with a spot welder like yours, if you place two steel pieces between the aluminum parts and copper electrodes. See the following RUclips video from ‘Lazze’. The link is ‘ruclips.net/video/gcgC3V3mkcw/видео.html’. His RUclips name is ‘lazzemetalshaping’.
I’m sure you know this trick already, but your viewers may find it useful. The steel generates the heat required as it will resist the flow of current. This then heats the aluminum. I don’t think the aluminum gets as hot as the steel, but the melting point of the aluminum metal (not the aluminum oxide) is lower. What do you think of this method Dan? Good idea, bad idea? :-)
Yes, this is a great trick and will work. I did not know it. Thanks!
"Home made one"... You're putting so much pressure on my house Dr. Gelbart.
I know right! I havent seen a DIY spot welder like that, just the typical microwave transformer one
I never wanted a spot welder. Then I watched this video. Now I NEED one. Thanks! :)
Just another big thank you Mr. Gelbart for your generosity in sharing all your knowledge. Priceless stuff.
The craftsman is not only a good teacher he is a fabrication genius! :) Liked !
Dear Dan!
When I watched the first 5 minutes of the waterjet video, I could not stop until I watched them all. They were the best teaching course I’ve ever seen. In my entire life! They are so valuable for DIYers like me! I could spend decades experimenting and never invent such a laser pointer drill press centering jig!!! Or a webcam on a lathe!!!!! You are absolutely the genius!
And I dream to ask you one question. In the spot welding video you count the welding exposure in “cycles”. What kind of a timer or a counter did you use to count AC cycles? All timers/time relays I was able to find online count seconds and decimal fractions of seconds. I did not find a single “cycle counter” which would be able to start counting from the zero crossing and have the complete AC cycles as a unit of counting. I think, this is important to minimize the welder’s interference to the power circuitry of a building and other negative effects. How such a device (AC cycle counter) is called correctly and where can I find it? Or all I wrote is a bullshit and I should not worry about this cycle counting when I build a spot welder? Thank you so-so much!
+Spock First, thanks for the kind words. Re cycle based timer: you are right, when I built it, over 40 years ago, the reason was to minimize interference. A counter was counting cycles and triggering a triac. Since it was built, solid state relays (SSRs) appeared and are inexpensive. Those relays are designed only to switch as the zero crossing of the AC line (again, to minimize interference) so you can use any timer to control them. A good range for the timer is 0-25 second in 0.01 sec intervalas. Most welds are done in under 0.1 seconds (3-5 cycles).
+Dan Gelbart Dear Dan, I could never dream of so quick answer, you really keep your finger on a pulse! The 0.01 second precise timer + solid state relay was my plan, but I was not sure how good they may work together until you told me. But still, did the cycle based timers exist 40 years ago before SSRs came, and disappeared nowadays because of no demand? Or you designed your timer yourself? (History is also very interesting, not only modern trends :) ). Thank you very much once again!
+Spock Designed my own as I had no money to buy anything those days. The spot welder was built from a 1/2" x4" CRS bar, the cover was already spot welded with the half finished welder.
+Dan Gelbart Dear Dan! I thought so, I thought so! :) You made my day month! Now I know enough to build my own welder (first prototype actually welded already). Yes, your welder is a piece of art as mawitonik said! Just THANK you!!!
I love practical engineers. This guy Dan Gelbert knows it's stuff, it speaks for itself. Not just theory but applied practice and experience. That, to me, is science square.
Surely that enclosure is not big enough for a 15kVa transformer? or is it mounted remotely?
The transformer is actually 10KVA, but because of the intermittent use it can deliver 15KVA. It is about 4"x8"x8".
Great video! All of your hand made machines look so beautiful. Could you please consider showing your viewers how you made them? Thanks
Wow so much good info in this video! I’m amazed at the way you can explain subjects in such an easy to understand manner. We may all benefit from your immense wealth of knowledge and hands-on experience, thankyou Dan
I have never welded, nor do I plan to in the foreseen future. I accidently clicked on this video and cannot stop watching.
Thanks for sharing the knowledge. Been watching all the RUclips videos, really appreciate your work.
Not only have I not come across another video on spot welding which is half as informative about how to use it for a multitude of useful tasks, but I've yet to come across a spot welder build video that produces such a useful tool as you built yourself fifty years ago. The pneumatic closure and interchangeable tips take it to another level of useability.
I'd love to build one for our hackspace, and the sheet metal bender you made around the same time would be very cool too.
Dan, thank You very much for taking the time to share Your knowledge!
I learned more in 30 minutes about spot welding than I ever knew before.
I am not a master machinist like You are, just an electronic engineer making my own prototypes for my line of work. Never figured a spot welder could be this versatile and useful for prototyping. It is now definitely on the WTB list for my shop. I really like Your design, I may try to copy it.
I did once build a small capacitor based spotwelder for welding small wires for use under a microscope. The pulse was initially to fast causing gassing of the metal in the weld so the wire would not fuse to the base material well. In some cases I think You get a better result slowing down the current pulse a bit, there seems to be an optimum, but that is for much faster pulses than 50/60 Hz cycles of course.
Best regards and thank You again, Erik
Short pulses should not be a problem if sufficient pressure is applier. I have a capacitive spot welder as well.
One problem for us was that contact pressure was limited due to the substrate being a rather soft circuit board that could not take very high forces . The wires were round and just a few 1/100 of a mm and usually tungsten or similar material very different from the substrate. Welding times i think was rather on the order of microseconds. My guess on why to fastest pulses did not work is that above a certain di/dt the thin wire seems to act similar to a EBW exploding bridgewire detonator type device and plasma pressure pushes the contacts apart. The result is just a spark, no fusion and also some undesirable metal plating on the surrounding structures. It did work when inductively limiting di/dt but the sweet spot was not so easy to find. I have also read about the double pulse method for capacitive welders where the first pulse creates a larger contact area and the second pulse fuses the weld, I guess to alleviate similar concerns. I do not know if that is practical for microscopic stuff due to the extremely short pulses required.
Best regards and thank You again for Your excellent videos!
Incredibly smart and eloquent man. Thankyou for capturing these videos.
Excellent. No hesitation when explaining shows just how well you know your subject.Thanks for the information,
Keeping in mind that hesitation can also be an indication of pausing to think or to find better wording.
Hi! how you made the current limiter ? do you use a circuit ? I have 4 capsule diode 200v 6000A to make the rectifier and ceramic tube adjustable rheostat resistor 30x220 ohm 470 but how I can setting the current ?
You don't really need the current limiter and for sure you don't need a rectifier.
Pro level...when you build your own one.
Thank you for this very clear and professional video.
hello Mr Gelbart thank you very much for sharing your knowledge, i would like to ask you at what voltage you spot welder operates and the reason for making the arms (what appears to me) out of solid copper bar. thanks again. Peter
The spot welder generates 2.5VAC at 5000A, so it can operate from a domestic 240V 50A outlet. If you have more power available I would go to 3.5VAC. You need the heavy copper bars to carry the current without losses.
thank you for taking your time to answer my question. i have 220 and think the circuit of my shop would handle 50 A max so i`ll have to downsize a bit. you say you would go to 3.5 vac, what would be the advantage over 2.5 vac. i`m planning to go as much as 14ga (2,1mm) but seeing you welding the balls have opened a big door for design. do you think i would still need the 5000A for this?
thebrokenbone In your case stay with 2.5V, as 3.5V will draw about 75A from your outlet. Max thickness you can weld will be a combined thickness of 5mm in steel and 6mm in stainless.
Dan Gelbart The answer can be use some large industrial capacitors to collect energy, and push really large current you need. The disadvantages as cost of this caps (I mean something this like www.energy-t.ru/media/zez2/compVN.jpg) and time waiting charge before each spot
The rating marked on circuit breakers is the *continuous* current. Brief pulses of higher current -- such as occur every time an electric motor are switched on (think about a refrigerator cycling on and off for decades) -- are fine and will not trip the breaker. There are limits; a direct line short should trip the breaker immediately.
Circuit breakers and wire specifications are primarily intended to prevent fire and wire damage from overheating, and respond to the average heat dissipation. Wires are strung through the walls of houses; if not protected then they could become igniters. *Brief* pulses of high current simply do not have time to heat up the wires significantly. They are not a hazard, provided they are not so frequent as to push the average load above safe limits. If they *are* that frequent, the breaker will trip.
Don't try to take this too far; use heavy wire, doesn't entirely apply to switches, etc. If you trip the breaker a lot, you have to start thinking about its contacts and what happens if the breaker fails shorted.
what type of solid state relay can you use to switch 5000A?
My second question is what are the transformer specs? (Input Voltage, Phases Used, Output Voltage)
thanks for your videos they are so great learned a lot so far.
The SSR is o the input side of the transformer, switching only 50-100A. The transformer is 240V primary, 2.5V secondary, 50A primary current. SSR needs to be rated higher because of transients.
sir you told the power of spot welding mch is15kva then the basic rating of the powertransformer is2.5v /6000A then my questation is how i can accomodate cu wire on the smaller size of the trans core crosssection my questation is can you give an guideline for the transformer design because the design is differ from conventional transformer.
The primary winding is conventional, the secondary is about 2 turns of an annealed copper bar with a cross section of at least 8 square cm.
The transformer is in intermittent use, which reduces heating constraints and allows use of smaller conductors than would be required for a continuous-duty transformer.
Too small of conductors will however increase the secondary resistance and reduce the current capability.
Still one of the best videos on YT.
Hi Dan,
I love all the videos! Amazingly informative! I am building a welder and have designed a number of mechanisms for the linear motion... From looking at the fastener locations, none of them seem to match. This is a pretty basic question, but if you are willing, I am super curious about your design. Thank you!
Mine uses a homemade track, where the front steel plate forms part of the track.
@@dgelbart Thanks for the fast reply! From what I can tell there are two vertical plates bolted to the back of the front-sliding plate that engages the back of the front-fixed plate. That takes up all the clamping force. If this is correct, I'm wondering where the seating-force comes from that holds the sliding plate against the chassis when the jaws are open. I know there are many viable solutions here including off the shelf linear slides. I'm mostly asking because all of the solutions I have come up with don't seem to match yours and I'm sure yours is quite simple and clever.
That's cool, I like what you did there ;)
This seems to be a doable build, and I am also interested in building a capacitive discharge welder. I can use regular 5amp outlet to charge it slowly and discharge through an scr across 2 sheets. weld more thickness by adding more capacitors. Can do Aluminum as well.
But relatively, there's very little information on the net for sheet metal welding purpose.
I think a 5 Farad 10v cap should do.
but what kind of scr would this require? Is there anything else I require to know before building this?
Thanks for the videos. I watched them all, now reading all comments in all videos. U are the best teacher I've had.
Spot welding is awesome. I bought a spot welder for a project basically because of this video, and it has been extremely useful for many things. I even used it to fix a broken sensor on my car, saved me $296 - pretty much paid for itself just with that.
Gosh that was so much information packed into a short video!
I've just purchased an older type micro welder (made by Hirst in the UK) and am in at the deep end with it. This video has helped me no end to get the machine restored, tested and back into operation. I make metal flowers and the possibilities of such a machine are endless.
Thanks for sharing this with us.
Hi... I am struggling with Ni-sheet welding.. since 2-3 months... I have 0.5 mm Ni-sheet. I want to spot weld it with another sheet of same size. But my electrode is getting melting ... arcing... oxidized joined... Please give me some idea...how I can achieve clean and strong welding
+Shivendra Maurya Use Cu-Cr electrode tips, high current and pressure, short weld time. Typical setting 5000A for 3 cycles or 10,000A for 1 cycle.
+Dan Gelbart Thanks for replying.... I am giving you detail of my work.. I am using Unitek -250 Welding Machine with following options:
1. Pulse set option : 1 to 3 pulse
2. Polarity : Straight/ reverse
3. Manual heat options
4. Switch up to 250 WS manual
Presently I am using electrode of OFHC copper/ copper with tip dia 1.5-2 mm and want to weld two Ni--222 sheets of thickness 0.5-0.7 mm each. Up to 75 WS it is fine but above 75 to 250 WS it starts arching/ melting of electrode/ puncture of job/ oxidized welding area. So please suggest a solution.
What are you general comments about surface roughness of the faces to be welded etc?
+Shivendra Maurya No experience with the Unitek. Would try larger electrodes with spherical tips.
thank you very much for this series !! :)
Dan! Good stuff! I'm here bc of Dale Derry...oh look, there he is right below this comment!
I am amazed of the fine educational video you are providing for us all on RUclips.
What type of pressures you have been able to seal with the silicon+spot weld lap joint? Thanks in advance!
Skyler Olsen Typically a spot welder is set for about 100Kg, and this is ample for sealing.
Dan Gelbart I should have asked a bit differently. Have you pressure tested any of the joints you have created with the silicon+spot weld technique? If so, what were your results? Thanks again!
Skyler Olsen I only leak tested, not pressure tested, the joints. I believe the pressure limit will be tearing out the welds and not the silicone rubber seal, as the seal is loaded in shear mode and has a large area. If you really worried about pressure better to TIG weld the edges.
Dan Gelbart Thanks again for the reply. Yea, TIG welding is the go to if this method doesn't work, just always have to worry about warping with larger panels. It sure would be great if your technique worked up to around 3 bar! I'll run some tests and report my findings.
What a great job!
A couple (or a little more...) of questions:
- when you say "cycle", do you mean a full 60 Hz cycle (16.7 ms), half of it (8.3 ms), or something else?
- When you say 15 kVA, do you mean the size of the transformer used?
- What are the open-circuit / full-load voltages of the secondary winding?
- Is there anything between the secondary and the electrodes?
Thanks in advance!
Cycle is a full 60Hz cycle, 15KVA is the size of the transformer, open circuit about 3V, more for a larger transformer. One side of secondary connected to moving electrode by flexible link made of many thin hard-rolled copper strips, about 5cm2 cross-section.
A great video. Thank you very much.
1) Current discharge rate and
2) time factor.....
What about Pressure factor
Any pressure required for spot .... ?
The more pressure the better. Shorter times are better but no less than half a cycle (8mS) for thin parts a fe cycles for thick parts.
thank you sir, i wish i knew some of those kinks 40 years ago!
+Dan Gelbart Hey - can I ask you how you designed the 'clamping' mechanism? I am looking at using an offset crank-slider quick return type of design but am struggling a little with the details, such as how to make the motor stop at a predetermined pressure, then reverse itself to bring the arm back up.
uses air cylinder.
Sir nice and deep explanation ....
What to do if aluminium spot welding....?
Place the aluminum sheets between two pieces of stainless steel sheet. The heat from the stainless will melt the aluminum. This was a tip from one of the viewers!
Talking about safety: is it problem you pushing your finger between electordes ? What pressure does this weld machine do ?
Dmitry PonyatovLess dangerous than other foot-pedal activated machine with higher pressures (press brake etc).
I've never heard anyone say that glasses are good enough. No idea if that's true, but wearing safety glasses over regular glasses is an awful experience.
Try different safety glasses to find a better fit.
Prescription safety glasses are available, $$$ though.
Try (vented!) goggles. Much cheaper to replace and keep e.g. sawdust out of the eyes.
Get glasses with big polycarbonate lenses, and there are side-shields that slip on.
2:47 I recall some time back someone spot welded aluminium sheets together by sandwiching the aluminium sheets between steel sheets. The heat generated by the electricity passing through the steel conducted to the aluminium and made the al sheets fuse together.
SUPER
learned a lot. thank you!
your the legend
"Strange electrodes" Would be a wonderful name for a book.
What is the diameter of the electrodes you are using? Also, I can't seem to find the copper alloy used for the tips on McMaster Carr. Thank you! Great video!
I just chose 12.7mm as electrode diameter. The inserted copper-chrome tips are 6.35mm (1/4"). McMaster carries the material under "copper alloy 182 rods".
@@dgelbart Thank you so much for your reply! I'm learning so much from your videos.
Is there a good reference on spot welding ? I can find guidance on car panel welding and the largely automatic battery welders, but I have a device intended for precision welding at fairly low current (1000A) and it has a huge number of adjustments (pulse length, number of pulses, energy per pulse etc) that I have no idea how to optimise.
Look under "resistance welding". In your welder just use one pulse, 1-10mS, maximum current.
@@dgelbart Hi Dan, How did you insulate the horizontal Cu bars from the chassis of the spot welder? It appears the sliding mechanism is not electrically conductive, or there is a different way to hold the bars without completing the circuit.
The copper rods are insulated from the steel parts by thin fiberglass washers and sleeves. One rod is wired to the transformer with a flat copper bar, the moving one is connected via a flexible bar made by laminating many thin sheets.
Dan, can you point to design information about pinch/spot welders for "welding" ~30 gauge copper wires together?
Copper can not be spot welded easily but can be TIG welded or laser welded nicely.
@@dgelbart OK, thanks. I don't think I have room inside my project for anything that big though (TIG). And laser welding is most likely beyond what I could do at home, I think.
Can you point me to design information on DIY pinch/spot welders anyway? I'd like to build a _SAFE_ small spot welder for my workshop -- I've heard too many bad things about the microwave PSU unit-based spot welders.
@@bobvines00 Google "resistance welding".
sir where from ican collect cu chrome alloy or equvalent material for tips please help. thank you.
You can easily buy it, for example from McMaster-Carr in the US.
McMaster-Carr sells spot welder tips, as do other companies.
Where can i get this spot welder?
You have to build it, but you can buy on Ebay lower power ones quite cheap. .
I already bought 1 on Ebay, too low powered. I have been looking for a more powerful model but not the huge industrial ones, with this model i could redesign the electrode holders and it would be perfect. I am interested in the component design of model.
Dan, if I can call you for your first name, I'm a native spanish speaker and maybe I did not understand all your technical specs about the machine, so I get to ask you, and I know you have been interrogated múltiple times bout it by people like me, interested in learning from you. What do you think about making a little spot welder powered by two twin microwave oven transformers of 1500 Watts each one, with their secondary coils rewinded with heavy copper wire? you stated the power in KVA, but the only thing I know about them is their consumption in Watts. Thanks in advance if you get the time to answer me, and sorry for my poor english.
+Gerónimo LEVRERO These are way too small transformers. Better to find a large one, at least 5KW (or KVA) and remove the secondary. KW and KVA rating are the same thing if the load is resistive. A 5KW transformer can easily supply 10KW for the short duration of the weld, which is under a second.
+Dan Gelbart Thank you so much for your fast answer to my message, I'll try to get a transformer from an Arc welder to make it. Of course, you're right about KW and KVA, just got a little confused when you said inductance increases as the electrodes lenght increases too, but a quick look at my notebooks clarified it for me. Sir, I must congratulate you for your excellent serie of vídeos, as an engineering student and enthusiastic "machinist", I find them way instructive and understandable.Many people gets benefits from your experience. Greetings from Uruguay and good luck!
+Gerónimo LEVRERO Arc welder transformer are not good for that (have a special design) . Just get an old power transformer.
+Dan Gelbart you are right again, I did not consider the movable Core, I will look for a common big monophase 220v transformer and rewind the secondary coil. I have 15 mm copper rods for the electrodes and I can machine them with my old Atlas 618. I think I heard 500A, but what should be the approximate voltage between terminals being the transformer without any charge? I mean in a machine like yours, I will not weld things thicker than 1/8"
+Dan Gelbart you are right again, I did not consider the movable Core, I will look for a common big monophase 220v transformer and rewind the secondary coil. I have 15 mm copper rods for the electrodes and I can machine them with my old Atlas 618. I think I heard 500A, but what should be the approximate voltage between terminals being the transformer without any charge? I mean in a machine like yours, I will not weld things thicker than 1/8"