/diy/ - Do It Yourself

Some vids of the 2 other spot welders I have been testing theories with,

MOT Spot Welder m4v (10.72MB) uses 8-strand 10AWG and 1 winding
http://www.mediafire.com/?k71cj181w7v78a3

Stereo Transformer Spot Welder m4v (12MB) uses 8-strand 12AWG 3 windings.
http://www.mediafire.com/?bgpv5onjgmwqy62

For the OP transformer, I'm planing on using something far larger than 10AWG wire. This time, I'm going to try to use a copper grounding rod for the secondary winding. It's 5/8 inch thick and from my calculations should be able to fit into the MOT for one complete winding. However, it is not insulated. I plan to buy some tool-dip (Plasti-dip Synthetic Rubber Coating) and once I get the coil made I'll dip it in. This should give it enough insulation to keep it fro grounding.shorting out on itself or the E-I frame. If that fails to squeeze in, I'll try the same thing with a few pieces of 4AWG wire twisted together, tinned, then tool-dipped.

Anyone have any ideas for MOT Spot/Arc welder designs? Like the housing, not the actual wiring and circuitry.

>>143806
Nice, reminds me of that super high current transformer Photonicinduction rewound with that massive cable.

>amp unto

It's funny. When I see a MOT welder with multiple MOTs they always have tons of windings for the secondary coil. I guess this is to keep the MOT cool and/or lower the amps enough to bring them to the right amp range for the sticks or material they are welding.

>>143810
2nd pic of this, not mine.

>>143807
lol Yeah, it's like he made a lightbulb with a screwdriver as the filament. Or a really hot heater at least.

>>143807
Didn't Photonicinduction get his youtube account deleted?

>Photonicinduction

MFW

>>143814
No....
http://www.youtube.com/watch?v=xI7RHeUixvY
he deleted it for these aforementioned reasons.
Quite depressing imo ;__;

>>143818
>copyright BS

It's the INTERNET. HERP DERP

>>143827
Yeah he is a little more butt-hurt then he needs to be, people need to not let shit like that get to them.

52 KB

Dumping some MOT Welder pics.

This one came from here,

http://www.dutchforce.com/~eforum/index.php?showtopic=15668

It seems the big copper secondary winding is a copper tube with copper wire inside.

Pic from here,

http://nakedproof.blogspot.com/2008/07/mot-welder-02.html

http://www.dutchforce.com/~eforum/index.php?s=397a0dd26cdfdd2c742f17655342a7f0&showtopic=17841&a
mp;a
mp;st=75

Man, I wish I had all those transformers!

>>144463
http://nakedproof.blogspot.com/2008/07/mot-welder-03.html

http://aaawelder.com/results.html

Nice looking build here, but I'd be afraid of overheating

>>144465

http://www.instructables.com/id/Make-a-240V-MOT-high-voltage-power-supply-with-120/

Looks like this instructable uses the capacitors from microwaves too.

http://www.instructables.com/id/Spot-Welder-from-a-microwave-oven-transformer-and-/

http://laserpointerforums.com/f48/mot-short-cool-spark-pictures-d-42802.html

http://www.instructables.com/id/Build-a-Microwave-Transformer-Homemade-Welder/?ALLSTEPS

>>144468
that one is pretty interesting
made portable inside a tool box
as for the heat issue, i would re mount all of that into a surplus ammo box, cut a fan hole on either end, install a computer fan in one hole, cover both with computer fan grills
same concept but with more durability and cooling

>>144475
oh i didnt see this, he did install a fan
still would go ammo box though, plastic when hot will melt

>>144475
>>144478

That is what I was thinking too.

This one, now this one is slick. All metal and a fan,

http://shaddack.twibright.com/projects/hw_SpotWelder/

>>144480
It even has a thermistor to protect from overheating. I have one from a toaster. I may put that to use on my MOT welder when I get to that part.

>>144481
HA that ones cute, all inside a pc power supply case :)

This looks very interesting. I still have a microwave transformer lying around, I knew it would come in handy one day!
How are these compared to retail welders? Do they quickly overheat when in use?

>>144507
>Do they quickly overheat when in use?

They are intended for light duty spot welders. If you want to make an arc welder or a higher duty spot welder you'll need to cool them or have several hooked together in order to spread the load out and not fry the primary coil.

>How are these compared to retail welders?

Like all things, it depends entirely on the design, the way you use it, and materials used to make it. Otherwise, you can build one that will outperform a $600 welder and make it 100% duty. But, the internet is rife with people who didn't count on them overheating, got their welding rod stuck and burned up one of the transformers because of lack of cooling.

http://www.dansworkshop.com/2008/03/homebuilt-arc-welder/

Nice one here with circuit diagrams.

>>145740

http://www.rcuniverse.com/forum/m_8265553/anchors_8622112/mpage_1/key_/anchor/tm.htm#8622112

http://www.dutchforce.com/~eforum/index.php?showtopic=23124&st=125&pid=301815&

Now this diagram is interesting. Two primary coils on one E-I frame with one secondary. I can see two primaries and two secondaries. They'd need to be properly phased I'm sure.

>>145741

How is that gate trigger circuit meant to work? By gate leakage? Or is something missing?

>>145757
D1 is a trigger diac, if that helps.

>>145757
This help?

C1: 600pf 2kv ceramic
C2: 0.1mf 400v epoxy
C3: 22mf 250v electrolytic
Q1: IRKT71 SCR module
Q2: Lamp dimmer triac
BR1: RB152 1A bridge rectifier
D1: Trigger diac
R1: 1M Linear potentiometer
R2: 5k Linear potentiometer

I've built a MOT welder, and it works too well. The current is way too high and it's only good with large workpieces, anything too small ends up melted. So I've been working on a saturable reactor (in series with the primary) to control the current, but it doesn't give me enough reduction, only a couple of amps. I've stuffed it with as many windings as I can, still not enough.
Anyone have any luck with these things?
I also have a large 30-ohm rheostat that someone gave me, said it would work fine. Thing is, it's got two ratings stamped on it, one says 10 amps and one says 3 amps. Both of which are too low, this thing draws 20 at worst. The rheostat gets ridiculously hot, too, so I'd rather use it to control a much lighter 3-amp load to the control winding of the sat. reactor.

>>146009
Which coil are you using the rheostat on? The primary where the source power is going to the transformer?

I did a quick test with one of mine by putting a 25w light bulb inline. It completely stopped the MOT from even sparking. I have a 5Amp fan speed controller/light dimmer I'm going to be trying on the primary side soon.

>>146040
I cut off the secondary, re-wounded it on the outer legs so no voltage is induced in the primary. I'm applying the control current to the primary.

>>146048
>re-wounded it on the outer legs

So you have 2 coils across those and is still too many amps? What watt was the appliance you got the transformer from?

>>146064
I have no idea the wattage. It's of average size, and average quality.
I built it like it is on this site: http://aaawelder.com/reactor.html

>>146069
Use thinner wire so you can wrap more times.

>>143833
>>143827
>>143818
>>143814

It sounds more like he's worried about kids and yahoos hurting themselves. When other people uploaded his videos it's many for ePenis reason and will put the kids/yahoos back at risk for pretty petty reasons. He probably has conscience and worries about that kind of stuff.

I don't worry as much so he's a torrent of his stuff I just found.
http://thepiratebay.se/torrent/6944756/Photonicinduction__s_Videos

Altho if anyones new to this kind of stuff I would join/visit a Hacker Space and consult with them before starting.
http://hackerspaces.org/wiki/List_of_Hacker_Spaces

>>147693
Thanks.

.

What is the thickest metal you can weld with one of these things? I mean >>146009 sounds like it could weld some really thick metal.

bumping this thread because i just got a free microwave from craigslist and i'm trying to get busy,

also general welding question:
whats the amps,volts to diode diameter? such as: how much juice is needed to weld with a 1/8 rod, 3/16 and so on? and how does this calculate to the thickness of what you can weld?

the microwave is a 960watt and is pretty new, the only case i got around is an old mac g3 case, will it work? trying to use this project to get self schooled on electrical.

>>150131
Yes, the 960watt MOT will work. I'm not sure about the case since I've not seen one in person. Make damn sure you slap some heat sinks on the MOT and blow at least one fan across it before you even start to use it. Remember it'll be like 5%-20% max duty cycle unless you have serious cooling for it. You'd get away with using it as a spot welder much easier. For stick welding it needs to be the right amps for the stick.. When you go to buy the sticks you'll be able to read the recommended amp range on the package.

If you get a cheap Clamp Meter from Harborfreight.com ($11-$19) you'll be better off since you'll be able to measure the actual volt/amps on the secondary wiring side.

If you need to weld deep you use the 70xx sticks with high amps. Otherwise, you should be able to weld 1/4" thick stuff.

http://www.millerwelds.com/resources/articles/index.php?page=articles16.html

>Current setting: The correct current, or amperage, setting primarily depends on the diameter and type of electrode selected. For example, a 1/8 in. 6010 rod runs well from 75 to 125 amps, while a 5/32 in. 7018 rod welds at currents up to 220 amps. The side of the electrode box usually indicates operating ranges. Select an amperage based on the material's thickness, welding position (about 15 percent less heat for overhead work compared to a flat weld) and observation of the finished weld. Most new welding machines have a permanent label that recommends amperage settings for a variety of electrodes and material thicknesses.

http://www.hobartwelders.com/elearning/

>all set to make a transformer oil-cooled MOT stick welder
>finally find a place to order transformer oil that's not 55-gallon minimum order or "price inquires only".
>order 1 gallon
>a few hours later I get a call from the company I ordered from
>they tell me they are back ordered and no other outlet of theirs carries it
>it'll be up to "a few weeks"

okay.jpg

I guess I'll just fiddle around with the spot welder stuff instead and figure up some more design ideas.

Is the transformer of a 800W microwave sufficient for a welder?

>>150563
>transformer oil

Can't you use something like motor oil?