/diy/ - Do It Yourself

doesn't matter at all.
Proceed

>>157570
thanks! while i'm here, has anyone every built a MOT welder with 1.4kw and 900w transformers or similar? i have 4,6 and 8 awg wire, any advise?

>>157573
Never build a welder but I have used them for 1to1 isolation transformers. In idle they do get hot after a while (in 10 minutes or sooner) which indicated that either the steel is shitty and is suffer from Eddy current losses. Or the primary is over saturating the core. Or / and the prower factor is bad so you might want to connect a household watt meter and start adding some Ac motor capacitors and see if you can correct the power factor and drop the losses.

yo diy/hards did i fuck up this MOT wat do?

>>157570
I'm seconding what this anon has posted.

>>157573
I have.

Use a massively thick secondary winding. The fewer the winds the more amps. You can even make it with 1 winding for the secondary coil. the duty cycle will be extremely low for a single MOT welder or even 2 MOT welder. The more MOT you have the higher the duty cycle.

However, the duty cycle is only low because of the intense heat build up in the primary wiring. If you attach heat sinks to the metal chassis and very very carefully attach some to the primary coil and blow a fan across them it'll increase the duty cycle. Use of a dielectric coolant like transformer oil (mineral oil) will vastly increase the duty cycle of a single MOT welder.

>>159533
The primary wiring looks like it's been cut on the front. If that is true then yes, unless you can connect the cut pieces without shorting it out on the frame or each other.
Otherwise, its still fine, but would suffer from some magnetic field problems like eddy currents. It'd still work pretty well though.

>>159543
Here's a couple test vids of mine,

Stereo Transformer Spot Welder
http://www.mediafire.com/?bgpv5onjgmwqy62

MOT Spot Welder
http://www.mediafire.com/?k71cj181w7v78a3

I'm making a 3rd one that will be an arc/stick welder. I'm currently waiting for my shipment of transformer oil for it. To make a stick welder you really need serious cooling. Otherwise, the duty cycle will be so low that you won't be able to use it much and if the stick gets stuck it'll fry the transformer before you can get it unstuck or shut off.

If you know some electronics you can use a thermal switch on the transformer to shut it off in case it gets too hot. You can get those from toasters and overhead projectors. Basically, it's a solenoid that trips when it's too hot.

>>159544
FYI, the stereo transformer is 560 watt and the MOT in the video is from a 960 watt microwave. My 3rd one, pictured here, is from a 1,450 watt microwave.

The 960 watt MOT performs very well as a MOT Spot Welder, but the duty cycle is very low. It has a single winding of 8-strand 10AWG wire as the secondary coil.

>>159544
>>159543

thanks for that, here's what I'm working with, finally got some juice, a 900 and a 1.4, what gauge wire has worked best? i've heard people say everything from 6 to 12 awg? opinions? will bump with OC and shit.
thanks again diy/hards.

better

some OC

>>159827
> i've heard people say everything from 6 to 12 awg? opinions?

It's best to have the thickest single core copper wiring you can fit into the secondary. Electrons like to flow through big corridors not little ones. For my 1.45KW transformer I'm going to "try" to shape a copper house grounding rod and coat it with tool dip as the secondary winding. It's like 5/8" thick and I might be able to get one winding with it.

For mine, I cut the welds off and removed the I from the E-I metal frame then slipped (hammered carefully) the coils off. This made it easier to put a new secondary coil on.

Best recommendations is to take a file or something and round off all the inside corners on the metal chassis so it won't cut into the wire you are winding as the secondary coil. I did that and still had shorting issues with the last one I did. I had to reinsulate the wiring about 6 times to get it right.

Get a multimeter and check to make sure your secondary wire is not grounding out/shorting out on the metal chassis BEFORE you ever turn it on. This is a MUST.

pic of the process for the 560 watt stereo transformer

>>159839
Nice.

Bumping because of similar subject here, so the OP can see it,

>>160313

bump, since this board is so slow Im going to bookmark it and read the thread tomorow

>>159839

Did anyone else look at the thumbnail for this and think it was a shit drawing for Auschwitz.