Question about AC welding machine

[RJSakowski]

When looking for a suitable candidate for a transformer, I would want one with power rating of 1 kva or more. This would be equivalent of an input current rating of around 10 amps. A lower rated transformer wouldn't have sufficient iron in the core and and the flux would saturate. In addition to a microwave transformer, a large battery charger transformer might work well. I have one with a 25 amp intermittent rating, so good for 3 kva in a low duty cycle mode. A spot welder is tupocally low duty cycle so it would be a good match. A thrirf possibility is a Variac. Replacement brushes are insanely expensive and many of the old Variacs are just scrapped. A 2 kva Variac should work well. The toroidal construction makes adding a high current secondary winding simple. Just strip off all the hardware and add the cable winding.

As to using MIG tips for the contacts, they will probably not work well. They have too much resistance for the amount of current required and would heat up excessively, causing distortion of the tip. You can buy spot welding tips on Amazon.

 

[Mutt]

I think Panasonic introduced the inverter microwave around 20 years ago, so you have to go back a ways.
Usually, the iron core models are heavier though so that's one way to tell
-M

Thanks. A friend of mine had a few old microwaves laying in the scrap pile. I picked up one and it didn't seem very heavy. Picked the other up and it was much heavier. Yanked a few screws and there it was. Got it out and fixing to start building the spot welder.

 

[markba633csi]

One thing to be aware of: The magnetron unit contains beryllium spacer pieces (usually pink or white) which are carcinogenic if broken and particles are inhaled
Try to avoid damaging the magnetron- it's the box-like thing with the cooling fins near the transformer
Also be careful of the large high voltage capacitor nearby it may still have some charge
-M

 

[Mutt]

I only remove the transformers and momentary switches out of them. The rest got to the scrap yard

 

[AGCB97]

I built one that didn't work very well. Now I have a harbor freight 220 volt

 

[Mutt]

I built one that didn't work very well. Now I have a harbor freight 220 volt

all this one has to do is spot weld 2 pieces of .060" steel together in 3 places. I have $14 tied up in it total.

So has anyone ever been actually been inside their 110v and the 220v from HF? They both look the same from the outside. I'm just curious if the only difference is the actual plug !!!!!!!!!!!! I mean, a coil of wire is a coil of wire.

 

[woodchucker]

One thing to be aware of: The magnetron unit contains beryllium spacer pieces (usually pink or white) which are carcinogenic if broken and particles are inhaled
Try to avoid damaging the magnetron- it's the box-like thing with the cooling fins near the transformer
Also be careful of the large high voltage capacitor nearby it may still have some charge
-M

I thought the beryllium is only dangerous if filed or sanded... dust being the problem? many tools are made of beryllium for use around MRI machines..

 

[AGCB97]

Let us know how it works.
Aaron

 

[Weldingrod1]

I have a switch to run my 220 HF spot welder on 120 vac when I want to be gentle. Works fine.
I've never played with the 120 version.

Sent from my SM-G892A using Tapatalk

 

[Lo-Fi]

The audio is not great, but this is a half hour of solid gold on spot welding: