I managed to acquire several 350 volt 10,000 uF capacitors second-hand. My (originally) cheap welder didn't have any. I connected them in tonight and I was impressed!
I had a warm-up without the caps, then added one (10,000 uF). That allowed me to actually weld on the lowest power setting where the welder used to sputter and make pigeon droppings. I got a nice little arc and it was very smooth - in fact at some settings it was almost silent! Welding very thin sheet steel was nice and controlled, which is what I want. I noticed that starting the arc seems 'soft' - I guess the voltage builds up more slowly as the caps charge. This didn't seem to be a problem though. I added a second cap in parallel, which made things even smoother (although probably not as noticeable as the first cap).
On higher power settings, it really sizzled, but also seemed less inclined to make holes in sheet steel - is this normal? I thought it was definitely a lot better than before.
At one point I was getting a strange arc with a really big gap and not a lot of heat. After a while I realised that the wire feed was too slow, but I didn't recognise it right away because I am used to it sputtering and surging if the feed is too slow.
I also noted that the caps hold some charge so I can get a spark off the torch well after I stop welding (and sometimes stick the wire end to the work...). People have mentioned the addition of a resistor to discharge the caps. Is this necessary / a good idea?
I have 4 of these 10,000 uF babies, but using 2 seems to work pretty well. Overall I am impressed, as it has certainly changed how it welds. I need test it on some real panel repairs now.
Thanks everyone for posts on this site with advice about things like capacitor addition!
I had a warm-up without the caps, then added one (10,000 uF). That allowed me to actually weld on the lowest power setting where the welder used to sputter and make pigeon droppings. I got a nice little arc and it was very smooth - in fact at some settings it was almost silent! Welding very thin sheet steel was nice and controlled, which is what I want. I noticed that starting the arc seems 'soft' - I guess the voltage builds up more slowly as the caps charge. This didn't seem to be a problem though. I added a second cap in parallel, which made things even smoother (although probably not as noticeable as the first cap).
On higher power settings, it really sizzled, but also seemed less inclined to make holes in sheet steel - is this normal? I thought it was definitely a lot better than before.
At one point I was getting a strange arc with a really big gap and not a lot of heat. After a while I realised that the wire feed was too slow, but I didn't recognise it right away because I am used to it sputtering and surging if the feed is too slow.
I also noted that the caps hold some charge so I can get a spark off the torch well after I stop welding (and sometimes stick the wire end to the work...). People have mentioned the addition of a resistor to discharge the caps. Is this necessary / a good idea?
I have 4 of these 10,000 uF babies, but using 2 seems to work pretty well. Overall I am impressed, as it has certainly changed how it welds. I need test it on some real panel repairs now.
Thanks everyone for posts on this site with advice about things like capacitor addition!