Thoughts on this used welder?

[joshuabardwell]

I went ahead and ordered the diodes just now. The originals were 70 amps and 300 volts. The closest match I could find was 70 amps and 600 volts, but in the interest of beefiness, I ordered a set of 85 amp / 600 volt diodes. It was a difference of $3 each. My Internet research suggests that the higher amp rating will make them more forgiving of heat and will increase their duty cycle (if not the duty cycle of the other welder components). The higher voltage will make them more resistant to damage from voltage spikes. I also got some thermal paste, which is supposed to significantly improve their ability to transfer heat to the aluminum heat sinks. With any luck, I'll be DC welding before too long!

 

[k0ua]

I went ahead and ordered the diodes just now. The originals were 70 amps and 300 volts. The closest match I could find was 70 amps and 600 volts, but in the interest of beefiness, I ordered a set of 85 amp / 600 volt diodes. It was a difference of $3 each. My Internet research suggests that the higher amp rating will make them more forgiving of heat and will increase their duty cycle (if not the duty cycle of the other welder components). The higher voltage will make them more resistant to damage from voltage spikes. I also got some thermal paste, which is supposed to significantly improve their ability to transfer heat to the aluminum heat sinks. With any luck, I'll be DC welding before too long!

I agree with your substitutions and reasoning. I hope you are welding DC soon too!

 

[CNC Dan]

I agree with your substitutions and reasoning. I hope you are welding DC soon too!

Me too. You are realy going to like DC welding

 

[joshuabardwell]

The diodes came today and I just got finished installing them. My little 30 watt soldering iron couldn't even begin to make a dent on those thick wires. I have a small butane torch that came with a soldering tip, so I tried that and it was even worse. I ended up basically brazing the connections with the torch's open flame instead of soldering them. I tried to be very careful not to overheat the diodes. On the last one, I must have been directing the heat somewhere other than where I thought I was, because the solder kept on not fluxing, and then all of the sudden I noticed that the body of the diode had taken on a slight brass color, instead of the gray steel that the others had. Oops! I quit heating it immediately and once it cooled down, it measured the same on the multimeter as the others. The rod will tell the tale! I'm about to go clean off a piece of scrap and run a bead.

 

[dex3361]

The diodes came today and I just got finished installing them. My little 30 watt soldering iron couldn't even begin to make a dent on those thick wires. I have a small butane torch that came with a soldering tip, so I tried that and it was even worse. I ended up basically brazing the connections with the torch's open flame instead of soldering them. I tried to be very careful not to overheat the diodes. On the last one, I must have been directing the heat somewhere other than where I thought I was, because the solder kept on not fluxing, and then all of the sudden I noticed that the body of the diode had taken on a slight brass color, instead of the gray steel that the others had. Oops! I quit heating it immediately and once it cooled down, it measured the same on the multimeter as the others. The rod will tell the tale! I'm about to go clean off a piece of scrap and run a bead.

Well let us know how you like DC welding. You will be surprised.

 

[john_bud]

I'm late to the party here, but your "work" pictures seem to be just a bead on top of some metal. That's really pretty limiting. You should be cutting that scrap of metal apart and welding it back.

The difference between a good welder and a novice is in large part the prep work done. Pre-fitting, tack welding, grinding bevels, etc etc. Then you have to learn to listen to the arc.

One tip on method. Your beads don't really show that you are moving the rod side to side in a "C" shaped motion. It also seems that you are probably moving laterally too quickly.

 

[joshuabardwell]

SUCCESS! I burned two rods at various amperages and polarities and had no troubles. Welding on DC is different, and I hate to say it but I think my beads actually look worse, but I guess that's to be expected since all my practice so far is on AC.

"Thoughts on this welder"? After 22 pages and 7 weeks or so, I'd say the welder is 100%. Total cost in is under $200, including the fan and the new diodes. I'm going to say I did okay. I am going to keep practicing and see where it takes me.

Thanks very much to everyone who provided so much input, and especially to James.

 

[joshuabardwell]

I'm late to the party here, but your "work" pictures seem to be just a bead on top of some metal. That's really pretty limiting. You should be cutting that scrap of metal apart and welding it back.

Someone suggested to me (don't remember who) that you should practice laying beads first, then once you've got a feel for the effect of different amperage settings, etc..., move on to joining. Also--and I acknowledge this is a poor excuse--but the metal that I'm working with is kind of a PITA to cut apart with my little abrasive chop-saw. I need to pick up some 1/8" bar stock and just cut it into pieces.

One tip on method. Your beads don't really show that you are moving the rod side to side in a "C" shaped motion. It also seems that you are probably moving laterally too quickly.

I have been wondering that. I am not moving side to side at all, really--just dragging the rod and trying to keep it ahead of the puddle and keep the puddle the right size. I think I need to go back to those instructional videos and brush up again.

 

[k0ua]

I need to pick up some 1/8" bar stock and just cut it into pieces.

Good idea:thumbsup: And as others have said, when time and money permits, get a good wire cup brush to really clean the metal of course practice beveling, and puting it back together. Stay with it. And when you get some welds you are really proud of, post em back here and we will all enjoy them. You have already discovered you can actually fix things.. and later when time and experience and money permit you can get a cylinder of Argon, and a regulator and a 17V torch and we will get you into DC TIG for steel.. really great for all those thin metal and little household pieces that need repair.. TIG is 10 times the fun of stick. Stick is great for fixing big ole things but TIG gives you more control than you would believe. If you will follow this link, it is a little TIG repair I did a few months back. Now all that said, don't ever mistake me for an experienced TIG weldor, but I have fun. btw for larger things like that diode, I use a Weller 240 watt gun It also helps to "tin" the wire and "tin" the diode anode before you put them together then you can "sweat" them together, and just as the start to fuse add a little extra solder flow.. also don't fall for this new "clean" rosin free solder, it is crap. some nice old Kester 60/40 or Ersin solder is what you want with the proper tin/lead mix and real rosin, not this "clean" crap. If your throat is not raw after a day of soldering, your not doing it right

http://www.tractorbynet.com/forums/welding/239186-am-i-stupid-crafty.html

James K0UA

 

[joshuabardwell]

The possibility of TIG does intrigue me. It seems clear that stick welding is a good way to get your fundamentals straight, but at the same time, I doubt I am going to weld much thinner than 1/8" metal, at least until my skills improve a lot. And the real sticker is that many things that I would want to build could be built with thinner metal, which would decrease weight and cost. On top of that, I can see that I am really under-equipped to deal with other aspects of fabrication using heavier metal--specifically cutting. My chop-saw really struggles to get through even the T-bar that I have, which is something like 1/4", especially at the joint of the T where the metal is thick. Just grinding away, popping the circuit breaker if I try to push it any faster. It'd be awesome to have a band saw or a cutting torch, but I can see that building a metal fabrication shop is a long road full of very expensive equipment, and at the end of that road is quite a lot of expensive stock to ultimately build whatever it is you're building. So I have been pondering whether the direction to look is smaller, not bigger. It seems like an awful lot of good could come from materials 1/8" and thinner, which are out of the range of my current welder. But honestly, this is all quite a bit premature, as I have barely been through thirty rods at most, and most of that being flat beads--not even joints. I just need to get some rods under my belt and work on projects as they come up, and eventually I will figure it out.

What I wouldn't have given for that Weller gun tonight. Thing is, I almost never need to solder things, and when I do, I usually muddle through with that little pencil-style iron. I doubt it would make sense to spend $40 on a bigger gun, but I was pretty sure I was going to burn up at least one of the diodes with the butane torch tonight. I looked up the specs, and the lugs are rated for about 400 degrees. My solder fluxes at right around there, so maybe I wasn't as close to the edge as I thought. Still, I discolored the housing of one of the diodes with heat, so I know I got it at least a little bit hot!

I do have a cup wheel and a good ole Harbor Freight 4.25" grinder, though.