Thoughts on this used welder?

[joshuabardwell]

Sometimes, as James, alluded to, they will appear to be ok until a decent amount of current is passing.

When you say, "a decent amount of current," are we talking about the few amps of the tail-light, or are we talking about the 50+ amps of the welder? If the latter, it seems that one test that could be performed would be to get a rod that is designed to work at the welder's lowest setting, to see if that improved things. But honestly, other than shorting the leads through a resistor (would have to be a mighty big resistor to resist the welder's amperage) and then measuring the voltage drop through the diode, I don't know how one could detect a diode that was only failing under heavy load like that.

 

[cqaigy2]

When you say, "a decent amount of current," are we talking about the few amps of the tail-light, or are we talking about the 50+ amps of the welder?

Sure, like James said to use as a test. Sometime the current flow used in diode testers won't reveal a problem so i would think a few amps would be a good test. Technically, a diode current flow may change at any and including a damaging voltage/current. I've seen larger diodes, like the ones used in the rectifiers of something like a welder have even had mechanical problems that don't show up until heated or cooled but those typically are situations where the problem is transitory.

 

[k0ua]

I am pretty convinced that the diodes are good, If they pass a fair amount of current (couple of amps) one direction and none the other way, and show the proper .7 volts of drop.. yeah I think they are OK. So does current flow thru that choke? Connections clean on the sockets and plugs? I am starting to run out of ideas here... something else causing a voltage drop out of the transformer?

James K0UA

 

[joshuabardwell]

Well, I think if we can conclude the diodes are good, I am going to call that a good pausing point for now. I am actually just about to be without Internet from Wednesday of this coming week to next Monday, and I'd hate to leave y'all hanging in suspense! More troubleshooting when I am back.

 

[Docgrubbs]

I do not feel the 50 amp machine will provide any comfort at all. Try for one of the 180 to 250 amp machines that will have to amperage you need for all work. Remember that size of electrodes determine necessary amperage and not the thickness of metal you are welding. Thicker metal requires more passes but a battleship can be built with 1/8" electrodes if you have the patience. If funds are available, go with a 220 amp machine and have the power when you need it. Welding is my passion so I tend to go for the better side of needs rather than the get by side.
docgrubbs

 

[oleman]

I use a little Hobart Stickmate LX. This is an AC/DC buzz box 230A on AC and 165A on DC.
I have built some tractor stuff made from 1/2" 4" angle and it is fine with multiple passes and 5/32" 7018 on the 1/2".
I have done as a low limit for me 14 gauge using 3/32 7018 it's basically hunt and peck at 50A or so.
My eyesight is not good anymore so it is hard to do a good clean weld because I have problems viewing the puddle.
New this machine can be had for around $400.
If you can find one look for a used Lincoln Idealarc; one of the best stick welder ever assembled especially if you want a serious high current (300A) welder but a used one cost more than a new Hobard stickmate.
I was watching a 6.875 natural gas main going in the other day. I questioned the welder and observed the equipment.
On schedule 40 gas line he was running 160 +- amps using 5/32 6012 rod. I ask about 7018, he said it was not necessary and cost too much for him!
This is a 360 degree weld, so it a portion that is overhead, out in the open field. No jigs no fancy adapters no nothing except a man a stick and a helper to run the wire brush.
Really wish I could have learned to weld like that.
He was running an old Hobart 400A amp gas powered welder.
Every weld has to be xrayed he said normally he is running 99% pass but there are times when things just don't go right and welds run at 50% pass.
Just goes to show that welding is an art that people with all the practice in the world never consistantly get to 100%..

 

[Sberry]

A bonded 3 wire appliance will not energize grounds, this is from the service main its bonded at the panel, all service mains, new or old. Josh has his 3 wire dryer correct, must be bonded. One other thing,, in a 120V circuit the white is not a neutral, it lands at the service main connected to a neutral, as part of a 120V it is a grounded conductor. A ground wire ends up back at service main also but is insulated from the grounded conductors, this keeps current from flowing on the chassis.

 

[joshuabardwell]

Well, I'm back from my trip, and I have a small update. I got the new fan installed! It came with no leads, so I just soldered on the leads from the dead motor. I will always be thankful to my dad for teaching me to solder years and years ago. It has come in handy more times than I can say.

I had to put the fan on the opposite side of the mounting bracket, in order to leave room for the amperage slider to go up and down. To keep the airflow going the same way and to keep the fan from rubbing on the bracket, I shimmed it out with some extra nuts that I had laying around. I also re-used the bolts that held the original fan on.



On suggestion of the Internet, I also rewired the fan so it is on the service side of the welder's main switch. This keeps the fan running even after the welder is shut off, so that it continues to cool the transformer. I find this particularly useful because I usually turn the welder off in between rods, just to keep any little accidents from happening. I know this may not be strictly necessary, but at least until I am more familiar with the process, it makes me a little more comfortable.

EDIT TO ADD: An additional benefit, at least while I'm jacking around inside the darn thing, is that the running fan serves as a reminder that the welder is plugged in, and the service poles of the main switch are hot. At least once, I have gone to reach inside the box while it was plugged in and had to smack myself when I realized what I was about to do.

Here it is, working away!

 

[joshuabardwell]

Also: now that it's the 1st, I have a bit of pocket money again, and will probably buy an auto-darkening helmet. Maybe also a small box of fresh rods, just to rule that out as a possible cause of the DC problems.

 

[joshuabardwell]

I got an auto-darkening helmet today, and boy howdy is that a treat. Only thing is, now I have to remember to make sure it's turned on again when I get done grinding. There's an accident waiting to happen. Maybe I should use a different face shield when I grind. So far, I just look away and tap the work piece to confirm that the lens darkens before I start welding in earnest.

Anyway, here's today's work.



I went out and bought a brand new box of 1/8" E6013 just to rule out bad rods as a source of my DC problems. All of the above beads were run with those rods. I was able to consistently get a DC arc struck, but I had to run the welder all-out at 140 amps to do it, which seems higher than would normally be recommended. The DC beads also seem taller than they should be, to my amateur eye. Bear in mind this is on a piece of about 3/8" thick T-stock, if that's relevant. On the AC side, I think the 6013 runs a little nicer than the 6011 I was using, although the auto-darkening hood and my slight increase in experience probably play in.