7018 Vs. 7018AC, Need Layman's translation please:

[Gary Fowler]

That old SA 200 Lincoln will be loaded to the gills if you fire up a 3/16" 5P downhill on a pipeline, but if properly tuned it will labor along all day, everyday and keep on ticking because it has solid copper windings. I have seen them hooked togethere to arc gouge with so you get 400 amps.

Regarding the original posters questions, I think that when they stated not recommended for low voltage welders, they were speaking of the Harbor Freight type machines that even though they run on 230 V the transformers capacity and duty cycle is only like 140 amps or so for like 5 minutes. Output voltages on DC machines rarely exceed 40 volts regardless of capacity of the machine. I dont know what the AC machines run but I would expect them to be fairly low to avoid the possibility of electrocution.
As for rods, just buy the 7018 AC rod and you can use it on AC or DC. You can run the DC rods in the Lincoln buzz box but they are extremely hard to start and will occassionally arc out on you for no reason. I welded with them for several years back in the late 60s at my Dad's farm and they worked OK for everything but overhead work and then it was a real pain to keep them burning. Overhead requires a very short arc and AC machines dont like to work with short arc length. For horizontal and flat, they worked OK, just hard to start and sometimes they arc out and you have to restart them.

 

[Shield Arc]

Shield Arc,

What type of work are you doing that requires that kind of amperage???

Bridges.

 

[easygo]

Miller Trailblazer 55D, 450-amps, CC/CV diesel powered machine, with 3-stage slope.
I've ran it for 10-hours a day for months at a time at 575 to 600-amps running Innershield wire. Each morning I had to replace the Tweco lead fittings at the machine!

Are those drums in the photo are for holding flux core wire? I assume the quick connect fitting were just toast at the end of the day. That must be industrial welding in every sense of the word.

 

[shade tree welder]

Overhead requires a very short arc and AC machines dont like to work with short arc length. For horizontal and flat, they worked OK, just hard to start and sometimes they arc out and you have to restart them.

AC rod due to transition from EP to EN have a momentary transition of zero
current. To maintain the arc on AC you need to have a longer arc length and
the 7018AC rods have a little iron or iron oxide powder in the flux to aid in
supporting the arc during this transition.

Bridges.

AWS D1.5 fun stuff.

Big Wave I have two questions for you.

1) What machine are you welding with. This is more out curiosity than need.
Do not feel if you do not have great equipment over the years I welded with
cheap Chinese imports that were AC only to some really nice machines.

With practice they will all make sound welds, maybe not X-ray quality, but
sound.

2) What are you planning on welding on? Based on the discussion here I
doubt you have a rod oven. (and a light bulb in an old fridge does not make
a rod oven) so purchasing 7018 of any kind is going to be a waste of money
for you. I would steer you toward 6011 or 6013 or even dare I say 6010.
No rod oven need to keep you rod dry, from absorbing atmospheric moisture.

If you are welding on hot rolled steel (ASTM A-36) or structural tubing
(ASTM A-500 Grade B) being the most common steels out there they have
tensile strength of 36,000 psi minmum. 60xx rod has minimum tensile
strength of 60,000 psi and 70xx has 70,000 psi min. TS.

601x rod tends to be cheaper than 701x rod and does not need to be kept
in a rod oven, as it is not a low hydrogen rod. But HR steel like A-36 is not
very suseptible to hydrogen cracking so it is not really an issue.

Also 601x rods run well with a little moisture absorbed into the cellulose
based flux, whereas "wet" 7018's run like crap.

 

[Big Wave D]

Shade Tree Welder,

Replied to your questions by Private Message.

Thanks

 

[Soundguy]

remember.. that's 225 OUTPUT amps.. not input amps. keep in mind there is a xformer in there. your output voltage is dropped ( compaired to line ) ( stepped down ) but amps are up...

soundguy

I hadn't really thought about the numbers all that much, but when I started to think about the facts, it makes sense.

Yes, I am using 230v coming out of the socket and into my welder, but I'd not really thought about the fact that I can turn my welder up to 225 amps. That's more than the breaker on my house at 200 amps. Therefore, every time one used that setting, theoretically, the house breaker should trip and it doesn't. Further compound that thought with the fact that the welder works on a 50 amp breaker and it becomes apparent, something had to give, and for the welder it's its working voltage.

Now I understand their statements about "low-voltage" and "208/230v" welders.

A big dog welder has more oomph(voltage) coming out of the machine. I don't know but I'd guess maybe 50v's or greater.

Thanks again to everyone for their help in me to mentally toss this around until I was able to understand what was the underlying principle involved in all of this.

An extra shout out and props to Easygo for your link and comments. Those really helped me to solidify my understanding of things.

 

[Big Wave D]

Soundguy,

Yes, my explanation was more than a bit fuzzy, but yes, I know that I'm not inputting that amperage.

Thanks for keeping me on my toes though.

 

[Soundguy]

that's why the house breaker don't trip..

soundguy

 

[Shield Arc]

Are those drums in the photo are for holding flux core wire?

Drums? Are you talking about the black round things with the Miller sticker on them? If so, the one on the wire feeder will take / protect 33-pound spools of wire, (any wire) and the bigger one next to the welding machine will take / protect 60-pound spools of wire.

 

[Big Wave D]

I'm hi-jacking my own thread because while I have all of yours attention, I could really use some advice please.

I've attached pictures to hopefully help out

Problem: Top link arms have broken in half (Front View)

Compounding Problem: I'm not quite sure what kind of metal I'm dealing with (Metal Identification) (Break)

Tried: I cleaned everything up, really chamfered pieces at break (while chamfering, sparks lead me to believe I was working with Cast Steel or mild steel, now I'm leaning towards Cast Iron), welded back up with 6011 rod, did not preheat prior to welding, held for 6 or so hours of hard use then reverted to previous state (broken)

Questions: Am I correct in thinking that I am now dealing with Cast Iron? What rod is best: Ni-55, Ni-99, or S.S. 312, or something else? If cast, how hot am I aiming to heat area before welding? I have no Sand Box for slow cooling, what else that is simple will work? What is the best way to reinforce the break? I've thought about welding washer to front and back side, yeah or nay? I also thought about laying a bead of 312 along arm and upright bracket, yeah or nay? Anyone ever used a rod by KT Industries known as Nomacast and is it (rod) or they (KT Industries) as a supplier of rods any good?

Thank you all for your time and sharing of knowledge.