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Welding Shop

AC/DC Welding Questions


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  #1  
Old 04-25-2019, 09:31:41 AM
Tracy T Tracy T is offline
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Question AC/DC Welding Questions

other than one being alternating current and the other being direct current just what is the difference? i have done alot of stick welding, tig welding, and mig welding but to my knowledge its all been AC. reason i ask is i have a ancient welder that been in the weeds for several years that was in a barn before it fell. I believe its a lincoln sae 400 and probably dc. thats the closest thing i could find on the web that looks close. this one is 3 phase and i am considering a repower with a tractor engine i already have.
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Old 04-25-2019, 12:05:31 PM
ibdennyak ibdennyak is offline
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Default Re: AC/DC welding questions

Well, stick can be either, MIG is DC, and Tig is usually DC except for aluminum. This is the output of the welder. As far as input, that can be almost anything from 3 phase to engine driven. As a rule, DC is more versatile as a general rule. At 400 amps, your welder is probably DC. I had a huge 400 amp Lincoln engine driven welder years ago. It was DC only.....nice welder. Personally, I kind of prefer the old timey generator welders....seems like they lay a nicer bead. Of course, the new electronic stuff has more knobs and dials to set. The new TIG welders especially have settings that reduce heat input while improving cleaning action etc.

Got a picture of the old beast?
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Old 04-25-2019, 01:12:26 PM
Tracy T Tracy T is offline
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Default Re: AC/DC welding questions

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Originally Posted by ibdennyak View Post

Got a picture of the old beast?
not at the moment, its located on another property of mine about 50 miles away. I need to get back down that way and finish clearing some land i started on last fall, truck started breaking down on the way home with dozer in tow! it made it home though and has since been fixed. next time i am down that way i will see if i can get it moved to a better location for loading and snap a few pictures.
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Old 04-25-2019, 06:24:50 PM
Tracy T Tracy T is offline
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Default Re: AC/DC welding questions

so with this many views, and only one reply i assume there is not that much difference between the two. i thought maybe better penetration or the likes, or maybe better for overhead welding and such.....
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Old 04-25-2019, 06:52:45 PM
cornbinder89 cornbinder89 is offline
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Default Re: AC/DC welding questions

DC is far better for out of position welds (over head, vertical etc) I am no weld expert, but DC would be better in almost every way to A/C.
AC boxes are cheaper.
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Old 04-27-2019, 09:15:00 AM
Tracy T Tracy T is offline
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Default Re: AC/DC welding questions

got the old beast home yesterday, this was a high end welder for its time! I will get some pictures up today. so yet comes another question, it has a option to reverse polarity, whats that all about? may sound like a dumb question, but i have not a clue.
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Old 04-27-2019, 01:01:05 PM
sftyvlv1 sftyvlv1 is offline
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Default Re: AC/DC welding questions

Quote:
Originally Posted by Tracy T View Post
other than one being alternating current and the other being direct current just what is the difference? i have done alot of stick welding, tig welding, and mig welding but to my knowledge its all been AC. reason i ask is i have a ancient welder that been in the weeds for several years that was in a barn before it fell. I believe its a lincoln sae 400 and probably dc. thats the closest thing i could find on the web that looks close. this one is 3 phase and i am considering a repower with a tractor engine i already have.
We used old Canox "hydro pole" type AC transformers at a ship yard back in the 90's and were antiquated back then.
The advantage, use of high amperages with little drop in power. Especially when your machine was hundreds of feet away and your welding with 3/16-1/4 inch electrodes. My favorite part of using those machines NO arc blow.

Last edited by sftyvlv1; 04-27-2019 at 04:09:47 PM.
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Old 04-27-2019, 02:10:02 PM
Heins Heins is offline
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Default Re: AC/DC welding questions

Reverse polarity puts most of the heat on the metal you are welding. DC will push 7018 rod better than AC. Straight polarity puts most of the heat on the rod. Use reverse polarity on most things you weld to get a stronger weld. Use straight polarity when welding light metal and putting on hard facing. If you use a DC welder, you won't go back to an AC.
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Old 04-27-2019, 04:49:58 PM
Tracy T Tracy T is offline
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Default Re: AC/DC welding questions

dang! is it 4:30 already!? i have been working on this thing all day long then. thing was stuck, and stuck good! I have both ends apart and havnt seen anything major yet. funny thing, on the exciter brushes they used stainless steel springs and the springs are like new! on the DC end they did not, and every one of them need replaced. same with bearings, exciter end is a sealed bearing and appears to be fine, other end was not and needs a new bearing. getting the exciter appart was a head scratcher! somebody was going to drive it from that end with a driveshaft, and i dont know how they splined the shaft but the splines had to go. no way for it to come apart, splines were bigger than the rotor/ armature what ever you call it! well let me get my hind end to town and get some batteries for the camera, i highly doubt there are any here!

---------- Post added at 04:49:58 PM ---------- Previous post was at 04:32:31 PM ----------

well i found batteries, have pictures and cant get the dang laptop to open them! give me a few minutes, i will try from my old dusty desktop down stairs'
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Old 04-27-2019, 05:05:28 PM
Tracy T Tracy T is offline
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Default Re: AC/DC welding questions

its been a while, so here we go. I think!
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Old 04-27-2019, 05:11:28 PM
Tracy T Tracy T is offline
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Default Re: AC/DC welding questions

bear with me i am rusty at this and this computer is old and does not want to work with me.
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Old 04-27-2019, 05:14:15 PM
Tracy T Tracy T is offline
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Default Re: AC/DC welding questions

eh being a pita! maybe the wife can figure out the tablet in the morning. this computer will lock up and do all kinds of weird things.
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Old 04-28-2019, 01:25:26 AM
cobbadog cobbadog is offline
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Default Re: AC/DC welding questions

Sounds as though one end got a rebuild not so long ago and the other end did not as it was possibly working at that time then died so they gave up on it. Sounds as if your the man to resurect it back to life with the late model parts like SS springs etc.
Keep us informed with your progress.
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Old 04-28-2019, 07:22:32 AM
Tracy T Tracy T is offline
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Default Re: AC/DC welding questions

I dont know if i am the man to resurect it, but you are the 2nd person to tell me that! anybody have any idea how to get the armature out of this welder without destroying it? i have never dealt with anything of this magnitude! I am thinking i need to uncart it and stand it on its end and use a hoist to remove it. that dont sound to hard if you say it fast and dont think about it too much.
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Old 04-28-2019, 02:47:41 PM
ibdennyak ibdennyak is offline
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Default Re: AC/DC welding questions

huh.....I recognize that thing. In the early 70's I had a job using one of them. Good welder. I also learned that it is a bad idea to sit on the pipe you are welding when the stinger screw is too long, and you are wet from sweat. Kind of shocking.

In answer to your question about AC vs DC, DC is preferable because it gives you more options. This isn't so much because of the ac or dc ness, but because it gives you more electrode options. For general stuff you will probably run 7018. Kind of a good all purpose rod. It must be run DC reverse. (they do have a version now that is rated for ac, but it doesn't run as good). For dirty or when you need deeper penetration and fast freezing (like overhead) 6010 is usually the go to. This is also DC reverse, although 6011 is the AC version.

As far as repairing it, I can't help you, other than it is a good welder if you get it going. I tried to answer yesterday, but my computer must know yours. When I hit reply, it just sat there looking at me. Today it works and I didn't tap it with a wrench or anything.
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Old 04-28-2019, 03:22:06 PM
Tracy T Tracy T is offline
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Default Re: AC/DC welding questions

I dont think its going to take much to put it back in action, normal stuff. some areas need the insulation freshened up, brush springs on the dc generator, brushes on the exciter and a few wires replaced. the biggest thing i see is it needs a thorough cleaning! I honestly think its stuck condition was due to 50+ years of dust blown into it, once the armature moved it contiued to move. going to have to divise a way to get that heavy armature out of there to know anymore.
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Old 04-28-2019, 06:50:19 PM
Tracy T Tracy T is offline
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Default Re: AC/DC welding questions

well its offical! it is now on a cement floor with a roof over its head and in a tempature controlled enviroment as of right now! for the first time since when god only knows. I appoligize for not getting more pictures up sooner, wife had to work today and tried to figure things out and i told her dont let it make you late! she is off tomorrow and we will go from there. dont expect anything early, i aint running her out of bed when i get up, she has to work tuesday and i know she needs rest.
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Old 04-29-2019, 11:20:37 AM
Tracy T Tracy T is offline
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Default Re: AC/DC welding questions

well now i am confused. the tag is stamped code # then below that says serial no, then out from it is a stamped number A117172. so i dont know if thats a serial number or a code number? It also has a tag above this tag that says reconditioned by lincoln electric, so it has been reworked in the past. a few more numbers i have no clue about one is MX427 another is 3944 and the last is 8765. I found a brush spring on lincolns site that looks like what i need but its been a dead end so far. say its the old style and the part # they list is 9st1448 and its not listed as obsolete...
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Old 04-29-2019, 02:13:16 PM
Tracy T Tracy T is offline
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Default Re: AC/DC welding questions

wife figured it out, now if she can teach me! armature is out, not the best picture may try another with the flash turned on. the dc end looks pretty good, the ac end is shot. it was rusted together. and i messed up the exciter rotor, but it may get rewound. its small enough i dont think it will break the bank.
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Old 04-29-2019, 06:37:26 PM
Sonny Reese Sonny Reese is offline
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Default Re: AC/DC welding questions

I started out welding with a Hobart dc 200 amp welder powered by a 1937 216 Chevy truck motor. The dc arc is smoother, starts easier, less prone to rod sticking, etc.
In high school I had to learn on Linc. 225 amp ac welder!--couldn't lay a passing bead to save my life!!---Talked the teacher into letting me bring Dad's welder in to do my test to prove that I could actually weld. -- He did finally ok the idea so the next day Dad pulled the old Hobart in to school and after the teacher watched me weld on dc, he couldn't believe how nice dc was! --- Dad had him try it and then asked the students to each weld a test bead with it. They all did great and was amazed how much better dc was.
I now use the old Linc. 225 ac here and have an old wire welder. I still miss the old Hobart! thanks; sonny
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