Miller Thunderbolt AC only stick welder refurb questions

[rangerfredbob]

last year I picked up a Miller Thunderbolt stick welder:

Once it's going it welds fine for an A/C welder, but striking an arc is an exercise in patience... (my other stick welder is a Montgomery Wards branded Century AC/DC unit, I'm not a novice) it was picked up on an online estate auction, looks like it was sitting for a while, cooling fan works, ground clamp was junk so I changed it, electrode clamp is fine. To me it seems like the contacts are likely corroded and it takes a bit to get through the corrosion or whatever but don't know if I'm thinking right... The picture likely doesn't show good enough but there's high and low amp plugs on the front and the crank on the top for amp control. At one point I got frustrated and cranked it up so it would strike an arc but it burned through just after that so there's some contact issues I'm pretty sure... I haven't removed the panels to look at cleaning the contacts and maybe increase any pressure on contacts if needed but it would be a handy backup welder for the garage... A/C isn't my favorite but it works just fine and for around $100 I hopefully didn't do too bad once it's going... been a while since I've cracked open a welder and figured I'd ask before I jumped in...

Thanks

 

[zzvyb6]

I had the same problem after buying a used AC/DC version. It came with 50' leads that were usually coiled up around the handle when I would use it. I cut them back to 10' and that fixed it. Looks like our leads are a bit longer than 10'. I presume that the long wire length had excess inductance, causing the arc problem.

 

[Citydude]

Some machines are finicky. With my machine, it has to have a very good ground for easy starts so I put in the extra time to grind a good spot for the ground.

 

[Tinhack]

Can't help any more on the welder but just wanted to give a big on the vise setup. I've got a similar setup for a tire changer in my barn floor.

 

[rangerfredbob]

I'll check on the length of the cables, don't think they're any longer than 15', will eventually check on the contacts on the other 3 ends of the cables (since I replaced the ground clamp... )

That stupid little vise is handy, it's a cheap vise (basically free but was broken when I got it, everything is just light duty cast iron or mild steel apparently) but that square tubing is light wall so I didn't want a big one on it... it's super handy to be able to walk around something while grinding...

 

[BukitCase]

ZZ, your comment about coiled up is the giveaway - coiling weld leads while in use will seriously affect the inductance of the circuit - the electrician's term for that is a CHOKE.

I sometimes use as much as 60 feet for each lead on my old 250 amp ac/dc (brand name solar, just a rebranded Lincoln IIRC - The two things that let me get away with that are heavier leads for less voltage drop (1/0 or bigger) and NO COILS while running - all my stick leads are either 10' or 25', all have the same male and female lead connectors, except for a pair of 1' long adapters for Dinse to Tweco leads, so I can use all leads on either stick machine. I do have one slightly lighter gauge 8' "whip" for the stinger if I need more flexibility.

Doing it that way, it takes me maybe 20 seconds to add or remove lead length so zero CHOKES get added to the circuit.

I have noticed easier starts with the newer Power iTIG 200, ever since I "RTFMed" the part of the manual about hot start and dig - the Everlast version of that is adjustable by "per cent of total" or some such - took a little while, but I got the stick side of the welder where it's next to impossible to get rod stuck OR burn thru... Steve

Here's a pic of SOME of my leads - the bundle of 2" square tube in the pic is about to get capped - for that I cut a bunch of squares from 3/16"x1-3/4" flat bar, stick each one inside with rectangular magnets so they're flush, then quick corner tacks, then finally relax the strap and insert 3/8" bolts BETWEEN the tubes and finish welding.
If I'm careful, a light touch with a flap disk and it looks like all one piece. (occasionally, that actually WORKS

 

[big bubba]

a lot of the ground clamps on the smaller units (including my own) have inadequate flimsy ground clamps. 1st thing i did on my Hobart AC/DC unit, something like this:

https://www.amazon.com/QWORK-Welding-Bronze-Ground-Pounds/dp/B08W5551JW/ref=sr_1_6?crid=1TIG017WK5O0K&keywords=heavy+duty+welding+ground+clamp&qid=1679257766&sprefix=heavy+duty+welding+ground+clapm%2Caps%2C128&sr=8-6

 

[BukitCase]

Yup, did that to all 4 of my welders and the plasma; when I did that, Harbor Freight had a "400 amp" version that actually opens up to 2", a lot of 'em don't. HF's current offering is a different brand, and I've not had a chance to see how wide the Berger version opens -

400 Amp Welding Ground Clamp

Amazing deals on this 400 Amp Welding Ground Clamp at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

Gotta say, the price is OK though... Steve

I also borrowed a trick from Jody at weldingtipsandtricks.com , only instead of trying to flatten a short piece of weld cable I just used one of these (inserted between the conductor side of ground clamp and the work)

https://www.amazon.com/Braided-Battery-Ground-Strap-Compatible/dp/B00FB81ER4

- between the two changes, haven't had a single grounding prob in about 10 years...

 

[Alan W.]

I have one of the miller buzz boxes. Bought new many years ago.
Was told by the welding shop I bought it from not to weld below 150 on the high side.
That it would not work right and they had no idea why miller didnt blackout the range below 150 on the high side.
If I dont follow this the arc is terrible and erratic when it does start.
Other than that the welder runs fine for an ac machine.

 

[rangerfredbob]

That is very interesting! I will have to give that a try since I'm just using 1/8" 6011 I'm just at around 100A. That would definitely be the easiest fix...

I cheaped out on the ground clamp and just used the $7 offering from HFT, they work ok and have a strap going from side to side unlike most factory clamps, sure there's better but there's worse and it's 1000% better than the jumper cable clamp that was on it...