Welding heavy steel

JayWal · Sat Feb 15, 2020 6:19 pm

I've got a couple heavier parts than im used on my bench right now. 3/4" steel clevis hitches that bolt onto the front frame of our farm trucks. I'm looking for opinions on the best way to weld these up.
I did leave space on the back side intentionally, to plug weld them as well as run a fillet around the front side.

My first thought was dual shield, tho I've heard that you should avoid dual shield in the flat position because there's a good chance of getting slag inclusions in the root.

If I was doing a bunch of them I'd go out and get a heavy metalcore wire or something the like and spray em on. But I'm doing 10 for now and I doubt I'll have to do more in the future so I'll probably just use what I got.

So the options I have are I have 0.45 dual shield, which is what my welder is set up for now, with C25. Running off a PowerMig 300.

I also have a tank of 92/8 and 0.35 solid wire.

3/16" dia 7018s, bout 3 months old and I dont have a rod over. Have a bunch of other rods in various dias

And a 200 amp tig machine with 1/8" filler [emoji3]

Any input much appreciated

BTW these hitches are for hooking up to trucks stuck in mud or soft dirt or whatever. So not for pulling trailers on a road or anything like that.

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JayWal · Sat Feb 15, 2020 6:20 pm

Forgot to attach pics again [emoji849]

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Coldman · Sat Feb 15, 2020 7:19 pm

I would not use solid wire for this job.
Either your flux core or 7018 would be ideal. You do have a rod oven, just send your better half out shopping for half a day and she won't know you've been baking rods to recondition them.
Either process will require multiple passes to achieve throat thickness equal to the thinner parent metal.
Interesting job and nice prep.

bap_ · Mon Feb 17, 2020 2:19 am

Wow that's some stout material. Let us know how it goes!

smithdoor · Mon Feb 17, 2020 2:36 am

I have use E71T-1 with CO2
Works great and good looking weld too.

Dave

smithdoor · Mon Feb 17, 2020 2:40 am

FYI do not do all welding on one side it will worp and hard to fix.

Dave

JayWal · Mon Feb 17, 2020 2:01 pm

bap_ wrote:Wow that's some stout material. Let us know how it goes!

Will do. Might be a while tho, in the middle of moving house right now

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Poland308 · Mon Feb 17, 2020 6:48 pm

I’d be using 7018 3/32 or 1/8. Easy to get in between and no gas issues. An almost impossible fail is always a good option to me.

JayWal · Mon Feb 17, 2020 9:42 pm

Poland308 wrote:I’d be using 7018 3/32 or 1/8. Easy to get in between and no gas issues. An almost impossible fail is always a good option to me.

Hmm. That would need too many passes to get a good sized fillet, no? I considered 5/32 or 3/16

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Oscar · Mon Feb 17, 2020 10:43 pm

035 or 045 ER70S-6 or S-3 using pulsed-spray transfer. Ride the lightning.

JayWal · Tue Feb 18, 2020 12:51 am

I did check to see how my mig gun fits in between the 2 pieces, no issues at all. I can definently weld inside without some crazy stick out or gun angle. So I'll probably do most if not all with .045 dual shield since thats what I'm set up for now. Tho I'm tempted hook up some 92/8 to pulse spray a couple for comparison.

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MinnesotaDave · Tue Feb 18, 2020 8:00 am

Poland308 wrote:I’d be using 7018 3/32 or 1/8. Easy to get in between and no gas issues. An almost impossible fail is always a good option to me.

Yep, what he said

JayWal · Tue Feb 18, 2020 2:35 pm

Back plug welds are done, started a couple of the fillets. So far I've managed to trip the 50 amp breaker 6 times. I guess that's why people use 3phase wiring on bigger machines.

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MinnesotaDave · Tue Feb 18, 2020 2:44 pm

JayWal wrote:Back plug welds are done, started a couple of the fillets. So far I've managed to trip the 50 amp breaker 6 times. I guess that's why people use 3phase wiring on bigger machines.

I wouldn't worry about 3 phase, your breaker is just too small. That machine lists 62 amps input at 300 amps. I didn't see a listing for it's max input at 350 amps.

One of my machines has to be on a 100 amp breaker or it trips too easy when welding aluminum.

JayWal · Tue Feb 18, 2020 4:11 pm

It's a 300 amp machine, that's why only a 300 amp rating. The plugs I use are only rated for 50amps, but I was pretty tempted to swap in a bigger breaker anyways.

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JayWal · Tue Feb 18, 2020 6:03 pm

Got it done anyhow

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Coldman · Tue Feb 18, 2020 6:12 pm

Looking very good so far.
Show us another pic after you've finished the triple run fillets to complete the throat thickness.

JayWal · Tue Feb 18, 2020 7:17 pm

Coldman wrote:Looking very good so far.
Show us another pic after you've finished the triple run fillets to complete the throat thickness.

I'm debating if I need a triple pass weld. I have 16" of fillet weld all around...3" of plug weld on the backside. I'd say the tongues would give out beside the 2" holes before my weld would. Or am I wrong

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Oscar · Tue Feb 18, 2020 7:26 pm

JayWal wrote:
Coldman wrote:Looking very good so far.
Show us another pic after you've finished the triple run fillets to complete the throat thickness.
I'm debating if I need a triple pass weld. I have 16" of fillet weld all around...3" of plug weld on the backside. I'd say the tongues would give out beside the 2" holes before my weld would. Or am I wrong

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What does the client want?

JayWal · Tue Feb 18, 2020 7:56 pm

I am the client

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Poland308 · Tue Feb 18, 2020 8:42 pm

Only question I’d ask to make a final decision is what’s the reasonable cost of a failure, if we’re talking low speed worst case end up with some bent metal. Then I’d probably weld less as well. Engineers make this call every day in joint design. It only has to be strong enough, not as strong as possible.

Coldman · Tue Feb 18, 2020 8:43 pm

The weld size should equal the thinner of the two parent pieces otherwise the weld becomes the weak point as is now. You don't want your welds to be the weak point.

JayWal · Tue Feb 18, 2020 10:13 pm

Its just a recovery hitch for when the trucks get stuck in the field. For comparison, here's the original design, 3/8 x 3 bent flatbar with another on top, fastened with 4 1/2" bolts. And it last a good long while, but it was hard to hook a strap onto. And with the tough harvest last fall it wasn't strong enough.

So I made a new cross member out of 3/8 plate so I can bolt the new hitches to that.

That said I do agree with Coldman I'd very much hate for my welds to be the weak point. I'll leave a few for the lighter trucks and triple weld the ones on the heavier rigs.

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Coldman · Tue Feb 18, 2020 10:25 pm

I hear what you say. Still doesn't change my mind. You don't know what happens in the future. You might sell a truck and the forget to take the bracket off and it gets used for something else. Still comes back to you.
Build it right, sleep at night.

MinnesotaDave · Tue Feb 18, 2020 10:42 pm

JayWal wrote:It's a 300 amp machine, that's why only a 300 amp rating. The plugs I use are only rated for 50amps, but I was pretty tempted to swap in a bigger breaker anyways.

The power mig 300 is rated at 60% at 300 amps. But its max is 350 amps.
Don't worry much about the plugs. They hold way more than 50 amps.
I hard wired to my 100 amp breaker though. But I didn't for several years.

: lincoln power mig 300 specs.JPG (67.85 KiB) Viewed 4821 times