Can I use my 100A welder on 1/4” thick steel?

[StevSmar]

My made in Manitoba AC Welder has taps for: 25A; 50A; 75A; and 100A.

For my Mill stand, I need to weld 2”x2”x1/4” thick square tubing at 90 degrees to each other.

I’ve been looking at TimWeld’s Youtube channel and he recommends:
- 6061 for penetrating welds (butt joints).
- 7018-AC for general welds.

From the labels on the Princess Auto 3/32” welding electrodes they suggest I’ll need a welder that can deliver 100A. My welder can’t deliver enough amperage for 1/8” electrodes.

I’ve got some offcuts from cutting the tubing, and I plan to practice on these until I’m confident enough to tackle the stands welds. I can cut these to see what the welds look like.

So onto my question… whats the opinion on whether 3/32” rods be adequate to weld with? (likely with multiple passes)

 

[Proxule]

You can weld what ever you want how ever you want, Success might be limited.
3/32 rod is designed for 45-90 amps depending on flavor used 7014 7018 6013 6010 6011 etc etc

You can run your machine at 100amps but the duty cycle might be very low ( duty cycle or power cycle is the fraction of one period in which a signal or system is active ) - So 50% duty cycle will need 30 minutes off for every 30 minutes on.
Should be on the nameplate or some where on the back of the machine.

In the home shop I find 3/32 best suited for most things. Multiple passes if required. Crank the amperage and or DIG setting to get a nice penetration, Or lower it back down for thin metals.
Too low and you will find the rod sticks and has a lazy arc. Arc length will play a big role here.
The only real answer I can truly give you is strike an arc on some scrap coupons and like materials and weld away.

Tips and or tricks for thin material is swapping polarity on the 6013 rods from DCEP to DCEN.
But I see you own a AC only machine so that's pointless.

1/4 thick HSS at 80-90 amps on 3/32 rod using 7018 AC stick or 6013 ( can be run on AC or DC ) will be a beauty!
Give her a go, Report back and we will guide or help.

Gluck

 

[phaxtris]

100% no problem, 3/32 for a 7018/6013 type rod, 1/8 for a 6010/6011, they all will run under 100

Is this an old school tap only machine ? Or does it have a tap and a fine dial?

If it's a tap only machine 100a is gonna be smokin for a 3/32 7018ac or 1/8 6011, your gonna want to practice with the 75a tap

 

[WilliamR]

I think duty cycle on your AC drooper at full power might be pretty low (~15%?) based on 10 minute cycle.

I would use the 7018AC, but that's personal choice.

 

[boilerhouse]

From my experience, I agree with the others. I use 105 amps on my Lincoln AC machine for 3/32 7018 AC or 7014 and 105 amps for 1/8 6011. So 100 amps should be in that same ball park. But 6011 is not a great beginner rod, it is a deep penetrating, fast freeze rod that can be very aggressive. Which, in the hands of an experienced welder, makes it a better rod than the others depending on the circumstances.

 

[StevSmar]

You can run your machine at 100amps but the duty cycle might be very low

You were right, I’d never checked the duty cycle on my welder but it’s a measly 20%.

In the home shop I find 3/32 best suited for most things.

That’s great to know!

Thanks for your advice @Proxule

 

[StevSmar]

Is this an old school tap only machine?

It has four transformer taps on it.

If it's a tap only machine 100a is gonna be smokin for a 3/32 7018ac or 1/8 6011, your gonna want to practice with the 75a tap

I’ll definitely be practicing! I was wondering if 1/8 6061 would be too much for my welder but it seems not!

Thanks for your advice @phaxtris

 

[StevSmar]

I think duty cycle on your AC drooper at full power might be pretty low (~15%?) based on 10 minute cycle.

That’s good to know that duty cycle is based on a 10 minute cycle. So with my 20% duty cycle that’s 2 minutes welding and 8 minutes waiting.

Mind you I’ll be welding in an insulated garage so I could just suck in some of that duty cycle enhancing Winnipeg Winter air!

Thanks for your advice @WilliamR

 

[StevSmar]

But 6011 is not a great beginner rod, it is a deep penetrating, fast freeze rod that can be very aggressive. Which, in the hands of an experienced welder, makes it a better rod than the others depending on the circumstances.

My plan is to use the 6011 for tack welds, and then the actual welds with 7018.

Once I get the hang of it I‘ll be interested to cut one of my trial joints apart to see what the penetration is like.

My step father was a boilermaker so I learned a little from him when I was a teenager. I don’t ever remember cleaning the mill scale off before welding, we’d even weld galvanized tubing. Makes me wonder how good a boilermaker he was…

 

[Susquatch]

That’s good to know that duty cycle is based on a 10 minute cycle. So with my 20% duty cycle that’s 2 minutes welding and 8 minutes waiting.

Mind you I’ll be welding in an insulated garage so I could just suck in some of that duty cycle enhancing Winnipeg Winter air!

Thanks for your advice @WilliamR

This is not meant to be more than getting others to chime in who know more than I do.

I do believe the ratings are based on 10 minutes. However, I don't think that is meant to suggest you can run yours for 2 minutes continuously and then stop for 8. I believe it means you can run it for 2 minutes (TOTAL) within a 10 minute period. The 2 minutes should be broken up into multiple smaller chunks.

As it was explained to me by a welding guru, running for the full 2 minutes continuously can still overheat the unit and potentially damage it.

I'd love to hear what those who weld for a living think.

 

[StevSmar]

I'd love to here what those who weld for a living think.

I’d like to know too! Makes me think a 100% duty cycle welder might be in my future one day…

 

[Doggggboy]

In my very limited experience the duty cycle has only ever come into play while mig welding.
I'm pretty sure it's impossible to make a single rod last for 2 minutes of continuous welding.
For me it's more like 3 seconds of welding , 10 seconds of waiting for my vision to clear so I can see what went wrong, 3 minutes of trying to figure out why I'm suddenly an inch away from the joint I was trying to make, 5 minutes of getting better light on the potential weld, 4 minutes of improving the fixturing to help it not walk away again while I'm trying to wrench the stuck rod off the fixture, 8 minutes of Google searching to see what i should have set the welder at, 11 minutes of patching the hole in my foot from the melted slag, and then 2 minutes to put on the proper footwear and try again. But sometimes I also need a snack and a nap.
Follow me for more welding tips and tricks.

 

[140mower]

One thing about stick welding.... You have maybe 30 seconds of burn time and your rod is gone, flip your helmut, change the rod, chip your weld, hit it with a wire brush, a little bit of admiring your last weld and you have burned up another minute and a half or so. That's about 25% duty cycle and about as fast as I am likely to be going at it these days.
Duty cycle comes into play a lot more with a wire feeder where you don't need to change rods frequently.

I'm definitely not a pro though.....

 

[phaxtris]

yes duty cycle is based on 10 minutes

On just about anything newer than what the op has you can weld the full duty cycle, the output will just shut down, thermal protection is built into newer units...anyone with a 110 mig has probably experienced that

What the op has, that thing will weld until it melts into a pile of copper and steel on the floor, no thermal protection, so no, not a great idea to push the limits of the approved duty cycle, yes it can be damaged......however duty cycle is derived with the machine sitting in a "room temperature" environment, welding until some "safe operating temperature" is reached....so the thinking of throwing it outside at -20 to extend the duty cycle is not wrong......just like leaving a machine in the blaring sun at +30 effects the duty cycle

it takes around 1 minute to burn a full, standard length 1/8 7018, and with what @StevSmar is building, 2" stringers, tacks, chipping, clamping, bla bla, 20% would work ok

to burn rod steady, 60% is the number that is commonly accepted for general commercial work, a maxstar 150 on 220v will burn 1/8 7018 all day long, 1 box a day, and never hit the duty cycle....60% does not apply to pipeline or mig welding

@StevSmar that oldschool tap machine is going to take some practice, the 60hz sine wave and no good current control will have a steeper learning curve than a dc machine, i would pick one rod and stick with it, 6013/7018AC would be the easiest......if you go with 7018 make sure it is 7018 AC....your gonna fight sticking the rod with 6011, if you plan to grind your welds down at all you should put a small bevel on the joints...like 1/8 at most...assuming its a tight joint

you dont need to grind any scale off, if your fil was a boilermaker/welder he was probably pretty decent, that is all really crappy in position open root type work, not very many shitty welders can make it as a boilermaker/welder

 

[ShawnR]

@StevSmar Can you post a photo of your machine? Lots of good advice here. I really like what @phaxtris suggests about having the machine outside if you have a cooler climate. Will help protect it from meltdown. Shorter welds, then all of the clean up, admiration, cursing, grinding, etc, inherent in being a newer welder, equate to time delays and will be good for the machine. I think @Doggggboy and @140mower have been taking notes on my welding abilities. Sounds like any operation in my shop! I often worried about Duty Cycles when buying machines but they are usually quoted at the max output of the machines and charts will often reveal a decent welding duty cycle at lower currents, ie might find 100% at half the rated max output. Unfortunately for you, you are asking the machine to run at max.

One other thing not mentioned is preheating of your material, which will help with penetration and integrity of your welds too, if I understand correctly....others can yay or nay that.

I wonder if 1/4" thick material is necessary for your stand? Sounds heavy duty. Maybe 1/8" material would be heavy enough with a good design and much more in the wheelhouse for your welder....? 2 x 2 x 0.125" is pretty heavy for a 36" high stand and a small mill. I believe that I used 1/8" material for mine and think we have a very similar design. I meant to post a photo for your reference in your other thread. Sorry for not doing that sooner. I am using 1 1/4" square tubing for the legs, not sure of the thickness. The stand is plenty strong enough for this machine. The wheels not such a great idea for stationary use but I have been meaning to install solid feet....it is on the list...

Just my 2 cents.

Great project! Great learning experience. Good luck.

Shawno

 

[ShawnR]

I’d like to know too! Makes me think a 100% duty cycle welder might be in my future one day…

See above message but, depends on your needs......

The attached photo is of an Everlast welder spec sheet, found here. You can see how 100% DC is available at 90 amps but yet the machine would be considered a 35% DC welder as that is at a higher welding current. You need to be realistic in what your needs are. As mentioned earlier, Pipeliners will want/need a 100% machine, the average home shop guy, not so much. If you want to frequently weld 1/4" material and not worry about DC, then any 250 amp welder should put you in the wheelhouse for a 1/8" - 3/16" rod with an acceptable DC. And that spec in the attached doc is at 40C ambient temperature! I would not want to be welding in that heat! Must be testing way warmer than in Northern Ontario!

Just saying all this so that you don't go looking for a 100% capable machine. Trying to put the specs into perspective. Check the specs before you buy.

 

[phaxtris]

There are no 100% duty cycle welders for sale that I am aware of, even a machine that runs sub arc is not 100% rated at full output, you just need a machine that has enough duty cycle for what you are doing

Pipeline needs more like 80% at welding current, not really a problem tho considering most engine drives on the pipeline are 300a @ 100%

5/32 is realistically the biggest rod you would ever need to run in a home shop (and even that's a stretch), most 200a machines have enough duty cycle to run 5/32 7018 steady....heck other than pipeline hot pass guys, anything above 5/32 is not very common these days even commercially

A 200a 3in1 is the perfect machine for the garage imo, more than enough for stick/tig, and enough for general purpose MIG

 

[Johnwa]

Duty cycle is usually not an issue unless you’re burning rod after rod. In my case it’s likely no more than 2 rods and then a bunch of fit up and prep. This along with slag removal Is usually enough to let the welder cool down.

 

[StevSmar]

For me it's more like 3 seconds of welding , 10 seconds of waiting for my vision to clear so I can see what went wrong

LOL, I suspect that my experience will be similar to your’s. My duty cycle is likely less than my welders.

 

[StevSmar]

that oldschool tap machine is going to take some practice, the 60hz sine wave and no good current control will have a steeper learning curve than a dc machine, i would pick one rod and stick with it,

That’s good advice, I’m not going to buy lots of different types of rods. I’m thinking small packages of two or three types, practise, and then buy more of the rods that seem to work best.