# The when and why of flux core



## Hukshawn (Jun 29, 2017)

under what circumstances would you want to use flux core, or dual shield flux core?


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## Hawkeye (Jun 30, 2017)

I've been messing with MIG welders for some years now. I have gas connected, but have never used it for anything but the aluminum spool gun ( or the TIG welder). I like the convenience of turning on the welder, tweaking the settings, welding the project and shutting it down without turning gas on, adjusting it, welding, then shutting down the tank and draining the regulator.

I know that solid wire with gas is a lot cleaner, but I don't mind cleaning up the spatter for the sake of all the other conveniences. If I was doing really thin metal, I'd be more inclined to use gas.


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## mikey (Jun 30, 2017)

I use flux core when I'm outside, when the wind can blow the shielding gas away, or when I take the Mig somewhere and I don't want to haul the tank with me. I also use it when the metal is not clean or is a hassle to clean. Flux core is messier, though.


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## dlane (Jun 30, 2017)

^ x2


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## Ulma Doctor (Jun 30, 2017)

use flux core for general welding
use dual shield when you want to pay twice as much to weld something, you'll be buying the wire and shielding gas too.
the advantage i'm aware of with dual shield is that you can weld stainless with argon as the shielding gas

flux core can be made less messy by paying attention to stick out length and amperage in most cases.
inexpensive flux core wire is also a fastpass to a spatterfest and a crappy weld too.
anti spatter juice helps out, if you'd like the extra expense


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## Hukshawn (Jun 30, 2017)

So it seems it really does come down to just preference? 
I've been stick and MIG welding for years but nothing beyond hobby or the odd favour job. I recently picked up a new-to-me machine that is much bigger than my previous 110v mig and seperate 225a stick machine. An airco unit that does mig, AC and DC stick, and Tig (with the right equipment) 
I remember when I first bought my 110v machine a decade ago, it came with low quality flux core wire. Coupled with my brand new inability to weld and the underpowered 110v machine, the flux core was a messsss. Once I put gas on that machine it was like night and day and swore I'd never do flux core again. 
Fast forward 10 years. I'd say I'm a fairly intermediate welder with enough knowledge of an ignorant hobbiest BUT with a taste for YouTube teachers now. I've seen many YouTubers use flux core. Chucky2009 uses it often, sometimes explains why but not why he chose flux core. Also Jody from welding tips and tricks, same fiasco. 
So it raised the question. 
I've also noticed a drastic difference in price between what appears to be crap flux core and a good flux core...? Nearly $80 for a big roll (this airco only takes big rolls, unless I build an adapter) 

Right now it has .030" wire. With about somewhere between 1/8 and 1/4 of a roll left. I might to go .035" once it's gone. 
The machine runs really well after I cleaned everything up, but I don't often get the nice bacon frying sound when I have the heat a bit higher. More of a popping than a frying. I usually have to have the feed knob maxed. Maybe trying to weld too much with too thin of wire? On a bit lower heat on thinner guage it sounds fine. But otherwise, nice bead, good penetration, clean, fairly happy.


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## Ulma Doctor (Jun 30, 2017)

a lot of the 110v machines will run better on a 20 amp circuit.
i have a HF 90 amp (110v operation) flux core unit, it is set to max amps, i vary the wire speed & i use .030 innershield NR232
i also have a Lincoln SP125 (110v operation) mig that i use for thin stainless welding .030 309L wire & Tri mix (argon/helium/CO2 mix)
both welders are incomparable to my PowCon 200s (220V 3 phase) FCAW .035" NR232 innershield, the penetration and range of thickness of materials i can weld is much greater than any 110v unit 
110 units you are limited to 3/16"ish material
220 units can weld thick sections without a problem


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## brino (Jun 30, 2017)

Ulma Doctor said:


> fastpass to a spatterfest



oooohhhh, I like the sound of that........is it too late to change my username?
-brino


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## Buffalo20 (Jun 30, 2017)

I run a lot of .045", .068" and 3/64" flux-core, on remote jobsites


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## mzayd3 (Jun 30, 2017)

I use .023 with gas for everything under 1/8". 1/8" and above, I switch to flux core, I get better penetration that way- flux core burns hotter 


Sent from my iPhone using Tapatalk


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## Hukshawn (Jun 30, 2017)

I suppose the better quality flux cores aren't so splattery? Or atleast the flux comes off better? I didn't like it before cause it never looked good on that 110 machine. But probably cheap Canadian tire wire. However I was surprised how well it would weld with gas. I changed the power cord to a 12 awg and used it on a 15a circuit that was direct. Using it on a 20amp circuit doesn't give you any more amps than a 15a just means it won't trip out at 15. But being a direct circuit and a beefier cord will give the welder more headroom to pull the amps it wants. A 15 amp circuit will happily give you 20amps for short periods of time as long as it's not a spike. 
We used to instal construction heaters in new builds during construction. 30a heater in the stove and/or dryer circuit on a 20a breaker all day long. We did that because once the heater got caked in drywall dust it would trip the breaker before burning out the heater. 

This airco machine I'm using now is 220v and much more powerful. It'll do 160 amps 22v for mig and 200amps 28v for stick. I have 25/75 gas and is far I like it. But, I don't weld much heavy duty very often. I did some 1/4" last week and it did fine. Moving a bit slower with .030 wire but god penatration. More often than not it'll be 1/8"


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## Ironken (Jul 3, 2017)

Hukshawn said:


> under what circumstances would you want to use flux core, or dual shield flux core?



Like was mentioned here, flux core is great for windy/outdoor conditions and being able to go remote without shielding gas. Flux core can also give underpowered machines a bit more poop. Flux core generally is run with a bit more stickout, this is to preheat the wire some, and should run in a "spray" type transfer. If you are short arcing flux core, she ain't gonna run right.

Dual shielded wires are wonderful when high deposition and high penatration are desired and the slag is usually easy to remove.

Metal core wire is another high deposition option for larger machines. No slag, high dep, spray transfer and beautiful appearance. I use Hobart Fabcor 86r and love it.

There are adapters available to adapt the small 2# spools to your machine that uses the 10" or 12" spools

https://www.amazon.com/Universal-Welding-Spool-Adapter-Spools/dp/B00DU03UEA


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## Hukshawn (Jul 3, 2017)

I fabracobled a new mounting plate to accept a smaller roll. 





Gave it a test run. Ran HORRIBLY... Remembered flux core us run reverse polarity. This airco welder doesn't have any option for that. I'd have to actually go inside the machine and change some leads around, which would result in modifying the machine. 

Is it my understanding that in order to run the reverse polarity that you simply swap the ground and hot leads? 
How do other machines achieve this with only switching one wire under the hood? 

I had been thinking about rigging up such an option. Under the feed section of the unit, installing and rewiring an option to easily swap the polarity without having to dig into the machine itself. 
Which is no small task. The leads are all bolted to that blade switch. 



I did try to just switch the ground and hot lead to try but the eyelets and bolts are two different sizes. Likely designed as such. 

I havr been trying to dig up more info about this machine, but there really isn't much. Trying to join Miller's forum but it's a slow process. Most of the information about this machine is actually there. 
I found the owners manual and there's no mention of flux core. So obviously, never designed to run it. 

The whole reason for this flux core is our small construction company is in the process of buying a dump trailer that will need a couple repairs. Those repairs will be done outside. So, as stated several times, flux core is desirable in those conditions. 
If it's not reasonable to make this work, then I have a roll of Hobart flux core to take up space on my shelf and I'll just stick weld everything. Lol


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## Ironken (Jul 3, 2017)

Hukshawn said:


> I fabracobled a new mounting plate to accept a smaller roll.
> View attachment 236796
> 
> View attachment 236797
> ...



I forgot to mention the polarity thing. Generally FCAW is ran in straight polarity and solid wire, FCAW-G (dual shield) and metal core are ran in reverse polarity. Straight polarity is DCEN....have you considered (if there's room) using Tweco connectors? You could extend the output lead from your machine to the feeder and extend the work lead as well. You could then cut the leads in a convenient spot and install the Tweco connectors. This would allow you to swap leads easily. Like these.

http://m.cyberweld.com/cabcon.html?...DHN3dXgZjEgRT1CSKwJuDfpr3JQ989FRoCClcQAvD_BwE

None of my Millers are a one lead swap to change polarity. No machines that Im aware of work that way. Gotta swap both work and power.

If you can tent, tarp or the breeze is calm, I would just run gas on your dump repair and save some hassle and cost.

Gasless fluxcore has its purpose but, Is usually last on my list.

Your small spool adapter looks slick. I like it.


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## Hukshawn (Jul 3, 2017)

Essentially what I was thinking, but mounting it inside the feed side cause there's so much room. And if I mount it, say, on some delrin for insulating, then I don't have the big connectors just flapping around on the inside. And, it'll give me an excuse to machine something. I machined that small reel mount. It's all shoulders for getting nice tension. 
This is more so turning into determination thing, that's just what happens with me when I get something in my mind. Lol.


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## Ironken (Jul 3, 2017)

Hukshawn said:


> Essentially what I was thinking, but mounting it inside the feed side cause there's so much room. And if I mount it, say, on some delrin for insulating, then I don't have the big connectors just flapping around on the inside. And, it'll give me an excuse to machine something. I machined that small reel mount. It's all shoulders for getting nice tension.
> This is more so turning into determination thing, that's just what happens with me when I get something in my mind. Lol.



I get the determination thing....for me, it's not so much that I need something, it's me wanting to see if I can do it. If you want a project, go for broke and make some insulated pass thru parts with terminals. Pics...lots of pics.


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## 56type (Jul 3, 2017)

Ulma Doctor said:


> a lot of the 110v machines will run better on a 20 amp circuit.
> i have a HF 90 amp (110v operation) flux core unit, it is set to max amps, i vary the wire speed & i use .030 innershield NR232
> i also have a Lincoln SP125 (110v operation) mig that i use for thin stainless welding .030 309L wire & Tri mix (argon/helium/CO2 mix)
> both welders are incomparable to my PowCon 200s (220V 3 phase) FCAW .035" NR232 innershield, the penetration and range of thickness of materials i can weld is much greater than any 110v unit
> ...



If you haven't already, you may want to try the DCEN conversion on the HF 90-amp welder. It reduces the spatter a bit and seems to help with penetration as well. There are quite a few youtube vids on the conversion process. About $35-45 in materials.


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## Hukshawn (Jul 3, 2017)

Ironken said:


> I get the determination thing....for me, it's not so much that I need something, it's me wanting to see if I can do it. If you want a project, go for broke and make some insulated pass thru parts with terminals. Pics...lots of pics.



That's the plan! 
This week I'll go to the metal supply and get some delrin flat stock. I have some bar, but I don't think that'll work. 
And I'll rewire it.


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## Hukshawn (Jul 3, 2017)

56type said:


> If you haven't already, you may want to try the DCEN conversion on the HF 90-amp welder. It reduces the spatter a bit and seems to help with penetration as well. There are quite a few youtube vids on the conversion process. About $35-45 in materials.



I'm only going to add terminals to switch the polarity of the mig gun. I can control the stick section of the welder via the selection knob.


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## Hukshawn (Jul 3, 2017)

So I made some threaded bushings out of delrin. I decided I didn't need delrin plate, and that I could just make bushings. I'll drill a hole in the feed housing in the wall between the feed and electrical section and thread the bushing through. 
I need longer bolts tho so I can use two nuts. One to hold the stud to the housing, the second to hold the cable and to give some extra distance between the male bushing and the housing. Don't need to be making any contact with the housing and blowing everything to smitherines...









What's delrins heat rating? Just in case I wind up with an issue with heat?


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## Ironken (Jul 3, 2017)

Hukshawn said:


> So I made some threaded bushings out of delrin. I decided I didn't need delrin plate, and that I could just make bushings. I'll drill a hole in the feed housing in the wall between the feed and electrical section and thread the bushing through.
> I need longer bolts tho so I can use two nuts. One to hold the stud to the housing, the second to hold the cable and to give some extra distance between the male bushing and the housing. Don't need to be making any contact with the housing and blowing everything to smitherines...
> 
> View attachment 236826
> ...




I like where you're going with this. I have no idea what Delrin can take as far as heat goes. Is it necessary to use copper studs for conductivity?


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## Hukshawn (Jul 3, 2017)

Hmmm. I have some copper bar, but I've never worked with copper. I hear it can be difficult cause it work hardens. Is brass any better?


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## MozamPete (Jul 4, 2017)

As long as the steel bolt is just providing the clamping force and is not part of the current path you should be fine - i.e. you're connecting the two cable ring lugs directly together not one at each end of the bolt.


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## Hukshawn (Jul 4, 2017)

Hmm. I was going to leave the leads inside the electrical side and use them as a current bath, but I suppose the safer bet, without making copper studs, would be to bring them into the wire feed side and just use them for clamping...

Back to the sake of going the mile, maybe I'll try to thread and tap a copper nut and bolt. See what happens. I'd it doesn't work, then I'll just do clamping force.


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## Ironken (Jul 4, 2017)

Hukshawn said:


> Hmmm. I have some copper bar, but I've never worked with copper. I hear it can be difficult cause it work hardens. Is brass any better?



That I couldnt answer. I believe the connectors that Tweco and Lenco makes are brass.....brass bolts and nuts are available on line but they are very proud of them.


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## Hukshawn (Jul 4, 2017)

Proud of them? Sorry, I didn't understand that.


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## StepSide 88 (Jul 4, 2017)

Proud... means they believe thet have a very valuable piece of commodity.


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## Ironken (Jul 4, 2017)

Hukshawn said:


> Proud of them? Sorry, I didn't understand that.



Sorry, I was speakin' Merican slang. Like Stepside said, expensive.


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## Terrywerm (Jul 4, 2017)

Brass should work just fine, but as already mentioned, can be expensive. It is a good conductor and resists corrosion better than copper. Work hardening is non-existent.

If you choose to make copper hardware and find that work hardening becomes an issue, heat the part up cherry red and quench in water to anneal it.

According to information I found on the web from various plastics suppliers, Delrin® has a melting point of 347° F and lists a 'maximum serving temperature for long term' of 185° F.   It also lists an 'applicable temperature range for thermal expansion' of 85 to 140° F.   Another reference lists its maximum working temperature at 248°F. My guess is that it should work just fine for your application. If you have trouble with it, you might want to look at using something like phenolic instead.


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## Hukshawn (Jul 4, 2017)

I got brass 2" 1/4-20 bolts and nuts from home Depot. Basically amounted to a buck each, with washers. 

If I have a heat issue, then I have bigger issues than dealing with the delrin. My conductors would be underrated then.
But, I think this will work fine and will be a good addition to this welder - to have th flexibility to switch to flux core when needed. As a hobby welder (sometimes fabbing up some metal for table legs, etc, for carpentry work for my job (contractor)), I'm never just doing one type of welding only. Flexibility is an asset, and my bossman is happy to have this addition to our/my list of capabilities. He wants to have us get into building some furniture for clients when he can sell it. And I'm happy to ablige. He likes that I have a metal shop as well as the woodshop.wnd I like that he likes that. Excuses to stay home and build something AND get paid. Not something I can enjoy as a hobbiest. Lol.


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## Ironken (Jul 4, 2017)

Hukshawn said:


> I got brass 2" 1/4-20 bolts and nuts from home Depot. Basically amounted to a buck each, with washers.
> 
> If I have a heat issue, then I have bigger issues than dealing with the delrin. My conductors would be underrated then.
> But, I think this will work fine and will be a good addition to this welder - to have th flexibility to switch to flux core when needed. As a hobby welder (sometimes fabbing up some metal for table legs, etc, for carpentry work for my job (contractor)), I'm never just doing one type of welding only. Flexibility is an asset, and my bossman is happy to have this addition to our/my list of capabilities. He wants to have us get into building some furniture for clients when he can sell it. And I'm happy to ablige. He likes that I have a metal shop as well as the woodshop.wnd I like that he likes that. Excuses to stay home and build something AND get paid. Not something I can enjoy as a hobbiest. Lol.



Problem solved in about a day and a more capable machine. I would call that a win! Well done.


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## Hukshawn (Jul 4, 2017)

I haven't put it all together yet. Still at work. I'll do it tonight and take pics.


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## Hukshawn (Jul 5, 2017)

Ok, first of all, here is the big stupid bastard. (The eye burning purple light in the background is the leds I put in the back of my truck contractor cap. I had some leds left over for the electrical days and forgot these were like 6000k leds. The white is so cold it's purple... but, they work, so they stay.

I'd like to do a paint job, but there's a lot of writing to mask out. 



I posted a picture of the bushings yesterday. Here's all the parts.
The bushings I made, the brass is Home Depot, and the lugs are from my electrical wholesaler



All of the leads converge on this big blade switch.
I was an electrician before I was a full out contractor for quite some time. Electricity doesn't scare me, but oddly enough, threading my hands into this mess, gave me jitters at first.



So here's the bushings installed.




I disconnected the work and gun leads from the blade switch (one at a time so as to not get mixed up since nothing is labeled...) cut them or changed out the wires to an appropriate length and crimped on the new lugs on the cut end.



I made a little jig for crimping since I don't have a lug crimp this big.
Was just a piece of aluminum with a 7/16" half circle to cup the lug then just a piece of key stock to act as the stud. Then squeeze.




Fished the wires in around everything in a way I liked so nothing rubbed or interfeared, and reused the necessary strain releafs. And bolted everything together. I even labeled the new leads. There's two sets of nuts, one to keep the bolt tight to the bushing, then the second holds the lug on. So everything doesn't fall apart when I switch polarity.



It looks like the lugs can touch if they move, but they can't. But, I may add a barrier at some point to ensure that.


Aaaaaaaaand,




Got great results.
This is varying heat and wire speed.

I didn't remember how different flux core sounds and acts. It's a different kind of puddle and almost sounds like spray welding rather than short circuit mig.
But after some clean up, wire brush then a wire wheel, looks good, happy. But maaaan, it's diiiirrty welding...

So, I'd call this an unbridled success. It's not horribly difficult to switch. The worst part is how unwieldy the spool is. I wasted more wire from spring-a-ma-thinging wire cause the end slipped out of my hand than I did welding. May have to work out some kind of wire guide or straw to keep the wire from curling off the spool cause it's so far away from the rollers.
Got lots of info and ideas here from the group. Always a pleasure! Thanks.


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## Ironken (Jul 5, 2017)

Hukshawn said:


> Ok, first of all, here is the big stupid bastard. (The eye burning purple light in the background is the leds I put in the back of my truck contractor cap. I had some leds left over for the electrical days and forgot these were like 6000k leds. The white is so cold it's purple... but, they work, so they stay.
> 
> I'd like to do a paint job, but there's a lot of writing to mask out.
> View attachment 236909
> ...



"Big stupid bastard" made me laugh! You did an outstanding job on that big stupid bastard......looks like it came from the factory that way.

Your bush fix crimper was genius. I have a big crimper but am filing your idea for future use.

Your welds look fine....maybe a bit cold or the whip made them look that way. You are correct, fuxcore should run with a soft arc and you use more stickout than with solid wire and use a slight drag angle. Small spools in general suck! Tubular wires like knurled drive rolls. This allows for less tension to avoid crushing the filler wire without slipping. Maybe a bit more tension on the spool would help the birdsnest issue. 

Now you have a machine capable of correctly running fluxcore. Awesome!


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## Hukshawn (Jul 6, 2017)

Nah, the first two were cold. Then the one in the middle is hotter and hire wire speed, hence the big puddle. It was deceiving cause the arc is totally different. Seemed I was burning hot but I wasn't. Could I say the arc is a bit violent? Is that something others have noticed with flux core over solid? 

Also, what's the difference with having the gas on too? Is it a specific kind of wire needed? I see no discernible difference.


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## Ironken (Jul 6, 2017)

Hukshawn said:


> Nah, the first two were cold. Then the one in the middle is hotter and hire wire speed, hence the big puddle. It was deceiving cause the arc is totally different. Seemed I was burning hot but I wasn't. Could I say the arc is a bit violent? Is that something others have noticed with flux core over solid?
> 
> Also, what's the difference with having the gas on too? Is it a specific kind of wire needed? I see no discernible difference.



The arc is *kinda* like running 6010/6011 without the deep dig, so a turbulent puddle and dirty all come to mind. The flux/slag package in GASLESS fluxcore creates the envelope to shield the arc and puddle so, using gas is just a waste and could possibly degrade the weld properties.  "Dual shield" flux core wire is an entirely different animal.  It is generally designed to use C25-C100 as shielding gas. With the exception of the soft arc and longer stickout, it runs nothing like gasless. The polarity is even different DCEP. It has a very easy to remove slag and produces a very smooth bead. It wets out very well too.

I used to burn a 50# coil of the 3/32" Outershield 70 (dual shield) in a shift......I don't miss that!

Wire quality really comes into play with fluxcore. I always had good luck with Lincoln
NR-211MP. I use the best filler metals that I can find, that takes at least one variable out of the situation.


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## Hukshawn (Jul 6, 2017)

Hmm. 
I bought this 
https://www.princessauto.com/en/detail/0-030-dia-x-2-lb-flux-cored-welding-wire/A-p8675597e


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## brino (Jul 6, 2017)

Hukshawn said:


> Could I say the arc is a bit violent? Is that something others have noticed with flux core over solid?



Absolutely agreed.
Flux core is a sparky, spattery, smokey mess. I believe it's the nature of the inner shield chemicals burning and expanding to create your shield gas cloud around the arc.

-brino


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## Ironken (Jul 6, 2017)

Hukshawn said:


> Hmm.
> I bought this
> https://www.princessauto.com/en/detail/0-030-dia-x-2-lb-flux-cored-welding-wire/A-p8675597e



Well, that doesn't sound like the problem. Here's a vid about fluxcore....maybe you can compare and see how your process looks.


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## SSage (Jul 6, 2017)

brino said:


> Absolutely agreed.
> Flux core is a sparky, spattery, smokey mess. I believe it's the nature of the inner shield chemicals burning and expanding to create your shield gas cloud around the arc.
> 
> -brino


Thats been my take too, but its convenient! 

I got lots of splatter from a Harbor Freight roll of flux wire that came with a 90 amp $79 welder. I decided to try a .35 because it was so cheap, well their .35 was nasty too, no more HF wire for me. Love the cheap little 90 amp welder though, it works good for light duty quick repairs on farm stuff. I welded up my turning disc for an hour off and on and it was nice to only need 110 volts. I was surprised how long it would go before shutting down, I pushed the time limits to see how long I could weld and its adequate for field repair work. All for $79! Great to have in your truck tool box.

Normally I use the Lincoln brand of wire and welders from Home Depot. I switched to .35 and .30 Hobart from TSC and that was much better. I liked the Hobart/TSC version of .35 best overall, very little splatter and cleaner. Swapped in a new small roll of Lincoln and I wanted the Hobart again. Maybe I got a good roll of the Hobart brand, I likey this roll. At work we always used some house brand out of an Atlanta welding supply that was good, it performed better than the Home Depot Lincoln stuff. I haven't gone to a welding supply in years though. Maybe my next roll of Hobart will be the same. Flux core is dirty, but I weld outside on miscellaneous red iron and farm equipment.


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## Hukshawn (Jul 7, 2017)

This was fun, I like this thread. 

I should have got .035 flux core wire. Or, maybe .030 is fine. Hard to tell. I had been doing a bit more heavy welding recently, but mostly I do 1/8". Time will tell.


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## SSage (Jul 7, 2017)

.35 is best for all around use or angle iron etc. Just make sure your machine is set up for it. Princess Auto is the Harbor Freight equivalent I think, but that .30 wire they sell is substandard. I have used it a good bit on rough farm stuff and it gets the job done though, in a splatter fest. Make sure you have decent protection on, full welding jacket and gloves.


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## Hukshawn (Jul 7, 2017)

Princess auto is Canada's harbour freight, yes. Very often the very same tools just a different colour. 
I grabbed the Hobart roll to get me by. If the need arises I will go to my gas supplier and get some good wire. It won't be long before I'm out of solid core wire anyways.


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