DCEP versus DCEN stick welding

[dom14]

Hey Guys,

I'm wondering what's your experience with the above.

I'm about to weld a bung onto a pipe using arc(stick) welding(an inverter welder).
I already made the hole on the pipe.

What is the best way to go about it?!!
Pipe is a 1mm-2mm thick whereas the bung is pretty thick.
I'm thinking of 2mm or 2.5mm rods.
Should I use DCEP(electrode positive) or DCEN(electrode negative) to get a good weld without blowing a hole through the pipe or creating a bad weld with small holes/gaps??!
What is the recommended amp range?
What is the recommended rod size?

Thanx

[dom14]

I found below thread is pretty useful.

http://www.tractorbynet.com/forums/welding/309835-positive-negative-ground.html

Explanation about the formation of lightening is pretty interesting.

[dom14]

And this,
http://www.millerwelds.com/resources/communities/mboard/forum/welding-discussions/22186-electrode-positive-or-electrode-negative

[GQtdauto]

Because of the thickness of pipe I'm assuming its exhaust , if you shape the bung to suit the pipe and keep hole size well under the circumference of bung you will probably still blow a hole in it unless your very skilled at arc welding .
Reversing polarity gives you more heat at electrode or more heat on the work surface dc neg or dc pos , to be honest it's been that long ago and after years of pain drugs I can't remember which is which but I can tell you arc would be my last choice for this job .
Either Mig , Tig or oxy would be my preference depending on what type of metal it is .
They do make a smaller electrode than 2.5 mm or at least they did 20 years ago .
If using 2.5 mm and you're going to give it a go start at lowest amps suggested and concentrate most of the heat on the thicker material keeping a short arc gap .

[PeeBee]

Dom, I am firmly seeing you as a total do-it-yourselfer, and I applaud you for that, but whats it going to cost to get the bung welded in at an exhaust place, $20??? Sometimes its best left to the guys who do this day in day out. They are familiar with the materials and the settings and style of welding. I can weld, MIG/TIG/ARC?Gas, but am in the novice class, so when there is a critical or tricky task, I leave it to the tradies to bring it home. I think this is really one of those examples as there are a number of variables you are asking to get answers on, and any one could end in tears if not correct. I hope you take this in the 'right light' it is offered.

[GQtdauto]

Well said , unless he has a bit of scrap lying around to practice on , which even I do sometimes , get someone with the right equipment .

[dom14]

Dom, I am firmly seeing you as a total do-it-yourselfer, and I applaud you for that, but whats it going to cost to get the bung welded in at an exhaust place, $20??? Sometimes its best left to the guys who do this day in day out. They are familiar with the materials and the settings and style of welding. I can weld, MIG/TIG/ARC?Gas, but am in the novice class, so when there is a critical or tricky task, I leave it to the tradies to bring it home. I think this is really one of those examples as there are a number of variables you are asking to get answers on, and any one could end in tears if not correct. I hope you take this in the 'right light' it is offered.

Hi Phil,
Thanx mate.
My MIG welder is out of action atm, hence the reason I'm going to stick welding.
I've done thin metal stick welding in the past(muffler), but basically learnt by experimenting.
You're right, it's not about the money, but me gaining some experience of performing tricky welds with less than perfect gear for the particular
welding task, hence the reason for my DIY.
I'm pretty sure I can manage this weld per day, but it generally comes out bit "gooey" looking due to it being arc welding, instead of MIG welding.

I've seen a guy welding two razor blades with perfect looking beads with a stick welder(in the internet), but indicated it's also from the particular type of welding rod he used, in addition to skill.

Thanx for the tips, but I'm still going to be adamant and DIY it and cry if I stuff it up. :D

Cheers

[dom14]

Well said , unless he has a bit of scrap lying around to practice on , which even I do sometimes , get someone with the right equipment .

I do have scrap(I'm a collector :) ) and have been practicing the "art" of thin metal stick welding. But, my welds still look ugly as hell.:)
I'm a long way to go, in terms of making them look nicer. :)

Cheers

[GQtdauto]

If you have an inverter welder and reverse the electrode and earth lead around you should get more heat off the job but your electrode will go red fairly quick , just keep changing them over , from memory you want to be well under 65 amp but on an inverter you won't know or be able to set it for that so practice on some scrap .
Keep arc gap to about 3 mm , rod about 45 degree angle to job and just a bit less in direction of weld , heating up electrode in an oven and using them hot may make them easier to start .

[threedogs]

do like my mate does if Im not around , stop ,start, stop ,start ,grind and repeat
you'll get it done in the end lol

[GQtdauto]

do like my mate does if Im not around , stop ,start, stop ,start ,grind and repeat
you'll get it done in the end lol
Classic threedogs love it .

[GQtdauto]

A local fast food joint when built came in kit form , the supports for roof were 8" poles which when assembled had a spacer inside so partA located into part B but had to be welded .
A guy I know was asked to do the welding and he couldn't weld so it was all birdshit and lumpy or not even there , he ground off the high bits and siliconed all the way around , reckoned it looked tops , lucky we are not in a cyclone area .

[Turtle_au]

What about welding the bung to a 3mm piece of scrap (about 20mm bigger than the hole) then weld that to the pipe. Curve the scrap to the pipe first though.
Could even use a flat washer that the bung will fit through to make the area aroung the hole thicker.

Sent from my SM-T355Y using Tapatalk

[dom14]

What about welding the bung to a 3mm piece of scrap (about 20mm bigger than the hole) then weld that to the pipe. Curve the scrap to the pipe first though.
Could even use a flat washer that the bung will fit through to make the area aroung the hole thicker.

Sent from my SM-T355Y using Tapatalk

Thanx.
Welding a flat washer at the area around pipe where the bung fits is good idea.
Or I can make my own washer with a thick piece of scrap.
Cheers

[mudnut]

You can always try a panel beaters trick with thin metal welds. File the bottom of the bung to fit the curve of the pipe. If you have a scrap piece of copper pipe you might be able to cut to length then cut it length ways and open it up to make it match the inner diameter of the pipe. Use a bit of smaller pipe to keep it in place. It should sop up any excess heat from the weld.

[billyj]

personally id use my mig but if i had to arc is id be dcep about 60-70a with a 2.5mm rod and go as fast as you can, thats the trick to stick welding on thinner metals hot and fast

[dom14]

personally id use my mig but if i had to arc is id be dcep about 60-70a with a 2.5mm rod and go as fast as you can, thats the trick to stick welding on thinner metals hot and fast

I have a gasless MIG, but it's pretty crappy to weld using it, 'cos it splatters the weld everywhere.

[billyj]

yer gas mig is the go. stick will work though. get some decent rods(i like wia 16tc's) that will freeze up a bit quicker and watch the weld puddle closely if it looks like its sagging and about to melt a hole just stop allow the piece to cool a little remove slag then continue

[dom14]

yer gas mig is the go. stick will work though. get some decent rods(i like wia 16tc's) that will freeze up a bit quicker and watch the weld puddle closely if it looks like its sagging and about to melt a hole just stop allow the piece to cool a little remove slag then continue

Yeah, it's about time I get a decent gas MIG unit. :)

[dom14]

Welded it but it's no cosmetic beauty. :)
Some grinding is needed.
I used 2mm sticks with around 40-50 amp.
Tried both DCEN and DCEP, I couldn't see much difference.
About a quarter of the weld I got done cosmetically perfect but start going gooey after that.
Not sure about the technique but it has a fair bit to do with preheating & the distance I hold the stick from the weld.
There was no risk of blowing a hole through at all. It can be the case if I used a higher amps, but I didn't want the risk. :)
Thin metal welding with arc welding is quite doable, but need bit of practice and tinkering with settings.

[billyj]

no need to preheat thin stuff like exhaust will just make it blow holes alot easier,

arc length is important as is rod selection, some cheap rods are just plain shit to use, cig satin craft rods are pretty nice to use and the slag will peel itself off if you get everything right but being a very runny rod their no good for vertical welds

[GQtdauto]

CIG also used to make Craft 12 which was green in colour , satincraft is blue , the Craft 12 we used to teach basic welding along with WIA 13s which are blue and white striped .
Both easy to learn with and very forgiving but the Craft 12 had a very fast weld pool freeze which made it ideal for thin stuff and out of position work such as overhead welding .
No idea why they stopped making Craft 12 but it happened when they moved the manufacture overseas .

[dom14]

no need to preheat thin stuff like exhaust will just make it blow holes alot easier,

arc length is important as is rod selection, some cheap rods are just plain shit to use, cig satin craft rods are pretty nice to use and the slag will peel itself off if you get everything right but being a very runny rod their no good for vertical welds

Yes, that is true. I just preheated the bung, 'cos bung is pretty thick, comparing to the pipe.

The rods I used weren't good quality, so that also probably explains why it was harder to get a better weld.

[dom14]

CIG also used to make Craft 12 which was green in colour , satincraft is blue , the Craft 12 we used to teach basic welding along with WIA 13s which are blue and white striped .
Both easy to learn with and very forgiving but the Craft 12 had a very fast weld pool freeze which made it ideal for thin stuff and out of position work such as overhead welding .
No idea why they stopped making Craft 12 but it happened when they moved the manufacture overseas .

The story of manufacturing industry these days. They all move into China, India, Malaysia, Indonesia, etc.
Australian car manufacturing industry is no more or pretty closer to that. It is a crappy situation.:icon_bonk:

[GQtdauto]

Yes I would hate to think how much industry and manufacturing we have lost to overseas .
As an aside once we were confident you could weld we weaned you off the Craft 12 and 13s and you used satincraft after that .