Finally Bought a small Mig welder

[striker]

Hey all,

Yesterday was treat myself day, because the summer has been lousy and I just needed to spend some money which would have normaly gone down the fillercap on the striker.

so I bought an older cebora Mig machine 125apms which had been converted to run gas. it was in pretty bad shape but a day of fidling with the wire feeder and the gasvalve + making a new side cover because the old one wasn't there, I was finaly ready to do my first practice this evening.

I have very little experience in welding myself, so I did a few tests on 3 pieces of round 4301 steel tube 1.5mm wallthickness I had lying around. tell me what you think. if it's ok I can finally start on the SC mounts for the engine.

here's the machine


here's the welds
the left one is the first try and the right one is the second with a little more wire feed which made it sound the way I normally hear my friend doing it, a sort of "crispy" is that right? I cleaned the right one with a wire brush
I had the current on low mode, but I don't realy understand the gas meter, I turned it up some and the welds don't look poreus so it's probably ok, can you have to much gas?



Grtz Thomas

 

[vn1uz]

u want gas flow around 14l/min
the welds look ok for a amature
u were right in upping the wire speed to a crispy sound
u will need your setting higher for engine mounts
as the plate will be heaver and u wont get good fusion on a low setting like u did with the 1.2 stuff

 

[striker]

Thanx for the tips!

engine mounts will be made out of 4mm steel so if I do a weld at both sides of the material I would be able to get good penetration on the High mode. if thats a good way of welding (???) I willl try that first and if it's not good enough I can now at least tackweld everything up in my own garage and then take it to a good friend with a big-a** welder, if needed

the supercharger mounts will be made up from 1.5mm WT square tube 20x20mm,

I always work with the understanding that if you can iift up the engine on a mount it's strong enough to support whatever it's supporting.....

So crispy sound it is then.

BTW this thing does 125 amps, what would be the thickest weldable?

and what's the smiley about, are the welds not good?

grtz Thomas

 

[markstoys]

Those welds look OK. The one on the right looks as if the start/stop is not completely fused together--although it is hard to tell in the picture. Fusing starts and stops is one of the harder things for a rookie to learn.The weld should be the same size all the way around--and when you do it properly, it is almost impossible to tell where you started/stopped.

If you are concerned about penetration, you can bevel the edges of your material a little--not to a point, just take like 1mm on each side of a 4mm plate. This will give you more area of fusion.

Mark

 

[striker]

Hey Mark,

Thats a very usfull tip on the beveled edges Thanx!

I didn't try to finnish the welds in one go 360 round, I was more eger to make a few starts because the machine operates Live current the torch knob only switches gas on and off. but I know what you mean, the rollbar on my striker is welded to the chassis at the tube behind your shoulders, you can't tell where they begun or ended the weld.
I will go and try a full 360 tommorow

thanx again for the tip, and keep them comming!

grtz Thomas

 

[Toysrme]

prety much everyone has told you anything you can be told through that pic.

AFA the welds, get a sharper picture up close. size of the weld looks good. as already said you need to start new weld beads ontop of the existing bead to avoid the gaps you're getting.

honestly we can't really tell you how thick it will weld. alot if you're beveling... the problem is that there's no way to know the actual amperage output on the cheap transformer units (unless you measure it). you'd have to tell us your wire feed speed. the WFS, amperage & travel speed all affect heat input.




for the shielding gas, depending on the gas, you want 15-20cfh (7-9lpm). know the gas the regulator is calibrated to use & if not correct, google a flow rate conversion chart. may save you penny's down the road. not sure what gas you're using (lighter than air gases require signifigantly more flow rate) but if the gas flow is 14lpm that's about 30cfh. in general that's getting too much. it's sorta a waste of shielding gas less you're using a very large gas cup. plus it's likely getting into the higher flow rates that cause turbulance problems, which cause the atmosphere you're trying ot purge to spill back onto the arc & weld.

30cfm. really you're only going to see that on a welder using globular transfer, which isn't going to happen on your welder it has neither the current, nor the voltage output needed to step from a short-circuit transfer into globular. plus, globular is a dinosaur of suckage. spray, pulsed & flux-core are all much better with little to none of the drawbacks of globular.




the WFS... WFS = heat input.
once you have enough to maintain an arc that is stable enough for you to control what's going on. (note technically you're always in short-circuit, which means the wire hits the base metal, heats, pinches off, the arc burns into the base metal. the process continues becuase the wire is still advancing)

the actual top end of wfs depends on the welder. the faster you can travel, the more WFS you can run. you want it to be almost buzzing sound. the classic "bacon frying" responce you normally get i think is abit too cold. the electrode movement stays very choppy because the arc isn't on enough. i never weld real low like that. i dislike it.
here's a video i googled
http://www.mig-welding.co.uk/wire-speed.htm

personally when i used my crappy china mig welder. im normaly about 1/4 to 1/2 of the way into the too-fast box. just keep in mind i don't doddle. i use a high travel speed to reduce my heat input.
but you can hear as it transitions from the good to too-fast box how it goes beyond random "bacon frying". that's where i like to weld my short-circuit welding at.
personal prefferance...



yeah for something like an engine mount that would be more 3/16-1/4" thick. on that welder you would definately want to turn it up, increase the WFS, slightly decrease the travel rate (all to get more penitration) and beveling the edge may be required.
















get you some plate & practice some 2F T joints, make some 2g butt welds & some 2g full-penitration welds. (60* bevel, 30* bevel on each piece)
abit more practice & id turn you loose easy.


oh. and when you end a weld, you need to hesitate at the end to leave it in place, then take a slight back-step. that way you won't get crater cracks.

 

[Toysrme]

afa beveling goes 2 things you need to know
1 feather edge VS landing
the feather edge is beveling it to a point. that's what youll want to do. it increases penitration. beveling it down & leaving a landing is required to decrease the penitration.
2 root gap opening
the size of the gap helps determine the depth of penitration, and the amount of base material breakdown.
you want the base material welll broken down on the backside (you want to see a consistant sized weld bead on the back. on the plate sizes you can handle, a consistant 3/32-3/16" is great. atleast flush, prefferable convex (humped over), as the convexity gives joint reinforcement.
for flat plate it's 30* on each plate to add to a 60* bevel. that's the easyest bevel to work with. but you've also got flare bevels & J bevels. I wouldn't work with them with your welder if possible. just cut / grind it down 30* to a feather edge.

id suggest sticking primarily to welding a feather edged 60* bevel, with a gap of 3/32" for the material thicknesses you can weld on that welder using 1 to 6 passes.
for pipe. if you get into welding some thicker pipe like schedule 40. you can bevel if needed, but simply leaving yourself a 1/16" to 3/32" gap between the peces is normally enough to do it in one good pass, or two smaller passes.

you can also bevel fillet welds if they're getting into material thicknesses you're iffy with. on a T joint you can bevel the end of the workpiece, weld that. then ontop of that weld proceed to do your fillet weld<s> as usual. the bevel in this case would be 45*.

 

[Toysrme]

to go back to shielding gas.
the standard is 20cfm for co2, c25 and most c02 mixes. 15cfm is acceptible given proper technique, and you're not welding out of position on sensative materials.
if you HAVE to run 30cfm (14l/m) to get rid of porosity, you have leaks in your system. spray the hose down at all connections (even internal) with some soapy water (an alcohol based glass cleaner is a classic method) and it will bubble at the leaks.





you're using a good filler wire correct? what type is it, what's it's designation?

 

[mranlet]

Welding two pipes or tubes together end to end is often easiest when you hold the torch parallel to them.

A trick I sometimes use to half-assedly preheat thicker metal is to add an extra tack about where you're going to start welding. If you wait a moment before starting to fully weld you not only are able to see your starting point better due to the light emitted from the tip of the wire, but it also heats up the surrounding metal a bit slower than just nailin it straight away.

 

[Toysrme]

define parallel
parrallel to the pipe would give you an incorrect electrode angle for the joint which can result in undercut of th near edge, overlap of the far edge, incorrect joint to toe profile, and poor shielding gas coverage.

you want the electrode to travel down the weld joint at a 10-15* travel angle through the middle of the joint, unless you're talking lap joints. im assuming thats what u meant, i just dont want ppl getting confused

 

[mranlet]

If you're trying to weld a contunuous bead around a piece like an exhaust pipe (in which strength isn't imperative), I find that it's easierst to hold the torch in the same direction as the exhaust pipe.

If welding for strength in something like a driveshaft, most definitely hold the torch so that it aims across the piece rather than along the same axis.

 

[striker]

Wire is 0.8mm SG2 standard wire for normal steel, I know that I should not do 4103 steel with that but it was only bead laying pratice!
Gas is normal Argon-CO2 mix

anyway I tried what you discussed, and indeed I get a nicer looking bead with the torch lengthwise to the tube but you get one pipe hotter than the other, so structural seems the question.

grtz Thomas