Beginner - advice on current / rod size?

[Chaoticbob]

Hi. I joined this forum back in November last year asking for advice on buying a welder, but with one thing and another didn't get round to buying one until a few weeks ago. It's a Parweld 160 MMA / TIG job. After laying beads when I got time, and thinking I was beginning to get the hang, I tried making something today. Just a BBQ grate out of 3/16" (4.5mm ish) square bar, so a grid tacked at the crossing points. The welds, to put it kindly, were 'good in parts'. I ended up using 3.2mm rods at around 65A - is that anywhere near reasonable for this kind of work?
Regards, Rob.

 

[pondy]

65a is very low for a 3.2. Packs are usually marked at 90-130a for that size

 

[Bill Edwards]

Try 110 ish as a starting point.

 

[Kent]

Way low not less than 100 with 3.2. You need a 2.5 mm which is about perfect at around that power and material

Ok there are exceptions but these are cheats not proper welding. You did well to light and run on those little welds with a 3.2 at that low a setting - are you sure 3.2 mm rod at 65 amp?

 

[norlander]

Look on the box, set the amps to that, test on scrap, if possible same joint you want to weld, you may need to tweak amps up for some jobs-makes sure the arc has enuf grunt to go in, if you see the slag swirling about and there are slagholes, up the juice and check your rod angle.
You might want to try lighting up on a scrap piece then tacking up, I can't explain it, but I strike up just beyond the joint and then run the arc in and on. Maybe push the amps up a bit more for tacking up, no definitive answer for every job.
If its not going in, change juice, change rod angle, check ground (earth).
Stick welders are the boyz

 

[Chaoticbob]

Reet, thanks for advice chaps. What actually happened is that I thought I had left a 2.5 stick in after my last practice, so set the machine at 65A (the 2.5 box is marked 40-70A AC/DC[-]). It was actually 3.2, but I was striking and holding an arc ok (surprisingly!), so I carried on with 3.2's. My welds had loads of slagholes, so it sounds like I was running way too low on current. I think my problem is lack of confidence in starting and finishing - I tend to dwell on the start, to steady my nerves, then snatch at the end. Back to the beads with more attention to starts and finishes!
Rob

 

[Paul G]

Hi. I joined this forum back in November last year asking for advice on buying a welder, but with one thing and another didn't get round to buying one until a few weeks ago. It's a Parweld 160 MMA / TIG job. After laying beads when I got time, and thinking I was beginning to get the hang, I tried making something today. Just a BBQ grate out of 3/16" (4.5mm ish) square bar, so a grid tacked at the crossing points. The welds, to put it kindly, were 'good in parts'. I ended up using 3.2mm rods at around 65A - is that anywhere near reasonable for this kind of work?
Regards, Rob.

I never cease to be amazed at the number of people that give advice WITHOUT reading the original post.

Quote "a BBQ grate out of 3/16" (4.5mm ish) square bar,"

" turn it up to 100/110 "

Kent is close to it, but I'd reach for a 2mm.


Sorry if this offends,
Paul G

 

[Bill Edwards]

2.5 might be more suitable but the OP is asking about 3.2mm rods, it was I who suggested 110 amps as a starting point as 65 is far too low. It's perfectly possible to weld 4.5mm square with that, more or less a quick tack and it's done.

 

[Chaoticbob]

Thanks for further replies. It's beginning to make more sense to me now. I did try using the 3.2mm rods at higher power, but it mostly ended up a mess. I accept that it can be done (I fluked a couple of good joins), but not at my skill level! I've ordered up a box of 2mm rods and shall have a go with them tomorrow. I guess it's just practice, practice, practice, seeing what works for me. I'm not giving up anytime soon - I think I might become an addict!
Regards, Rob.

 

[Chaoticbob]

Success! Using 2mm rods at around 50A seems to work, I even got that rippled look rather than the ugly blob I'd been getting with fatter sticks. And I can't part the joins by hammering, the parent metal gives way first. So something's going right!
Thanks guys, Rob.

 

[Paul G]

Glad you got on better with the 2mm's Rob. Well done for sticking (sorry for the pun) with it.

Love your terminology regarding electrode sizes by the way. "Fatter sticks". Te Hee! I'll remember that one.

ATB
Paul G

 

[Chaoticbob]

Thanks for your encouragement Paul. I went back to laying beads with the skinny sticks and I felt much more in control. It reminded me of leaning to drive - I thought I'd never stop yanking the steering wheel when I changed gear, but it somehow happened and I never knew exactly how. I'm getting goodish beads now - but I don't really know why!
Rob.

 

[TechnicAl]

a good rule is 40 amps per mm...........so 2.5 = 100 amps
tweak it from there if you want
easy to remember

 

[Richard.]

a good rule is 40 amps per mm...........so 2.5 = 100 amps
tweak it from there if you want
easy to remember

That must be very top end rule of thumb al.
I don't run em that hot.

 

[TechnicAl]

That must be very top end rule of thumb al.
I don't run em that hot.

I think it depends on skill level.........the more skilled will run lower...........its a good rule for me though

The rod also makes a difference but overall its a good guide