The right settings

[caveman]

Hi guys have finally got to grips with my new Portamig after purchasing a year ago but have came across a bit of a problem and wondered if anyone could help. Basically had the welder set up for welding thin sheet 0.8-1.2 mm,then disaster strikes my dad came over at Xmas and used the welder to weld some 5mm plates and changed the settings and now I can't get it set back to what it was before its either blowing holes or lumping up the weld high,can anyone recommend any settings for thin stuff pls this is really ******* me off,I've know barred him from my garage

 

[GrahamGKD]

I normally just have a fiddle about with some scrap until it looks about right? There is a power and wirespeed calculator on the tutorial page which will give you a starting place (I've got the resulting table laminated and taped to the front of my Portamig).

To answer your question properly someone would need to know which Portamig you have.

.... just had a look at my table generated from the calculator and it says setting '2' for 0.9 to 1.2 - that's for a Portamig 215 and I think they may have reduced the minimum setting since mine was built? I usually start out with the wirespeed half way.

 

[caveman]

Cheers graham mine is a 215 aswell il give it a try.

 

[Exuptoy]

Get it roughly set then on a scrap piece of metal dial in the wire speed until it sounds right.

 

[slimjim]

setting coarse 1, fine 2, wire speed 3

 

[caveman]

cheers guy will give this a try at the week end and post progress.

cheers caveman

 

[puffernutter]

On the same thread, I am currently restoring a Triumph Stag.

Whilst I can test on scrap as much as I like, when you get to a rusty car it's not quite the same, even if you have cleaned the metal back as much as possible, the thickness can vary and you either don't penetrate fully or blow holes on the same piece of car within a few inches of each other.

I cannot continously vary the speed/power, so how do more experienced welders of cars manage?

Cheers

Peter
Trowbridge

 

[Daz1968]

My method involves very small welds linked together and making sure it is fully cut out to good metal. Have managed with 0.8 wire up till now but recently changed to 0.6 and its easier to control. I'm not an experienced welder by a long way. An auto head shield also helps a lot

 

[Exuptoy]

Try to leave a small 0.5-1mm gap between edges of a plate you've let in as this will allow a little better penetration and weave from new plate into the old metal. Probably better off doing short bursts to give it a chance to cool as you will usually go through on the old stuff. If you blow through just wind it down 1 notch and try to fill the hole with quick squirts around the hole with the torch pulled back a little. It probably won't be pretty with rusty metal. Been there today sorting my rusty bus.

As said, try and get back to solid metal. Been there and worn the T shirt. Only cut the rust out while trying to keep the hole small and you'll end up leaving the rusty stuff there inside. Don't forget the rust is usually as bad inside.

The lamination I've found in the chassis has made 3mm steel about 0.5-1 mm by the time you bash it with a hammer. Not nice welding to this stuff, get it as far back as you can.

 

[slimjim]

On the same thread, I am currently restoring a Triumph Stag.

Whilst I can test on scrap as much as I like, when you get to a rusty car it's not quite the same, even if you have cleaned the metal back as much as possible, the thickness can vary and you either don't penetrate fully or blow holes on the same piece of car within a few inches of each other.

I cannot continously vary the speed/power, so how do more experienced welders of cars manage?

Cheers

Peter
Trowbridge

you should be replacing all the thinned metal, but if for any reason you can't then you can use a bit of flattened copper pipe, placed at the rear, to take some heat out and support the weld at the rear, that and using the thin metal technique in the tutorials!

 

[puffernutter]

All,
Thanks for the helpful replies. I'll have to have a read of the tutorial.

I agree that taking out as much as possible is the best option, the trouble is that there are times you think that you've got to solid metal, but it turns out not as thick as you think....

At the last MoT for the Stag (December last year) I have on the road, the tester pointed out a hole (approx. 3/4" diameter) that needed repairing. By the time I had got back to solid metal that I considered was sound enough for welding I had a plate that was 3" x 8"!

Cheers

Peter

 

[puffernutter]

The other question I have is whether it is better to use 0.6mm or 0.8mm wire.

I was always of teh view (maybe incorrect) that 0.6 was used for the thinner steel, e.g. car bodywork. However when I was welding the Stag over Christmas, one area was a piece of angle to rejoin the floor to the sill and the other was a plate covering a hole in the passeneger footwell, regardless of what current or wire speed I used, I couldn't get on with the 0.6. In the end I went with 0.8 (but that seemed wrong!)

Any suggestions, or just use what seems to work?

Cheers

Peter
Confused of Trowbridge

P.S. Any car body workwelders in Wiltshire willing to spend a day helping a tyro and his Stag (for appropriate remuneration!)- I need to weld a piece in the bottom of the A-Post, repair the inner sill then fit the outer sill. A lot of the prep is done, I just need help to join metal together rather than blowing holes in it

 

[Daz1968]

I have been restoring a mk1 mini and used 0.8 for most of it, never had any major problems but as I ran out of wire I changed to 0.6. Difference I noticed was I could weld on lower power and control the weld better. But I am no expert in welding just diy taught on cars. I would use either just needs more care with 0.8.

 

[gavuk]

I've never bothered with 0.6mm wire,always 0.8 or bigger,it feeds better and seems to work for me with co2 and the "thin metal technique" ,I will use chill blocks made of brass if possible.......Peter If you can transport your welder,I'll be happy to host a little training session .....happier than crawling under your stag anyway ......what welder do you use? perhaps you should start another thread ?