Clarke 90

[Shaggy33]

Just bought a clarke 90 for some hobby task ie welding thin mild steel sheet (2/3mm approx) for brackets etc.
Can I just ask a basic question regarding the quoted metal thicknesses on welder specs.
If it states that it will weld up to 4mm does that mean I can weld two pieces of 4mm together or is it collective thickness of both pieces.

Example. I have a 3mm sheet of mild steel and want to weld it to another sheet at a 90 degree angle. Because the collective thickness if 6mm will it fail to weld? Or will I only need to penetrate each piece by about 1-2mm (collective 2-3mm) to get a good result?

 

[keith19]

It may fail to weld anything over 2 mm. If the metal is prepped first, it might manage a 3 mm butt weld. Have a look at this test:
http://www.mig-welding.co.uk/clarke-90.htm
Re the basic question, only one metal thickness is counted. Welding two bits of 2 mm thickness together, no matter what joint, is regarded as a 2 mm weld, for example. Doing a fillet weld as you describe, the weld would not be expected to go through the metal, but have around 2/3rds penetration on each.