[tooler777]

Hi there. Im practicing for my 3 g mig test. Its in 3/8 plate. Beveled at 37.5 degrees each. I put a 1/6" landing on the pieces and used a 1 inch backing strip, 1/4" thick. Im getting way to much undercut as you can see.my settings are gas 75/25 25cfh. Voltage is 18 and 280 ipm. Should i hold longer on the edges,im only holding for a second but should i hold for 2 secs? Or is it my settings? Thanks for any feedback.

[weldin mike 27]

Hey,

welcome to the forum.

Yep hold the edges a bit longer as well as having the weld filled almost all the way up before capping it. Not much more than 1mm below the plate surface.

Mick

[tooler777]

Hi mick

I tried another test plate tonight, i held the toes for two seconds per side this time and still some undercut. A lot better tho.
The cap is high too maybe a shade over 1/8". I might lower the settings ,seeing as its still hot enough from the filler pass.
Thanks for the input man. Appreciated



Cormac

[rake]

You could also try a little more wire speed. If it's hot enough to burn the corners away you're most likely getting enough penetration.
A bit more wire speed may help satisfy the puddle and take care of that undercut.

[weldin mike 27]

Hey,

Also increased travel across the middle of the weld will decrease the metal build up in the centre. Pause at the sides, motor across the middle. Not excessively but not slow either.

Mick

[MobileWelder]

.035 wire when i go up hill. 17.5 v- 175ipm. works for me. also that's with a millermatic252x