Multimatic 200 erratic mig wire speed

[rick66pony]

I just got a new multimatic 200 and used it for the first time today. When running mig (.023 wire and 75/25 gas) I'm getting erratic wire feed speed. Watching the drive roll, when I press the trigger the wire starts to feed and looks fine. After about 2 seconds the wire feed speeds up and the drive wheel rotates at a noticeably faster speed. It is also evident that it is speeding up from the sound of the wire feed.

I've tried different setting for the drive tension knob with no change. I've got the right contact tip and liner. Also, there does not appear to be any obstruction in the liner.

My previous machine was a multimatic 130 XP and the wire feed speed was constant at a given setting.

Here is a video: http://www.maywebsite.com/downloads/welder.mov

Any thoughts.

[cruizer]

Ummm, normal, its got a preset "run-in" speed, starts slow, then speeds up to what ever you've got it set to.

[rick66pony]

Thanks cruizer - I was hoping that it was normal. Since I'm an amateur welder and wasn't aware of this can you or someone explain what the benefit is of the "run-in"? Not intuitively obvious.

[Cgotto6]

Smoother starts with less burn back and spatter.

[Broccoli1]

Run in speed is slower so the the arc has more time to get going which reduces spatter and Burnback.

Some machines have a preset run in speed where as the more advanced machines have the ability to adjust the run in speed.