Hello eilers, I went through quite an interesting process concening welder calibration. In our particular instance we were initially told that EVERYTHING had to be calibrated in our shop since we were performing welder certification. I'm talking calibrated thermometers in the rod ovens to verify temperature, calibration of : oxy-acetylene gauges on all torch sets, flow meters on all wire feeds, all welding machines, ipm meters on wire feeders, you get the idea. Now back to your question, one thing you should know, only the welding machines that you have with digital readouts and analog meters are required to be calibrated, in our case we have two miller 8packs that we use on a portion of our arc welding stations, these cannot be calibrated since they don't have meters, this was information that I received directly from Miller. If you contact them they can give you a host of information regarding welder calibration. As John stated in his post, having an outside entity take care of it will be a much more cost effective process in most cases. Regards, aevald