A year ago I wrote about the value of buying setting plugs along with adjustable thread ring gages, particularly special thread rings. One point I made was that setting plugs should be used for the resetting of adjustable thread rings in accordance with the standard. Taking measurements of them was not accurate enough.
The problem starts with buyers of special rings who do not wish to pay for proper setting plugs. When it’s time for calibration, the hunt begins for someone who has plugs and of course, it’s unlikely they will be found because calibration laboratories would go broke keeping special setting plugs on hand in most cases. Some laboratories are ready to cash in on this situation by offering to “measure” special adjustable thread ring gages so the technician won’t have to buy the right thing. And, wow, the cost will be a lot cheaper than buying setting plugs.