Lin - We use pin gauges. The type most common are known as "compensated", and are either "plus" or "minus" compensated. Because it is theoretically impossible to fit a true 50-mil pin into a true 50-mil hole, a 49-mil pin is the largest acceptable size for a 50-mil hole. Again, in theory. Compensated pins relieve this confusion. A "minus" pin is the face value of the pin, minus .1-mil . Thus the slightly smaller 50-mil pin will fit into a 50-mil hole. But pin gauges pressed into holes have much room for application error when weighed in the world of gauge reliability and repeatability. If it's snug, give the pin a wiggle. Have burrs, protrusions? Pin gauges make for handy point-of-measure reamers in soft solder. For my time & money if I need to make a few critical, nondestructive diametric measurements I grab an optical loupe of at least 10X with a reticule bearing a scale not broader than 5-mil increments, then backlight the hole. Cheers! Bob Lazzara Circuit Connect, Inc. In a message dated 12/20/00 9:33:20 PM Eastern Standard Time, [log in to unmask] writes: << Hi, TechNetters, Does anyone know about the captioned metters and would offer me the answers £¿ > When measuring a hole dia., let's say a hole of 46+/-3mil, some of our > customers use a calliper gauge of 50mil to measure. If the gauge passes, > they say it is unacceptable ( tolerance included). Some use a 49mil gauge, > if the gauge passes, they also say it is unacceptable(tolerance excluded). > I would like to know if IPC has any specification on the measurement and what result is accepted? > Lin Ting > QAA Engineer >> --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------