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
---------------------------------------------------------------------------------
|