Hmmm... in a word, No. I'm not sure what you are driving at but finished plated thru holes are dependant upon a lot of variables... location, diameter, relationship to other holes and the board edge, plating thickness, drill wear, runout in the gears that drive the positioning of the drill machine chucks, drift of the drill when stack drilling, there are probably thousands of variables... Hitting the target is harder than setting the goal. But the designer is tasked with setting the expectation and criteria for the hole to be created so that it can be manufactured and assembled under any circumstance. That is what I am talking about. The size and tolerance of the acceptable plated hole diameter to be set such that it takes all of those variables into account and then specifies it such that when it is delivered within the tolerances specified, it will work with the fixtures, tooling, insertion or pick and place machines, etc. and within the parameters that they require to assemble, test, and manufacture the board successfully. That is designing. Not pulling a number out of a hat and applying a rule of thumb tolerance to it and calling it good... leaving the assembler, and manufacturer to figure out how in the heck they are going to accomplish that feat... Best regards, Bill Brooks - KG6VVP PCB Design Engineer, C.I.D.+, C.I.I. Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510 Datron World Communications, Inc. _______________________________________ San Diego Chapter of the IPC Designers Council Communications Officer, Web Manager http://dcchapters.ipc.org/SanDiego/ http://pcbwizards.com -----Original Message----- From: EIMCNews [mailto:[log in to unmask]] Sent: Monday, February 13, 2006 4:49 PM To: [log in to unmask]; Brooks,Bill Subject: Re: [TN] Hole size specs Bill, Doesn't this assume that each hole diameter is the same? In reality, given the variations or differences in plated hole thickness, are they ever the same? Regards, Roger Mouton --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------