I would agree with your formula, however, when I met Mark Simmons at IPC EXPO 1997 he pointed out that tip wear was indeed a measurable factor. Basically, I would do(and did) the following: 1) Find out the 'worst case' tip wear, i.e.: how short the flat or rounded cutter of the blade is from a perfect point before re-sharpening [in my application .005"] 2) Determine your manufacturing tolerance of artwork (registration, dimensional stability etc..) [in my application .006"] 3) Now the math parts, use the .021 and add the .005 to it, then apply this to your formula. A) In addition, in my case I would account for the web not being centered by adding and additional .001-.002. 4) The answer to this particular instance, for me, would have been .022". JOE SENDZ...... (Joe Duclos - TYCO Printed Circuit Group, Stafford Division) If you would like to contact me on or off line for more info [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask] Sent: Thursday, July 30, 1998 12:42 PM To: [log in to unmask] Subject: [TN] Scoring I am looking for input as to what others use as a rule for cutting back copper on artworks <<<SNIP>>> Thanks Ernie Smith [log in to unmask] ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################