It seems that there are a lot of very experienced fabricators in this forum. I have learned a great deal from reading the posts. I started laying out boards in 1998, it is not my chosen profession but is starting to become my chosen profession. I enjoy it very much. When I started a old manufacturing engineer gave me a set of guidelines to follow and something's I am still figuring out on my own. With that said here is my question to the forum. Right now I am sending all my gerbers and drills out in millimeters in a 3,5 274x format. So that means I am calling out things at 1/100,000 of a millimeter. I know that this has to be way beyond etching tolerance and what a drill can hold on tolerance. This is kind of what I started with. I have begun to change all of my designs to a .05 millimeter grid. But I still have some old legacy stuff from when I really didn't know what I was doing. So my question is what is realistic. At how many decimal places in millimeters or mills does it become nonsensical and a waste of time for the guy or program that has to round everything off. What kind of tolerance can a modern drill hold? At what point does the photo plotter or direct imaging machine run out of gas? Once again I have learned a great deal from this forum and would appreciate any kind of response Thank You John Foster --------------------------------------------------- Technet Mail List provided as a free 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/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------