Victor, Ask 10 different engineers and you will get at least 9 different answers. External generally because you can see the teeth and they cut into the "bonding" surface. My experience, if you don't want it to vibrate loose - 15-20 g operation, use a nylon patch nut or as a minimum blue Loctite 242. Phil -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez Sent: Monday, December 01, 2014 11:28 AM To: [log in to unmask] Subject: [TN] Washer selection, current or voltage Fellow TechNetters: Is there a washer selection guide when selecting a washer design, internal/external teeth, flat-split, for a circuit to conduct current and/or voltage? Victor, ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________