Hi Geoff; I agree with you 110%.
Regards TDK (Terry) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Geoff Harland Sent: Saturday, May 20, 2006 10:34 PM To: Protel EDA Discussion List Subject: [PEDA] Mechanical layers (was Re: 99SE PCB Component gone afar.) When I first started using AdvPcb 2.8 (which provided only four Mechanical layers, and a situation which remained in force until Protel 99 SE was released), I opted for always using the Mech 3 layer to specify the board outline. (I won't describe the reason why I chose that particular Mechanical layer for that purpose, because I would probably start a flame war if I did (not that the explanation would be likely to offend anyone who has contributed to this thread to date - but some of the other members of this mailing list would probably feel differently)). My current (and hence updated) view is that there is a lot to be said for using the Mech 1 layer for that purpose instead, as there was a time (before AdvPcb 2.8 was released, during at least the era of the DOS versions of Protel) when there was only ONE Mechanical layer available, and because the concept of assigning a Mechanical layer for the purpose of specifying the board outline is so "fundamental" to every PCB file that it is "natural" and even, to some extent, "expected" to use the "first" Mechanical layer for that purpose. Having said that, I fully agree with Andrew (aj) that everyone has the right to assign the usage of each Mechanical layer provided as they see fit, so even if anyone uses the Mech 16 layer to specify the board outline, I have absolutely no intention of declaring any pogrom against them. (I will say though that I am emphatically a member of the school of thought that a Mechanical layer should be used to specify the board outline, rather than using the Keep Out layer for that purpose - but once again, I still have no intention of declaring any pogrom against any users who differ on this matter.) An aspect of AD6 that arguably is disappointing though is that there was no further increase in the number of Mechanical layers provided (nor of any other types of layers). Although many users would find sixteen Mechanical layers to be more than sufficient, the ever-increasing complexity of PCBs still means it is becoming increasingly likely that that number of Mechanical layers will not always be sufficient. As such, there is a case for increasing the set of available layers, and while there would be some merit in providing certain new types of layers of a dedicated type (such as two pairs of Glue layers, and a pair of Assembly layers), it would still be very desirable to expand the set of available Mechanical layers at some stage. The provision of the ability to pair Mechanical layers has been helpful, though there is a downside that such layer pairings can differ between different files. As such, I would especially see merit in increasing the set of available Mechanical layers in the form of *eight* new *pairs* of such layers, in which the pairing of all of those new layers is of a "hard wired" nature. So the newly provided 'Top Mechanical 1' layer would *always* be paired to the newly provided 'Bottom Mechanical 1' layer; the newly provided 'Top Mechanical 2' layer would *always* be paired to the newly provided 'Bottom Mechanical 2' layer; ... ; and the newly provided 'Top Mechanical 8' layer would *always* be paired to the newly provided 'Bottom Mechanical 8' layer. Like all of the existing Mechanical (and copper) layers, users should be able to assign their own names to each of these new layers, but another aspect which would reduce (if not entirely eliminate) the issue concerning layer pairings differing between different files is that whenever a "legacy" file was (re)opened in a version of AD supporting these additional layers, a Wizard could be invoked to poll users on how the previously used Mechanical layers should subsequently be reassigned. If *none* of the previously used Mechanical layers had been paired to one another, the default outcome of the Wizard would be to reassign none of those layers; OTOH, if *all* of the previously used Mechanical layers had been paired to one another, the default outcome of the Wizard would be to reassign all of those layers to the newly provided Mechanical layers (paired to one another in a "hard wired" fashion); in other cases, the default outcome of the Wizard would be to reassign (just) the paired layers to some of the newly provided Mechanical layers. In all cases though, users should be provided with the ability to specify which particular layer that each of the previously used layers gets to be reassigned to. An associated aspect would be withdrawing the ability to be able to pair the *existing* Mechanical layers to one another, as the newly provided Mechanical layers would provide eight pairs of such layers of an "always" paired nature, resulting in reduced incompatibility between different files. Or would anyone see merit in (otherwise) continuing to provide that capability (so that users could then have up to sixteen different sets of paired Mechanical layers, if they so wanted)? (Probably pros and cons for each of those options.) Any change to the set of all available layers is of such a "fundamental" nature though that it is very unlikely that it would be implemented with the release of any SP; it would be far more appropriate to do that with the very first version of a new major version. Hence it is very regrettable that this was not implemented in AD6, and as such, users should collectively insist that this be implemented with the next new major release (as not having that implemented at that time either would almost certainly result in having to wait until at least the next major release following that one). Regards, Geoff Harland. [EMAIL PROTECTED] > Hmm... > > Everyone has a standard for THEIR use of mech layers. > > Mech layers are, by default, not specified, for the specific reason that > they are open to use by a given tecnician or engineer at the technician > or engineer's discretions, aside, of course, from employer mandates... > > The idea is that they are amorphous, ie, unfixed in their assignment. > Otherwise, we would call them "board outline", "PCB documentation 1", > "contour route layer", etc. In fact, they were provided for that very > reason. Engineers (and technicians) were tired of being told what layers > were to be used for what purpose all the time by an EDA vendor, when all > they were really doing in the first place was providing a subset of a 2D > CAD program, and so we repeatedly requested a group of layers which WE > could control to OUR liking. Much like the annoyance that comes about > from having proggies like PCAD demand that we choke on their > auto-specified ref-designators, having some brain-dead person require > our use of layer X to satisfy their concept is intellectually offensive > to those of us who have to use our creativity (ie the reason you're not > still using tape and mylar). > > I guess what I'm saying is this...Please don't give the moron management > team at Altium another stupid excuse to take control back again. > > aj > > > >Augh. I use mech 2 for the board outline, and mech 3 for the > >enclosure details. > > > >Anyone have a "standard" for mech layers ? > > > >Dean Carpenter > > > > > > > Yep, > > > > > > Mechanical Layer 3 has always been the default for board outline, > > > Keepout layer (of course) for the keepout and Mechanical > > > Layer 14 for any documentation such as special pcb material etc. > > > > > > Best Regards > > > (Mr) Laurie Biddulph ____________________________________________________________ You are subscribed to the PEDA discussion forum To Post messages: mailto:[email protected] Unsubscribe and Other Options: http://techservinc.com/mailman/listinfo/peda_techservinc.com Browse or Search Old Archives (2001-2004): http://www.mail-archive.com/[email protected] Browse or Search Current Archives (2004-Current): http://www.mail-archive.com/[email protected] ____________________________________________________________ You are subscribed to the PEDA discussion forum To Post messages: mailto:[email protected] Unsubscribe and Other Options: http://techservinc.com/mailman/listinfo/peda_techservinc.com Browse or Search Old Archives (2001-2004): http://www.mail-archive.com/[email protected] Browse or Search Current Archives (2004-Current): http://www.mail-archive.com/[email protected]
