【转帖】updating legacy drawings

yang686526

updating legacy drawings
is it common practice to update drawings that go through eco/dco to current standards?  for example, if you have older drawings that are using ansi y14.5m-1982, should they be updated to meet asme y14.5m-1994 standards?
there are a lot of factors to be considered, not just updating for the sake updating.  i think as long as the standard being used is identified on the drawing, there is no real reason to update.  am i way off base?
but what... is it good for?
engineer at the advanced computing systems division of ibm, 1968, commenting on the microchip.
we have been updating dwgs to the new std and all new dwgs are to use new std. because all vendors and customers are up to the new std.
the whole idea of standards is to get everyone working "on the same page". if different revisions of standards are used then ... what's the point of having standards in the first place.
from (the city of) barrie, ontario.
i tried sniffing coke once, but the ice cubes got stuck in my nose
i feel that updating existing drawings to current standards should be done, but should be a low priority (as long as the standard that they were drawn to is noted on the drawing).  get out the current work correctly, and then worry about updating.
i agree with corblimey that we all should be working from the same page, but as long as we know what standards to use, there should be no problem interpreting older drawings until such time they are updated.
any time you change something you have the risk of introducing an error.
next question becomes, if making necessary changes to an old drawing, do you make the changes to the old standard, or the current standard?
in our case, we "try" to update older drawings to meet our "current" corporate standards.  new title blocks, new logos, converting 2d drawings to 3d models with new drawings, ect.  most times however, not all drawings have gd&t so there is no concern.  many of the older drawings (pre-'88) need some form of gd&t, and when added, conform to the 1994 standard.  but this gets time consuming to say the least (tolerance studies, etc).
we use a rule if there have been no problems during qa/qc processes, then nothing further needs to be added to the drawing.  but this also takes into account that we have been, or will continue to use know vendors that are familar with our parts and requirements.  the arguement can be made that there is no guarantee that purchasing will not use different vendors to save $.05, and that all information on any drawing should be up to industry standards, not just our  corporate standards.
but what... is it good for?
engineer at the advanced computing systems division of ibm, 1968, commenting on the microchip.
when making changes to an old drawing is a good time to update the standard.  i have worked a places where that was the house rule - don't worry about updating standards until the drawing is being revised.  do not make changes per the current standard without updating the entire drawing.  they don't mix well.
i agree with mintjulep that time you change something you have the risk of introducing an error. i have seen hundred of thousends of us$ go to the drain when someone decided to move from a hand made drawing of pneumatic manifold to a cad made drawing and missed a dimension arrow, connecting high pressure line to a low pressure line by mistake.
as a rule i always demanded that if it is necessary to redraw a part drawing a test batch should be manufactured from the new drawing and then all dimmensions should be checked and qualified to the new and the old drawing both. after that the parts should be assembled and go through the qualifications tests before the new drawing is approved.