【转帖】standard when creating mirror image parts

yang686526

standard when creating mirror image parts...
what is the drawing standard when detailing a mirror image part (such as a manifold)?
does one need to re-dimension the mirrored part?
note: these 2 parts would be on one drawing with different configuration numbers.
hopefully this makes sense...
hi cadfreak
i have seen several methods ie:- mirrored parts on same drawing but only one dimensioned and a note that says one as shown, one opposite hand.
individual drawings for each one both fully dimensioned which in my opinion is the best as it doesn't leave anything open to interpretation by the person producing the
component and they cannot misread and produce the wrong handed component.
regards
desertfox
...but that also entails 2x the effort of keeping the drawings up to date, and makes it easier to miss something when a change does occur.
we only dimension one side, usually the lh part, and note on the drawing that the rh part is an exact opposite in all respects (datums and dimensions).  we only "model" one part; the other model is a mirror copy, and is completely associated to the original, so changes are only made one time.
as far as where this is determined in any official standard...?
hi ewh
you have a fair point there, i suppose it comes down to how well you trust your supplier not to foul up.
regards
desertfox
our parts are usually cam, and as long as they are using the correct model file, there should be no problems.  we have yet to see any "wrong" parts come in due to this.
it is in asme y14.100.  but it is in the "nonmandatory appendices" d-12.2.
two methods  described: first is that both drawings are dimensioned fully one one print.  second is basically how desertfox described.
if you are confident that the subsequent revision evolutions will be the same for both parts throughout their life, i could see keeping them linked.  my experiences have been that eventually mirrored components diverge as they evolve.  we end up making the models, part numbers and dimensioned drawings unique for each part.
regards,
this is a possibility, but when it happens, a number change must also occur, as they are no longer mirrored parts, and a change in form, fit or function has occurred.
ewh,
   how i build a model has a lot to do with my design intent.  if my intent is that the two components are left and and right hand, i would prefer to tabulate the drawing and provide the note.  if the lh, rh is something that happened and that i may or may not maintain, i would make two separate drawings.
   your point about form, fit and function is absolutely correct, and it renders much of this discussion moot.  
   i really appreciate how you show the left hand components, and you tell the fabricator that the right hand component is opposite.  it is about time us left handed people got recognition or priority or whatever.  
                       jhg