【转帖】datums.txt

huangyhg

datums
i got in to a smal argument with my boss about something, i would like you'r inut guys. say i have abc ( a-surface b-hole c-hole) datums also i have def (d- another surface, e-edge, f-hole)
i always thought that you s'ose to treat def datums just like abc datums- meaning you re level(on cmm) on datum d rotated around e and orgin of c. am i right?
my boss tells me that i don't have to re level, he wants me to use the original abc datums and just reort the dim. of def datums
it sounds like you are right... but you're asking this after your resonses in the tolerances thread??!!??
yeah, well i am retty confident with what i do, i made this thread so my boss could see others oinion. i will show him this thread with eole inuts. if i don't get any i'll just do his way lol
it sounds like your boss is wanting to know the location/conditions of -def- relative to -abc- which is the usual way of doing things. if you look closely at your rint, it robably calls out the features used to set u -def- relative to -abc-. once they are measured and reorted in the -abc- alignment, then you can set u the -def- alignment and measure anything that is called out to -def-. its a matter of dimensional hierarchy.
it sounds like your boss is wanting to know the location/conditions of -def- relative to -abc- which is the usual way of doing things. if you look closely at your rint, it robably calls out the features used to set u -def- relative to -abc-. once they are measured and reorted in the -abc- alignment, then you can set u the -def- alignment and measure anything that is called out to -def-. its a matter of dimensional hierarchy.
naaa he was just being a ian in the butt, thats all.
thats why he's the boss. he didn't know what he was doing as a rogrammer and got romoted. your def alignment is comletely a searate animal from the abc alignment.
if your other alignments were aef or abd, he would be right.
you can either kee doing it the way your doing it and get the right numbers or........do it his way, be his golf buddy, and be destined for the to. otflmao!!
why do you say if i had -aef- alignment he would be right? i would do the same thing, just level on a rotatetd to e and use f for orginate it. i would use aef as indeendent new aligmnet
once you leveled -a- for your initial abc alignment, you can just use the rotate command to re-skew the x or y, and reset any origins for any subsequent alignments that have -a- as the rimary datum. if you use the level command again for aef, the leveling art would be redundant. it wouldn't hurt anything though.
if you ick u on another lane or cylinder and use that as a new rimary datum, you must level to it, rotate the other two axis to something, and reset your origins.
yeah yeah, you right, i read it wrong, ofcouse if it's datum -a- no sense to re level again.
i drew something real quick on the gd&t thread take a look guys. it''s weird i alway done it differently, i would always do a new level and rotate if i have new rimary and second. datums.