huangyhg

need help with this gd&t callout
i have a true position to "a" and to "b" on a print. but it's on a unusual surface,(least for what i do) the top underside surface.
i'm assuming they want to control that surface position to the axis of "a"?
solid edge v20
i do not see a "position" to check for true position. i would use profile or parallel for this. also the position of the a datum should be in line with the dimension. for a flat plate the positon of the datum symbol in reference to the dimension makes a difference. looking in the standard to see if the same applies to a diameter, i found that there is no example with the datum symbol on the witness line but not in line with the dimension. as such i think the interpetation is the same, but i would mark it up to be moved to be in line.
peter stockhausen
senior design analyst (checker)
infotech aerospace services
positional is used on features of size and i see the end of a tube. the feature control frame should have reflected a profile of a surface rather than positional.
dave d.
i just threw that one dimension and the rest as it show's on the customer print.(not allowed to put the whole customer print on here) so i can't right now mark anything up on this print.
i more wanted to know if they applied the wrong modifying symbol. or, does this actually mean something? thinking that someone screwed up at our customer.
solid edge v20
given that most people don't really understand even the most fundamental definition for position and profile gd&t's i wouldn't doubt that, cadman.
matt lorono
cad engineer/ecn analyst
silicon valley, ca
i agree about the true position. i would remove it and add either flatness or parallel on the outside of that part and add a thickness there. it would be difficult to measure the inside of that surface accurately.
chris
solidworks 09, catia v5
are you sure this is per asme y14.5m-1994? if this print were created per iso, then it would be acceptable as iso is allowed to use position in the same way asme uses profile to locate a surface. iso also allows the use of a the tangent line to the od or id of a cylinder as a datum when indicated like yours is.
in the event that the drawing specifies asme as the standard to interpret the drawing to, i'm on board with the idea that this drawing was just created by someone that really didn't know what they were doing.
powerhound, gdtp t-0419
production manager
inventor 2009
mastercam x3
smartcam 11.1
ssg, u.s. army
taji, iraq oif ii
powerhound,
he stated he is not showing the whole drawing, only what is in question. i agree what 'is' shown is not correct.
chris
solidworks 09, catia v5
chris,
what i'm saying is that what is shown could be legal depending on what standard it is interpreted to.
i don't know what part of my post you are addressing with your response. i didn't say anything about a whole drawing.
powerhound, gdtp t-0419
production manager
inventor 2009
mastercam x3
smartcam 11.1
ssg, u.s. army
taji, iraq oif ii
quote:
are you sure this is per asme y14.5m-1994? if this print were created per iso, then it would be acceptable as iso is allowed to use position in the same way asme uses profile to locate a surface. iso also allows the use of a the tangent line to the od or id of a cylinder as a datum when indicated like yours is.
duh.... i look at the print closer, it is iso even knowing there not specifying it on the print. so i guess it makes since in a away if it is iso. but, still is confusing
solid edge v20
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