yang686526

callout: hole termination
i don't think this is defined in any standard, so i wanted to check here. i have a machined hole that requires a flat bottom, but i do not feel a section view is required for it. in the past i have used the counter-bore symbol to define a flat-bottomed hole without trouble.
my last employer/vendors had no problem with this method of call-out, qa/vendors at my current location are questioning this practice. any suggestions?
"art without engineering is dreaming; engineering without art is calculating."
i've always specified flat bottom in the hole callout.
believe it if you need it or leave it if you dare.fff"> - robert hunter

a counterbore means that there is a larger diameter flat-shoulder seat for a fastener head. if i were quuoting or making the part, i would not take cb to mean flat bottom of hole.
the c'bore symbol when it isn't actually a c'bore might confuse me too.
i'd say "flat bottom" or something if i really didn't want to put even a partial xsection.
kenat, probably the least qualified checker you'll ever meet...
a c'bore would be confusing because a c'bore usually refers to a bigger diameter sitting on end of another diameter. i would use a note, and possibly a section view, that a drill point is not to be used. a dimension to the flat bottom is sufficient...how the machinists gets the flat bottom is up to them.
chris
solidworks/pdmworks 08 3.1
autocad 06/08
all right, i guess i was trained improperly. thanks all.
"art without engineering is dreaming; engineering without art is calculating."
if it has to be flat you might want to give a flatness spec. it does not have to be to tight, but it would get the massage across beter then words will.
chris
why not simply show a section view. dim the dia and depth and you have it defined. no symbols reqd.
ringman, the drawing in question is fairly complicated, four d-size sheets, multiple sections and details already. this hole is not that critical to the entire part, i just didn't feel like creating section n-n (call it laziness).
in some situations one would use the term counterbore, but in others they could be referred to as spotfaces, all depending on their purpose. i'll just replace the c'bore symbol with "flat bottom".
"art without engineering is dreaming; engineering without art is calculating."
i agree with kenat, just call out flat bottom if you can't do a broken out view or section. btw, have you considered using a broken out view?
matt lorono
cad engineer/ecn analyst
silicon valley, ca