03 Apr 2008 19:29:47
Blip
Drawing questions

I see these frequently on PCB figures (REF BSC TYP). Could someone
kindly explain what these mean? REF = reference (to what)? I pretty
sure that BSC is basic spacing between centers? TYP = ?


Also, in datasheet packaging sections, there is often a thin
horizontal rectangle subdivided into (usually) 3 or 4 sections. Each
rectangle usually starts w/ a symbol (for example, 1/2 circle or
theta)in the first section, followed by sections w/ alphas or
numberics - oftentimes accompanied by a letter in a circle. Could
someone explain this or point me to an explanation as well?

Thanks, Tom


04 Apr 2008 04:36:52
Brad Velander
Re: Drawing questions

This is a multi-part message in MIME format.

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charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

Blip,

BSC: Basic Dimension. Theoretically exact value shown without =
tolerances.

REF: Reference Dimension, usually without tolerance, for information =
purposes only.

TYP: "typical" dimension.

The details you seek are all dimensioning standards encompassed in =
ANSI Y14.5M, search the internet for it and you will find your answers. =
However I am not sure you will find an online source, a quick search I =
did only turned up books for sale, no online versions.

The rectangular boxes with symbols and figures is part of the ANSI =
standard dimensioning where the figures indicate the type of =
measure/tolerance (center point, perpendicular, surface flatness, =
parallelism, etc., etc.), the letter usually indicates a datum to which =
the measure/tolerance pertains and the numerics are typically the actual =
measure and/or tolerance.

--=20
Sincerely,
Brad Velander.

"Blip" <blip@krumpli.com > wrote in message =
news:f7jav3t08ntqh4v84sd7mp0ij5bg1rr51m@4ax.com...
>I see these frequently on PCB figures (REF BSC TYP). Could someone
> kindly explain what these mean? REF =3D reference (to what)? I pretty
> sure that BSC is basic spacing between centers? TYP =3D ?
>=20
>=20
> Also, in datasheet packaging sections, there is often a thin
> horizontal rectangle subdivided into (usually) 3 or 4 sections. Each
> rectangle usually starts w/ a symbol (for example, 1/2 circle or
> theta)in the first section, followed by sections w/ alphas or
> numberics - oftentimes accompanied by a letter in a circle. Could
> someone explain this or point me to an explanation as well?
>=20
> Thanks, Tom
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<BODY >
<DIV >
<P align=3Dleft ><FONT face=3DArial size=3D2>Blip,</FONT></P>
<P align=3Dleft ><FONT face=3DArial size=3D2>BSC: Basic Dimension. =
Theoretically exact=20
value shown without tolerances.</FONT ></P>
<P align=3Dleft ><FONT face=3DArial size=3D2>REF: Reference Dimension, =
usually without=20
tolerance, for information purposes only.</FONT ></P></DIV>
<DIV ><FONT face=3DArial size=3D2>TYP: "typical" dimension.</FONT></DIV>
<DIV ><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV ><FONT face=3DArial size=3D2>    The details you seek =
are all=20
dimensioning standards encompassed in ANSI Y14.5M, search the internet =
for it=20
and you will find your answers. However I am not sure you will find an =
online=20
source, a quick search I did only turned up books for sale, no online=20
versions.</FONT ></DIV>
<DIV ><FONT face=3DArial size=3D2></FONT><FONT face=3DArial =
size=3D2 ></FONT> </DIV>
<DIV ><FONT face=3DArial size=3D2>    The rectangular =
boxes with=20
symbols and figures is part of the ANSI standard dimensioning where the =
figures=20
indicate the type of measure/tolerance (center point, perpendicular, =
surface=20
flatness, parallelism, etc., etc.), the letter usually indicates a datum =
to=20
which the measure/tolerance pertains and the numerics are typically the =
actual=20
measure and/or tolerance.</FONT ></DIV>
<DIV ><FONT face=3DArial size=3D2></FONT><BR><FONT face=3DArial =
size=3D2 >--=20
<BR >Sincerely,<BR>Brad Velander.</FONT></DIV>
<DIV ><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV ><FONT face=3DArial size=3D2>"Blip" <</FONT><A=20
href=3D"mailto:blip@krumpli.com" ><FONT face=3DArial=20
size=3D2 >blip@krumpli.com</FONT></A><FONT face=3DArial size=3D2>> =
wrote in message=20
</FONT ><A href=3D"news:f7jav3t08ntqh4v84sd7mp0ij5bg1rr51m@4ax.com"><FONT =

face=3DArial=20
size=3D2 >news:f7jav3t08ntqh4v84sd7mp0ij5bg1rr51m@4ax.com</FONT></A><FONT =

face=3DArial size=3D2 >...</FONT></DIV><FONT face=3DArial size=3D2>>I =
see these=20
frequently on PCB figures (REF BSC TYP). Could someone<BR >> kindly =
explain=20
what these mean? REF =3D reference (to what)? I pretty<BR >> sure that =
BSC is=20
basic spacing between centers?  TYP =3D ?<BR >> <BR>> <BR>> =
Also, in=20
datasheet packaging sections, there is often a thin<BR >> horizontal =
rectangle=20
subdivided into (usually) 3 or 4 sections. Each<BR >> rectangle =
usually starts=20
w/ a symbol (for example, 1/2 circle or<BR >> theta)in the first =
section,=20
followed by sections w/ alphas or<BR >> numberics - oftentimes =
accompanied by=20
a letter in a circle. Could<BR >> someone explain this or point me to =
an=20
explanation as well?<BR >> <BR>> Thanks, Tom</FONT></BODY></HTML>

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04 Apr 2008 11:31:02
Blip
Re: Drawing questions

On Fri, 04 Apr 2008 04:36:52 GMT, "Brad Velander"
<bveland@SpamThis.com > wrote:

>Blip,
>
>BSC: Basic Dimension. Theoretically exact value shown without tolerances.
>
>REF: Reference Dimension, usually without tolerance, for information purposes only.
>
>TYP: "typical" dimension.
>
> The details you seek are all dimensioning standards encompassed in ANSI Y14.5M, search the internet for it and you will find your answers. However I am not sure you will find an online source, a quick search I did only turned up books for sale, no online versions.
>
> The rectangular boxes with symbols and figures is part of the ANSI standard dimensioning where the figures indicate the type of measure/tolerance (center point, perpendicular, surface flatness, parallelism, etc., etc.), the letter usually indicates a datum to which the measure/tolerance pertains and the numerics are typically the actual measure and/or tolerance.

Thanks for the help...