Ahne,

The key is that the 0.009 inch tolerance is expressed as a diameter, not as a
radius.  This of course reduces the tolerance you calculated by a factor of two
to 0.00318 inch (3.18 mils).

Jay Soderberg

As always, all opinions expressed above are mine and mine alone.  Do not confuse
them with opinions of the ownership or management of this radio station.


Ahne Oosterhof wrote:

> More fuel for the fires of confusion:
> If you have to place a hole within 9 mil of its perfect location (true
> position) it seems that you are allowed to be off by 9 mil in any direction.
> If you can only measure x and y errors and they have to fall inside that 9
> mil true position spec, they can be 9 / root(2) = 6.36 mil positive AND
> negative, compared to 9 mil true position.
>
> Did I goof?
>
> Regards, Ahne.
>
> -----Original Message-----
> From:   TechNet [mailto:[log in to unmask]] On Behalf Of Jay Solderberg
> Sent:   Thursday, June 03, 1999 7:14 AM
> To:     [log in to unmask]
> Subject:        Re: [TN] True Position
>
> Richard,
>
> Ed has the formula correct.  However, maybe an easier way to think about it
> is to take the diametric true postion and multiply by 0.3535 to arrive at
> the bilateral (+/-) tolerance.  In your case, 0.009 X 0.3535 = +/- 0.0032.
>
> Jay Soderberg
>
> Remember,  all opinions expressed above are mine and mine alone.  They do
> not necessarily reflect the opinion of the ownership or management of this
> radio station.
>
> >   ------------------------------------------------------------------------
> >
> > Subject: Re: True Position
> > Date: Thu, 3 Jun 1999 08:18:10 -0400
> > From: Ed Cosper <[log in to unmask]>
> >
> > Richard,
> >
> > The equation for true position is 2 multiplied by the square root of the
> (X
> > axis squared plus Y axis squared ).  There is also a true position chart
> > that can be used to easily find true positions. Because you are specifying
> a
> > .009 true position location tolerance there really is no equal +/- value
> for
> > each axis. The true position value is dependent on the relationship of
> each
> > axis. However, to give you a middle of the road starting point, a True
> > position of .009 equates to about +/- 0.0032. This is actually a true
> > position of .00905.
> >
> > Hope this helps,
> >
> > Ed Cosper
> > -----Original Message-----
> > From: Richard Hamilton <[log in to unmask]>
> > To: [log in to unmask] <[log in to unmask]>
> > Date: Wednesday, June 02, 1999 4:56 PM
> > Subject: [TN] True Position
> >
> > >Hello all,
> > >
> > >I am sure this one will stretch the memory!! I used to know the
> specifics,
> > >but when you don't use something, well, it kinda goes away!
> > >
> > >We have a hole position tolerance of .009"TP (True Position). Can anyone
> > >tell me how to convert this tolerance into an X-Y location value? Like,
> > >based on the zero datum you are allowed a maximum of .003" x .003" off
> the
> > >defined location. Or, you are allowed a maximum of .006" in any direction
> > >combination which represents the .009"TP.
> > >
> > >The only number I am using from actual is the .009"TP. Taking that
> > tolerance
> > >and defining the location values allowed is what I am having a tough time
> > >finding out.
> > >
> > >Thanks to anyone who can save me here!
> > >
> > >Richard Hamilton
> > >Clemar Mfg. / Rain Bird
> > >[log in to unmask]
>
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