Calibration company came in to do it.  They used a "leveling system" which
arrived in 3 large equipment cases.  Took them more than 4 hrs. as I recall.

The original certificate of accuracy indicates that the manufacturer
calibrated the granite headstone (surface plate) using a "Watts
Auto-Collimator".

Mark

        -----Original Message-----
        From:   Franklin D Asbell [SMTP:[log in to unmask]]
        Sent:   Thursday, January 30, 2003 2:19 PM
        To:     TechNet E-Mail Forum.; Mark Hargreaves
        Subject:        Re: [TN] Calibration/Verification of granite-surface
block

        We'll be using this one for the same purpose, do you calibrate
in-house? If
        so, what do you use to verify it...thanks...

        Franklin


        ----- Original Message -----
        From: "Mark Hargreaves" <[log in to unmask]>
        To: <[log in to unmask]>
        Sent: Thursday, January 30, 2003 10:31 AM
        Subject: Re: [TN] Calibration/Verification of granite-surface block


        > Hi Franklin,
        > Our granite surface plate is used strictly for warp & twist
measurement of
        > pcb's (very light use).  It's on our recall list.  The calibration
is
        rather
        > expensive.  I was able to move from yearly cal to 3 year cal by
        downgrading
        > the plate from "A" (inspection grade) to "B" (shop grade, I
believe) which
        > is still well within our accuracy requirements.
        >
        > Regards,
        > Mark Hargreaves
        >
        >         -----Original Message-----
        >         From:   Franklin D Asbell
[SMTP:[log in to unmask]]
        >         Sent:   Thursday, January 30, 2003 10:57 AM
        >         To:     [log in to unmask]
        >         Subject:        [TN] Calibration/Verification of
granite-surface
        > block
        >
        >         Can anyone describe to me the method of
calibrating/verifying a
        > surface
        >         block???
        >
        >         Also, in regards to calibration recall, would this need to
be on a
        > recall
        >         list or would it be verify it once in it's lifetime, what
would be
        a
        > cause
        >         of initial calibration being voided...
        >
        >         Thanks,
        >
        >         Franklin D Asbell


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