White paper
hp M3035 / M3027 MFP
Security Level: For HP and Channel partner internal use
Date Written: 05/04/2007
Document Summary
 Explanation of Skew specification when feeding from the ADF and recommendations to improve.

What is it?
The ADF skew specification determines what is considered acceptable printed image placement on a
page when making copies using Automatic Document Feeder (ADF) to feed the originals.
The specification is ≤ 1%. This is how it translates to millimeters:
% (length of the media)
Skew in mm = ------------------------------100%
Example using letter size paper:
1% (279mm)
Skew in mm = -------------------- = 2.79 mm ≈ 3.0 mm
100%
Also: .01 X 279mm = 2.79 mm ≈ 3.0 mm, which means the image may skew up to 2.79
mm over the length of 279mm and still be considered within specification.
To measure skew when feeding from the ADF, locate two points (A & B) on one of the longer sides of
the copied document, as far apart as possible. (It is best if the document has a margin printed on it).
Measure the distance between A & B, multiply the distance value by the percentage (.01), to obtain the
target specification. Then measure the distance from points A & B to the edge of the media; if the
difference between these two values is less than or equal to the target specification, then the amount
of skew is within specifications.
Example for a Letter size paper:
. - Let’s suppose the drawing below represents a letter size paper with a margin printed inside.
. - The margin measures from point A to point B 200 mm, multiplied by .01 gives 2 mm as the target
specification. (See drawing below).
. - In the example below, the distance from point A to the edge of the paper is 5mm and the distance
from point B to the edge of the paper is 7mm. This difference of 2mm is considered within
specifications.
Process direction
Leading
Edge
7mm
5mm
200mm
A
Points A & B
B
Skew amount of 2mm
difference is considered
within specification for
this example.
Trailing edge
Page 1 of 2
white paper
NOTE: Before attempting any troubleshooting steps, verify that the amount of skew is in or out
of specifications. Make sure to set the right customer’s expectations. Do not replace parts to try
fixing something that is not broken or within specifications.
These are some recommendations to prevent inducing additional skew when feeding
from the ADF. Please communicate all of these recommendations with the customer.
. - Make sure the paper guides located at the input tray of the ADF are adjusted until they are
snug against the media.
. - VERY IMPORTANT. Verify the ADF input tray is properly seated and not misaligned. The plastic
tabs that keep the tray in place may be broken; ask the customer to check the tray installation.
NOTE: Failure to check the above two items, may result in a significant amount of skew.
. – When copying a stack of paper, make sure the paper is neatly stacked before placing it in the
ADF input tray. Avoid excessive off-set between sheets.
. - Avoid feeding originals that have folded corners, especially in the corners located at the
leading edge of the original. The folded corners are also known as dog ears.
. – Make sure the original is in good condition –not folded or bent-.
NOTE: If it is, then recommend using the flatbed glass instead.
. – Make sure customers are not leaning on the ADF while copying. This may shift the media
being fed through the ADF, creating image skew.
. – Make sure the original to be copied is not already skewed.
. – Check the input trays at the engine and make sure the paper guides are snug against the
paper.
In case the skew amount is out of specifications and the above recommendations
have been followed in detail, but still excessive skew is experienced, check the
following:
. – Perform a scanner calibration and check for improvement.
Document Attributes
Author: Luis Morales Technical Marketing Boise Division
Product Models: HP 3027/35 mfp
Product Numbers: CB414A, CB415A, CB416A, CB417A
Page 2 of 2
white paper