electronica EL400 Manual

Using Segmented Linear Error Compensation (SLEC)

to calibrate magnetic scales with an EL400 display:
Congratulations on the purchase of your Electronica 400 series kit. This article addresses how to calibrate
magnetic scales using Segmented Linear Error Compensation (SLEC). Note: SLEC is a much more
advanced form of correcting for error compensation. Most calibration issues (if any) can be corrected
using Linear Error Compensation (LEC), not SLEC. DRO PROS does not recommend utilizing SLEC
unless you're already familiar with advanced error compensation procedures.
SLEC works by applying a graphed correction factor to your scale from a chosen reference point (referred
to as the Master Reference Point). In order for SLEC to work properly, it must always know where the
master reference point is. As such, every time the display is powered up, the master reference point must
be 'recalled'. While performing SLEC can make every measurement along the scale "perfect", for most
users, having to recall your master reference point every point you power up the display is going to be
more inconvenient than it is beneficial.
The following procedure assumes that your kit has been properly installed and the readhead / scale gap
has been properly set with the included shim. While the "best" calibration results are obtained with a
laser, it is possible to achieve satisfactory results with a high grade gauge block combined with a high
quality plunge type dial indicator. Best results are usually obtained by the simplest, most robust setup. Be
sure to also check / adjust your machines jib play before attempting to calibrate scales.
SLEC consists of three separate steps. First, you must discover and designate a "master" reference point
for applying SLEC. Second, the SLEC correction factors must be entered. Third, the master reference
point must be referenced before each operating session (or each time the display is powered up if the
display has been turned off).

Step 1 - Find and designate a Master Reference Point.

Magnetic scales have factory embedded, permanent reference marks located along the length of the
scale, approximately every two inches. Our first step is to find, and then designate, which mark is the
"best" to use as the Master Reference Point. Typically, it would be the reference mark closest to the
negative end of our scale. As these reference marks are not visibly marked on the scale, we must first
discover where they are, and then choose which mark is the closest to the end of the scale while still
allowing the readhead to 'sense' it.
Move your readhead to the far end of the scale. Be careful to not run the readhead into the endcap.
Press the "homing" function button.
You should see "hoME" on the X axis display window.
Push the "ent" button once. You should see "SELECt" on the X axis display window.
Push the "X" button once. The X axis display window should now be flashing "0".
Move the X axis of the mill until the X axis display starts counting normally. As soon as the X axis begins
counting, reverse the travel, and go back so that the X axis window displays "0.0000". This indicates the
exact position of a reference mark. With a scribe/pen, mark the location relative to the readhead, so that
you know specifically where the reference point is located.