38 SERVO 09.2013
Heat your extruder, then start the print once the
extruders target temperature is reached. For new PLA, start
out at 185 degrees Celsius; for ABS use 230 degrees
Celsius. Adjust as needed. When the print is complete, it
will look like the one shown in Figure 2.
Since you are calibrating the filament, there’s a good
chance that the print will be far from perfect, so pick a
smooth spot and use a set of digital calipers to measure the
thickness of the last layer printed (Figure 3). The goal is to
measure only a single layer. Measure at several points
around the object. It's very easy to get
readings over the actual printed thickness.
If you measure more than one layer, it will
show a thicker reading. I squeeze the
calipers with a good deal of force when I
take my readings.
In my example, the measured thickness
was . 37 mm (Figure 4); the target was
. 4 mm. To get your multiplier, divide your
target by your measured thickness. In this
example, I will use an extrusion multiplier
of 1.08. Plug this value into the Extrusion
multiplier field and do another print.
Your measured value should match
your target value. That's pretty much how
you calibrate your filament. To make things
easier to set up when calibrating filament,
keep a set of saved configuration settings
just for calibration.
ABS vs. PLA
In the past couple years, several types
of filament have emerged. ABS, PLA, PVA,
nylon, polycarbonate, and even some liquid
MDF materials are starting to show up. By
far, the two most popular are ABS and
PLA. They each have their own strengths,
weaknesses, and printing requirements,
but first let’s talk about why you might use
one over the other.
ABS shrinks as it cools. When the
bottom layers of the print cools while we
are still printing on the top layers, we get
warping. The larger the print, the worse
There are two ways to minimize the
warping: a heated bed and brute force. A
bed heated to about 100 degrees Celsius
will reduce the warping on larger prints but
won't eliminate it. On smaller prints with
good adhesion, the warping
will be unnoticeable. On
larger prints, the force of the
warping will pull the print
away from the bed as shown
in Figure 5.