User manual

28 User Manual
Arduino Materia 101
One of the most critical parameters of 3D
printing is the surface of the printing bed.
When you extrude first layer of the object,
it is smeared by the brass tip onto the print
surface. If the cooling plastic loses adhesion,
it is very likely that the print will be damaged
before the object is completed. There is
no single solution for all types of filament.
Because of this, we mainly focus on the two
materials most commonly used; PLA and
ABS, and compare these with other materials.
HOW ABS BEHAVES
It is a thermoplastic with characteristics that
can be varied by changing the relationship
between the three main components
(acrylonitrile, Butadiene and styrene) to
obtain a material with more flexibility,
strength, a melting point higher or lower
and even other physical parameters such
as the percentage of thermal retraction/
expansion. ABS is used extensively in
industry with injection moulding of common
everyday objects. It is also the material that
the first RepRap 3D printers were using
to print engineering parts and gears. It
resists high temperatures before softening
and losing its mechanical resistance and
dimensional stability. On the downside it
needs a higher printing temperature of 230
or more degrees Celsius and during cooling
its size reduces noticeably, leading often
to deformation of the first printed layers
and the consequent detachment from the
printing surface. To avoid this phenomenon,
there are two countermeasures to use
in combination. The first one is to have
a surface covered with a material that
has strong adhesion with the ABS. The
second is to keep the heat of the surface
(between 70 and 115 degrees) to allow the
printer to build the entire piece without
thermal retraction being so pronounced.
A piece that is kept in shape with these two
countermeasures throughout the print will
be far more dimensionally accurate with
the 3d model. Often, however, it happens
that there is a partial detachment on thin
parts, elongated with significant coverage
of the bed. In these cases, the printing is
completed but the deformed parts might
be arching upwards. This is called warping.
The material, which at the moment is very
handy for keeping the ABS attached to the
printing plate, is the hairspray. Its water-
soluble components allow you to create a
surface that adheres to the glass sheet and at
the same time blends and binds with the ABS,
keeping it firmly stuck in place. To remove the
printed part, use a utility knife or spatula. If
these do not “cut it” and you can not remove
the piece (a testament of the good bond
between the hairspray and the ABS), you
can remove the glass tray from the printer
and put it under water to soften the lacquer
until the piece will come off with ease.
HOW PLA BEHAVES
This material is created by processing plant
pulp waste rich in cellulose. It is preferred by
many, over ABS, even though temperatures
over 60° tend to make it soft. It prints at
temperatures between 180 and 230 degrees
depending on the additives that have been
added to color it and modify its physical
and mechanical properties. In relation to
ABS, it is more environmentally friendly and
emits almost no smell when printing. The
surfaces of the objects printed with PLA are
more reflective and transparent. Also the
size fluctuation is much less noticeable with
PLA, thanks in part to the lower extrusion
temperature. Unfortunately, the range of
temperatures in which the PLA remains
elastic is wide: so if the piece in print is
not properly cooled, there is a risk that it
might lose it structural integrity and appear
deformed or lose all smaller details.
For optimal adhesion of PLA, spray the
glass with hairspray outside of the printer
and return it to the printer. For items with
a base of a significant area, you should
use a preheated plate at 60°. This is a
good hack to add to your Materia 101. If
you add a heated bed you also have to
add a more powerful power supply.
HOW OTHER MATERIALS
BEHAVE
The behavior of other materials
can be related to PLA and ABS.
See the examples in the table
on the next page.