3D models of ABS and PLA are printed upon a build plate that is attached to the platform. Before printing the actual object, the printer may, based on user settings, build a raft on which the model will be constructed. The raft is larger than the model being printed and therefore provides more adhesion which in turn minimizes the possibility of the edges of the printed object from detaching from the build platform, or in a word, warping. The raft is removed post print.
The raft must be removed from two different surfaces. The first surface the model must be removed from is the build plate. The second surface is the printed 3D model. The removal from the build plate and the printed model tends to be difficult unless certain conditions exist during the print process. These conditions include but are not limited to ambient temperature, heating of the platform, and density of the raft. A raft density of 4 is more successful than a 3 density and a density of 2 or 1 is almost guaranteed to fail.
Note: The density of the raft is referring to the thickness of the raft that is printed on the plate before the printing of the model. The density can be changed in the printing screen that appears just before the file is sent to the printer.
The finish on the build platform affects the ease of raft removal from the build plate. FR-4 (Glass-reinforced Epoxy Laminate) build boards come with the Afinia H-Series 3D Printer. These boards can be used as is or different finishes such as Kapton tape, blue painting tape or an acetone/abs mixture can be applied to the build plate with a paintbrush.
A model with a large base prints well directly onto one of these perforated boards without raft. However, without the raft, the extruded filament penetrates the small holes on the surface, which in turn makes it more difficult to remove the model from the build plate. Also, the perforations create a pattern on the back of the model that resists sanding.
On the other hand, a model with a small base may be more successfully printed when the build plate is covered in blue tape or Kapton tape. If a taped platform is desired, the build plate should be covered with the tape, taking care to place the tape strips touching but NOT overlapping.
After removing the raft from the build plate, the raft must be removed from the printed model. Removal of the raft can be accomplished by using an Xacto knife or paint scraper, both of which are included in the Afinia Accessory pack.
It is VERY IMPORTANT that safety measures are taken at this point. Safety glasses and thick work gloves are necessary to avoid possible injury. Once safety measures are taken, the tool of choice must be placed between the raft and the printed object. It is necessary to do a sliding, twisting motion as the blade is pushed between the raft and the printed model. Also, when using an Xacto knife, the flat edge should be against the bottom of the model and the sharp edge should be towards the raft.
To see a good demonstration on how to remove the raft from a 3D print go to:http://vimeo.com/18525405