So, I just got home and checked my mailbox; Take a look at the cover of this weeks Economist:
"Print me a Stradivarius; The manufacturing technology that will change the world"
The cover reads: “Print me a Stradivarius; The manufacturing technology that will change the world” It features a 3D printed Stradivarius violin, made on an EOS system. Likely it was made of a laser sintered plastic, because the caption reads “(and it plays beautifully).” If it was made on one of EOS’s metal sintering systems, I don’t think it would play as well.
You can check out the two 3D printing articles that appear in the print version here online:
Things sure do seem to be moving at an exponential rate in the 3D printing world these days… especially if such a world-class and well respected publication like The Economist is taking notice.
The Plastic Extrusion Tool takes in a feedstock of 3mm ABS plastic filament. The filament is compressed between a servo motor driven knurled pulley and an idler wheel. The filament is then forced down through a 0.50mm nozzle heated to 230°C [446°F].
Initial Plastic Extrusion Toolhead
The black parts that comprise the body of the extruder were made on a commercial 3D printer. In the above image, the extruder controller board [left] provides power to the nichrome wire heated extruder barrel and nozzle using PID control. The brass nozzle and heater barrel are covered with ceramic insulation for better temperature control. This heated portion is then itself insulated from the plastic tool housing via a PTFE tube, which was later changed to PEEK.
Backside of the Plastic Extrusion Tool
Six 1/4″-20 screws fasten into the tool head to secure it to the Z stage.
First Moutning the Plastic Extrusion Toolhead Mounted onto the Z Stage
Current Plastic Extrusion Toolhead
This is how the current Toolhead looks. The PTFE tube was replaced with a PEEK version, which is better suited to handle the loads of the melting plastic under temperature. Also, an aluminum plate was bolted to the black housing to provide more structural rigidity. A magnetic rotary encoder [right] provides closed loop feedback on the drive motor for more accurate extrusion, though getting this to work correctly with the extruder board firmware has proven difficult. Also the magnetic rotary encoder board is mounted to the drive motor via a custom part that was printed on this machine.
People have experimented with a variety of build surfaces on which to print ABS plastic such as MDF, acrylic, painters tape and sandpaper. One of best materials to use was found to be a high temperature Polyimide (Kapton) film while it is being heated to around 100°C. So, for my first build surface I decided to fabricate one with this polyimide film.
Polyimide (Kapton) Film Build Surface
This build surface is simply a .125 inch (3.18 mm) aluminum plate with through holes for eight mounting screws. You can see the adhesive backed polyimide film is not one entire sheet as the largest size I could find it in was 1 x 1 foot (30.5 x 30.5 cm), so I had to cut a few sheets up into sections.
Polyimide (Kapton) Build Base mounted on the Build Plate
Build surfaces mount to the build base plate (the one with the heaters mounted on it) with eight screws, so they can easily be swapped out to experiment with another build surface. For example I have found, as others have, that the polyimide film does tend to wear out over time as the plastic will fail to stick. The next build surface I am working on, will be made of PET film which can be wiped down with acetone if it begins to wear. It is also much less expensive than polyimide film.
