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Project Rationale
Project Rationale
The goal of this project is to design and manufacture a functional Novelty, "Robotic pen", which contains an outer shell of which open to reveal the pen tip, whilst enclosing the top of the pen mechanism
Overview:
Overview:
A fully 3d Printed Novelty pen of which takes inspiration from the “Froggy pen” and was designed entirely in Fusion 360. It possesses an external hard shell of which is spring-loaded and magnetically locked and upon opening springs open to reveal the contained pen section.
It is fully custom designed and uses a rack and pinion plunger mechanism to convert the longitudinal compression of a compression spring into a rotational movement to operate the mechanism. Such a mechanism is opposed by the attractive force of four magnets within the shells, which keep the pen closed, and upon manually separation the shells via the button, the mechanism is set into motion and the pen opens.
Demonstrations
Demonstrations
Further Details and Timeline of Design:
Further Details and Timeline of Design:
There were 4 main design Iterations:
Large V1 with Mechanical Clasp
Large V1 with Mechanical Clasp
This version was much larger than the newer models and utilized an unreliable mechanical clasp. Upon pressing the buttons, the external shell would displace in the direction of the press and separate the latch mechanism, allowing the spring mechanism to open the pen. This model was very large and hard to carry and write with. In addition, upon storage, minute forces would accidentally shift the shell and open the pen.
This model also utilised M2 screws as hinges as well as fasteners.
Small V2 with Mechanical Clasp
Small V2 with Mechanical Clasp
Version 2 of the pen was downsized and longitudinally scaled down by a factor of almost 0.45. In addition a failsafe was added to the spring mechanism's bolt to tension such mechanism, aiding in preventing accidental openings.
Small V3 with Magnetic Clasp using Screw Hinge
Small V3 with Magnetic Clasp using Screw Hinge
Version 3 replaced the unreliable latch mechanism with a magnetic locking system, in which 4 neodymium magnets maintain the pen in a closed state. Upon pushing the buttons, a wedge would be driven between the pen shell. Due to such the equilibrium maintained between the spring and magnet mechanisms would be disrupted and the shell will spring open and lock again in the open position under the combined influence of the magnet and spring systems.
Small V4 using Magnetic Clasp and Wire Hinge
Small V4 using Magnetic Clasp and Wire Hinge
Version 4 entailed a tolerance redesign of the mechanism to remove excess play from its motion whilst allowing metal wire for use as pivots in the stead of m2 screws, minimising the required M2 screws making the design more cost-effective. In addition, the shell was redesigned to include less steep overhangs and reduce the need for printing supports during printing, whilst improving the shell's print quality. Overall reducing the material needed and time required to manufacture.
In addition, Custom Glow in the dark details were added to improve the design's aesthetic and glow in the dark letters were embedded within the shell.
Design Library:
Design Library:
This link contains a thorough archive of the design's photographic documentations.
Future Scope
Future Scope
The next step for this project would be the improvement of the pen's ink capacity for a longer use period. After such, the ease of modification and disassembly of the pen will be improved, replacing the hex screws fastening the device and ink compartment with user-removable compliant tab locks, simplifying assembly, maintenance and Bill of Materials for the device.
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