Monday, February 26, 2018

3D Printed Key Hook

Above: Details of original design as shown on this blog last year
Challenge: For student to create an original, labelled hook, that could be used to hold an important key in the context of school activities, and for a student to create a labelled bag hook for themselves.
Background: This print was originally featured on this site in its developmental stages.  In the original print the intention was for a bag hook as a marker for the student.  Following this design, the original was completed and then a problem that was created by a need for a label for an important key, needed for the running of the school.  Students have responsibility for the running of the school PE shed (where the students gear used at lunchtime is stored).  A number of students need to access this key on a regular basis.  When the student heard this, they re-designed their original brief, and instead modified it to be used for the location of the key.    A crucial component of this was the strength of the PLA used to create
the 3D Print.  It would have to be drilled through, with an electric drill to ensure that the print could be secured to the wall to mount it.   The students as a result took a series of test prints of the name hook, under adult supervision and started using an electric drill to drill through the print.  They were looking for signs of damage or cracking on the student created work.  The drilled prints were either 5mm or 7mm thick, as the finished print was.    The students discovered that they could indeed successfully drill through the prints without their being any damage to the print itself, meaning the completed key holder could be secured to the wall.  It was noted by the students that the point where the print appeared to be weakest was where the lettering was located (in this case where the lettering naming the key was held as shown left).
Level of Difficulty: Medium-High given the variations that this print has had to go through.  The design has gone through a number of variations and stages.   The PLA is strong enough to have an electric drill screw right through it and still maintain its strength.   Given that the intention is for a key to be held in place weight is not necessarily an issue (although this will be tested for the final design of the bag hook as potentially this could be an issue. 
Above: The final print in place and working
Time frame: Six Hours.   This was in essence a test to ensure that the PLA could withstand drilling and be mounted to a wall.   Depending on the size of the label and the lettering required this could be considerably altered.  As is usual a 8mm nozzle was used on a regular print setting.
Size: The final print for the wall was 5mm thick, 75mm across and 95mm high.   This was perfectly suited for the purpose that was required. 
What we would do differently:  Consideration was not given for the colour of the PLA relative to the background colour which it was going to be mounted on.   The lettering on a white PLA background did not stand out given that it was mounted in an office, and consideration could have been made to having a different colour, or possibly glow-in-the-dark filament.   One point that was careful for this mounting was to ensure that the print was safely mounted to the wall (and not drilled into the wall near the electrics) which is reflected in the single screw that is shown in the picture.
Next steps for the students: There are additional prints that are intented in this design, following the process to have specific locations for high usage keys which students need to access from a set location (and also to ensure it is easily recognizable if a specific key is not there).  There is an obvious opportunity for labelling for a bag or other item of importance in the classroom.


  1. What a great idea. Truely practical and useful.

    I found it a bit hard to read the text on the white background. When you 3D print can you mix the colours so the lettering stands out or can you paint it in some way to give it a little standoutability???

  2. Allanah
    Thanks for your coomment, as always we really appreciate it. The text was a little hard to read because of the PLA cover and also the office where the Key is located, the light blew out, so its essentially white plastic, in a dark room, with a flash light from a phone illuminating it. We'll take a photo when the light is repaired, it will seem stronger, but agreed the white is probably not as clear as another colour could have been.