Here's a few things we took away from our Design Review:
-3D print Lego stud design to test fit prior to machining/injection molding; adjust CAD if necessary based on 3D printed tests.
-Possibly 3D print Lego logo for to more precisely recreate the iconic design with thermoforming. Such a thermoforming mold will be weaker, however, and may deteriorate quicker than aluminum.
-Be aware of shrinkage regarding the interference fit (parts may shrink differently), possibly start with more interference, and if necessary we can always cut more material from the mold.
-Can we simplify the back Lego stud design for tooling time/manufacturing? It is currently quite complicated and requires a small end mill.
We decided to follow through with this feedback by first trying to 3D print the thermoform mold with the Lego logo, as well as the front Lego face of the Yo-Yo (positive stud side). We will be using the FormLabs Form2 3D printer for these parts. From tests conducted by other users, the Form2 has a dimensional accuracy of up to approximately 100 microns (~0.004 in), which should be good for initial tests.
We'll also be taking a look at the back Lego face design to see if it can be simplified/optimized as well. Below is a revised design, where we filled in some areas connecting the circular stud fittings for ease of machining. The altered regions also do not directly affect the Lego stud fitting.
This mold differs from before in that the Lego logo feature more closely represents the actual Lego logo, something which (at this size) wouldn't be possible with a mill.
Below is the setup of the 2 parts to be 3D printed:
In addition, we continued making small modifications to our CAD models (drafts, interference fit, etc.) and finalizing our housing mold with ejector pin holes, sprue holes, etc.
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