Having produced a complete CAD model of the glider, I started printing the parts for the glider. I own a Mini Kossel printer, which is a delta style printer (as opposed to the standard cartesian printer) The components were printed at a layer height of 0.4mm, for greater structural strength and faster prints. Printing all the pieces took approximately 80 hours. I had to print some pieces multiple times to get the dimensions of some features correct (bolt and tubing holes, etc).

The hydrofoils attach quite firmly to the glider body and are unlikely to slide off during operation.For the majority of the parts, no post processing was required, but for a few parts the printer had a printing error which caused the layers to become stepped (I have since fixed this error). As the printing error would not affect functionality, I decided to not redo the prints and would clean the affected pieces using a dremel.

The nosecone pieces after post processing, you can see the stepping error at the join

Printed material is less dense than water, so I made the models hollow in some areas, so that they could be filled with ballast. I am going to use a PVA/sand mixture as the ballast, as this is denser than water (~1.7g/cc depending upon the ratio of PVA to sand) and can be formed quite easily.

The hollowed internals of the hydrofoils, ready for ballastThe planetary gearbox also required a lot of work regarding the tolerances of the gears. Although it is not perfect and there is still a slight amount of slip, I am happy with it to a sufficient degree for a proof-of-concept.

I have hooked the stepper motors up to an Arduino and over the next week or so, I will test the movement sub-systems and post a build update showing basic functionality.