Our Syringe Buoyancy Engine is available for release. All the parts are available in the downloads section now. The design uses a Medline 30mL Luer Lock disposable syringes (part number SYR130010), and a common M3 /55mm shaft linear actuator module.
Originally the thinking was that BBs could also be added to a hollow piston when a weighted piston was called for in the design. While BBs worked for weighting pistons in several available notable glider projects using syringe buoyancy engines, we found BB weights just didn’t work well for the much smaller piston size we were using. While we explored the use of a custom lathed pistons made from a heavy metal like brass, and printed hollow pistons filled with powdered metals like iron and capped with glue, we were unable to find a solution that was still both affordable and easily constructed. Ultimately, we flagged how to weight the piston as an open question to be researched later.
Earlier designs also had a “tunnel”, for the shaft to travel within. This was an artifact of having a weighted plunger. The tunnel was meant to keep the weighting media from contacting the threaded shaft. The tunnel was vestigial in an unweighted design and removed.
Unlike our earlier designs, the design being released uses two nuts on the drive shaft, one locked on either side of the piston, rather than a single captured nut. Earlier designs also had a “tunnel”, for the shaft to travel within. This was an artifact of having a weighted plunger. The tunnel was meant to keep the weighting media from contacting the threaded shaft. The tunnel was vestigial in an unweighted design and removed.
The motor side of the piston chamber is now air tight, and as such sees a 16PSI pressure swing as the piston is drawn back. The cross pins used in earlier designs were swapped out for directly bolting the motor mount to the syringes support flanges. This change creates more unbroken glue to barrel housing surface along the motor mount to syringe join. The flat cap piece was also swapped out for a slide on cap which creates a glue seal with more area – and helps reinforce the motor chamber.