I have tinkered with small PVC rocket motors using sugar fuels in years past thanks to information posted by Richard Nakka, Dan Pollino, and Jacob's Rocketry. The frustrating part of the build, particularly for smaller diameters, was the nozzle. After building a 3D printer, it was time to print my own nozzle molds.
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| Nozzle molds on print bed. |
I modelled the molds in OpenSCAD and printed them out. With a little trimming, they were ready for a motor casing.
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| Casing, mold, and retaining rings. |
Once in position, the molds were fixed in place using ABS glue (acetone + ABS).
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| Molds in place with ABS glue. |
Retaining rings were cemented with PVC cement and the nozzle was cast in PourStone. A pager vibrating motor was taped to the casings during casting to ensure minimal bubbles and maximum packing.
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| Cast nozzles. |
Stay tuned for the first static firing using some KNSU fuel. Future tests will be using KNSB fuel.
Too cool. Do you think layer roughness affects nozzle performance? Have you ever tried smoothing 3D prints with acetone vapor?
ReplyDeleteThe cement nozzles erode quickly, so I doubt it makes a huge difference. I have not vapor smoothed prints yet, but I often brush on acetone to smooth it out.
DeleteThe cement nozzles erode quickly, so I doubt it makes a huge difference. I have not vapor smoothed prints yet, but I often brush on acetone to smooth it out.
DeleteDo you have the stl's for your nozzle design?
ReplyDeleteSecond that - would be cool to have a copy.
DeleteGreat idea using the thin wall & cement backer.