3Dprinting supersonic speed airgun pellets
So why do print airgun pellets?
I am interested in high speed photography, and want to capture supersonic speed (>343m/s) pellets inflight.
In 100% size photo part below I did five 2µs duration 10000lm led flashes, 100µs apart for capturing pellet shot with airgun inflight:
https://forums.raspberrypi.com/viewtopic.php?t=319956&start=25#p1956584
Normal airgun pellets (mosquito/hornet) are way too slow for this (80/120 m/s only), with old 7.5J airgun of a friend I use.
Before I got my Prusa MINI+ 4 weeks ago, I printed pellets on Ender-5 3Dprinter of younger son. Today I printed bottom 4.4mm diameter 0.6mm high cyclinder, top 1.4mm high ring with 4.4mm outer and 3.2mm inner diameter. Here is nozzle camera video of Prusa MINI+ print of 9 pellets:
Two of those pellets did show 396.8/392.5 m/s supersonic speeds (>1400km/h) in gun chrongraph:
I did create 2.0mm high ring, with positive 1.9mm high cone on top, with negative cone eliminating unwanted material yesterday in FreeCAD and 3Dprinted as well. Those pellets have 4mg more weight (32mg) than the previously discussed pellet (28mg), with Fillamentum PLA. The last (still slightly supersonic speed) was measured for shooting a cone pellet:
I have experimented with smaller than 0.6mm thickness ring borders, but got only bad results. While I do print with 0.4mm diameter nozzle, as the youtube video shows the MINI+ prints two circles for each pellet and layer.
RE:
I played a bit more with a construction that I tried with Ender-5 3Dprinter of younger son before, this time with Prusa MINI+.
I played with 0.05mm layer height, but my filament was too wet for that to work.
So I went back to 0.15mm Quality, with 100% infill, 0.5mm high cyclinder, three FreeCAD polar pattern pillars of height 2.0mm and thickness 0.6mm, and on top 4.4mm/3.2mm outside/inside diameter ring. Filament was wet, so stringing was expected. Next I did weigh, although longer than the other pellets, with only 18mg most lightweight sofar. Airgun shot showed 350.9m/s, so while more lightweight, a bit slower:
Oops, found similar construction done 3 months ago with 3Dprinter of my son, and there this pellet type achieved 439.2m/s (1591.12km/h) or mach 1.28, fastest speed I measured with gun chronograph:
https://forums.raspberrypi.com/viewtopic.php?t=319956&start=25#p1952927
RE:
I have experimented with smaller than 0.6mm thickness ring borders, but got only bad results. While I do print with 0.4mm diameter nozzle, as the youtube video shows the MINI+ prints two circles for each pellet and layer.
I created a thread asking for help on this, and got help:
https://forum.prusa3d.com/forum/prusaslicer/why-does-prusaslicer-show-one-ring-but-prusa-mini-does-print-two-per-layer/#post-596047
Now only one circle per layer for exactly 0.4mm pellet border thickness:
RE: 3Dprinting supersonic speed airgun pellets
This looks interesting.
RE:
I bought caliber 4.5mm plastic sphere airgun pellets of weight 125mg and achieved 220m/s reliably:
https://forums.raspberrypi.com/viewtopic.php?t=319956&sid=3d9ce3eaa2e2dc5a4ff0e0887d2e9621#p1917937
I experimented with 100% infill half sphere plus cylinder below, 65mg achieved slightly supersonic speeds:
https://forums.raspberrypi.com/viewtopic.php?t=319956&start=25#p1951893
Recently I 3Dprinted emptvy 20mm diameter 0.4mm wall thickness single perimeter sphere of 555mg weight only:
Sphere surface area is 4πr^2, so 4.5mm diameter 0.4mm thick sphere should weigh 555/(20/4.5)^2=28mg only. When back home from hospital (broken elbow) I will 3Dprint empty 4.5mm spheres an measure (hopefully supersonic) speeds. Many problems from previously printed pellets should go away because of pellet symmetry ...
RE: 3Dprinting supersonic speed airgun pellets
nice information