We tested at 150 psi, and did two magazines of ammo. Didn't get a good tweak on the gun until the second magazine full, but it did fine. I've got 3 more printed and they will be made into cannons for me by Brian K who owes me big for printing the parts for him to build a 3D printer In. His. School. Colors.
Hey Tuggy, Awesome stuff here. I'd suggest you do a static pressure test on an assembled gun (block the gun barrel) and gradually ramp pressure until something popped (obviously, do this in a safety chamber so no shrapnel in the people-space). Highly recommend that this is done for knowledge base of designers (you & RC) but not published. This would give you peace of mind as far as safety at normal operating pressures AND give you a heads-up on any potential failure points.
I will do that. I gave Brian 3 more magazines to turn into cannons for testing. Unrelated note, tell Spudsy that some members of his fan club (me) miss him and want to chat I tried dropping him a line on his forum but no joy.
anything new on ant farming tug and i have a question why can't you compresion couple the magazine to the guns? they have plastic line at lowes they use the inside brass sleeve to keep them from collapsing that sleeve inside the plastic on the ant farm should work here. im just curious materials wise whats an ant farm cost to make i know the printer media isnt cheap.
Fast gun does not use 1/4" . Not sure if there are standard fittings that would pass a 1/4" and restrict properly.
I got some pictures of the guns that Phil built with the magazines. Interestingly enough, he used rubberized CA to attach the magazine and copper pipe. Not something I would have tried, but it seemed solid enough and it has been through several battles.
Can you reliably print the threads like on the copper Tee? Thinking that you would just basically graft an uptube to the outside of the coil, basically taking out the 1 inch in the picture above. Not sure if you would ever get rid of the 90 degree copper breach elbow as impacts to the rising BB's would damage the elbow?
I've printed some threads to hold the MAV thread adapter on my torpedoes. They came out pretty rough, but cleaned up OK with a tap. I agree that the elbow will always be metal. On the other hand, if it is curved so that the BB gradually turns, rather than impacting the elbow, maybe it would work.
One of the guys in the Mid-Atlantic Battle Group (Brian, I think) machined risers with an internal curve from PVC, so it can be done. Although his were used in big gun cannons, not fast gun cannons, so the increased pressure of the fast gun cannon might cause an issue... You can't find his construction articles any more because they haven't rebuilt the site since it got hacked over a year ago.
I'm wondering what settings to use when printing ant farms? I tried one with 3 perimeters and 40% infill in ABS. It printed nicely, but it's not air tight. I think I need to increase the extrusion multiplier a bit. Since it's not going to hold pressure, I'm thinking about using it for destructive testing. I don't have any cannons, yet, so I'm wondering at what range would a shot from a Daisy Red Ryder be comparable?
Infill doesnt much matter. I used 4 perimeters w\ a 0.4mm tip @ 0.2mm layer height Our cannon typically fall between 200 and 300 FPS if I remember correctly the numbers others have relayed.
printed at both 90% and 10% infill no difference in failure. if your not airtight something is extruding wrong.
Brush the outside with acetone and run some through the magazine. At 150 psi the smallest gap will be found. For 3D printed accumulator ends I dip the whole part in acetone for about 5 seconds. When I assembled an accumulator without the acetone treatment, tiny air bubbles would work their way right through the whole part, which was about 1/2" thick.
