3D Printing 75mm strong nose with electronics

[kramer714]

Designed and printed a 75mm nose cone with a 'modular' electronics mount

• Shoulder (lavender)
  • shoulder with a 'Gaudi' vaulted cap, and ribbed 'atrium' (https://sagradafamilia.org/en/antoni-gaudi/
  • Stepped Shoulder - nose cone wall thickness LARGER than bodytube thickness
  • 2s lipo pocket installed shoulder
  • Standard bolt patter 8 holes for flexibility
  • worm holes for wire pass-through (qty 2)
  • slight undersized at 68F to allow for CTE differences between the PET-G and Fiberglass bodytube (wont bind on hot days)
• Nosecone (Blue)
  • screwed to shoulder countersunk holes molded in place
  • flange thicker than body tube 3.3mm (vs 1.5 mm body-tube)
  • Ogive - (the one shown has a thicker wall than needed to add some nose weight)
• Electronics Mount (green)
  • uses (4) of the standard holes for mounting
  • simple standard screw switch design (gold)
  • shown with Stratologer mount, simple modification for other altimeters / trackers
  • second level mount
    • shown with holder for tracker (blue)
    • could have a Eggfinder mounted
• Battery Pocket
  • insert used to hold battery allowing for different sized batteries
  • battery cover (gold) allows for wire access and able to charge without removal

 

[kramer714]

STL Files (use for personal use only) if you make any changes - improvements send me a copy!

 

[kramer714]

 

[Rschub]

I don't know if I would rely on the threads on that eyebolt alone for the parachute attachment.

 

[kramer714]

I'm not too worried about the pull out strength for just the nosecone.

I make the hole undersized, drill to the proper tap size and tap the hole. I NEVER use 3d printed threads for anything that see actual load, I don't even print the holes to the tap drill size, always a bit smaller and wet drilled to the proper soft material (aluminum) tap dill size, tapped with water as a tap lubricant. Soft materials get a 75% thread, fora 1/4-20 this is a #7 drill (.201) a 13/64 can work too but is a bit larger. Be careful, many tap dril charts only list the soft OR hard material szie (75% OR 50%) cut thread.

1" of engagement on a 1/4-20 thread PETG. The pull out should be VERY strong, plus the (4) ribs keep the center hole stiff. Nope haven't tested but should be way in excess of 500 lbs. Having said that, I have molded in 'hex for a nut' on other parts without the long engagement.

Side Note, on the red part, the 'upper' (in relation to the way the part sits in the printer) two flats on the hex are canted 45 degrees to ensure it prints cleanly. I dont like to use overhangs greater than 45 degrees, the hex without the cant would be 60.

 

[kramer714]

worm holes...

 

[kramer714]

stuffed.... tracker on top

 

[cwbullet]

Nice print.

 

[kramer714]

on the rocket....

 

[Zyzzyva1000]

I don't know if I would rely on the threads on that eyebolt alone for the parachute attachment.

I have wondered about that, as I have several similar nose cone ebay setups. I usually just make the hole smaller than it needs to be (and reinforce 100% infill around the hole), then tap and fill with some epoxy as I thread the eye bolt in. This seems to be working well so far. Time will tell.

 

[cwbullet]

Is that fin can a print?

 

[kramer714]

um, yup,

For ROCstock (local 3 day launch this weekend), I built a flying motor case rocket. Looks like a disposable L motor with a stealth 38mm motor mount. The rocket uses a 3d printed centering 'canister', faux nozzle and thrust ring, faux forward closure, slip on fin can, and a bolt on upper rail guide. Even printed a cap plug. The centering canister has 4+ 1 ribs, the extra rib has slots in the bottom. I used this to wrap a shock cord around it
before bonding it all together

 

[kramer714]

 

[kramer714]

I have wondered about that, as I have several similar nose cone ebay setups. I usually just make the hole smaller than it needs to be (and reinforce 100% infill around the hole), then tap and fill with some epoxy as I thread the eye bolt in. This seems to be working well so far. Time will tell.

not sure if you need the epoxy but it cant hurt. One suggestion, use the actual tap drill, 75% cut soft materials. Tap Drill Guide For example a 1/4-20 uses a #7 (.201 inch), and use water as a lubricant for the drill and for the tap. Important to note, I'm using the eye bolt just to hold the nosecone to the rocket, the parachute is tied to the same eyebolt. The threads just need to hold the nose under a 'twang' ejection, not the load of a chute popping open, or the load of the upper and lower portion of the rocket separating .