So I went ahead and 3D printed part of the hinge, but before really committing to all of them Im curious on the force that is applied to them and if it will withstand that load. The part has reinforced continues strands of carbon fiber inside the part so its between the strength of nylon and aluminium. My crazy self wants this to be as light as possible, so using these would help reduce wait even if its a little. Opinions thoughts?
I also have a 3D printed 17-4 version of this printing currently. The part though should be lighter then the normal aluminum part due to how its printed. This is the other method I’m looking at to save weight, but its more time consuming to produce. (Will Post Picture when finished)
That might be ok for that piece pictured because it is sandwiched between the carbon arm pieces. However, the other piece needs to be much stronger because there is a lot riding on that joint. If that hinge breaks under thrust load the whole arm, motor, and prop assembly will fly forward and cut you and your lines to pieces. I wouldn’t feel comfortable with either part of the hinge 3D printed. Even with carbon reinforced plastic you are still only as strong as the layer bonding.
I want to cut weight too but I’m not looking at ounces or grams but rather pounds! I’ve been flying with 4 Bonka batteries which total 24 lbs. When I fly with only 2 batteries I don’t like how hot the batteries and wires get even with 8 AWG wires on the batteries (just bought a second set of 4 and they have 8 AWG instead of 10 AWG). I love losing that 12 lbs but everything stays much cooler with 4 batteries. Maybe I can get some batteries with a higher c rating and even heavier gage wire because I’d really love to lose that weight!
How much flight time are you getting with 4 bonkas? I think I saw you mention that you just power up to the thermals? How heavily/often do you use the thrust?
Here is how the part is printed internally. The Blue in the picture in a continuous strand of carbon fiber that reinforces the mounting holes. So the plastic of the part is not the one bearing the load its the carbon fiber within the part doing most the work. What i need to know id what force is applied at the joints to figure out if it is safe enough.
Honestly, the best way to know how safe it is would be to stress it to failure. But here is a quick calculation: From the hinge bolt to the front of the hinge is 3.5 cm. From the hinge bolt to the motor is 23 cm. The leverage on the bolt would be 6.6 times the thrust of one motor (23/3.5=6.6). The system puts out 150 lbs of thrust according to Paul which is almost 40 lbs per motor. 40x6.6=264 lbs on that bolt. Plus you want at least 1.5 saftey factor so to be safe you would want that hinge to hold about 400 lbs at the bolt.
You can’t rely on the cage to add strength here because it’s too flimsy particularly at the joints so unless you change the cage design I wouldn’t figure anything in for that.
I mostly fly in calm conditions and get 25 minutes of flight with 24lbs of batteries (4 Bonka’s). It doesn’t seem to matter how I manage the power I still get the same flight time. Fast climbs with longer glides vs level flight all gives about the same flight time in calm conditions.
That’s disappointing to hear you’re only get 25 minutes. I was hoping for 35-40 minutes from 4 Bonkas. I’ll soon have my unit ready to fly, maybe this weekend or next, and will post my results of time aloft on 4 Bonkas.
I don’t have access to a 3D printer to make the dyi stop plates for the hinge that connects the bottom part of the center section to the legs. I was wondering how I could find a way to quickly unfold the legs to the same position each time so that the hoop lines up perfectly. I have found a simple, easy way. Just set up the frame and completely assemble the netting so that it is ready for flight. It may take some small adjustments to get the center plate at the right angle. When it is perfectly adjusted, take a marker (I used a silver magic marker) to mark the position the hinge was in by making a straight horizontal line across the hinge. This way, each time when you unfold the hinge, you’ll know exactly how far to unfold it to get a perfect straight hoop with tight netting. See pic for silver marks on hinge.IMG_0460|669x499
If you get a file to me I actually work for a 3D printing Service, and can probably help you out with that if your looking for something more then just a pen mark
Thanks for that information, PcPanda. I’m entering into another area of technology of which I have no experience, 3D printing. The hinge stoppers I am referring to are the ones designed by Paul B (Gliderpilot) in the thread “Paul B and Braedin B”. He shows a pic of the hinge stopper he designed and has files attached to print them out. I’d like to get these printed out if possible. My email is bhocker2001 at yahoo dot com
3D Printing Update was able to successfully print a metal hinge piece and prep for sintering. Will update once that possess is done. Till then here is up date photos of the part.
Just remember that PLA when it heats up can warp easily, so if you store your stuff in a garage or in a car in the heat for to long it could ruin those parts. If you can i would at least recommend printing in ABS its bit more heat resistant and a bit tougher.
