3D Printing

Hunter 400 V-Tail Quad

It has been too cold for me to paint the fairing for the CBR600RR and not long ago I found a deal on Kijiji for a drone kit that I couldn’t pass up so I have been putting in some time on the drones lately.
I don’t care to remember how many years ago it was when I bought the Hunter 400 but I have loved flying it from the very first time I got it in the air. I think this one is an early one that was designed and made by DiaLFonZo-Copter before they were acquired by RobotShop as when I got it, it was running on an Arduino mini with a board from a Nintendo Wii controller running Multi Wii so there was no self levelling, only acro mode.

When I bought the drone kit, it was to upgrade the power train on the Hunter that seemed to be struggling a bit with performance and flight times. The new motors were too big to fit in the holes so I had to invert all of the arms, other than that it was a fairly smooth install.
The drone kit even came with a KK flight controller and I had a set of unused motors in a drawer that must have been there for 5 years! At first I thought about assembling all this stuff on the frame that came with the kit but since I had a bit of time I thought I’d reverse engineer the Hunter and 3D print a frame to mount the stuff in. I figured I’d try to emulate the original design that was cut from carbon fiber sheets so that the 3D printed parts would be interchangeable in case of crash damage.

Here’s what I came up

I had to drill holes to get to the motor mount grub screws and the battery tray doesn’t hold the battery very tightly but otherwise I’m very happy with it. I printed my model out of PLA at 220°F with the bed at 50°F and 30% infill and got great results. The landing gear was a bit too flexible so I decided split the CAD model in half so that I could thicken it up without having to use support but it does mean that you have to print two (one mirrored part) and then glue them together.

After a bit of messing about disconnecting the old motors from the ESCs (that were hard soldered together), installing connectors on the new motors and ESCs, and then installing everything, I was ready for flight testing.

The 3D printed version is on the right in case anyone was wondering 🙂

I had intended on using an old Naze32 flight controller because the KK that came with the kit was too big to fit in cockpit area but it was blown and wasn’t recognizing inputs from the receiver, that’s why the KK is mounted on top of the cockpit.
This was my first time messing with a KK flight controller and I found that I had to mess with the default settings quite a lot to get it configured correctly. Once I got it flying, it was quite unstable and I’m still tinkering with the PI settings to try and get it dialed in. I’m almost tempted to ditch it and try a different flight controller as I’m struggling to figure out how to adjust these PI settings to make it fly like the original, even after following the instructions off several YouTube videos.

I found that several if not all of the motors had come loose and one mount had lost a grub screw, the other was also loose! After fixing all that it still didn’t fly great so I decided that I might as well try the old 2 blade props just to see … finally it hovers much more stable but still has a bit of a wobble. I had to drill holes in the arms in order to access the motor mount grub screws and I didn’t like that so I re-designed them and printed out new ones. When I installed the new arms it was a bit of a bind to push the motor wires through the holes and I must have damaged a couple in the process because one of the front motors stopped working. That ended up causing a crash that broke all the landing gear leading to a re-design to give them some flex. With new landing gear, all the wires fixed and the mounts secured, it flies much better and yet still has a bit of a wobble in the roll even without self-levelling.