Another 3D print I designed in FreeCAD and printed for someone else. These things break all the time because they’re pushed in to the ground and are fairly expensive to replace so 3D printing is a good option. Printed in PETG.
3D printers are an endless source of usefulness. My ancient bathroom sink drain plug lifting mechanism broke such that it was always stopping the drain. I couldn’t leave the plug out because if you drop something in the sink, down the drain it goes. So I made a plastic version sized slightly different than the original so it would not stop water from draining.
I’m building a gear indicator and information display for my CBR500R. It uses an Arduino Pro Mini, Nokia 5110 display, and hooks in to the Honda diagnostic connector under the seat. Protocol is a custom OBD k-line format. Here is some useful information on the protocol used.
The first version I created used 2N7000 MOSFET’s for the serial interface and it worked fine on a breadboard. However, before I could build the final physical version I received some LIN transceivers that should simplify the circuit considerably. I’m working on a new version of the hardware design now.
This is a small 25mm by 30mm MultiWii board I started designing a while ago. I haven’t had much time to refine or test it. I did create a prototype board but that’s about it. The intent was to create a board small enough to be used on micro quads, helicopters, and planes.
I’m providing the KiCad schematic and board layout here.
Had a Rakon DFC CNC head that was not square from the factory so I pounded on it with a hammer to make it straight.
It appears to be possible to use an S107 tail motor to repair/replace the 130x servo motor. The S107 motor is 4mm and the servo motor is normally 5mm so there is some extra space. I used a piece of 1.5mm carbon rod to take up the extra space and it seems to work fine. I may try to find some other method of holding the motor in place. Also, rumour is that some S107 clones have 5mm tail motors.
Attached is my ER9x model for the V922. I have the HT8 set for Futaba mode. Note this model has no “beginner” mode or even idle-down (ie. full 3D always). To fly start with the F.MODE switch all the way up (ID0), move pitch/throttle to mid-stick, then switch F.MODE down one click to “1”. It will spin up to full throttle within a few seconds. The throttle cut switch works but what I do is just flick the F.MODE switch all the way up, this is much faster than reaching for the throttle cut.
I have converted to brushless using the HK 14000kv motor and a modified HK XP-3A ESC that has new double-stacked FET’s. I’m using Hyperion 550 mAh batteries for about 6:30 minutes flight time.
I measured the PWM signal on the main motor FET gate. It appears to have an 80us cycle time which means 12.5 kHz signal. With a 9x/HT8 the PWM signal starts minimum throttle (18% duty cycle) at approximately -52% and is full throttle at around 39%. These are only approximate because of calibration and PPM timing differences between radios.
Attached to this thread is a custom version of BLHeli specifically built for the V922. BLHeli normally only supports a maximum of 8kHz PWM on its signal wire but the V922 motor output runs at 12.5kHz. What this does is make the throttle skip from 66% to 100% with no way to use any value in between. My custom version of BLHeli multiplies the signal by 1.5 to bring the 8kHz calculations up to 12kHz and this makes the throttle perfectly linear. Also attached are patch files that show the source changes I made. I built versions using BLHeli 9.4 and 10.3. I use 9.4 but the latest BLHeli is 10.3.
BLHeli 10.4 now supports 12kHz so no need to use my version of BLHeli unless you want to run an older version (I currently still use 9.4).
New paper canopy, although I think I’m going to end up using this on my mCPX. It’s made with card stock which is a little too heavy for my liking (3.7g). I’m going to try to make another with lighter materials.