3DPMRS - 3D Printed Modular Rocket System

So, I've been stalled out due to lack of motivation and a broken bearing carrier on my printer. This caused the Y axis to be extremely inconsistent, which meant circles came out looking more oval than I'd like.

Apparently, this is common with the DaVinci printers. Instead of ordering parts, I got bored and made one of my own. A few clicks and I had a replacement drawn up in SW.

Seeing as it'd be difficult to print one with the broken printer, I turned to my CNC mill. However, I didn't have any blocks of plastic to mill it from. So... I melted down some old filament I wasn't using.

After I had a good sized chunk it was just a matter of milling it.

... and installing it.

Now, my printer is back to its old barely acceptable prints! I'm working on a second rocket design now with plans for a throw-away 3D printed motor. More updates to come.

Well, I've finally launched one of the printed rockets. Ran into a few issues, though. First, the battery I brought with me wouldn't ignite the engine. So, like any rational human being, I hooked the rocket up to my car. It worked.

It launched smoothly and flew extremely well, even with the high winds. Sadly, the streamer broke free from it's tether and the rocket was free to fall into the parking lot. Only damage was a broken fin. Excuse the language in the video, we got a little excited.

Overall, I'm excited to get going on the electronics side of the project now that the rocket itself has been proven.

I'm still fully intent on finishing the rocket and launch system, life's just gotten in the way. Next week I'll have some time to relax and job out, so I'll be sure to push for some progress.

Got some basic files drawn up in eagle for the launch control board. I'm working on a project for work at the same time, and that's been eating a bit of my free time. I'll try to get a log for that made up.

Well, it's fully assembled now. But, I'm going to have to make some changes, albeit, fun and exciting changes. Turns out I'm an idiot and have D12-0 motors, meaning they have no delay or ejection charge. This opens the door to some awesome problem solving opportunities!

It fits! So, the good news is everything has been lining up, and looks good.


AUW so far is 5.75 oz. The recommended max airframe weight for the D series engine is 14oz. So, I've got some wiggle room to add a system to deploy the chute that is completely independent from the motor. This also allows me to build my own motors (down the road, of course) that have no requirement for an ejection charge!

Well, it looks like a rocket...

The plan now is to use an ATiny85 (seeing as I have a few on hand) along with a 9g servo to deploy the chute. To simplify this I plan on using a delay system, thus avoiding any need for sensors or external input (outside of one initial input to start the clock). The way I plan to do this is by coupling the initial input signal into the relay I'm using to launch the rocket. By using a DPDT relay, I can initiate two signals of different voltages at once, 9v for the rocket igniter and 5v for the ATiny input. By mounting a small contact (most likely a pin) at the bottom of the rocket, I can allow the ATiny to receive this 5v signal when the motor is ignited. By calculating the time the rocket will take to reach it's peak, I can program the ATiny to actuate the servo at the correct time, pop the top and have it float down.

Time to get busy with eagle and get some boards cut!

Print came out clean enough. I'm not overjoyed with how clean the slits in the body are (cut them with a dremel), but they're clean enough and they work. I drilled four 1/8" holes and installed rivets to lock the body to the motor mount/fin assembly. Then I used a very light bead of 527 glue to fill the gaps around the fins. It's currently drying now.

Still need to get started on the launch mechanism.