Hello.

There is UDI U941 I was presented (actually, this is what caused me to dive into quadcopter world!):



After some flying and drowning it in the river near my house ( from onboard camera) I removed the camera module, which was dead anyway.

The bigger problem with this quad was that it was very sensitive to the quality of props - the more props were damaged, the more vibration caused gyro to drift. As it can be flown only in stabilize mode, drifting gyro required to recalibrate often (every 1-2 mins!).

So I decided to make my own frame for it. The main goal is to fix controller on foam to prevent vibrations from causing gyro drift. I have a foamed PVC sheet, it is light and strong and it can easily be cut with the knife. So I decided to use it as a material. This is first try:



And assembled:



Despite it looks pretty terrible, it was not much heavier that original frame, so it was able to fly. The initial problem was solved - gyro was no more drifting.

But... as far as you start improving something, it very hard to stop, isn't it?

So, I thought how I can make frame better. And, as I was building the 250 quad at that time, I wanted to make this lighter frame to be as cheap as possible too.

As the material I took same PVC sheet and bought one 2mm carbon rod. I wanted 3mm initially, but only 2mm were available here.

So, this is how it expected to look:



There is platform in the center and motormounts on the edges of rods are from PVC, and X is rods.



This is first step - the motormouns are still one part with the center plate to be able to drill holes for rods.

After that I cut the rods, inserted them into drilled holes and put epoxy in to secure rods in holes:



After 24 hours I cut unneeded PVC out:



And there is build on new frame:



I'm very happy with it, it very light (unfortunately I can't say how exaclty - the weight of frame is comparable to the measuring error of my kitchen digital scales) and very cheap (it costed me about 3$ for materials).

Can't believe no one has commented on this. Great dedication to build your own frame. I love how it came out with the new arms.

(28-Apr-2016, 05:13 AM)K24cl9 Wrote: Can't believe no one has commented on this. Great dedication to build your own frame.  I love how it came out with the new arms.

Thanks!

I found one issue with this frame - motors can slighlty rotate in mounts, which causes them to twist wires when propellers stuck in something.

It caused one mosfet to burn out because of motor twisted it's wires too hard so they shorted. So, a little of two-sided tape between mount and motors is needed to secure motors from rotating.

I'm now thinking about how to use same technique to create two-level frame, which can then be used to install FPV gear.

Btw, frame weigths only 7.3 g:



And quad assmembled slightly more than 30g (this is Quanum Pico FC, nothing left from initial udi u941 at this moment):