Building on the Panda Cavity

 OK guys here it is, my favorite racing frame.

This document is dynamic and it will be added to and clarified as I receive feedback.

The Panda Multirotor's Cavity, you can pick it up here.

How to assemble the Panda Multirotors Cavity can be found here.

Parts List can be found here.

Technical Jargan Dictionary can be found here.

Your completed build will look similar to the purple on the right.  The Cavity on the left is one of the older cavities. 

What minimal tools you will need to complete this build:

Soldering Iron (minimum 40watts)
A wet paper towel or sponge to clean the tip of your iron

1.5mm hex
2mm hex
5.5mm socket or deep nut driver
Wire cutters
A multi-meter

Additional Helpful Tools:

Solder Sucker (in case you have used too much solder)
Wire strippers
Tweezers (for holding the wires as you solder)
Jeweler's needle nose pliers (or other tiny pliers)
Wire mesh for cleaning the iron, it works better than the sponge method
Different tips for your soldering iron

Having flux on hand will help when dealing with battery connections and if you have to desolder or go back after completing the build on any soldered connections.

When soldering keep these things in mind:
1. A clean soldering iron makes for good heat transfer
2. Solder will flow towards heat
3. Don't dwell on a solder pad for longer than the count of 3, or you will risk damage.
5. Pre-tin your wires before you ever try to solder it.  (one exception will be talked about in this tutorial)
6. A clean soldiering iron has better heat transfer.

When you complete a solder joint, and after it has cooled. GENTLY tug on the wire to ensure a solid connection has been made.  If for ANY reason your joints aren't bright and shiny after you have soldered, redo the joint.  That is a cold solder joint and does not conduct electricity very well.


I have included a few tips and tricks that have helped me, and I hope they will help you as well.

Because this frame isn't symmetrical between the front and rear, I have used the panda sticker to indicate the front of the frame.

Here we have the bottom assembled frame for a guide line how it will look when you have assembled your Panda Cavity.  Install your M3 screws for your stack on what you want to be your top plate, then run your battery strap through the slotted cutouts.  Conveniently you can change a broken strap without tearing down the stack or the frame, its just much easier to do it now. Then, each arms are sandwiched between the top and bottom plate of the frame. When you sandwich your frame arms, use the slightly longer screws that came with your Cavity for the inboard side of the quad, and the shorter ones outboard.  The outer screws are then secured with an M3 nut, snug is all these need.

If you have fully assembled your frame backwards, and finish the build the pod won't fit in the proper place, and if you have ordered the hybrid arms, you have to do a complete tear down of the frame and stack to reassemble it correctly.  This is part the reason I'm doing this tutorial, I built my first Cavity completely backwards.  Notice how the stack is so close to the pod, that is actually the rear of the frame.

 Lets get back to having a successful build.

Then, flip your frame over, and it will look similar to this.  I went ahead and put stand offs on the rear screws since mine liked to fall out.

Next you want to begin installing your motors.  With this frame having awesome 5mm thick arms, chances are the screws aren't going to be quite long enough.  Panda Multirotors thought about this and included a bag of motor screws with your frame.  I like to put a drop of thread locker on my motor screws to help keep them from backing out.  Protip: When installing your motors on your frame make sure your screws DO NOT touch the motor windings.  Open bottom motors, really makes this quick inspection convenient!

After you have installed all 4 of your motors and verified that there is plenty of space between your motor windings and screws, I like to mock things up to figure out how I want to run my motor wires.  I'm using the Panda Hybrid Pod for this build.  There is a nice spot between the pod and the nut I will be tucking my wires into.  Also, pay attention to the space there is between the front of the stack screws and the rear of the pod.  There is plenty of space there, telling us that we have the front of the frame properly identified.

Once I have an idea how I'd like my motor wires ran, I drop my ESC in place on the stack screws.

Carbon fiber IS conductive, so verify NONE of your electronics ever touch the carbon.  This is an example of what will fry your components:

Next, begin shimming your stack until none of your components will touch the frame.  I used the spacers that came with the Aikon 32 for my ESC and a nylon M3 nut for a shim.  I like a touch more space between my frame and stack, it helps keep my ESC cool. You may like having less space than what I have, and its fine just be sure none of your parts will touch the carbon.

The Aikon 32 Pinout is here.

Next, I soldered up my motor wires.  Don't worry about trying to keep your wires looking nice here, focus on keeping the wires in place and enough solder for a solid connection, Also, pay attention to not splattering solder on your board or bridging the connections between the pads on your ESC.  WARNING:  DO NOT LINGER ON ANY PADS! 2-3 Seconds per connection is ideal.  If you stay too long you will lift a pad and can render your ESC (or other component) useless.  Protip: Tin your wires, and put a solder blob on your pads of your ESC. 

I almost always run capacitors on all of my builds, but I don't like them on the XT60 connectors or right next to my stack.  So what I do is make a short harness to run my caps against the rear arms of my frame.  What I did here is clipped the leads shorter on the capacitor, stripped just enough off the wire to fit my iron between the body of the capacitor and the insulation of the wire.  This is the one exception I have about pre-tinning a wire, DON'T do it if you want to do this capacitor mounting method.  Then poked the lead through the center of the wire and then soldered them up.  After that I ran heat shrink down over the solder joint to help minimize the chances of my caps being shorted.

The Aikon ESC in this build has lead-free solder from the factory on the battery pads.  Follow this next step carefully, or you may risk damaging your ESC.  In general, its best to assume that any presoldered connections from a factory have lead free connections.

1) GENEROUSLY pre-tin your wire for the cap(s)
2) Apply flux to the soldered pad on your ESC
3) Turn your soldering iron up to maximum 11.
4) Clean your iron.
5) Wet your iron with a little solder
6) Take one lead, VERIFY your polarity on your cap and harness!
7) Hold the lead against the pad you want it to be soldered to
8) Wipe your iron off quickly.
9) Put your iron on to the wire
10) let the solder begin to flow around the connection.

Successfully done, it should look like this:

Now remove your FC, I'm using the Aikon F4 for simplicity, it directly plugs up to the ESC without having to repin my harness.  Put your anti-vibration grommets into the holes on the FC.

The Aikon F4 Flight Controller Pinout is found here.

Now, plug your harness into the FC and then insert the other end into your ESC.

I like to tuck my harness underneath my flight controller, I think it helps keep the connection solid while keeping wires away from potential damage.  Take note of the little arrow on the FC, it should be facing the top and towards the front of the quad.

Once you have completed that, get your other components out and ready for installation.  In my case its a camera, VTX and receiver.

What I like to do is look at my pinout for my specific FC.  I start by tinning strictly those pads.

Then, I like to trim my harnesses where I will have space to lay them out and still have access to be able to come back and do maintenance on my quad.  About 1.5" of pigtail per component is more than adequate for me. This is personal preference on how much you actually want to use.  I recommend holding the wire on the pad you need to access and gently pulling it out until you feel like you have enough slack to access what you need if that part has been removed. PROTIP: If you have a monkey fist of wire hanging outside your stack, you should shorten your wires.  It can introduce unwanted noise into the gyro on your FC, and create a great way for Murphy to introduce problems when you're flying.

Due to the previous step taking 2 hands I was unable to get any pictures, sorry.

Once I have sized my wires sized about where I want them, I clip the ends.  Pull off a small amount of insulation, then tin the ends of each of the wires on the pigtails.  Then using tweezers I hold the wire in the direction I'd like the wire to run based on where how the component will sit inside the stack.  For example I know my camera pigtail will exit the stack to run to the camera, so I want the wires to leave straight out the front.

Once all of your components are soldered to the correct pad.  I start stacking my components into the stack how I like them stacked.  My RX antenna wires I want coming out the back of the stack, I will show you why when we get to that part.  Also, because I know a VTx makes more heat than the receiver, I want it on the outermost portion of my stack to ensure airflow around it to help prevent it from burning out.

 Next I size RX as if I were going to mount it under the stack mount, DO NOT mount it yet, we are eye balling a few things.

 Next I set my VTx on top to ensure I like the positioning of the RX and VTx.  Again, not affixing, mounting or even securing anything at this point, we are checking fit.  Then with everything tucked in I installed my XT60 for my battery connection.

Once you think you like what you see, then run a zip tie around the 2 components just to hold them, but not secure them.  Then slide your canopy over the stack, ENSURING nothing is being pinched, if you notice I have my run cam in upside down, but it is connected.  When you have the canopy on, don't secure it. What we are doing here is verifying everything is positioned well and won't be pinched, none of the wires are hanging out of the build.  Wires look like spaghetti is fine, as long as they are not positioned to be pulled out, pinched, or what ever else you think Murphy will throw at you when your in the air.  Protip: on a runcam, the connector and letters indicate which way is up, if you put the camera in your canopy and have to hold the canopy upside down, your camera is installed upside down.

 Also look down at the top of your quad for wires hanging outside the stack area, you see I have my VTx connector just chilling outside the stack.  This is an example of wrong.

Now, once you have ensured your stack looks nice and tidy, remove your canopy, clip your zip tie.  I like to shrink wrap my UF.l connectors on my RX and my VTx at this point.

Pull out your multi meter and set it on OHMS (the symbol that looks like this: Ω)  You should see it flash OL, OFL, or some other meaning for open line, then the resistance will change because you have capacitors on the ESC and the FC.  If you see resistance LOWER than 200k, you may have a short somewhere.

This is important to know, since we used a meter and not a smoke stopper, your components will be unharmed, and you can find the location of the short.  If you do see it and fix it then you may proceed.

Before you think its time to plug in, DON'T! Look thoroughly over your components ensure you don't see any solder splatter anywhere.  The only place that should look freshly soldered are where you have applied solder.

Once you have completed that, you may now put a smoke stopper on your connector and then plug in. Get your RX bound if you use an RX that requires you to push a button.

After that reassemble everything back into your stack and look forward to my guide on how I like to set up my quads on Betaflight.


  1. This is awesome, thank you for the excellent walk through and detail! My son and I would like to do similar builds, but we'll use a 30x30 stack to make things a little easier.

    Quick question on the Cavity frame. They have 4 versions – Stretch X 5", 5.5", 6", and a True X hybrid with 5" front and 6" back. Do you have a preference on which to use? I like the idea of the True X hybrid for versatility and they say it keeps the rear props in clean air, but wanted to get your take since you've built and flown a few of these.

    Also, any recommendations you may have on a 30x30 stack as an alternative to this 20x02 stack would be greatly appreciated.

    Thanks again!


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