Designing and building my own mini-quad!

mpbiv

New member
Before I get into it, I want to give a huge shout out to untestedprototype.com and also Twitchity on the forums here. Twitchity helped me get the ball rolling by cutting my frame plates last week! They came out fantastic! Having parts in hand has been a huge part in keeping the momentum going on this project.

I cannot remember exactly when it started, but I had been wanting to get into multirotor flying for the purpose of building an aerial photography/videography rig. About 5 months ago I finally took the plunge and started my first build (a tricopter).

Moving ahead several months now, I've successfully built my tricopter, but also built a quad copter, and I have a hexacopter that is sitting in some state of incompleteness. After playing around for a while, my goals in the hobby have totally changed. While at first I wanted to build for the purpose of having an aerial photo/video rig to film cool things, I've now realized how much I just enjoy the aspect of flying.

I decided a couple months ago that I wanted to design my own mini quad copter. This wasn't the original plan when I began down this path. My original intent was to find a kit that was small, easily transportable, with the ability to handle a GoPro camera. I came across a few options, the main one being the Blackout Mini Spider Hex. It did most of what I wanted, but the big deterent was that the kit was hard to get; no vendors seemed to be able to get them in stock. Then when you added in the cost of the electronics and motors, building a mini-hex seemed like a costly idea. I spent a good deal of time looking at different options, but it seemed most frames weren't designed for GoPro cameras, and that mounting a GoPro was a clumsy operation on most of the 250 size quad copters available.

I didn't have much luck finding a frame to fit my needs, but after months of reading the forums and seeing what people were doing on their own, it inspired me to have my own go at it. It seems that quad copters in general are fairly easy to design and as long as you follow some general rules its not hard to design your own airframe. There is a wealth of knowledge out there, and to be honest I am pretty sure I am not going to be able to give all the credit that is due to those who have gone before me from which I have gained a lot of valuable knowledge.

Let me first start by saying that the design I have settled on at this point is an amalgamation of stuff from other designs which I have chosen to incorporate in my design to address my own needs. I wouldn't feel right without first giving a large shoutout to untestedprototype.com for providing the DXF files for which I based my design on. If you check out this site, you will see the owner has posted a ton of his own designs and offered the DXF files for the frame plates of each design. That being said I have also drawn a lot of my design inspiration from the Lumenier QAV line of quadcopters and have chosen to incorporate elements of their products into my design.

So getting to my own design requirements, below is a list of objectives I hope to achieve with my quad design:

  • 250-300mm Size rotor span
  • GoPro Hero 3 mounting with integrated video output
  • Vibration isolated clean and dirty plate design
  • Capability to run 6in props
  • Low profile design with mass close to roll center of multirotor

At the time of writing this post I have already completed a large portion of the design, and I am hoping to go back and document what I have done so far before I get too far ahead of myself. Just to show where I am at with the project here is a picture of the parts I have already created:
Quad Mini.JPG

Here is also a link to my blog where I spent a good part of this evening taking photos and writing up my current progress. Consequently I really have a new found respect for everyone who shares their projects here because I now realize it takes a lot of time and effort to take pictures and properly document the process.
 

Twitchity

Senior Member
That frame looks great put together. I would have replied earlier but I've been extremely busy at work this whole week (it's a good thing you contacted me to cut it when you did). I'm looking forward to see the rest of the build, especially since you showed me the 3D render when you were over. Good luck with the build, and keep posting pictures :) You know how to get a hold of me if you need anything.
 

Twitchity

Senior Member
If you're interested in getting a custom frame cut, send me a PM and we can discuss it there. 1/16" G10 which is a fantastic alternative to carbon fiber is rather inexpensive at around $8 per 12" x 12" sheet... Shipping on the hand costs around $16. You might be able to find a better shipping option, but I really like the black G10 I've gotten from eplastics http://www.eplastics.com/G10_FR4_Glass_Epoxy_Sheet

I placed an order for a few sheets, but it's on backorder until August 8th.
 

mpbiv

New member
Thanks to Twitchity, I finally have a set of useable motor arms.

I have several posts on my blog at http://theroamingengineer.blogspot.com/ which keep track of my progress, and if you read through it, I originally had plans to make the arms out of 6061-T6 aluminum. I even had a set of arms 3D printed by Shapeways just for test fitment.

Here are the 3D Printed versions of the aluminum arms I had made for test fitment purposes:
blogger-image--1607047161.jpg

Unfortunately the manufacture of the aluminum arms keeps hitting road blocks and in an effort to keep this project going I decided to redesign them out of G10. Twitchity was kind enough to find time between all his projects to mill my G10 parts, and as usual, the price was fair and the quality was great. I don't think I can give him enough props for the help he has given me in keeping this project moving.

Below are the new arms, made of .125" thick black G10/FR4:
DSC_2321.JPG

Arms Assembled to Dirty Frame Section:
DSC_2320.JPG

I included a couple slots in the arms so I can use a ziptie to secure the motor wires:
DSC_2325.JPG

The aluminum arms were going to be threaded, but the G10 arms require a nut/spacer/bolt combo:
DSC_2329.JPG

Here you can see the aluminum spacers and where the motor wires will pass through to the ESC:
DSC_2330.JPG

Now that I have a good set of arms in place, I'll begin wiring up the ESC, Naze32, and Receiver connections:
DSC_2328.JPG

I'm still waiting on my GoPro housing to be made by Shapeways, but it will sit roughly here:
DSC_2327.JPG

Here is a screen shot of the GoPro housing model in Inventor Fusion:
GoPro Housing CAD.jpg

The GoPro housing will attach to the front of the frame with self tapping screws. It includes a recessed pocket to house the Lumenier GoPro connector, and the Lumenier Layer Lens strap will secure the GoPro into the housing when it is all said and done.

I think at this point, after seeing how stiff the G10 arms are, I am probably going to give up on getting the aluminum arms made because they add a lot of cost to the project.
 

FinalGlideAus

terrorizing squirrels
Nice work mate :).
Scotti, who is the man behind untestedprototype.com flies in the quad group I'm a part of although he's been MIA lately. He's a bit of a genius with not only his designs but his knowledge of the Naze 32 and PID controllers. Apparently his university thesis was on quadcopters.

There is a whole underground community of people who have taken Scotti's basic designs and modified them to suit their needs. I keep meaning to do a thread on it but something else always keeps me busy these days. I'll have to bite the bullet and do it soon.
 

Twitchity

Senior Member
Your quad is really coming along nicely. I really liked the finish of those 3D printed arms; it's a shame you won't be able to use them for your build. For arms that size, I doubt you'll be disappointed with the G10. It's a pretty tough material and with them being that wide and short, there won't be much flex if any in the arms. Keep up the good work, can't wait to see it in the air.
 

mpbiv

New member
Nice work mate :).
Scotti, who is the man behind untestedprototype.com flies in the quad group I'm a part of although he's been MIA lately. He's a bit of a genius with not only his designs but his knowledge of the Naze 32 and PID controllers. Apparently his university thesis was on quadcopters.

There is a whole underground community of people who have taken Scotti's basic designs and modified them to suit their needs. I keep meaning to do a thread on it but something else always keeps me busy these days. I'll have to bite the bullet and do it soon.
Yeah that would be a good thread! I am curious to see what others have done with his designs. I did notice a "Cloneout" thread on FPVLab that seemed to start with one of his designs and slowly evolve.

This has been a good design exercise for me so far. Pretty soon I will have this one flying, but I'm pretty sure I will start designing a version 2 soon after. It will be interesting to see how much of the original design survives in version 2; I originally started with the files for the GoMini V2.
 

mpbiv

New member
I started wiring up the motors and ESC in the dirty section over the weekend.


I began by extending the wires for the motors using 18ga black wire:
DSC_2358.JPG

I added heat shrink to each motor lead, then covered the whole bundle with some expando to clean it up:
DSC_2359.JPG

All four motors with wires extended and routed:
DSC_2363.JPG

Finished soldering all motor connections and added capacitor, battery lead, and vtx power lead:
DSC_2393.JPG

After I finished wiring the motors/ESC I built, I moved onto to connecting the Naze32 to the receiver. I wanted to get everything hooked up so that I could begin configuring the ESC and Naze32. Once I got everything hooked up and my receiver bound, I fired up baseflight.

I wanted to test the rotation direction of the motors to see if I needed to flip/resolder any of the leads on the ESC, so I went and used the master throttle slider, and unfortunately something went wrong. Basically all the motors spun up properly except one, which began cogging immediately. Within a matter of a second or two before I really had time to react and pull the slider back down, a component on the side of the ESC connected to the cogging motor released the "magical white smoke".

My Ready to fly quads 4in1 ESC has effectively been converted into a 3in1....

I am not sure whether it was something faulty with the ESC, or if maybe a winding in the motor had a short causing a current overload on the ESC. Either way I have ordered another Sunnysky 2204 motor just in case. I have also ordered a set of 4 Lumenier 12a SimonK ESC's to replace the RTFQ 4in1. I think I'd rather replace one ESC if something like this happens again, rather than having to unsolder and redo all four motors.

As far as I know I should have everything I need to rebuild the dirty section by the end of this week. So hopefully I can still get her flying this weekend.

The 3D printed GoPro housing was supposed to ship from Shapeways earlier this week, but I was informed there was a slight delay, so hopefully it will arrive early next week.
 

mpbiv

New member
It's ready to fly!

Well almost I still need to do some initial setup on the Naze32 and make sure everything is balanced.

After last week's snafu with the 4in1 ESC, I spent most of the weekend gutting and re-doing the dirty section of the frame to use 4x 12amp Lumenier ESC's. At least if I fry an ESC this time, I won't have to redo all the wiring over again. I also replaced the motor that was connected to the channel on the ESC that was friend; I have a sneaky suspicion that I pinched a motor winding due to excess epoxy on the wires.

Since I was going to be using the traditional 4 ESC setup, I needed to devise a way to distribute the power. Inspired by the "Cinecoin" used in the Cinetank MK1, I ran down to RadioShack and bought a double sided copper clad board. These are generally used for making/etching your own PCB. I took a dremel and cutout a small piece to make the power distribution plate shown below:

One side of the copper clad board is positive, the other negative:
DSC_2406.JPG

All the ESC's soldered the power distribution:
DSC_2410.JPG

ESC's and power distribution installed in dirty frame:
DSC_2411.JPG

The 3D printed GoPro housing I designed finally arrived!
DSC_2413.JPG

GoPro seems to fit well:
DSC_2414.JPG

Lumenier GoPro connector also seems to fit well:
DSC_2415.JPG

I used M2.2 self taping screws to hold the GoPro connector in:
DSC_2416.JPG

Housing attached to frame using M3 self taping screws:
DSC_2420.JPG

GoPro strapped in using Lumenier layer lens:
DSC_2424.JPG

The whole package, almost ready to fly:
DSC_2425.JPG

I haven't really given this thing a proper name yet, but with many of the components from Lumenier it might as well be a QAV300 (although it is 290mm rotor to rotor).

I need to balance the frame and the props, make sure all the video connections are working, and get some maiden flights in. After building this one up, I already have ideas to make an improved "Version 2", so stay tuned to see what I learn from this exercise.
 

mpbiv

New member
http://youtu.be/oFOzT1YVL3k

I've already flown it several times since this video. Still working on tuning the PID's, which will probably take me several flights. I've only got one battery for now.

I've already started revising the design. Currently working on revising the battery mounting area to make pack changes a little easier. I am also going to swap the aluminum standoffs and steel screws in the clean section for nylon hardware. The big change is that I plan to run 4s on the Version 2 frame. I already ordered a set of Cobra 2204 1960kv motors, just waiting to get some KISS 18a ESC's.

I'd really like to turn one of the dirty plates into a PDB like Twitchity (and others) has done on his designs, but I'm still looking for the right design tool to start that. I want to try PCB123 free from Sunstone Circuits, but I don't have a Windows PC setup right now.......working on that. Has anybody used this software? Supposedly it outputs price quotes on PC boards native to the program, but of course it limits you to Sunstone Circuits as the supplier.
 

Twitchity

Senior Member
Sooooo much sand! With how well I fly, I do not want to be anywhere near there.

That quad looks great, especially the tidy wiring you did (I like neat wires). It looks like it records great video too from what I could tell. You know how to contact me if you need anything else made for the quad, or for the new design when you get there. I'm glad I was able to be a part of this build and helped you get the quad you wanted to build.

As far as software goes for circuits, I'm clueless outside of jhitesma used DipTrace and Eagle for the final version of the quad PDB.
 

cranialrectosis

Faster than a speeding face plant!
Mentor
Beautiful copter!

What a sweet build.

Please don't crash those beautiful motors in that sand. It would be a crying shame.
 

jhitesma

Some guy in the desert
Mentor
I tried PCB123 along with a number of other packages. I wasn't impressed by PCB123 at all and sunstones prices on boards was pretty high. I believe the big issue I had with PCB123 was there was no way to import a shape to use for a board which is kind of necessary for the boards I've been working on with Twitchity.

Eagle would be tough due to it's size limits. It's a great package but the low cost versions are VERY limited (100x80mm) and even the $600 "standard" version is limited to 160x100mm which would probably be too small for a setup like yours. Beyond that you're looking at about $1,200 for a version with higher limits! That said Eagle is probably the most powerful "prosumer" level PCB design software out there and what most hobbyists use. The other complication for us is that we'd like to sell our finished boards at some point and the lower cost versions of Eagle that's not allowed.

Diptrace I actually like the workflow in a lot better. Some people don't like it because components and packages are treated as two different things and most EE's consider them to be one unit. But I like that separation - case in point the LED's I used on the first round of boards are too small. With Eagle I'd have to go back to the schematic - replace them with a new part then re-route them in the board layout. In Diptrace I can just swap them to a different footprint but keep everything else the same. Diptrace starts with a $75 version with no size limits but limited to 300 pins and 2 layers. For a PDB that's no limitation at all.

The drawing tools for placing traces in Diptrace also just seemed to work better for me.

The one big problem I have with Diptrace is I can't get any kind of imports to work. So to take a board outline from Twitchity and bring it in I have to load it in eagle then run a script in eagle which generates a diptrace file I can then open in diptrace.
 

mpbiv

New member
Sooooo much sand! With how well I fly, I do not want to be anywhere near there.

That quad looks great, especially the tidy wiring you did (I like neat wires). It looks like it records great video too from what I could tell. You know how to contact me if you need anything else made for the quad, or for the new design when you get there. I'm glad I was able to be a part of this build and helped you get the quad you wanted to build.

As far as software goes for circuits, I'm clueless outside of jhitesma used DipTrace and Eagle for the final version of the quad PDB.
Thanks for all the help! Honestly, considering the lack of interest from local shops to quote me, if you hadn't cut the frame plates for me, this thing would have never made it past being a concept. I cannot tell you how many times I just sat around looking at the partial frame waiting for new parts to arrive. It kept me motivated. Not to mention the G10 arms ended up being a better choice in the end.

I'll try to stay out of the sand!

I probably have about another month before they start laying down pavement and grass in my flying area. It used to be an orange grove, but soon it will be another new housing development and I will have to fly somewhere else once the houses go up.

I tried PCB123 along with a number of other packages. I wasn't impressed by PCB123 at all and sunstones prices on boards was pretty high. I believe the big issue I had with PCB123 was there was no way to import a shape to use for a board which is kind of necessary for the boards I've been working on with Twitchity.

Eagle would be tough due to it's size limits. It's a great package but the low cost versions are VERY limited (100x80mm) and even the $600 "standard" version is limited to 160x100mm which would probably be too small for a setup like yours. Beyond that you're looking at about $1,200 for a version with higher limits! That said Eagle is probably the most powerful "prosumer" level PCB design software out there and what most hobbyists use. The other complication for us is that we'd like to sell our finished boards at some point and the lower cost versions of Eagle that's not allowed.

Diptrace I actually like the workflow in a lot better. Some people don't like it because components and packages are treated as two different things and most EE's consider them to be one unit. But I like that separation - case in point the LED's I used on the first round of boards are too small. With Eagle I'd have to go back to the schematic - replace them with a new part then re-route them in the board layout. In Diptrace I can just swap them to a different footprint but keep everything else the same. Diptrace starts with a $75 version with no size limits but limited to 300 pins and 2 layers. For a PDB that's no limitation at all.

The drawing tools for placing traces in Diptrace also just seemed to work better for me.

The one big problem I have with Diptrace is I can't get any kind of imports to work. So to take a board outline from Twitchity and bring it in I have to load it in eagle then run a script in eagle which generates a diptrace file I can then open in diptrace.
That's all great info I didn't know!

So it sounds like PCB123 isn't a viable option.

If I am reading the website correctly, diptrace supports importing DXF layouts? Have you had any opportunity to try importing DXF files? I may have a stab at downloading and trying it out myself, since it looks like Mac OS-X is supported.

Thanks for the advice!