The build log finally!
Sorry about the wait! I was planning on posting this some days ago but it was somewhat forgotten in my move back to Melbourne for Uni. Throughout the process so far I have been taking photos to help illustrate my process. This is my first build log so if there’s anything I missed out just let me know.
The picture below shows where I stand currently in the build. I am waiting on another ESC to replace one which died and the batteries from home so work has been halted until they arrive.
I thought I should also explain the basic concept behind this quad. As we all know vibrations are a big annoyance in multirotors, especially with CF. My idea with this design is to have a ‘clean plate’ which is completely suspended. On this clean plate will sit the flight controller, battery, camera and vTx. I have made a wooden prototype version of this quad and it did a very good job at eliminating vibrations so I have high hopes for this CF one.
This whole frame is CNC cut out of one sheet of 3mm CF and two 1.5mm sheets. It was cut by a guy I used to work for and it took a whole day as it was his first time cutting CF and we had to do a bit of work on the design to get it ready to cut. I was amazed at the accuracy and the amazing finish of the CNC router and would not hesitate to cut another frame with this method. For anyone that wants to know I think we were using a 1.4mm 4 flute diamond end mill. Below is a short film of the CNC router cutting out the CF (nothing special but vaguely interesting to me anyway
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The pieces were covered in dust so before I did anything to them I sanded all the rough edges and gave them a bit of a clean. The 3mm holes had not quite cut to size so I had to drill them all out with a 3mm drill bit.
I began by sandwiching the four 3mm CF arms between the two 1.5mm bottom plates. At the moment I am using M3 15mm bolts with lock nuts but I’m planning on changing to M3 20mm bolts as explained later. I was very happy with how it went together. It is a very sturdy and durable frame with very little flex. The one main issue I have with these two bottom plates is that I would like to put the power distribution in between them but evidently it is too thin. More on that later.
As you see in the photo at the beginning of this post, the central plate is suspended between the bottom 2 plates and some 1.5mm CF supports. The below images show the supports and how they go together. Some sanding was needed for the tabs to fit into their slots as the cheap CF from ebay was 1.6mm and the slots only 1.5mm. Once I was happy with them I superglued (CA glue) them together. The front support is very very strong and is more than sturdy enough for the task it will be performing. In theory the separate pieces will break apart in a bad crash rather than the pieces themselves breaking but I am unsure if this will actually happen.
After putting both of the braces together I realized the rear support was not sturdy enough. For some reason while I was designing them I thought that the fact that the vertical supports in the back were angled would be enough but apparently this was not the case.
To fix this I redesigned the rear supports to add the braces you see in the front support. This made the rear one just as sturdy as the front one.
The next step was to add the rubber o-rings to the bottom plates and the supports and then connect the supports. In the pictures above you can see the holes designed to hold the o-rings. They were too small in the initial design which made putting them onto the frame an awful task. You can see in the redesigned support in the above photo that these o-ring holes are larger than the original which makes them much much easier to put in. Some redesigning needs to happen to make this whole process of attaching the middle floating plate somewhat easier.
There was a fair bit of fiddling around to try and find the correct size o-rings to get the floating platform to sit where I want it. I got it to a point where I like it but to make it perfect I think I will need to play with it some more. I noticed that when the supports are in the correct position that the o-rings hold them down quite well. This meant that I could avoid using glue which I was very pleased with. All I needed was some zip ties to make sure they don’t fall over and once they’re in it’s a very solid setup.
At this point I had to dismantle it to bring it back to Melbourne with me and today I rebuilt it to this point. I made a few little tweaks including adding dedicated holes for the zip ties to hold the supports and making a few spacers out of the remaining CF to hopefully make the bottom two plates somewhat more useful. I made 8 spacers which means I can add an extra 6mm in between the plates which should allow for my power distribution board but I need to buy longer bolts for that to work (20mm M3). I might just bite the bullet and solder up a power loom thing. As yet I do not have any idea how I will do landing gear so if anyone has a good idea for that please share it. Also if anyone has any ideas about improving this design I would love to hear them as I would like to keep developing this design further. For now I just have to wait on the parts so I can finish this build and give it a maiden. I am beyond keen to get this thing in the air. Thanks to everyone who helped with the initial design feedback earlier in the year, keep it coming!
