My New Mini Quad 250mm

[krikey]

After being sent some images of some rather cool looking quadcopters, I was keen to see if I could have a go at making up a frame myself. As some of you will know, I recently bought a 3D printer, one of these http://www.wanhao3dprinter.com/main.aspx?id=2012050028 to be exact and after 5 weeks, I'm getting the hang of it now.

The build plate on the Wanhao is only 150mm x 230mm so printing even a small 250mm diagonal mini frame in one go is not possible, so I will have to break down the build into numerous pieces and re-attach them using some good old fashioned nuts and bolts.

Here's the first part of the puzzle, which will be duplicated 4 times for the arms. I'm using sketchup and the nice thing about this is that I can create a component, duplicate it and then just edit one of the instances. The other three follow suit.

I've also run a test to see if when I treat each of the 4 arms separately and then "slot" them together, sitting them side by side, will the printer print the adjacent walls or see the two pieces as one? The good news is that ReplicatorG joins them together as if they were one piece so no weaknesses introduced, meaning that I can keep the 4 arm sections separate.

My other concern is whether ABS is strong enough to withstand the rigors of flight and landing. I guess time will tell when its built.



I'll upload the body sections later.

[Coyote]

As I said on chat, bit dubious about the strength or flex, but must say its looking good mate :)

[krikey]

The initial design is complete now and is not dissimilar to The Lumenier QAV250 Mini FPV Quadcopter mainly because I used similar dimensions to their model.



Where it fundamentally differs from theirs is the arm configuration which is actually separate from the base plate, which means that in the event of a crash and a broken arm, it can be swapped out.

I have a few more mods to add such as some legs at some point and perhaps some more room between the standoffs to allow for more kit to be added in between the two plates.

[CurryKitten]

Or in the flesh, (with a few mocked-up components) looks a bit like this -



My initial thoughts were to put the lipo on the top of the bottom plate (if that makes sense) with the rest of the kit on top.  But as my 1600mah 2s lipos didn't fit there, the plates will configure nicely for the lipo to go underneath the bottom plate - which I think is a good place for them. 

But as the KK2 needs to be on the top plate (so I can fiddle with the settings), what might be the way to go is much shorter standoffs, with all the wiring for the power distribution hidden between the two plates, then VTX on back of the bottom, camera on the front, and then kk2 and rx on the top of the top plate.  It would be quite low-profile as well then, and possibly look a bit meaner :)

[krikey]

Looking good CurryKitten. Here's a link back to your build for anyone interested in progress: http://www.fpvhub.com/motors-escs-and-props/11/motor-recommendations-for-a-mini-quad/17214/msg143417#msg143417

Heres a quick mock up using shorter standoffs. By the way what did you use for your standoffs?

[CurryKitten]

I borrowed some ones I got with a little raised cage to protect that KK2 from.  I will need different things to put everything together properly though, as the two plates together need a longer screw to get all the way through - and you really want those quite flush as well if you are going to have a lipo under there.

So in summary, I don't know.  As soon as I work it out, I'll let you know what I used :)

[krikey]

Ive added some legs to the build, although Im not sure if they are necessary, they could be optional as they locate into the same holes that hold the frame and the arms together, making everything very modular.

[Gav]

Nice one, Neil.   How much was the printer?

[krikey]

It was about £900 from a UK dealer via ebay http://www.printme3duk.com/ who have been very good to me so far.

[krikey]

I wanted to offer some protection for a KK2 board when mounted on, what I'm going to call the K-quad 250, so I've designed a KK2 mount to fit as the top plate.

[CurryKitten]

I like the change - a few questions/thoughts.

- Do you think you'll have the room to route the ESC cables through for power distribution
- You'll need to either make that gap between the top/bottom place a specific size so that a threaded standoff can get in there, or alternatively have something where a single bolt could slide all the way from the top/bottom and then tighten with a nut in order to keep the frame sturdy.
- Chop some leg length off.  Short and wide works best, and a 1600mah 2s is 12mm deep.

Once my HobbyKing orders arrive, I should have all the parts to get the prototype flying :)

[krikey]

I like the change - a few questions/thoughts.

- Do you think you'll have the room to route the ESC cables through for power distribution
- You'll need to either make that gap between the top/bottom place a specific size so that a threaded standoff can get in there, or alternatively have something where a single bolt could slide all the way from the top/bottom and then tighten with a nut in order to keep the frame sturdy.
- Chop some leg length off.  Short and wide works best, and a 1600mah 2s is 12mm deep.

Once my HobbyKing orders arrive, I should have all the parts to get the prototype flying :)

I used 20mm standoffs and have allowed just enough room for the 10a ESCs

I use a single m4 40mm bolt all the way through the top plate, through the standoffs and through the baseplate and leg at the bottom, secured with M4 nyloc nut