T4 Quadcopter Mini 250 (5 inch props)

Features:

• completely 3D printable (without support)
• fully assembled frame weight less than 110 grams!
• strong, simple assembly with no bolts to save weight! Everything is secured using 2.5mm zip ties.
• includes three arm options - 24mm, 28mm, and 30mm motor cup (inside diameter). The 30mm cup has slots for 3mm motor bolts (the others are 2mm).
• strong braced tube section arms with plenty of room to conceal motor wiring
• designed for a 3S battery (1000 - 1500mah) located right in the centre of rotation/thrust (88 x 38 x 22mm capacity).
• plenty of space to mount ESCs - concealed but still well ventilated for cooling.
• top plate has space for a variety of flight controllers and a Mobius style camera. It also features 3mm mounting holes so stand-offs could be used to add an additional deck of components. Alternatively two hex holes are available to add 3D printed posts and rear upper deck.
• RF "invisible" frame - as opposed to carbon fiber or aluminium
• Sketchup file included so you can make changes to suit yourself

Printing

I printed all parts in PLA, 0.25mm layers with 40% infill, 2 shells and 3 top/bottom layers. Feel free to experiment. I didn't play around too much with the settings as these gave me a good strong result. Fitting the top plate and bottom tray Both the top plate and bottom tray are designed to slide from front to back (at 45 degrees) as they are being fitted into the body. In particular the top plate needs to be pressed firmly down onto the 8 angled guides as you slide it back. Once in place the top plate will clip onto the smaller bumps near the rear cable tie mount (just above the rear arms). Look closely at the parts and it will all become clear. Calibration test T4MiniTestSocket.stl contains a cut-down socket you can use for testing the fit of your arms before committing to the full Body print. A quick word about scaling According to Wikipedia apparently "there is no scale information [in STL files], and the units are arbitrary". There is often confusion with STL files and metric versus imperial (inches) units. I designed these parts in Sketchup using metric units and they import correctly into my slicer (which is also set to metric). If you have issues, check your application to see if has a way to select metric or alternatively scale down by a factor of 25.4. Also, the Sketchup file contents are scaled up by 1000 (attempt to solve some Sketchup quirks). I scale each component down by 0.001 before exporting the STL so they are in real millimetre sizes.

What you'll need

• 4 arms (9 grams, 0.5 hour print each*)
• 1 body (40 grams, 2.75 hour print*)
• 1 top plate (12 grams, 1 hour print*)
• 1 bottom tray (14 grams, 1 hour print*)
• 1 battery pin (almost nothing, real fast)
• 2 posts (optional)
• 1 post plate (optional) *times were recorded on my Makergear M2 printer which has a 0.35mm nozzle and was printing at 4500mm/min. ...and "hardware"...
• 2,5mm (wide) zip ties (approx 100mm long)
• some foam for padding the battery compartments. I ended up using self adhesive window draft-stop tape from my local DIY store.
• some Kyosho Zeal Gel or similar anti-vibration gel and rubber bands for mounting the flight controller and camera.
• double sided adhesive foam tape (for mounting other electronics)
• soldering gear and connectors to suit your electrical bits ...and stuff to make it fly...
• I pinched most of the gear from one of these ARF kits ...the quality is a bit average but it flies.
• UPDATE: 12amp Afro ESCs (SimonK firmware) made a big improvement.
• UPDATE: I'm now running Lumenier 2206-11 motors and Gemfan 5x3 propellers.
• I added a KK2 flight controller (because I had an old one lying around). There are probably better options but I haven't investigated yet.
• You'll also need a Radio control receiver (and transmitter) (eg a Taranis) The X8R receiver really is too big for this size model but it was all I had here so that's what I used.