Unbreakable $1 AnyCopter Motor Mount with Legs

There are several inexpensive bell-type motors that are great options for the AnyCopter, but if you have had experiences like I have, you probably hate the motor mounts that come with them. The problem is the two grub screws that hold the motor on tend to work loose, and then off goes the motor. Not necessarily tragic with a plane, but with a multirotor the outcome is likely to be worse. 

I made an AnyCopter a while ago and designed some motor mounts for the Hextroic 24g (but will work with any similar motor) that have been working really well, so here are instructions. They cost about $1 (for 4, so 25 cents), and have very workable, sturdy legs that are not so huge they interfere with airflow. 

Parts list:

4X 1.5” of 1/2” square aluminum tube

4X 1” of 5/8” square aluminum tube (telescoping with 1/2 tube)

4X 8” of 3/32” piano wire (very hard to bend wire)

8X 20mm M3 bolts and locknuts (or similar)

To start, take the 1/2 square tube and drill a hole that is slightly undersize for the base of the motor (like 1/64 less than the measured size) about 1/2” from one end. Then cut a small slit from the same end through the hole, and a bit past it to give a “saturn” profile like in the picture. Drill a bolt hole perpendicular to this about 1/4” from the end. 

Slide this piece about half way into the 5/8” square tube, drill bolt holes in both, and bolt them together (see pictures at end for final set up). Now slide the 1/2” wood rotor arm into the other side of the 5/8” square tube, making sure the fit is very tight. You can put a screw into this too if you want. I sanded all this down and rounded all the edges to make everything smooth (and not likely to cut wires etc.).

Now here is the important part. To mount the motor, pry open the ‘mouth’ of the hole very slightly to make the hole big enough for the motor base. Slip the motor into the hole and squeeze it shut a bit. Now put the perpendicular bolt in place, and when you tighten it, the jaws of the mouth will shut VERY tight, locking the motor into place. The surface area and force locking the motor into the mount is quite significant - I have tried to remove the motor by force, but can’t. 

Now make 4 legs. Simply cut 8” of 3/32 piano wire, bend a 90 deg. tab of about 1/8 or so on one end. Then bend at 4” to about 45 deg., as shown (this bend does not need to be exact, just don’t bend too acute since the ‘spring’ keeps it in place). 

Drill two 3/32” holes in the bottom of the mount about 1” apart, the second one should be far enough from the end to be into the wood. Put the tab end into the hole closest to the end (as shown). 

Now squeeze the wire and push the other end into the second hole. It should be tight, work it right into the wood until its all the way. The spring of the steel keeps it in place unless you missed the wood or make your holes too big. 

The copter should not sit level. These legs are not like rocks, but they are not supposed to be. On a hard landing they will flex or even bend sideways. Just bend them back, or make a new one if need be. Another interesting feature of these is they will stick in soft ground on hard landings, so no bouncing! Makes it look like you peg every landing. 

Here is a close up of the final product, bolted on. Note that if you used a larger bell motor, you could do this with a single piece of 5/8" aluminum instead of the two telescoping parts, but the base of the 24g HexTronic is not long enough to be held tight by a 5/8" tube.