This is a set of detailed instructions for a mod to the rotor shaft of the Picoo-Z mini-helicopter; replacing the original steel shaft with a carbon fiber shaft and installing ball bearings in place of the copper/brass bearing. This mod is based on a description from the website dedicated to Picoo-Z mods, it's under the Rotor Mods section.
Step 1: Parts List and Tools
You'll need the following parts;
1 - 1-9/16" length of .04" (or 1MM) carbon fiber rod
2 - 1x3x1 ball bearings (item Code m021 from http://www.precisionheli.com)
1 - Picoo-Z mini Helicopter
The tools required are;
small dental pick
a standard (flat end) screwdriver
a pair of locking needle nose pliers
a pair of diagonal wire strippers
1/8" drill bit
a large flat washer (I cut a small 1/8" deep slot in it to help remove the rotor)
Foam Safe CA glue
and a good magnifying glass will help too
Step 2: Opening Up the Body
Start by CAREFULLY using the X-Acto knife to cut through the glue holding the "Landing gear pod" to the lower part of the body. Don't cut too deep, there's wiring and a battery close to this area. Once it has been removed you'll see the IR detector for the remote control.
Next start cutting through the seam that runs all the way around the copter holding the 2 halves of the body together. I started at the the back where the tail rotor arm runs into the body (less delicate stuff in this area). Once you get it started you can pry it open slightly, so that you can see what you are doing, (to stay away from the wiring and battery, to get the two halves separated all the way around.
Once I had this done, (see 2nd pictures), I switched it on and ran the copter at low speed to makes sure I hadn't broken anythings up to this point.
NOTE: From the 2nd picture you can see why a push-pin (mod to add weight) in the nose of the copter could be a bad idea. It's close to the battery compartment, and a crash could drive the pin into the battery.
Step 3: Removing the Main Rotor
To remove the main rotor I used a pair of locking pliers to hold the metal shaft close to the drive gear. Then I slipped a washer (see picture) with a small slot in it between the pliers and the rotor. Now I used a flat end screwdriver between the pliers and the washer to press the rotor off the shaft. You may need to reposition the pliers as the rotor moves to the end of the shaft.
Step 4: Removing the Drive Gear and Bearings
Once the main rotor is removed, the drive gear and shaft can be removed by first removing the small brass collar at the bottom of the shaft. After the shaft has been pulled out remove the two flanged brass bearing at both ends of the rotor shaft mount (shown below being removed with the dental pick). Then push the large drive gear off of the steel shaft. Save the flat washers (2); one is at the top between the drive gear and the brass bearing and the other is at the bottom, between the brass collar and the brass bearing. We'll be re-installing the flat washers into the same positions during re-assembly, but the bushings can be discarded as they will be replaced with the ball bearings.
Step 5: Cutting the Carbon Fiber Shaft
I used a pair of diagonal wire strippers to cut the Carbon Fiber rod, it reduced the chances of splitting the ends. Just cut it to the same length (1-9/16") as the original steel shaft. Once the shaft is cut, install the drive gear at the same position that it had on the steel shaft (about 1/2" from the bottom end of the shaft). Use a little CA glue to hold it in position. You may have to "build up" the shaft slight with a little of the CA glue before installing the gear. I put a thin coating of glue on the shaft, where the gear would be placed, allowed it to dry and then pressed the gear onto the shaft.
Step 6: Installing the New Shaft & Bearings
I used a 1/8" drill bit to enlarge the holes (by hand) in the rotor bearing mount, so that it would accept the 3MM O.D. ball bearings. Once the bearings are in place take the new rotor shaft and place one of the flat washers on the short end and slide it up against the drive gear. Now slide the shaft in through both bearings, a small amount of the shaft should be sticking out at the bottom bearing. Place the second flat washer over the end of the shaft and press the brass collar on last with a small amount of the CA glue. Make sure everything is moving freely and then allow the CA to setup/cure.
Step 7: Re-installing the Main Rotor
Apply some of the CA glue to the rotor shaft and press the rotor assembly onto the new shaft.
Step 8: Glue It Back Together
First apply some of the Foam Safe CA glue to the motor mount frame and glue in back into one half of the Picoo Z body. Allow that to setup for a few minutes.
Check again to make sure the main and tail rotor are both working before continuing.
Next apply some glue carefully around the two halves of the helicopter body and press it back together and secure it with some rubber bands. You can also glue the "Landing gear pod" back in place as well. Now let it set until the glue dries (following the instructions for whatever type of glue you are using, just make sure it is Foam Safe).
Step 9: Ready to Fly Again
That's it, remove the rubber bands and the Picoo Z is ready to fly again. Now where's my Airwolf theme music?