This Instructable will guide you to modify Cube Servo to get a higher speed out of normal Cube servo.
Step 1: Get Ready Required Tools
What you will need:
1. a philips screwdriver.
2. Epoxy glue for plastic.
Step 2: Unscrew Cube Servo to Reveal the Gears
1. There are all together 4 Screws at the bottom cap of Cube servo.
2. Remove all 4 screws from the Cube Servo with philips screwdriver carefully.
3. Rotate Counter Clock Wise to unscrew the screws
Step 3: Remove Bottom Cap From Cube Servo
1. Carefully and slowly separate the bottom cap of Cube Servo from the body of Cube servo with the help of a cutter.
2. In order to do this, carefully force the Cutter blade into the small gap between the bottom cap and body of Cube Servo.
3. Force apart the cap from body by inserting the cutter at all 4 Corners of Cube servo near the screws holes. The bottom cap will slowly being separated from the body as you twist a bit the cutter up and down in the gap of cap and body
4. You will see the internal parts which are basically gears, gear shaft pins, motor and PCB after the bottom cap is removed. Be careful not to drop those part out of servo.
5. Take a clear photo for your servo so that you can remember the position of the gears.
Step 4: Recognizing Your Servo Gears
1. Carefully Take out the servo's Plastic Gears with clean hand or with the help of tweezers. Be cautious not to apply to much force that will damage the gear teeth.
2. Take out gears level by level starting from the from the smallest profile gear next to the metal gear of motor. Smallest profile gear is the gear with smallest gear teeth.
3. Continue this process until all the gears are removed from the gear metal shaft. Try to REMEMBER all the gears position in the cube servo. There are all 4 plastic gears in the bottom side of the servo.
4. Carefully observe the bottom side of each gears, you will find out that every gear has a small number marked.
5. Gear 5, Smallest profile gear is the gear nearest to the motor's metal gear. Next, Gear 4,3,3 and 2. There two Gear 3 which are exactly same gear.
Step 5: Preparing Gear 3 and Gear 2
1. We will reduce the Gear ratio of Cube servo by removing one of Gear 3 from the Gears set.
2. We will Glue Gear 3 and Gear 2 together with epoxy glue. We choose epoxy glue because it will give strong and long lasting hold of two gears together.
3. Remove a shaft metal pin from the servo using a pair of pliers. Be careful not to scratch the pin at the place where gear will rotate. If possible protect the shaft will small cloth before holding the shaft with plier. carefully twist to rotate a little the shaft to easily take out the shaft out.
4. Wipe the Gear 2 and Gear 3 clean from grease with clean cloth.
5. Put Gear 2 and Gear 3 together onto the metal shaft that we removed just now, Gear 2 on bottom and Gear 3 on top. Gear 2 is the taller gear. Refer to the picture for correct arrangement.
6. Get ready the the epoxy glue. Squeeze a little amount of epoxy glue out and mix thoroughly the 2 portion together with help of a toothpick.
7. Refer to the picture, apply the epoxy glue to the middle of two gears. Make sure the two gears are touching each other and not leaving any gap. Keep the teeth of gear as show in picture clean from glue.
8. Make sure the shaft is clean from epoxy glue also and it can rotate freely in gear.
9. Leave it to dry for hours or a day in order to make sure the epoxy to completely dry and harden.
10. after the glue dried, take out the metal shaft out of the glued gear set.
Step 6: Putting Back the Gears
1. Put back the metal shaft back into servo, press itLo firmly using hand into the shaft holder.
2. Start putting back the gears, starting from the gear set (Gear2+Gear3) that we glued together. Twist and rotate a little so that it can goes down to bottom easier because it might be blocked by the gear teeth misalignment of gear in the top side of servo.
3. Ignore the other gear 3. We will not used it anymore.
4. Cut a lollipop stick matching the gear 3 height, around 7.5mm using cutter.
5. refer to picture, instead of putting gear 3 that we will not use anymore, put the lollipop stick instead of gear 3 into the next shaft. The height accuracy of the lollipop stick is important, not too high or else gear 4 will stuck after the bottom cap replaced.
6. You can skip step 4 and 5 if you think it is too difficult.
7. Put Gear 4 back to it's shaft. Rotate a bit to easily if put in so that the gear teeth misalignment wont block it.
8. Put Gear 5 back into it shaft. Rotate a bit to easily if put in so that the gear teeth misalignment wont block it.
9. Be extra careful with Gear 5 because the gear teeth are small and more fragile.
Step 7: Replace the Bottom Cap
1. If u have plastic grease around, then add some grease to those servo gear.
2. Make sure the wire is still in place, if not arrange it into the wire slot. and press it with a screw driver. Make sure the wire will not block the semitransparent Latch of Cube servo after the bottom cap replaced.
3. Replace the bottom cap, observe the correct orientation of the cap (refer to pictures).
4. Press firmly the bottom cap at middle and side to make sure the cap not leaving big gap with the body.
5. Replace the screws and tighten the screws back.
Step 8: Test Your Servo
1. Rotate the Cube Servo output with hand to check whether all the gears and properly replaced. Keep the extra Gear 3, we will not use it in this modified Cube servo.
2. Check the Cube servo with main controller.
3. This modified Cube Servo will has less torques but higher speed because it has less gear reduction.