How-To: eliminate vibrations on a Brushless Motor with SK720

[bingo2001]

I’ve got vibs up to 6,01g without pinion installed. On the screenshot you don’t see any spikes, because the frequency is to high (my T-Rex 450 motor run with about 30.000 rpm), you just see the scale in Skookum Robotics Data Viewer (left side) is very high.


After finishing I’ve got scale 0,76g and an average of 0,07g.


How I did it:
• Take an cable ties around the motor (every step without pinion installed!)
• Make a vib measurement (turn on logging of vibs) and let the motor run 5sec
• Connect to computer and see the log files with Data Viewer, write down the uppest value of the scale on the left side

1. Make 4 measurements, where you rotate the button of the cable ties each 90°, make a sketch on paper and write down the results.
   My were: 0°=35,2g / 90°=35g / 180°=39,8g / 270°=25,9g
   
   
2. Now you should see one lower value in my case 25,9g. Mark that position (pre mark) with a pen. Now you take measurements around that position and find the lowest value. Mark that point with a pen (remove the old pre mark).
   
3. Now you take a peace of tape and stick it on the motor close to the marked position. I had to stick it on the bottom, because sideways it did not hold. You play around with different size of tape (= different amount of weight).
   My were: 1peace=0,76g / 2peaces=5,23g / 50%peace=1,17g
   
4. Now you can leave the tape on, or replace it by filling glue.
   Best way: open the motor and find center of gravity and put there the weight. You may have to fine adjust the amount of weight again. If you motor is already factory balanced you should see some kind of balancing weight anywhere close the center of gravity, just place the additionally weight there.

[Luvmyhelis]

Pretty good work here! Innovative.


AViking also did a brilliant thread earlier on how he did it with spots of two part adhesive on the outside of the can. I balance mine with balancing putty myself, but have all the correct fixtures and tools to do so.