Elev8 twitching
So I got my quad out for its first real flight today to a mixed success. No crashes, but it is constantly twitching and sounds like the motors are constantly being revved by the flight controller. On inspection, it appears one of the rotors wobbles about it's a is a bit. Could this be the issue? If the shaft it sits on is bent (and this is the problem) can just the shaft be purchased or is a new motor needed?
Comments
In theory you can just change out a bent motor shaft. The problem is finding a replacement. If you have the older Elev-8 w/ the orange motors, then I found a source for those and have repaired a couple of motors. It is much less expensive than a new motor. If you have an Elev-2 or the older red motors or other, then I'm not sure where to get shafts.
A bent motor shaft will vibrate, but probably wouldn't do what you are describing. Usually it takes a decent crash to bend a motor shaft.
You probably know this already, but the props require a small bushing (donut) to be installed on the motor side keep them running true.
The controller gain can also cause twitchiness. On the Hoverfly Open it is set by the 5th input channel, usually set as "Gear" on the radio. I think mine was set around 15 or 20%. A lower value will reduce oscillation. Too low will make the quad sluggish. Too high will make it oscillate.
I don't know for sure, but I think the gain is sampled during start-up or after arming and cannot be used for live tuning during flight.
I would check that all the props are seated squarely and running true to the motor and then try lowering the gain. BTW, no crashes = Success. :-)
-Russ
Do you happen to recall where you got the replacement parts? I do have the old orange motors and really don't want to have to replace all 4 with new ones. I can see the top of the shaft precess as it spins so I'm pretty sure it's bent. Thanks for the help.
Mike
http://www.eforchina.com/view/114873/10-x-Replacement-3.17mm-Shaft-for-Brushless-Outrunner-Motor.htm
It looks like they are out of stock. If you send me a PM, I'll mail one to you.
One other thing to look out for is bearing damage. I had one motor with a damaged bearing, you could feel a little roughness in it. After taking off the lower e-clip and removing the shaft from the outer housing, just slip the shaft into the bearing and rotate slowly. Beware that the shafts are a light press fit into the housing. A small press / drill press makes it easier to remove or install. Carefully tapping with a hammer seems to work ok too.
Good Luck,
-Russ