how to avoid grinding tricopter (metal gear) servo's nylon gear?

[peddiparth]

I am a noob to RC planes. I recently built my tricopter using David's V2.6 design. I used the turnigy MSG375DMG metal gear servo for the build as it came highly recommended.

On the second day of trying to learn flying it, the tricopter crashed on the back boom, twisting the motor mount in a bad way. This caused the servo's nylon gear to get chewed up. I have ordered replacement gears from hobby king, and just received it today in the mail.

I am wondering if there is any way to stop the servo's nylon gears from getting chewed up/grinding in such crashes?

Is it possible to modify the servo to allow it to rotate more than its limits without spoiling it?

 

[DDSFlyer]

I'm confused...you said you used the metal gear servo but you are chewing up nylon gears?

It's inherent that on a tricopter the servo arm is the most problematic though, how are you setting up your KK board (i'm assuming that's what you are using). Under the mixer editor you can set your 4th channel (servo channel) to Low instead of High if you are using nylon servos to not burn them out. That's the only thing I've heard about the servos jittering too much. Plus there is a setting for the servo filter to lessen the jitter as well.

 

[peddiparth]

The problem with Turnigy MGS 375DMG servo is that it has 1 nylon gear with the metal gears. Don't know why, but I am stuck with it. The threads on that nylon gear stripped down.

I am using APM 2.5 instead of KK board. Not sure if there is a similar setting on this flight controller.

 

[mlutze]

I feel your pain on this since l for what it is worth I am having a similar problem with the Blue Bird BMS-385DMAX. So far I have gone though 2 of them, at 20$ a pop ouch! The final gear seems to be plastic or a very soft metal, and the teeth get sheared off when I crash. I am using David's nose gear gimbal design, and the servo is directly mounted to the gimbal. I am remembering David's philosophy of using zip ties as motor mounts, since: "a crash will find the weakest point, so design in a weak point". So I guess the gear is the weakest point in that design. I am wondering if anybody has come up with a good design to decouple the servo from the gimbal? I was thinking I could put the servo under the arm and of using a control horn and a linkage, or perhaps move the the servo back to the center of the copter and use a rod of some sort to connect the servo to the gimbal. Any thoughts or suggestions would be very welcome!

 

[xuzme720]

I was thinking about this and wonder if a servo saver from road cars would work? I think it could be stiff enough to give positive control, but add some give in a crash...
https://www.google.com/search?q=ser...qksQS5pYGIDg&ved=0CAkQ_AUoAg&biw=1680&bih=958

This one looks promising:https://www.hobbyking.com/hobbyking/store/__18334__Heavy_Duty_Alloy_Servo_Saver_.html

 

[mlutze]

Wow! Cool idea, wonder if anybody has tried this????

 

[xuzme720]

Not that I know of, but it's certainly worth a try.