Home Forums Everything about the Mini Tricopter How to protect the servo?

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  • #25991
    juansacco
    Participant

    Hello guys! Im loving the Tricopter, yesterday I took it to a race 🙂

    I broke the BMS Servo, so now I’m using a Turnigy, do you know any measure I can take to protect the servo. Or is there any tougher I can get?

    For instance on my RC car I keep broking servo’s until I got a Savox HV, and that was it, any crash, major, minor never affected the servo.

    Thanks guys!
    Juan

    #25995

    What kind of breakage is it? Is it stripped, did the case crack, both, or was it something else?

    #26001
    juansacco
    Participant

    Its always gears getting stripped, during a crash that inflicts some force on the tail. Metal gears seems to get stripped too, so any advise? Keep buying servos will be a bit expensive

    Juan

    #26002
    Terje
    Moderator

    I made this tail tilt mechanism to protect my servo and improve response time: http://www.thingiverse.com/thing:1035497

    It takes the load off the servo, but on occasion the motor cup breaks instead…

    So a possible solution if you have a 3D printer, otherwise not so much.

    #26003
    juansacco
    Participant

    Terje, wow, looks awesome! I have to get a 3d printer now.. But how is that mechanism going to protect the servo?

    I crashed the hell out of my RC Cars and NEVER EVER had a servo broke after I got a Savox HV with metal gears, so its all about design, we cannot let the servo to handle a crash.. Its just not supposed to get that hit on the gears.

    I think we need to use something like this: https://www.teamassociated.com/parts/details/3760-ASC3760-direct_mount_servo_saver_for_airtronics_servos/
    It’s called servo saver and it will protect the gears on a hard crash. ( It’s supposed to be used on RC Cars)

    #26004
    Terje
    Moderator

    Glad you asked 🙂

    On impact the motor is most likely tilted to one side, asserting a lever force on the servos pivot. Since the servo motor is strong (and dense), the gears will absorb the force instead. The classic tilt mechanism tilts the motor to one side, the full weight of the motor will be asserted to the pivot point of the tilt mechanism.

    Placing the pivot point of the tilt mechanism in the center of the motor means the force of the impact will be evenly distributed on both sides of the servo pivot. Also the force will be less since the lever (distance from pivot point to edge of motor is smaller).

    Hope it makes sense to you? See attached picture 🙂

    Attachments:
    #26006
    rue
    Participant

    Interesting, @juansacco – was contemplating some kind of torque-limiting clutch to protect the servo myself. Do you know if this thing works? They seem to have a spring inside to “soft-couple” the servo. That’s probably not what we want, rather sth. that just slips above a certain max. torque. As discussed in another thread I suspect that e.g. the more torquey BMS-390 grinds gears easier in a crash than the smaller 210s since it takes more force on the spline until the motor starts turning. No reasonable statistics on this, of course, just a hunch.

    (One advantage of the 390 is, that you can fix it w/o spares and filing by just flipping the main gear by 180° so you’re getting one crash for free 😉 )

    I can definitely see an advantage of @terje’s nice tilt as it will usually result in less force on the spline. No 3D printer, here though and I know someone who’d grind me if I bought one. Too dangerous! Need to check a fablab.

    Cheers

    #26009
    Terje
    Moderator

    Using less zipties might be the easiest way to protect you servo 🙂

    #26011
    juansacco
    Participant

    Terje, I got it now, the force getting equally distributed. But I still think that a direct impact on the prop its too much to handle without a servo saver like the one I mention.

    So, I ordered one servo saver and I will try to use it on the servo mount you made!

    Do you recommend any material? Because I don’t have a 3d printer I will use: https://www.3dhubs.com/

    null

    Thanks

    #26014
    juansacco
    Participant

    I found this servo too.. Well its basically the same servo saver but for helicopters ( to protect the gears to get stripped ) maybe it wills suit better? Or maybe its too small what do you guys think?

    #26176

    Good point @Terje! 🙂

    There obviously should be a failure point somewhere, and it should be something that’s easy and inexpensive to replace. “Sip”-ties 😀 work great for that.

    #26563
    Joost
    Participant

    @Terje What material did you use for your tilt mechanism, PLA, ABS or something else?

    #26592
    juansacco
    Participant

    Guys… After upgrading the servo to a Turnigy 211 ( Its a copy of the BMS But it seems to be more durable ) and also, using Dal Props 6040 ( They bent instead of snap, so they handle the impact better )

    I can now say from the experience that it was it for me, no more servos brokens after weeks of crashing in a Garage! ( Yes concrete everywhere, no grass landing.. )

    So if you are looking to fly indoors, crash a lot, just go with Turnigy 211, DAL Props and you will be fine!

    Hope it helps someone else!

    #26611
    Joost
    Participant

    Do you still use the servo saver as well?
    Got some DAL props on the way, as well as Terje’s tilt mechanism. Will report how well that works out. Setting angles will be a bit more hassle, but probably worth it.

    #26612
    juansacco
    Participant

    Dal props and turnigy servo were enough!

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