Servo motors for cinestar

Discussion in 'Radian' started by Marc De Carlo, Apr 30, 2016.

  1. Marc De Carlo

    Marc De Carlo New Member

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    Hi all,
    Would someone out there be able to tell me where I can get replacement servos for an old cinestar gimbal. both roll & roll motors are fried. Ive tried to replace the roll with a Savox digital servo which almost works but nowhere near as well as the originals.
    Thanks in advance.
    Marc
     
  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Hi Marcosss, welcome to the forum.

    If it's not too much trouble, would you be kind enough to change your user name to your real first name and last name, please? The reasons for this (and how to do it) are explained here: http://forum.freeflysystems.com/index.php?threads/real-names.497/

    Regarding the Savox servos, what problems are you having? Provided you have the resistor installed, they should work -- I have a faint memory that FF's servos were from Savox, but I could be wrong.

    Thanks

    Andy
    ----------
    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
  3. Marc De Carlo

    Marc De Carlo New Member

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    Hi Andy
    Thanks for the reply & advice re name change.
    The Savox servo is a SC-1256TG, it is not a continuous rotation model, so it will only do a 100 degree movement, it also only has one lead coming out of it, so no room for a resistor.
    Like I said it does work but not effectively. I'm looking for a replacement unit that is the off the self equivalent to the original. Any clue on that?

    Thanks again
    Marc
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Thanks, Marc (for the name change).

    I checked my "last surviving Radian Gimbal" and there is no clue on the Savox servos what the model number is, I'm afraid.
    I suspect you may have to drop an email to support@freeflysystems.com and see if either (a) they still have a few in a dusty box in the back, or (b) they can tell you which model of Savox it is.

    Sorry I can't be of more help.
    Andy
    ----------
    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Afterthought; I did a search for "Savox" on the forum and I think this is the model number: SAVOX SC-1258TG

    See http://forum.freeflysystems.com/index.php?threads/wanted-freefly-f360-0866-servos.6922/#post-63607

    Andy

    ----------
    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
  6. Marc De Carlo

    Marc De Carlo New Member

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    Thank you so much for your time & help Andy. I'll have a look at the link. With some luck this will be the gold I'm looking for.

    M.
     
  7. Marc De Carlo

    Marc De Carlo New Member

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    Hi Andy, had a look at the spec for the Savox SC-1258TG & it is not a 360 unfortunately.
    I'll try to chat with the guy who mentioned it & see if he made mods to it.
    So close & yet no cuppy doll.
    Dimensions(mm): 40.3x20.2x37.2
    Weight(g): 52.4
    Speed(@4.8V sec/60): .10
    Torque(@4.8V oz-in): 133.3
    Speed(@6.0V sec/60): .08
    Torque(@6.0V oz-in): 166.6
    Gear: Titanium & Aluminum
    Bearing: 2BB
    Case: Aluminum
    Running current (at no load): 100 mA @ 4.8V
    Running current (at no load): 120 mA @ 6.0V
    Stall current (at locked): 4000 mA @ 4.8V
    Stall current (at locked): 5000 mA @ 6.0V
    Idle current (at stopped): 5 mA @ 4.8V
    Idle current (at stopped): 5 mA @ 6.0V
    Limit angle: 200°±10°
    Connector wire gauge: #22 AWG
    Connector wire length: 250 ±5 mm
    Horn gear spline: 25T
    Control system: Pulse width modification
    Amplifier type: Digital Controller
    Operating Travel: 100° (when1000→2000 μsec)
    Neutral position: 1500 μsec
    Dead band width: 3 μsec
    Rotating direction: Counterclockwise (when1500→2000 μsec)
    Pulse width range: 800→2200 μsec
    Maximum travel: Approx 130°(when900→2100 μsec)
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I think there's an internal potentiometer that is used to feed back the current rotational position of the servo. I suspect that FF disconnects that and replaces it with a resistor bridge that makes the servo "think" that it's always centered (faint memory, I measured the resistor pack that comes with the servos, and there are two 5.6K resistors with a center tap to the middle pin of the JR connector on the pack).

    Do a Google search for: modifying a servo for continuous rotation
    There are lots of results and that might allow you to take any suitable servo and make it spin forever! :)

    Andy
    ----------
    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
  9. Marc De Carlo

    Marc De Carlo New Member

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    Thanks again Andy, I've already looked at the 360 degree mod for the Savox, a labor intensive operation, but its doable, just need to get me some workshop space....haha!
    May take a few weeks at this rate, but I'll let you know how I go.
    Also found that the Radian was originally designed by Carvec & they have an interface called G-lock, sounds awesome until you come to the cost of 300 pound sterling for the update.
    Have you come across any hacks for the radian?
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I'm afraid not, Marc. The Radian is somewhat "last year's technology" and the industry has moved on to using brushless motors because they're so much smoother in operation and have less mechanical play in them than the servos with belt drives.

    Andy.
    ----------
    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
  11. Marc De Carlo

    Marc De Carlo New Member

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    Yeah I hear you Andy, I was gifted a cinestar due to broken servos I'd say. A lovely piece of kit, just to nice to scrap.
    Maybe I'll convert it to a brushless using an Alexmoss board.....:(
     
  12. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I tried that route, but I found that I was incessantly having to tweak the Alexmos controller parameters -- to the point that it felt like I was spending more time tweaking than doing anything else! Sorry to rain your your parade! :)

    Andy
    ----------
    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
  13. Marc De Carlo

    Marc De Carlo New Member

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    Not raining on my parade at all Andy, I'll take it as good advice & go down the road of modding the servos. I've asked the guy who mentioned the Savox servo in the thread you pointed me to for any clues or advice on modding the servos.
    Thanks again.
    M
     
  14. Marc De Carlo

    Marc De Carlo New Member

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    Hi Andy

    Just to let you know, I carried out the mod on the Savox servo, works almost perfectly.
    For some reason it will not accept the 30 & -30 degree travel limits, so if the gimbal moves any more than that the belt jumps, not that it will happen. Anyhow just wanted to thank you for your help once again.

    Marc
     
  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    That's odd. If the pulley is loosened on the shaft, the servo should spin the pulley indefinitely. Is the belt damaged, I wonder? Or is something out of alignment?

    Andy
    ----------
    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     
  16. Marc De Carlo

    Marc De Carlo New Member

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    Alignment is good, belt tension is good. it seems to be an issue with the radian not stopping the servo at the 30 deg + or - position. If it happens quickly the gimbals roll arm slams against the stop & the belt will jump a tooth. Seems odd that the radian is not sending a stop signal at the desired end limits.
    Current setting. Roll 1 default
     
  17. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Do you have a resistor pack installed on the servo?

    Andy
     
  18. Marc De Carlo

    Marc De Carlo New Member

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    I do, I removed the pot from the new servo & soldered in the pack from the original servo
     
  19. Marc De Carlo

    Marc De Carlo New Member

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  20. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Good find, Marc.
    Andy
    ----------
    Forensic Software & sUAV / Drone Analyst : Photographer : Videographer : Pilot (Portland, Oregon, USA): Trees=2, Ground=1, Props=11. :(
    The Ground Is The Limit™
    ---------- Forensic Drone Analyst : Forensic sUAV Analyst : Forensic Unmanned Aircraft Analyst : Forensic Drone Expert
     

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