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[on:]

Hi Guys,

I am looking for a
-high torque (100 or more oz-in, the more the better) accurate servo motor
-that turns at LEAST 180 degrees (360 would be a bonus, but not required.  Anything past 360 is un-useable travel for me)
-and preferably will run off a 6v 300mA power supply. 
-Speed is not a factor.

I am inexperienced in servo motors, and I bought a Traxxas motor off amazon that I thought fit the bill- and it DID everything described above EXCEPT it only traveled 90 degrees, which is no good to me.  I returned it to save myself the $30, but now I am looking for another product.  After reading up on servo motors, I found out that 90 degrees is apparently the norm...  Ooops.   

I am sure that the right motor is out there for me SOMEWHERE though... right?

I am hoping maybe someone here has some servo experience and can guide me in the right direction.  I have done a lot of online searches, but I was SO SURE last time and it turned out to be a non-starter- so I think seeking a little advice from here isn't such a bad idea!


EDIT:  inch-pounds... I'm silly.  Changed to oz-in

[Reply #1 on:]

Hi Guys,

I am looking for a
-high torque (100 or more inch/pounds) accurate servo motor
-that turns at LEAST 180 degrees (360 would be a bonus, but not required.  Anything past 360 is un-useable travel for me)
-and preferably will run off a 6v 300mA power supply. 
-Speed is not a factor.

inch/pounds is not a unit of torque - presume you mean inch-pounds ?  That's a huge torque for a hobby servo,
11 N-m if I get my sums right, I would doubt you'd find anything that big running at a tiny 0.3A.

[Reply #2 on:]

Oops! No, oz-in is what I meant.  Haha, that's just a jet mechanics old habits shining through!

I'll edit the original post to fix that.

[Reply #3 on:]

Even the smallest lowest torque R/C hobby servos can consume 300 ma or more of current. High torque servos will consume more then your target power supply can provide.

Lefty

[Reply #4 on:]

-and preferably will run off a 6v 300mA power supply.

Yeah, the power supply matching isn't required, just preferred if possible since that's what I have handy.  It is worth it to note, however, that the Traxxas motor I just returned was pumping out around 125 oz-in and ran just fine off 6V 300mA.

If you have suggestions and they don't match my power ratings- that is cool too.  Those ratings are just ideal for what I currently have is all.

EDIT:  Truth be told, I didn't actually test how much torque it was putting out, those were just the advertised max values.  It very well could've died if put to the test with only 300mA to work with.  It SEEMED like it was working well, however.

[Reply #5 on:]

Most hobby servos use potentiometers to measure radial location.  This limits them to the amount of rotation they can obtain.  You might be better off building your own servo with a radial encoder and a motor of your choice.  Then use PID control to set the position.

[Reply #6 on:]

I have found some really nice servos that run about 190 degrees (Traxxas model 2018) for $5.00 each. Brand new at www.philshobbyshop.com. If you call them, ask for the bulk servos that they have on sale. They have a metal spring compensated linkage that you pop off and have a regular control arm.

[Reply #7 on:]

Sail winch servos can have high torque output and turn more than 360 deg. I recently got the below servo (fairly inexpensive), but haven't tested it yet to see its actual performance. A large servo under load may need several amps for power. Your "accurate servo motor " requirement may not be met with the sail winch servos. As they say, "good, fast, cheap, chose any two".

http://www.hobbyking.com/hobbyking/store/__18743__Vigor_VSD_11YMB_MG_HV_Extra_Large_360_Degree_Winch_Servo_0_75sec_40kg_150g.html?strSearch=winch

http://www.hobbyking.com/hobbyking/store/__291__189__Servos_Parts-X_Large_Servo_50g_.html