Hd Servo Recommendations

Question

Hey guys.

I'm looking for recommendations for a heavy duty servo, the same size and power requirements as the EZ-Robot HD ones, but at least twice as strong in regards to torque and holding positions, and that will also play nice with the EZ-B.

I know that most, if not all servos will work with the EZ-B, and I have looked online to see what's available, but I'm hoping someone can recommend a strong reasonably priced servo you might be using and would suggest.

Thanks.

EzGreeney · Answer

Hey man, We bought some heavy duty servos for what we were doing, but they still only lift a few pounds I think. You might still want to do some research on them, but they sound like what you might want. They're called Hi-Tec (HS-5685MH) servos; here are two websites that talk about it: https://www.servocity.com/html/hs-5685mh_servo.html#.VVvYoPlViko https://hitecrcd.com/products/servos/sport-servos/digital-sport-servos/hs-5685mh-high-torque-hv-metal-gear-servo-/product We also bought some metal hubs for it instead of the plastic ones they have. Let me know if you want the link for that.

Steve G · Answer

@EzGreeney. Thanks for your response and recommendation. The Hi-Tec HS-5685MH you linked to is rated for 12.9kg-cm stall torque at 7.4v, where as the EZ-Robot HD servo is rated at 15.0kg-cm ST which is not strong enough for my needs, so it's not quite what I'm looking for but thanks all the same. I want something around the 30 to 40kg-cm range (or more) at the same voltage.

Dunning-Kruger · Answer

@Steve G... Unfortunately, I think it will be hard to find a standard sized servo that can output that much torque... Even the giant scale servos in inMoov only produce about 25kg-cm...

RoboHappy · Answer

Check out Pololu.com, I think I remember seeing a couple of servos that can lift up 1600oz/in, and run at 12vdc. A bit overkill maybe but really cool !

Dave Schulpius · Answer

Hi Steve, Not inexpensive at all but the HS-7950TH will give you a Stall Torque at 7.4V of 486oz/in (35kg.cm). It's very pricey at about 150 USD at Servo City. I have a few of these in my B9 arm and they work nice and are tough little standard size servos. However like all Digital servos they do have a whine when holding load. "Ultra Torque" HS-7950TH   If you really want to add some monster torque install them into a RobotZone Gearbox. Expect to pay about 220 USD or less at ServoCity for this setup depending on what you order. You can also put a smaller and less expensive servo in these gearboxes and drop the price. The gearbox alone will cost about 70 USD: RobotZone Gearbox & Servo

Steve G · Answer

@Richard. I'm beginning to think your right. I've had a good long net search without much luck, and the couple I did find were crazy expensive. The only one I did find so far that comes close to what I'm looking for is this. It's slightly bigger (at 6.5x3x5.7cm) but I may be able to work with it and look's strong enough, and not a bad price either...  Btw, I'm pleased that David C and yourself enjoyed your trip to the inner sanctum. Sounded like you had a great day at the office. I'm supper jealous, but maybe I'll get there, one day. @robohappy. Thanks for the link. I saw the servos you were talking about, but I'm looking for something to run on a 7.2 / 7.4v set up. I did see this however this which doesn't look to bad, and the price is right.  @Dave. Thanks for the recommendations Dave. The HS-7950TH is a bit on the pricy side as you say (but I've seen worse though), but does look a lot more like what I'm looking for so it's something I just may conceder. The gear boxes do look like a great option, and something I may consider investing in for a future project, but for what I'm looking for now, I have space restraints so unfortunately these I wouldn't be able to use one of these. Thanks guys.

Dunning-Kruger · Answer

Wow, nice find @Dave... but the price!

Steve G · Answer

@Richard. Yeah I gotta admit, that's the one thing holding me back from ordering one. Price.

Dunning-Kruger · Answer

@Steve.... Can you not use a cheap geared DC motor and potentiometer in your joint that you are controlling? However, I realize servos are more of an elegant solution to moving joints....

Steve G · Answer

@Richard.

It was something I considered a while back when doing my K-9 build, to control the neck mechanism. It may be something to look back in to, but as you say, a servo would be a more neater way of doing it. I reckon the 40kg-cm servo I linked to in post #7 may do the trick, but I haven't seen many reviews on it which is something I would like to check out if I was to spend 55/$77 on one.

Steve G

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