Author Topic: Good durable servo for product  (Read 1743 times)

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Offline Kyle BerezinTopic starter

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Good durable servo for product
« on: June 23, 2016, 02:50:34 PM »
I am one of the founders of OpenMYR, a startup that will soon be delivering a Wifi stepper motor and WiFi hobby servo controller to Kickstarter. The issue I am having is choosing a good micro hobby servo to ship with the board. Originally I intended to use the cheap plastic tower pro servo motor, it only costs about $1.30ea in the quantity we were looking to buy. I didn't intend them to be long term motors, just something to use out of the box without inflating the cost of the whole product.

The issue is the test ones we bought were breaking left and right, I was able to snap a gear tooth off by simply telling the servo to push against a solid object. I upgraded to the metal geared MG90s ($1.90ea) and had better luck at first, however after a bit of use, 1 lost its axle-gear grip on an internal gear, one gets its position wrong if it gets warm, and 4 were fried on a 12 volt rail (not the motors fault). I had 8, 4 fried, and 2 failed. That is 50% failure. I'm worried if I ship with chintzy OEM motors our backers won't have faith in our product longevity even though we don't make the servos. What is a durable low cost motor? I don't need strength or accuracy or response, these are just so you have something that works out of the box. Or would you personally be ok with getting a cheap motor since it brings the cost down and you already intend on replacing it with your own. Remember, if you believe I should offer multiple options, the cost of all of them goes up due to the quantity being split across 2 products.

Opinions or options are both welcome.

Kyle Berezin
www.OpenMYR.com

Offline Kyle BerezinTopic starter

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Re: Good durable servo for product
« Reply #1 on: July 07, 2016, 02:48:04 AM »
We eventually decided on the ES08MA II. For a marginal increase in cost we easily doubled the quality. It is metal geared like the MG90s but it is much smoother and quieter. It is a faster motor and it also handles heavy loads better. The end-stops don't jam because it has no end-stops. They never buzz. They don't get as warm. We haven't yet had a single failure yet, we put them through their paces by making a robot arm (https://www.youtube.com/watch?v=Qk_EETR0xx4) You'll notice the bottom segment holds up the entire arm with no support or mechanical advantage. If anyone is thinking of buying a tower pro MG90s, don't. For 25% more cost you can get the ES08MA II with at least twice the quality.

Kyle Berezin

Offline Kyle BerezinTopic starter

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Re: Good durable servo for product
« Reply #2 on: July 13, 2016, 02:45:02 AM »
We had one start on fire, how common is it to not have a thermal shutdown on a servo?

Offline Kyle BerezinTopic starter

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Re: Good durable servo for product
« Reply #3 on: July 13, 2016, 06:39:31 PM »
The manufacturer stopped responding to my emails after I sent them our failure analysis document on the motor that started on fire. So there is no way I am going to send these out. The ES08MA II from EMAX is a fire-hazard, and that puts me back to square one. Anyone know of something safer?

 


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