Help me choosing servos for OSR2+

DIY
1

I am a novice and I am planning to build my first osr2+Twist.Can you give me some advice?

1.Coreless servos and brushless servos.Which one will be better?
2.Is it necessary to use expensive servos for all axes?Or use expensive ones for main arms and cheap ones for pitch and twist.
3.Any model recommendations?
4.Where is the heat source usually located?In the middle or at the bottom?I want to install heat sink.
5.Any other noteworthy points, if any

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2

I would say cheap is okay for pitch. Twist, not so much if you care about noise. Twist is easily the loudest axis so I really prefer something that is brushless or just very quiet. If you don’t care about noise then cheap is fine for twist. Otherwise, I think you got it right.

I still have the same servos that @g90ak provided in his version. They work amazingly and are way quieter than what I had previously (lasted 3x as long as the previous servos too, so far). Flash Hobby M45CHW is the servo, best I’ve tried.

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3

Thanks for the recommendation
Did you use the Flash Hobby M45CHW for both the prone and rotational axes?

4

There are 180-degree and 270-degree versions of the same Flash Hobby servo. You want two 180-degree ones for the arms, and one 270-degree one for the Twist 5.

5

yes, used for all axis. For twist I’d recommend the 270° option.

Also, regarding heat source, it’s going to be the servos themselves, so a heat sink directly on the servo is best. Airflow is all that’s needed for the pitch and twist servo, no need for heat sink on those. Check the g90ak sales posts for reference photos.

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6

YUP! Exactly. Although, I actually use 270° for the roll arms as well and it works great, they were more readily available. Just gotta make sure it’s tuned down enough in MFP otherwise you could have the pitch and roll arms hitting eachother, or worse :grimacing:. I will say I’ve purposely hit the limit a few times though haha

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7

Great advice in this thread. My 2 cents is that while brushless may be faster/stronger/more durable, coreless seems to be smoother. They’re also a bit cheaper.

My only piece of advice for you is - if this is the first OSR you’re building, you may want to start with cheap bargain servos as you get familiar with setup and tuning of the device. There are things to look out for during installation and tuning that may make the arms move in opposing directions that burn them out. Better to have these “learning experiences” on cheap servos rather than fancy ones.

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