Futaba BLS276sv dry turn noise and uneven resistance

[amphibia]

Hi all,

I have always been a big fan of futaba products. I recently bought a set of 3 BLS253 for logo 600 sx cyclic and one BLS276SV for rudder.

However, the BLS276 has some weird situation during dry turn (turn by hand without power on)
1. noise that sounds like crashing glass, what made it worse is the inconsistency throught the travel
2. inconsistent resistance. From the most counterclockwise zero position, 1/4 travel and 5/8 travel are two spots that give more resistance than other positions. So for example, if I apply a consistent force to turn the servo horn slowly either direction, the horn would be mildly stuck at these two positions unless I apply a little more force. I do not dare to mount it with power unless I am sure this is normal.

The 3 BLS253s that I bought do not exhibit this behavior. All my other servos, such as JR 3500G, MKS DS95/DS95i and many other savox servos do not either.

Can anyone please tell me if it is normal for BLS274 rudder servo? or maybe other rudder servos such as BLS251 have the same behavior? I need to decide whether to return the servo.

Many thanks in advance.

[dchekas]

I have several of these servos, some exhibit some very minor sticking at those same points, others do not. I would not sweat it, all of mine are performing perfectly.

The BLS276SV uses all plastic gears except for the output gear. These are mass injection molded, and there is some some variance from mold cavity to mold cavity. I suspect this leading to a tiny bit of variance in the mesh, and it's what you're feeling.

[amphibia]

Originally Posted by dchekas

I have several of these servos, some exhibit some very minor sticking at those same points, others do not. I would not sweat it, all of mine are performing perfectly.

The BLS276SV uses all plastic gears except for the output gear. These are mass injection molded, and there is some some variance from mold cavity to mold cavity. I suspect this leading to a tiny bit of variance in the mesh, and it's what you're feeling.

Thanks for the reply.
Actually, having at least one plastic/nylon gear is what attracted me to the high end futaba brushless servos bls253/bls276. I always like the idea of a well designed product with sacrificial components.

I say this to compare futaba BLS servos against other high end servos like mks servos. With due respect, I love the MKS DS95/95i on my forza 450ex. But for bigger birds, I do not like the idea of full metal gears. I could be wrong but I feel a crashing with metal gear servos will not only destroy gears but also potentially ruin shaft/motor/position sensor/case/circuit. In fact, I do not think full metal gear should even be marketed as a positive feature.

But on another thought, choosing a servo with at least one sacrificial plastic/nylon gear would require faith in the brand's commitment to test their product thoroughly.

So back to my servos, based on what you say, I guess I would just plug it into vbar to see how it goes.

Thanks again.

[prokyon]

Originally Posted by dchekas

I have several of these servos, some exhibit some very minor sticking at those same points, others do not. I would not sweat it, all of mine are performing perfectly.

The BLS276SV uses all plastic gears except for the output gear. These are mass injection molded, and there is some some variance from mold cavity to mold cavity. I suspect this leading to a tiny bit of variance in the mesh, and it's what you're feeling.

Do they just have plastic gears for BLS276SV? Is there a metal gear upgrade set?

[Raptorapture]

Originally Posted by prokyon

Do they just have plastic gears for BLS276SV? Is there a metal gear upgrade set?

Not that I've seen. I think as was stated the whole point is not to go full metal for tail.