Servo Motor not fully centering anymore

[amorti]

@Zerobricks I know buwizz is developing a buggy motor, but it would be amazing if they develop a servo too.

There's a lot of room for improvement from TLG's attempt in terms of power, accuracy, and reliability.

People already pay 30e for TLG servos knowing they're no good but there's no alternative. So the market definitely exists. Maybe it's a use for the mysterious port on top of the thing?

[Odinkuijpers]

On 7/24/2020 at 12:09 AM, amorti said:

@Zerobricks I know buwizz is developing a buggy motor, but it would be amazing if they develop a servo too.

There's a lot of room for improvement from TLG's attempt in terms of power, accuracy, and reliability.

People already pay 30e for TLG servos knowing they're no good but there's no alternative. So the market definitely exists. Maybe it's a use for the mysterious port on top of the thing?

TLG new powered up system motors can be used as servos and they will be compatible with the new buwizz 3.0, so I don't see the need to develop a "buwizz servo". The only issue is the different form factor which makes it hard to swap them in for PF servo motors

[RocketPuppy]

13 hours ago, Odinkuijpers said:

TLG new powered up system motors can be used as servos and they will be compatible with the new buwizz 3.0, so I don't see the need to develop a "buwizz servo". The only issue is the different form factor which makes it hard to swap them in for PF servo motors

The PU motors leave a bit to be desired in a steering rack. They'll center perfectly on powering up or forcing a recenter, but develop slop in use. This can be slightly mitigated by building a beefy steering rack to reduce the amount of wiggle between pieces, but doesn't eliminate it. 

 

Going with an independent suspensions magnifies the problem. The tiny wiggle between pieces that allows an independent suspension to work freely causes a slight toe-in of wheels in the direction of travel (at least with a Macpherson, double wishbone, or pushrod suspension, or their closest lego equivalents). This is usually fine going forward, but in reverse it causes a toe-out on the steering, which will pull it off center (using a locked differential or no differential on drive wheels mitigates this, but under normal conditions powered wheel will slightly pull the vehicle in that direction when starting to move or over uneven/slippery surfaces).  Adding a torsion bar or sway bar helps a lot, but that isn't possible at all scales, and it can be difficult to build one flexible enough for the motor to overcome. 

EDIT:  Rubber bands mounted to pull things to center and prevent toe alignment shifts help too. 

Another annoying thing is the L PU motors are the same dimensions as the PF ones, with the same annoying mounting points. Really wish Lego would have made it a full stud wider instead of a half stud on the thicker sides, and added a few mounting holes. On smaller scale MOCs the compromised width without mounting holes can make mounting the motor take up more room than if Lego committed to a full stud length. 

Edited February 21, 2021 by RocketPuppy
Remembered another hack solution for off center problem.

[Odinkuijpers]

Lego has more than the L motor in the PU group, see the medium angular motors from the Mindstorms/SPIKE which have more pinholes

8 hours ago, RocketPuppy said:

Another annoying thing is the L PU motors are the same dimensions as the PF ones, with the same annoying mounting points. Really wish Lego would have made it a full stud wider instead of a half stud on the thicker sides, and added a few mounting holes. On smaller scale MOCs the compromised width without mounting holes can make mounting the motor take up more room than if Lego committed to a full stud length. 

 

[mktechniccreations]

 

[JJL]

My servo motors problem is different from what everyone else