Hacked servo speed

[izua]

I'm thinking of using hacked servos for my first robot. The advantages really outweight the flexibility if you build your own gearbox, wheel mounts, power and control stages, and so on. Plus, servos are widely available and cheap.

But what would the final speed be? I played with a friend's servo at 180 degrees (yes, from .5 to 2.5 ms pulse width ), and it took it about half a second for a half rotation. So, if I get a second for a full rotation, and at 60 mm diameter wheel, I'll get like, 6 cm / second speed. I don't think that's really fast, but then again, it might be even low, if they won't put out the required torque.

So, I'm asking you out there, who hacked servos, how fast are the hacked servos spinning compared to the original, angular, speed?
I'm also thinking, I could just use the gearing, overvoltage the motor and make a small power level inside the enclosure. I heard the hacked servos don't offer a speed ramp, either, so it's either full speed or stop.

[airman00]

when you hack a servo you lose position control , but you gain speed control.

[izua]

I know that. How fast would the hacked servo turn compared to the unhacked servo?

[airman00]

I know that. How fast would the hacked servo turn compared to the unhacked servo?

it would turn at the same speed as before

[izua]

So i guess i'll need quick servos for a good speed. Or is the average low-cost servo, with bigger wheels just fine?

[Rebelgium]

So i guess i'll need quick servos for a good speed. Or is the average low-cost servo, with bigger wheels just fine?

All depends on what you want your robot to drive over. For normal floors, normal servo's will be ok.

I know that.

According to the last sentece in your first post, you didn't.

[Admin]

A hacked servo (in theory because I never measured it) would be faster because there is no final angle for it to slow down at.

Servo speed is also affected by torque, such as a heavy robot to pull or arm to lift.

Doubling wheel diameter will double the robot speed (assuming torque isn't limited).

[izua]

So is the opposite true? Using a lower wheel diameter (lever) will grant me more torque, so I can go on steep hils or haul pb-acid batteries 

[Rebelgium]

yes

[paulstreats]

And so back to your original post.

How did you work out that a full rotation of a second on a 60mm diameter wheel would travel at 6cm per second?
this is more like 28.26 cm per second which will be fine. (if were working to the usual pi R2)