Modding

[soninja8]

Is there any way to mod http://www.hobbypartz.com/60gexidised2.html to do the continuous rotation? I have done mods to the Hitec servos....but is this possible?  


Also, if this cannot happen, what is a good servo that can go fast, yet has enough torque to drive an RC car.....it has to be able to spin continously or be able to be modded to spin.

[soninja8]

Anyone? 

[waltr]

Never used that servo but I feel that any servo could be modified for continuous rotation if your skills are good enough.
How hard that servo is to modify can't be determined from the info presented, one will need to buy a servo and disassemble it to see how to make the mods.

what is a good servo that can go fast, yet has enough torque to drive an RC ca

That question can not be answered without you defining the requirements.
What speed is "fast"?
What are the wheel diameters?
How heavy is the RC car and how fast do you need it to accelerate?
All of these parameters determine the performance and the motor/gearing.

For some help on determine these go to the SoR motor calculator in the Robot Tutorials.

[Razor Concepts]

Since it is a metal gear servo, the process may use slightly different tools (but the same idea).

Instead of grinding a plastic limiter nub on a plastic gear, there is probably a metal pin. Using pliers to take that pin out should do the trick.

If you don't want to spend the effort modding the electronics, metal gears usually have a plastic insert that connect to the pot, so if you just remove that insert and glue the pot in place you don't have to modify the electronics at all.

[soninja8]

what is a good servo that can go fast, yet has enough torque to drive an RC ca

That question can not be answered without you defining the requirements.
What speed is "fast"?
What are the wheel diameters?
How heavy is the RC car and how fast do you need it to accelerate?
All of these parameters determine the performance and the motor/gearing.

For some help on determine these go to the SoR motor calculator in the Robot Tutorials.

Speed I want: 5-10mph
Wheel Diameter: 11in
Weight: about 4 pounds
Acceleration: Fast


Thanks! 

[Razor Concepts]

what is a good servo that can go fast, yet has enough torque to drive an RC ca

That question can not be answered without you defining the requirements.
What speed is "fast"?
What are the wheel diameters?
How heavy is the RC car and how fast do you need it to accelerate?
All of these parameters determine the performance and the motor/gearing.

For some help on determine these go to the SoR motor calculator in the Robot Tutorials.

Speed I want: 5-10mph
Wheel Diameter: 11in
Weight: about 4 pounds
Acceleration: Fast


Thanks!  

Servos won't come close to those specs, look into large gearmotors instead. Keep in mind the motors in servos are tiny 180-sized things, no matter what spec these small servos are, the performance of that little motor limits overall performance.

[soninja8]

well, I just need it to go fast and have some torgue to roll over dirt and stuff...would the HS-311 be it? Ive heard it has a good balance of torque and speed...
Thanks 

[Razor Concepts]

Look at admin's $50 robot video, that's the performance you would get with the 311s. They're alright but not close to the specs you want.

The HS-311 is a good balance, but a lowww balance. The 311 is basically the bare, lowest specced standard servo hitec offers, which explains why it is cheap. Look at other servos that are $30+ and there are significant improvements on torque and speed.

[soninja8]

Look at admin's $50 robot video, that's the performance you would get with the 311s. They're alright but not close to the specs you want.

The HS-311 is a good balance, but a lowww balance. The 311 is basically the bare, lowest specced standard servo hitec offers, which explains why it is cheap. Look at other servos that are $30+ and there are significant improvements on torque and speed.

 http://www.hobbypartz.com/60gexidised2.html
That one has a whole lot of torque: 111.1 oz/in...And it turns 60 degrees in 0.09 seconds...Is that really fast if I were to mod it with the continous rotation?

considering the HS-311 is 48.6 oz/in and turns 60 degrees in 0.15

[rbtying]

(60 degrees / 0.09 seconds) * (1 rotation / 360 degrees) * (60 seconds / 1 minute) * (pi*11in. per rotation) * 0.000946969697 ((miles per hour) per (inches per minute)) = 111.11 rpm. * 34.56 inches per rpm * 0.000946969697 (mph per ipm) = 3.64 miles per hour.  Maximum.  And it's doubtful you'll get that high, even, due to mechanical inefficiency and a general tendency for servo manufacturers to overstate their stats.

[soninja8]

(60 degrees / 0.09 seconds) * (1 rotation / 360 degrees) * (60 seconds / 1 minute) * (pi*11in. per rotation) * 0.000946969697 ((miles per hour) per (inches per minute)) = 111.11 rpm. * 34.56 inches per rpm * 0.000946969697 (mph per ipm) = 3.64 miles per hour.  Maximum.  And it's doubtful you'll get that high, even, due to mechanical inefficiency and a general tendency for servo manufacturers to overstate their stats.

So still really slow...
Do you know of any servos that go quick and have lots of torque?

[knossos]

Why not just use a geared motor with motor controller?  Sounds like it would fit your needs better.

[soninja8]

Why not just use a geared motor with motor controller?  Sounds like it would fit your needs better.

I have wanted one, but can you still use a receiver with it? So I can control it with my 75mhz FM transmitter...

[waltr]

Why not just use a geared motor with motor controller?  Sounds like it would fit your needs better.

I have wanted one, but can you still use a receiver with it? So I can control it with my 75mhz FM transmitter...

Yes, through an RC to DC motor controller. Look at the RC vendors, they sell DC motor controllers.