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[davidm1945]

Hi all,
   I need to find a fairly powerful 90 degree servo. I have been searching various retail websites but they all seem to only sell 60 degree ones. Some model aircraft forums refer to 90 degree servos as being quite common, but if so I can't find 'em.
   Second choice would be to modify a 60 degree one to 90 degree but I don't know if this is possible.
  Any help would be gratefully received.....

Dave.

[Subculture]

Normal servos move 90 degree when fed between 1-2ms pulse. Manufacturers quote 60 degrees to make the servo action appear to be faster than it actually is.

[tugboyben]

Hi Dave
I have used these on my tug's on schottle drive's to get 90% left & right work great


http://www.mr-rcworld.co.uk/index.php?ukey=product&productID=991


http://www.mr-rcworld.co.uk/index.php?ukey=product&productID=992


http://www.mr-rcworld.co.uk/index.php?ukey=product&productID=1021


Jason

[tugboyben]

You can all so have a go at modding a servo your self


http://www.youtube.com/watch?v=Hst0hrpPCtg


Jason

[davidm1945]

Thank you all so much - exactly what I need!

Ask and knowledge will be given....   

Dave

[davidm1945]

Sorry Kenny, I should have thanked you for moving the topic to it's correct location.

Dave

[Norseman]

Nice info - useful.

Dave

[Subculture]

Be aware that modding a servo like the video will tend to reduce resolution of the servo. Also you might want to modify the final ouput gear, as many(most) servos have a mechanical blank on the gear which prevents it travelling more than 180 degrees, and depending on the quality of servo, it may overshoot a little, and you risj strippign your geartrain. You can file the blank off with a bit of care, which deals with that little problem.

[malcolmfrary]

Be aware that modding a servo like the video will tend to reduce resolution of the servo. Also you might want to modify the final ouput gear, as many(most) servos have a mechanical blank on the gear which prevents it travelling more than 180 degrees, and depending on the quality of servo, it may overshoot a little, and you risj strippign your geartrain. You can file the blank off with a bit of care, which deals with that little problem.

Some servos prevent full rotation by having a lack of teeth on a section of the output gear, almost all have a shoulder on the gear that stops on contact with mouldings inside the case which can be filed or sawn off.  Its purpose is to prevent the position sensing pot being driven past its end points, which would do nobody any favours.  Removing it is only a good idea when converting the servo into a winch.  Simplest way to extend the travel is probably the ACTion P96 Servomorph, apart from Tugboyben's suggestions.

[davidm1945]

Hi to Jason (tugboyben),
   Do you use commercial schottel drives or build your your own? I need the servo to turn one I am making and would be interested if you have done the same (or anybody else, of course). In the absence of a lathe I have used modified plumbing fittings and commercial prop, shafts, bevels and Kort. Time will tell if it all works!
Dave.

[Umi_Ryuzuki]

I used some high torque metal gear servos from Hi-tec to operate my small Graupner schottel.
I didn't use the partial steering gear, I grabbed a 79 tooth gear from the RC car rack at the hobby shop, and
installed that onto the steering servo. That gear, plus the servo expansion feature on the  transmitter
gave my schottel drives 270° of steering. I have a pair of 100 tooth gears, but never installed them.

I am currently trying to figure out ARDUINO programming. The intention is to use the ARDUINO to
interpret two channels from a joy stick, and mix steering and throttle via an ESC and stepper motor.

 

[davidm1945]

I am currently trying to figure out ARDUINO programming. The intention is to use the ARDUINO to
interpret two channels from a joy stick, and mix steering and throttle via an ESC and stepper motor.

 

Well, Umi this may mean a lot to you but it's some strange technospeak to me! I could Google ARDUINO or you could elucidate....

I intend to do as you have and drive the servo/steering with gears and the prop shaft with a drive belt at about 7000 rpm - what do you think?

Dave.

[Umi_Ryuzuki]

Large gears and high torque is the simple way to approach the steering issue.
A drive belt will require a very firm mounting base through the hull.
Tensioning the belt will often cause issues by pulling the drive out of alignment with
the drive or steering gear. But it is nothing that can not be dealt with.

___________________________________

The ARDUINO, and RASPBERRY PI, are both small stand alone computer boards.
They each have a simplified (if one works hard at it) programming language that
allows programs to be written so that it can act as a light switch, or drive a CNC router.

We just want a steering and ESC mixer.

Kagelmacher - Modellbau was offering a pre programmed set prior to it's temporary closure, but
the set has not returned now that the website and the owner are up and running again.
The price for the pre programmed set was around 350 euro.
An Arduino and RaspberryPi run about $35-50 USD But all the programming has to be created.

http://www.youtube.com/watch?v=g-z-mKjl6z8

The first portion of the joystick's throw tells the stepper motor where to steer.
Any increase in throw of the joystick, tells the ESC to apply throttle.

[davidm1945]

Hi Dave
I have used these on my tug's on schottle drive's to get 90% left & right work great


http://www.mr-rcworld.co.uk/index.php?ukey=product&productID=991
Jason

Hi Jason,
    I've just ordered one of those - will let you know how I get on...

Dave.