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[Black Shoe]

I tried a search but may not have used the correct phrases. I'm kit-bashing a relatively small ship that was designed for a static display. My desire is to RC this unit and because of space limitations I have to make good use of the available in-hull area. I've been told that a servo can be modified to function as the propulsion motor, and also be it's own ESC. Could someone please enlighten me as to the modifications required?
Thank you!

Tim

[essex2visuvesi]

http://www.acroname.com/robotics/info/ideas/continuous/continuous.html

There you go... only thing is I think you only get motor on or motor off in each direction

Heres a ready made one
http://www.servocity.com/html/hsr-1425cr__continuous_rotatio.html

[catengineman]

There are a couple of different ways people can mod servo's I would think that your going to remove the gearing and then fix a drive for the prop onto the motor this will leave you with the "esc" to sort out where you will need to set the dead band on the 'pot' so that the motor only runs when you want it.
I did one servo mod in my build

http://www.modelboatmayhem.co.uk/forum/index.php?topic=35058.0

[malcolmfrary]

http://www.acroname.com/robotics/info/ideas/continuous/continuous.html

There you go... only thing is I think you only get motor on or motor off in each direction

The response is still fully proportional - its just that the deadband is very narrow and full speed happens much earlier in the stick travel.  It is possible to modify the timing components on the servo board, but I have never bothered, eyesight, big fingers etc.  You just need to teach your fingers that there are positions between "off" and "full travel".
The link mentions replacing the pot with a pair of resistors - if I am using the gears I prefer to just disable the drive from the output gear to the pot by either shoving the pot down in its housing, or carefully drilling out the underside of the gear.  Some servos have an insert that can be removed.

[Rex Hunt]

The response is still fully proportional - its just that the deadband is very narrow and full speed happens much earlier in the stick travel.  It is possible to modify the timing components on the servo board, but I have never bothered, eyesight, big fingers etc.  You just need to teach your fingers that there are positions between "off" and "full travel".
The link mentions replacing the pot with a pair of resistors - if I am using the gears I prefer to just disable the drive from the output gear to the pot by either shoving the pot down in its housing, or carefully drilling out the underside of the gear.  Some servos have an insert that can be removed.

this works, have used this for 2 years on my Bulldog just gentle digits on the levers!
leave access to the pots to 'set zero' at neutral posn.

Rex

[ACTion]

On the other hand there's always one of these......http://www.action-electronics.co.uk/pdfs/P68A.pdf
Very small and light if you leave it out of its case and just shrink-wrap it.
Suit yourselves, as someone used to say.
DM

[barriew]

Dave's solution is far the best. I built a very small boat and started with the stripped down servo. I soon gave up as it was almost impossible to get the neutral correct. A P98A didn't take up much more space, and allowed accurate control.

Barrie

[Black Shoe]

Thanks to all for the help!