Model Boat Mayhem

The Shipyard ( Dry Dock ): Builds & Questions => Yachts and Sail => Topic started by: sinjon on April 23, 2009, 04:04:48 pm

Title: Servo spline dia
Post by: sinjon on April 23, 2009, 04:04:48 pm

Took my Yamaha RTW down to the pond today - first time on the water.
The servo was not performing - the splined shaft was revolving within the servo horn, I thought that I had somehow stripped the splines
When I got back home, I found the dia. of the splined shaft in the boat was 5.68mm, the horn 5.82.
Now where in the world do I get a double ended horn (22.5cms) with a drive dia of 5.68? or do I have to make my own ?

Any thoughts please

Colin

(New to sail)

Title: Re: Servo spline dia
Post by: Martin (Admin) on April 23, 2009, 04:45:09 pm

It there a make and model No. on ther servo?

Title: Re: Servo spline dia
Post by: sinjon on April 23, 2009, 05:31:30 pm

Hello Martin

The servo is a Sail Control Hi Tec HS-765HB
The control horn came with the boat.
Already I am thinking that I can epoxy a ' correct ' horn onto my twin arm Yamaha horn, maybe reinforce it with brass pins.
Do they really make different diameters for splined shafts, and if so, WHY.

Colin

Title: Re: Servo spline dia
Post by: Stavros on April 23, 2009, 06:14:12 pm

WOAH Futaba,Acoms,Hitech are all different splines.Try Mark at A modle World and he will sort you out



Stav

Title: Re: Servo spline dia
Post by: Martin (Admin) on April 23, 2009, 06:36:38 pm

Hi Colin,
Most servo manufactures have proprietary servo output shafts and splines, all you need to do is purchase the correct servo arm for you Hitec HS-765HB - ( http://www.servocity.com/html/hs-765hb_sail_arm.html (http://www.servocity.com/html/hs-765hb_sail_arm.html) ). As this is a specialist sail arm servo, instead of just buying a set of generic Hitec servo arms and find they don't fit, it may be worth ordering the correct arm and save yourself a lot of bother.
- http://www.servocity.com/html/56361_standard_spline.html (http://www.servocity.com/html/56361_standard_spline.html) - Inspect the output shaft and splines first for damage.

http://www.amodelworld.co.uk/

Title: Re: Servo spline dia
Post by: sinjon on April 23, 2009, 08:22:18 pm

Still confused, but at least I think I am heading in the right direction, I thought sail was a doddle !!
Thanks Stav & Martin
I am away in France (Honfleur) for a few days, so I will try to get my head around it when I get back.

Colin

Title: Re: Servo spline dia
Post by: andyn on April 23, 2009, 08:37:09 pm

You simply need a Futaba / Hitec Servo horn. I beleive what you have is an acoms horn, who were stupid and decided to fit sillysize servo tops...

Title: Re: Servo spline dia
Post by: tigertiger on April 24, 2009, 03:22:14 pm

I would strongly recommend getting the correct Hitec servo horn for that particular model of servo.

I have had issues using a Futaba servo horn (from Futaba standard servo) on a Futaba sail arm servo.
The sail arms are slightly different. It may be materials, or as you found a slightly different diameter.

If you have the original 'star' that came with the servo, you can make your own arm that you then screw on to the star. This arm can be made from a bit of suitable plastic.

See photo in reply#15 on this thread http://www.modelboatmayhem.co.uk/forum/index.php?topic=2716.0