Hi yes I did a search on one of our excellent on-line shops, Howes of Oxford. so a direct comparison on reference numbers.
Roy

@roycv

Are you quoting the same servo as I am using? £36 is about $68 cdn

Hi Ronald The sail arm servo has 140 degrees travel with a pull of 11Kgrm/cm. and in the UK is £36. But you can buy from the same source a standard size metal gear servo with a 16Kgrm/cm. pull for £7 (actually 2 for £14) and with the extender that comes to £11 plus make your own arm. So a no brainer for me.
Thanks for the photos.
Roy

@roycv

My servo’s are the HS 765 HB in most of my models.

Hi further to extending the servo arm length, an 8 inch extension has only half the power or pull of a 4 inch extension with 180 degree travel. and is more compact. Both have roughly the same distance of sheet travel.
Roy

It is easy to extend a servo with a length of plastic or Futaba have a couple of metal arms, but they all need attaching to a servo top. Small wood screws do the job nicely, nut and bolt for good fingers!

I use 5 gram, 9 gram, lots of theses, 12 gram and standard plus some of the dedicated sail servos. Most servos have upped their power over the years so I usually use a 9 gram servo for rudders, except for yachts which need a bit more power. I have a tiny 2 gram servo waiting to animate a crew member!

Aliexpress search as below:-
90 to 180 Degree Servo Expander Increase Steering Angle Extender 3.6-16V

About the same price as a servo.
Roy

@roycv
Which servos are you using?

Not sure what this extension looks like? Could you add a couple photos?

Hi Ronald, not mini servos but I use standard size servos which are quite powerful for controlling the sails in medium size yachts. If I put a 4 inch arm on my servo for 90 degree movement it does not have enough sheet travel for the mainsail. I use a tiny servo stretcher to get the other 90 degrees. of travel.
One of the advantages is that I can position the servo arm so that with the sheets in tight, with lots of strain from the sails the pull is across the top of the servo and is not putting a strain on the gearbox of the servo. I have stripped gears on one occasion, especially plastic ones.

The size of the arm can be restricted by the width of the beam of the yacht, so with the additional movement possible I can use an arm winch and there are some very powerful servos available now that are contained in the standard size servo.
So horses for courses! I also use the winches with a self contained winch drum.
One of my old but clever transmitters can give extra movement up to 20 or so degrees extra. Just avoid the plastic 'stops' in the older servos.
I hope this answers your query.
Roy

I introduced the 180° movement into the thread... I just mentioned it as part of the spec sheet for that model of servo. Apologies if it was misleading.

Having said that, most conventional RC Servos are I believe capable of 180° of movement, it's just that RC systems don't utilise the whole range.

Roy
Under what application is a mini-servo required to be 180 degrees? A gun battery? A mobile crane?

These are small motors and parts, is torque an issue?

Hi as far as the mention goes of 180 degree servos. Past experience is that it is capable of 180 degrees as you will need a servo expander to achieve the extra movement. I bought 4 expanders for £10 a couple of years ago from Ali..... You get 170 degrees which with the Tx. adjustment comes in as a little more. They are tiny about the size of a servo plug in a socket and go between control / receiver and the servo.
Roy

Hi Col, no trouble. And that is definitely a standard RC servo. Specs say 180° movement, 4.8 to 6.0V supply. Orange is the signal wire.

David the mount was in the files I downloaded for the puffer I'm working on.
Great set of 3D files and a bonus all for FREE Col

Hello David many thanks your all your help
the info on the side of the servo A/F
CF sunbird
Micro Servo 9g SG 90
Col

@ColRay Hi, that looks like a standard (9g as a guess) RC servo to me, in a rather nice 3D printed mount. So I'd say it should be good to go when connected to a receiver. If you could upload a picture of the model number on the side of the servo, that can be confirmed, or just look up the model number directly.

Re the Arduino reference. I've seen some servos listed as 'suitable for Arduino', but they are still standard RC servos, Arduino just uses a bit of code to allow standard RC servo control.

Best regards
David.