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Servo arms.

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Old Geezer16/04/2019 13:31:54
639 forum posts

Just want to get this off my chest.

Why on earth can't manufacturers of servos agree a standard diameter and number of splines for various sizes of servos so that servo arms can be interchangeable? O.K. for different sizes different diameter shafts - say micro, mini, standard , or up to 5gm, 5-9gm, up to 20gm and Standard.

It wouldn't be at that difficult and it would save hours of sorting through boxes of spares to find one that fits - or at least mould the manufacturer's name onto the blessed things, OK, you'd need a jeweller's loupe to read it, but it would give us a fighting chance to marry the blighters up.

There - that feels so much better.

Manish Chandrayan16/04/2019 13:34:11
606 forum posts
70 photos

At least Hitec has done that on the newer servos where they have moved to Futaba 25 teeth.

Martin Harris16/04/2019 15:23:20
8948 forum posts
221 photos

From time to time I've seen the results of people thinking they have a suitable arm only to discover (sometimes too late) that it can slip, where they've used a slightly oversized one.

Dwain Dibley.16/04/2019 15:53:12
1270 forum posts
1265 photos
Posted by Manish Chandrayan on 16/04/2019 13:34:11:

At least Hitec has done that on the newer servos where they have moved to Futaba 25 teeth.

That's interesting Manish, as I have a million futaba arms. Also I have decided to buy Hitec servos from now on to keep a standard with my new Tx. I will test the new hitecs with some futaba arms.

With regard to Old Geezers post, I keep all Servo arm types separate in Labelled boxes. I used Ex Indian/Chinese carry out boxes..........Mind you..........I am a terrible Anorak.



Edited By Dwain Dibley. on 16/04/2019 15:56:11

Geoff Jackson16/04/2019 16:28:54
160 forum posts
3 photos

Oh dear DD, Im an anorak same as you. Engineering and electronics background but doesnt it just make life that bit easier. There, s enough challenges and frustrations with model aircraft building without not knowing where all your bits are!!

Dwain Dibley.16/04/2019 16:33:35
1270 forum posts
1265 photos

Losing sight of Ones "Bit's" can be very worrying Geoff. laugh


Manish Chandrayan16/04/2019 16:49:05
606 forum posts
70 photos


Some more info to mull on. The info is taken from here

H25T Hitec Standard Spline (25 teeth)
HS-83XXTH and HSB-93XXTH series servos.
NOTE: This spline is the same as the Futaba 25T Standard Spline (3F).

At this time, Futaba manufactures servos with 4 different splines. When choosing components to attach to your servo, it is important to know what size of spline your servo uses. Below are the four various splines. If you have any questions as to what spline your servo has, please check the servo page or contact us via e-mail or phone.

1F Spline (15 tooth)
Futaba servos such as the S3111, S3114 & S3154.

2F Spline (21 tooth)
Micro servos such as the S3153, S3107, S117 and similar have the 2F size spline.

3F Standard Spline (25 tooth)
Most standard size Futaba servos have the 3F spline.

4F Spline (25 tooth)
This spline is found on most Giant scale servos like the S3306 and the S9154.

Dwain Dibley.16/04/2019 16:53:40
1270 forum posts
1265 photos

Nice one cheers.


Peter Miller16/04/2019 18:18:30
10317 forum posts
1231 photos
10 articles

I use quiter a few Turnigy micro servos. Even among them the splines vary.


I suspect that Turnigy scource their servos from various manufacuturerers.

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