Fighterpilot

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I am trying to find out which control horns are compatable with which different brand name servos. Does anyone know if JR servos will accept Futaba control horns or vise-versa?
The reason I ask this question is that an airplane that I have has mixed servos. Some are JR some are Futaba. Obviously JR control horns will fit their servos, but I have some Dubro heavy duty control horns for Futaba servos and I have some (different spline) for HI Tek. Does anyone know if either of these has the same spline as JR?
Thanks

tombob

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I looked at this problem about a week ago, and the answer is JR &Airtronics are interchangeable futaba & hitec will not work together or with others ,although they are very close the futba will strip out if used on hitec. du-bro makes arms for hitec servo's. :spinnyeye TomBob

Fighterpilot

My Feedback: (2)

Thanks Tombob, I already have the black servo arms from Dubro that will fit Futaba and the white ones from Dubro that will fit Hi Tek. I guess I'll have to go out and buy some servo arms that will fit the JR servos. I was just hoping that they would be compatable with either Futaba or Hi Tek, I guess no such luck. I really don't know why they don't standardize their fittings. They made a good start with the plugs, but I guess it's too much to hope for to have standard control horns.

A.T.

Futaba, JR and Hitec should not be interchanged.
The number of splines are different on Futaba and Hitec which results in a poor fit which slips under little load.
Hitec arms/discs will not fit Futaba or JR as the Hitec output shaft
diameter is smaller. A JR arm fits onto the Hitec output shaft but teeth of splines hardly meet and are just waiting for a hard load to shear the teeth off.
FWIW Current Heavy duty Sonic Tronics arms =
#340 = Futaba
#342 = Cox, Sanwa(Airtronics) and JR
Hitec provide their own very heavy duty arm sets at very reasonable prices
#56402=surface #56316 = Giant Horn set - see below. There is also a heavy duty servo saver set for use with 1/8 scale steering and also ideal for separate steering servo etc large aircraft. or where override function needed.

Current Tamiya servo saver packets provide individual discs to fit the splines of various brands as follows=

S4 = Futaba
S7 = Sanwa(Airtronics),Acoms,KO & JR
S8 = Futaba & KO = Old square output shaft
S10 = Futaba & Acoms the newer square output shaft
just prior to multi splines.
S11 = Sanwa & KO older spline pattern.

The best heavy duty horns for Hitec =
1. Hitec part Number # 56316 = Giant Horn Set
= a disc, 4 point and a 2 point with a metal ring to put around the base of the horn to prevent it splitting under load.
2. Hitec part Number #56402 = Surface control horn.= 2 x very solid 4 pointers
3. Hitec aluminium output arms as now provided with the new digital servos.
see =
http://www.hitecrcd.com/Catalog/Servos/Servo_Index.html

Please be careful with your old Futaba and JR horns - they may not be what you think they are as many of the older ones get quite brittle with age and break relatively easily. (just like humans -wisecracks not necessary - resisted temptation to try a little humour)
see also other references under "radio systems" at http://homepages.ihug.co.nz/~atong/
regards

Alan T

Fighterpilot

My Feedback: (2)

Thank you Alan T. I was aware that Futaba and Hi Tek were not interchangable but I did not know if JR would match up to either one. Thanks for the answer. I will attempt to locate some Dubro heavy duty control horns for JR at my local hobby shop.
Thanks again for the info.