Topic: Digital Jr servo's Different size shaft to ordinary JR servo's ??

Fitted some longer arms on my JR8411's at the weekend and went flying on test flight ( thanks Pylon ) ow him a pint though ! just on first circuit had mass aileron flutter so he landed it. and found that the arm had come off the servo. upon further inspection back in the workshop found that the shaft on the servos are smaller in diameter  than ones on a normal JR servo   is this a common thing ? are there different arms for Digital and normal jr servo's ??

Stephen

If they are different it will come as a nasty shock to all the JR digis in my jets!  They are the same, I have just been to the workshop to check, the output arms are a perfect interchange between a 591 and an 8511.  The 8511's shaft is 0.04mm narrower than the nylon shaft of the 591, probably to allow for the higher friction of the metal shaft when sliding an output arm on/off it.
JR only sells one set of plastic arms, one set of metal arms, (apart from special sets for mini servos etc) they don't have analogue servo and digi servo arm sets.

OOHH ERRRR then ! these were ones from my local model shop overlander / over-tec labelled. Just put the vernier on my 8411 and yes will agree it is 0.04mm smaller than my 579 I also tried the arm on.  really had to push the arm on the 579 but on the 8411 it just drops on and if you invert the servo and jiggle it abit it falls off.  

Stephen

I have used 8411/8511 in 3D models and always used servo arms with normal JR fitting horns with no problem and they were in models with vibrating YS's and high load 3D flying 

these are ones in a bag with different length blue coloured arms labelled with jr on ?

Stephen

What model are they in? Was there any slop in the linkage? The flutter could have started in the linkage 

they are in a Pilot Yak55 87" no slop in linkage as on Pete Tindell Ball linkages.

Stephen

It is just the fact the arms are sloppy on the digitals and not on 579 or 591's wondered why

these are ones in a bag with different length blue coloured arms labelled with jr on ?

Stephen

Are those 3rd party arms, allegedly JR compatible?  If so, that is the likely source of your problem, they may have too large a hole in them.  On my JR digis with genuine JR arms there is no way in a million years I could get the arm to fall off the shaft by holding the servo upside down and shaking it

Will order some different ones tomorrow. Allthough what is the point in advertising these as JR if they fit like this ??

Stephen