[HELP] 9396 - Rotor Friction

[JGW3000]

I have not been happy with the performance of my 9396 for a long time, so I am in the process of rebuilding it. The issue is that both the manual and motor-driven operation of the blades are sluggish and involves seemingly high torque, perhaps due to the large number of gears in the drive train, resulting in very slow turning blades. After completing about 82 steps in the rebuild, I got to a place in the build in which I can turn the blades with the hand knob, and again there seemed to be a lot of binding and "stiction" of the gears, which I traced to the gear directly driving the turntable being the primary trouble maker, highlighted as lime-colored in the LDD image. Loosening the build at this location, by forcing the two DSG11L beams slightly apart, resolves the issue, but is not a permanent solution as these will be tightly locked in place once the build is done. Does anyone else have similar issues, or suggestions to fix?

Edited December 2, 2015 by JGW3000

[Kumbbl]

mine are spinning very well with very low friction - you must have made failures during the build - ensure all gears and axles are spinning without friction during all building steps..

[Jim]

I can't recall having problems myself. Is it possible to shoot a short video.

Edit: I was supposed to write CAN'T instead of CAN.

[JGW3000]

As a follow up, after rebuilding the set, and finally adding the M-motor and BB, with fresh batteries, everything seems to be working fine and the rotors are spinning quite nicely. I must have had some gear binding issues in the gear box. Of maybe one of the clutch gears that engage a driving ring was backwards. I seem to recall small hands messing with the build during its first iteration several years ago, which may have been a contributing factor.

[steph77]

Hi,

I got lots of problem with mine too.

I spoted this issue:

The friction problem comes with the pitch system of the blades. The mecanics at the bottom of the mast generate a friction by torsion on the vertical axle. This is due to the friction of the grey pin connected to the lever that transfer the horizontal movement of the command to vertical movement for the blade's pitch control. Maybe you can check it on your model :)

[JGW3000]

Yup, you are correct in that the pitch control can also cause some friction in the rotation, need to make sure the blades are tilted for best swooshing.

[RohanBeckett]

on a side note.. my 5yr old son who loves playing with motors.. made a hub, connected the 2 big rotor blades, and then connected to the old (2ndgen) 9V motor..

he then span it up.. ( took a while to get to full speed)

I then stuck my hand it in... (to show him how Lego, used improperly, CAN hurt)

OUCH! those blades have a lot of power in them, when spinning fast!

Didn't quite draw blood, but left a nice dent in my hand, and stung for a while....

[Boulderer]

You should set yourself up giving HSE demonstrations ... sounds like they'd but much more exciting than the usual photos and death by PowerPoint