Rotor wobble

otherhalf2 · 07-11-2012, 11:30 PM

I have a KDS 450QS. The blades took a wack damaging them as well as the rear servo. I have replaced the blades, rear servo and main shaft but there is still a slight wobble at slow speed. This tends to disappear as I power up but notice that the rear servo is starting to randomly jump. The swash plate is balanced. Can anyone suggest what I sould look for/replace next. The new blades are only FG and they seem to be balanced OK.

chingie · 07-12-2012, 06:03 AM

Don't quote me on this but perhaps the feathering shaft in the head is bent and or the little collars in there etc failing that check it all over again did you balance the blades also? cheers and good luck ,

chingie · 07-12-2012, 06:16 AM

Sorry you did mention the blades were balanced, I understand the bearings can sometimes be damaged also in crashes causing vibrations etc so maybe check those and as if it couldnt get any worse if the main frames get damaged it is possible that the main shaft although new wont be aligned correctly due to bearing misalignment, sounds like it is in the head though to me (i'm no expert) as its noticeable to you only suggestions tho. Also check out the videos on set up in finless techroom on this site you might be able to spot it there?! Happy fixing thats what i'm doing as got my heli second hand so dont know how it flew before previous owner crashed it. Doing a full rebuild there are currently no screws or anything on the frames and awaiting a decent cache of parts cheers

otherhalf2 · 07-12-2012, 02:45 PM

Thanks for that. I'll probably replace the feathering shaft next although it looks straight. Bearings hmmm sounds tricky but I'll take one step at a time till I solve it.

otherhalf2 · 07-15-2012, 07:46 PM

Solved my problem and it was as simple as having the blades too tight. I guess it's a bit like making the power is turned on.

chingie · 07-16-2012, 06:08 AM

Cool nice to find out these things by yourself that way you get to know what does what aka learning stuff, ashamedly i was experiencing an out of control heli 3 channel. It was spinning fast in one direction and nothing i did on the TX had any affect. I rebuilt the whole thing checking everything meticulously and still it would just spin on the ground out of control. Last but not least i rotated the whole tail 180 degrees just to see what would happen and it flew!!!!! I reakon tail motor (brushed) short circuited and reversed due to melting wires !!!!!! Cheers and well done

asker857 · 11-03-2012, 01:29 AM

"It was spinning fast in one direction....".

This too can happen with a 6 channel 450. A "reversed" gyro is a possible cause. When it does, flip the REV switch on your gyro case and see if it goes away.

07-11-2012, 11:30 PM	#1
otherhalf2 Registered Users Join Date: Jun 2012 Location: New Zealand	Rotor wobble I have a KDS 450QS. The blades took a wack damaging them as well as the rear servo. I have replaced the blades, rear servo and main shaft but there is still a slight wobble at slow speed. This tends to disappear as I power up but notice that the rear servo is starting to randomly jump. The swash plate is balanced. Can anyone suggest what I sould look for/replace next. The new blades are only FG and they seem to be balanced OK.

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07-12-2012, 06:03 AM	#2
chingie Registered Users Join Date: May 2012 Location: NEW ZEALAND	Don't quote me on this but perhaps the feathering shaft in the head is bent and or the little collars in there etc failing that check it all over again did you balance the blades also? cheers and good luck ,

07-12-2012, 06:16 AM	#3
chingie Registered Users Join Date: May 2012 Location: NEW ZEALAND	Sorry you did mention the blades were balanced, I understand the bearings can sometimes be damaged also in crashes causing vibrations etc so maybe check those and as if it couldnt get any worse if the main frames get damaged it is possible that the main shaft although new wont be aligned correctly due to bearing misalignment, sounds like it is in the head though to me (i'm no expert) as its noticeable to you only suggestions tho. Also check out the videos on set up in finless techroom on this site you might be able to spot it there?! Happy fixing thats what i'm doing as got my heli second hand so dont know how it flew before previous owner crashed it. Doing a full rebuild there are currently no screws or anything on the frames and awaiting a decent cache of parts cheers

07-12-2012, 02:45 PM	#4
otherhalf2 Registered Users Thread Starter Join Date: Jun 2012 Location: New Zealand	Thanks for that. I'll probably replace the feathering shaft next although it looks straight. Bearings hmmm sounds tricky but I'll take one step at a time till I solve it.

07-15-2012, 07:46 PM	#5
otherhalf2 Registered Users Thread Starter Join Date: Jun 2012 Location: New Zealand	Solved my problem and it was as simple as having the blades too tight. I guess it's a bit like making the power is turned on.

07-16-2012, 06:08 AM	#6
chingie Registered Users Join Date: May 2012 Location: NEW ZEALAND	Cool nice to find out these things by yourself that way you get to know what does what aka learning stuff, ashamedly i was experiencing an out of control heli 3 channel. It was spinning fast in one direction and nothing i did on the TX had any affect. I rebuilt the whole thing checking everything meticulously and still it would just spin on the ground out of control. Last but not least i rotated the whole tail 180 degrees just to see what would happen and it flew!!!!! I reakon tail motor (brushed) short circuited and reversed due to melting wires !!!!!! Cheers and well done

11-03-2012, 01:29 AM	#7
asker857 Registered Users My HF Map location Join Date: Mar 2011 Location: philippines	"It was spinning fast in one direction....". This too can happen with a 6 channel 450. A "reversed" gyro is a possible cause. When it does, flip the REV switch on your gyro case and see if it goes away.