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Old Jun 11, 2008, 07:10 PM
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Changing out a HBK2 main shaft

New spindle shaft, new blades and I still can't get the blades to track properly. I think it's time to replace the main shaft. Maybe someone can refer me to a thread showing the easiest way to approach the change out or just describe how to do it in the simplest most efficient way. I'm lazy and don't want to remove, loosen, or disconnect anything more than necessary (the old
kiss principle).
Thanks for your help,
Don
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Old Jun 11, 2008, 07:33 PM
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If it doesnt wobble or have a vibration.....Its prob, not the shaft......Though it may be.
have you balances the blades good and make sure your flybar paddles are setup well and blanced? They throw it off to........Sometmes the blades wont track it there warped at all.......other times they wont track because they need a 1/4 turn instead of half.......

Other wise just remove the 2 allen bolts tha go through the shaft, Upper and lower........Disconnect the linkages from the swash and slide the head off assembled......... Jiggle th e shaft around and pull the pin out by the belt pully.....Oh and loosen the belt........ Slide that puppy out........... i think I got it all : )

Its fairly easy.........Jsut stare at it and only disconnect what ya have to..........Just in case I missed somthin
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Old Jun 11, 2008, 07:57 PM
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watch this, its about the 43t upgrade but you have to remove the shaft too, its around 5min into it
http://www.youtube.com/watch?v=uET6j...CFE327&index=3
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Old Jun 11, 2008, 08:50 PM
dze
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getting the shaft out is easy .. just pop off your blades .. disconnect your servo linkages .. take the screw out of the bottom of the shaft and pull up on the head enough to get the pin out of the belt gear .. now theres only one screw left at the top .. dont let the belt come off the gear just leave it sitting .. there as your working so it doesnt get out of whack and twisted .. asembly is reversed just tighten the collar at the top bearing last after u remove play ..like jst was saying though the tracking may be somthing else .. even the blades themselves either out of balance or not straight ..
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Old Jun 12, 2008, 09:19 AM
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I replaced the blades with new ones that I dynamicly balanced. Also replaced the spindle shaft with a new one. When I spin up the blades they stay in one plane initally then as rpm increases they separate by as much as 3/8 inch. I've never seen that much separation between the blades on spool up. I have tried adjusting the high blade down to a lower plane and normally I would get a proportional response, but in this case the response is unpredictable. One thing I noticed is alot of slop in the head-I guess it's just wear on the plastic parts- don't know for sure.
These new blades weigh the same and are straight and balanced.
Nuttcaze, thanks for the video clip and Jstcriusen and Dze thanks for your disassembly walk through. It makes things much easier for me.
Appreciate the help,
Don
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Old Jun 12, 2008, 01:49 PM
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http://www.heliguy.com/Forum/guide-h...replac%2A.html is a great pictorial of changing belt/boom/main shaft. You need to sign in but its worth it.
Don't lose the pin just above the pulley OR the brass spacer just below the pulley.
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Old Jun 12, 2008, 04:32 PM
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Quote:
Originally Posted by dicharry
I replaced the blades with new ones that I dynamicly balanced. Also replaced the spindle shaft with a new one. When I spin up the blades they stay in one plane initally then as rpm increases they separate by as much as 3/8 inch. I've never seen that much separation between the blades on spool up. I have tried adjusting the high blade down to a lower plane and normally I would get a proportional response, but in this case the response is unpredictable. One thing I noticed is alot of slop in the head-I guess it's just wear on the plastic parts- don't know for sure.
These new blades weigh the same and are straight and balanced.
Nuttcaze, thanks for the video clip and Jstcriusen and Dze thanks for your disassembly walk through. It makes things much easier for me.
Appreciate the help,
Don
I doubt the shaft is going to fix it.........If you want to shoot for perfect try the extreme turnbuckles from ushobbysupply........

Even then though they may change through out the rpm range. Some blades are perfect ,others ya just cant get right........Maybe its flex in the blades is all I can figure..........When theres more forces and variable lifts applied they flex differenttly...........Thats my opinion any ways.........

I track them at hover with a fresh battery and forget aboutit........I figure when there spinning there fastest is when you want them tracking good.........
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Old Jun 12, 2008, 11:29 PM
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Well s...!!! I knew I had problems when I pulled the old main shaft and it looked to be perfectly straight- rolled smooth across the desk top and spun true after chucking it up in the drill. I went ahead and replaced it with a new one but I've got the same problem- at 10 to 15% throtle the blades track true but as rpm increases to about
25% the separation becomes dramatic and sudden. It can't be the blades because this time I took them off of my other HBK2 where they track true through the full range. The center holder and inner shaft area of this head seem to be looser and have more play than my other HBK2. The paddles can be moved back and forth and wobbled around very easily and you can see all the movement in the center holder group. I'm to the point that all I can think of is rebuilding the center holder group and hope that solves the tracking problem. If anybody has another suggestion, believe me, I'm open.
Thanks,
Don
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Old Jun 12, 2008, 11:31 PM
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If you crash, check the seesaw bearing holder, if the tiny bearing holder where the screw goes in is broken, you'll never be able to track the blades.
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Old Jun 13, 2008, 12:06 AM
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If you cant find anything borke and they track within 3/8 of a inch I wouldnt rebuild it until the next major pile up...........You know how it goes, Fix it,get it perfect.......Then Crash...........back to step 1..............

If your willing to rebiuld it..........fly it like ya stole it............
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Old Jun 13, 2008, 08:04 AM
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Estarter, I think that bearing holder may be the problem because the screws (#022 in the HBK2 manual page 13 ) seem loose and will not tighten down. It just turns without ever tightening. That area, where the flybar holder ties into the inner shaft (part #023) is where you can see the wobble and looseness when you manupulate the paddles.
Thanks,
Don
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Old Jun 13, 2008, 09:23 AM
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its a possibility...........Those screws tend to srtip easily too,or shall I say......I had 2 stripped from the factory.......Also if its broke it gives you the feeling of it being stripped.

You'll know as soon as you go to take it apart.....If its broke the screw wont just come out...........It'll need a little tinkering as the nub will just spin on you.........
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Old Jun 13, 2008, 10:14 AM
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Quote:
Originally Posted by dicharry
Estarter, I think that bearing holder may be the problem because the screws (#022 in the HBK2 manual page 13 ) seem loose and will not tighten down. It just turns without ever tightening. That area, where the flybar holder ties into the inner shaft (part #023) is where you can see the wobble and looseness when you manupulate the paddles.
Thanks,
Don
Yes, this happens to me. This is probably my most broken part. If the screws don't tighten, you need to replace the seewaw holder. This will cause hell for blade tracking.
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Old Jun 13, 2008, 11:34 AM
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Depending on the damage, a small amount of CA on the pivot screw threads will also do the trick. Just be careful that you don't glue your flybar into the seesaw.

FWIW, I found that the screws in the replacement hardware kit (ek1-0302) were 0.35mm longer than stock, which gives them another turn of thread to bite into the seesaw. This could be random parts variation though.

-Jeff
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Old Jun 13, 2008, 06:59 PM
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I had 35+ crashes on my k2, mostly from inverted flights. Luckily, I never bent the main shaft, the spindle always bent, sometimes broken blades, head parts and .....
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