play in the main gear /hub

[joliecoeur13]

After some issues with my sk720 I finelly spooled this 6hv up , not so smooth... then noticed the main gear has some play up and down ? is that normal ?
the bearings seem ok , the inner sleeve could be worn I guess , do you bguys use any shims between the main and tail drive gear ?
and finelly do you run the gear?pinion mesh tight or on the loose side?
cheers

[alexmit]

I noticed that after around 100 flights the autorotation sleeve allowed for up and down play on the main gear. Mine was a little more excessive than I liked so I just ordered a new sleeve and it went back to a tolerance I felt good about. It seems that the pressure of the one way over time compressed the sleeve and the sleeve got a little taller as a result. I run my gear mesh somewhere between medium and tight if that makes any sense.

[joliecoeur13]

Originally Posted by alexmit

I noticed that after around 100 flights the autorotation sleeve allowed for up and down play on the main gear. Mine was a little more excessive than I liked so I just ordered a new sleeve and it went back to a tolerance I felt good about. It seems that the pressure of the one way over time compressed the sleeve and the sleeve got a little taller as a result. I run my gear mesh somewhere between medium and tight if that makes any sense.

thanks , that's what I figured, I ordered a sleeve hopefully it will run smoother....

[Jeff_Barrett]

Let us know how it turns out. What difficulties did you have with the SK720?

[joliecoeur13]

Originally Posted by Jeff_Barrett

Let us know how it turns out. What difficulties did you have with the SK720?

well when I spooled it up it sounded more like a lawn mower then a E heli !! way too much vibration for the sk 720 ... so hopefully after changing that sleeve it will be ok .
that's what you get by bying a used heli I guess

[Jeff_Barrett]

EEK! That would definitely be a bad thing!

Let me know how it goes!

[joliecoeur13]

well the saga continues !! I replaced the sleeve and also the main gear ( since the one it came with was a bit worn) and STILL bad vibration somewhere , the motor runs smooth when not engaged but when it's running the main gear it has vibrations , even without the head on, my sk720 is flashing !!! WTF

what else can I do ? pinion?

[Larry227]

Have you checked the motor bearings?

[Jeff_Barrett]

Have you eliminated the tail as a source of vibration?

I would remove the tail rotor blades first, and if there's still no love, try removing the belt from the pulley as well.

How do you have your SK720 mounted?

Larry also made a great suggestion with regards to your bearings (both motor and main shaft).

[joliecoeur13]

I did change the motor bearings (all 3) and main shft bearings , the ones I have not changed is the main gear bearings , that was my next step .
Vibration are coming from drive train , almost no vibs on the tail boom at all.

I tried different mesh with the pinion , tighter is abit better still no good , do the pinion wear ? I imagine these sound loud because of the M1 gear ?

thanks for helping out

[joliecoeur13]

have a look and see if this sounds like yours at all !!

can a worn out pinion sound like this?

[ame]http://www.youtube.com/watch?v=RFTg35Ntf0c[/ame]

[Jeff_Barrett]

Almost sounds like the main gear or pulley is rubbing on something.

Check the tail belt guide pulley bearings ... is there any up and down play on the main shaft??

[Dave Ketelhut]

are you measuring the vibes from how it sounds and feels. or from the logs from the skookum. i see its mounted on something. if i was you i would get rid of all of that and just mount the skookum to the gyro tray with gray 3m tape. that will give you tons of vibes.

[Danlb0y]

I have had the same concerns on the main gear. I have a belt cp v2 with upgraded electronics and found that there was to much up-down slop on the main shaft causing pitch issues and in-flight problems with the main gear moving up and engaging the drive gear at about half bite putting extreme pressure on the main gear because the ten tooth gear of the motor is not inline for a full bite. Long story short, I carefully drove the one-way bearing up to take up the slop and now the motor gear stays fully engaged under lift condition. The problem is now one of a design flaw. There should be a thrust bearing there instead of shimming it ore pushing the one-way bearing up to take up the slack.
I am and engineer by trade so I know enough to be dangerous.
I hope this addressed some of your issue?

[joliecoeur13]

Originally Posted by Dave Ketelhut

are you measuring the vibes from how it sounds and feels. or from the logs from the skookum. i see its mounted on something. if i was you i would get rid of all of that and just mount the skookum to the gyro tray with gray 3m tape. that will give you tons of vibes.

I think I know enough now , I can tell just by looking at it !! too much harsh vibs to even consider flying it ...
thanks for the reply I will check some of these items

[joliecoeur13]

So I narrowed it dowm to the motor , has almost as much vibration with the main gear removed !!! (just the motor running), I would guess it's the main shaft , looks worn where the bearings sit .
That's a tuff one with this motor , buy the can/shaft for $69 or a new motor for $99 some places....
I did just buy a Xera 4025-560 should be good for this heli I suppose...

[TallPaul]

I've had my skookum point at the motor for my atom 500 for vibrations. I wonder if the issue is the motor, a poorly designed motor mount, or problems reading the skookum correctly?

[joliecoeur13]

The vibs on mine are really exessive even with a MB you would have serious issues ...
I ordered a new shaft/can so hope it will go away...
I have also learned that some motors are just better balanced then others my NEU and Hacker motor are so smooth
Coming from a LOGO user I can tell you a carbon frame is problematic just looking at how the vibration travel all the way down the boom... the LOGO plastic frame ROCKS , may just stick with them...

[alexmit]

Keep an eye on the counter-bearing that sits over the top of the pinion. It should be set in the housing with green thread lock, then insert the motor shaft into the bearing with a little dab of green thread lock. The counter bearing wears quickly and easily if it is not locked in place and in turn wears the motor shaft where it meets the counter bearing and in the motor bearing closest to the pinion. I know this as I now have 1 motor that is destroyed from just such a situation, and one on the bench that needs have the shaft replaced. The destroyed motor had 100 flights on it. The latter one had heavy wear on the motor shaft near the bearing that sits under the pinion. My best recommendation is to replace the counter bearing every 50 or so flights. The other option is to buy higher quality bearings for the motor and counter bearing.

Another thing I noticed is the elaborate mount under your skookum. I don't think that could ever perform properly with that much dampening under it. Look up "milton mod" and see how that works for you. Most only run 2 pieces of the Parma, or clear 3M tape (maybe with the metal plate) and then strap it down with the milton mod. Excessive tape stacking only hides an issue that keeps a fbl controller from performing to its full potential.

[joliecoeur13]

Originally Posted by alexmit

Keep an eye on the counter-bearing that sits over the top of the pinion. It should be set in the housing with green thread lock, then insert the motor shaft into the bearing with a little dab of green thread lock. The counter bearing wears quickly and easily if it is not locked in place and in turn wears the motor shaft where it meets the counter bearing and in the motor bearing closest to the pinion. I know this as I now have 1 motor that is destroyed from just such a situation, and one on the bench that needs have the shaft replaced. The destroyed motor had 100 flights on it. The latter one had heavy wear on the motor shaft near the bearing that sits under the pinion. My best recommendation is to replace the counter bearing every 50 or so flights. The other option is to buy higher quality bearings for the motor and counter bearing.

Another thing I noticed is the elaborate mount under your skookum. I don't think that could ever perform properly with that much dampening under it. Look up "milton mod" and see how that works for you. Most only run 2 pieces of the Parma, or clear 3M tape (maybe with the metal plate) and then strap it down with the milton mod. Excessive tape stacking only hides an issue that keeps a fbl controller from performing to its full potential.

that's great info thanks , maybe not such a good motor after all...
I did notice that the smaller bearing inside the motor fits pretty loosely , I guess that's what it comes down to , you need very tight tolerence to get a smooth running motor ...
Looking at Boca bearings would you know wich type is good for a motor ?