Vbar Analysis of new Hirobo Embla motor, anybody care to have a quick look at this?

[maddog7]

Hi all,
I excitedly bought a new Hirobo Embla in the FL Haloween sale.
I went to test it yesterday and it was aweful despite having a silverline Vbar fitted which I bought with it.
It was overcorrecting and unstable and I struggled to get it back on the deck.

Before I maidened I did run it up on the bench and it vibrated pretty badly but I wondered if it was just some resonance from the lack of load. :-! (how stoopid am I!)

Anyway after poking about I've traced the issue to the motor itsself which is the kit motor. It took some doing, not least because the motor was the last thing I suspected for so much vibration and the maingear wobbling a bit threw in a bit of a red herring. I could see white dust coming away from the main gear as the pinion battered it to death.

I decided to give the Vbar Analyser a go and installed the motor into the airframe without the pinion attached. When I spun it up it seemed like the motor was pretty badly out of balance since the heli would move around on the bench and the cable detached itsself from the Vbar.
I did manage to get one run in and have attached the analyser trace for y'all to have a gander at.

Does this seem extreme to you all?
Remember this is just the motor in the airframe, no pinion, it's not connected to the drive train at all.

[milly0812]

Vbar Analysis of new Hirobo Embla motor, anybody care to have a quick look at this?

I did my 600 last night with all but blades on and highest was 200 I thought that was bad ?

[maddog7]

It's so loud and spinning at 30,000 rpm that I get a bit nervous just doing the test!

[milly0812]

Vbar Analysis of new Hirobo Embla motor, anybody care to have a quick look at this?

I'm not experienced with the vibe thingy but have you strapped the vbar down ? I noticed a big reduction in vibes just pushing down on the sensor whilst the test was running ;-)

[maddog7]

I havn't, yet.
I will when I've sorted the motor out, I just wanted some idea of order of magnitude. If the entire drivetrain of your 600 only scores 200 vibration points and my 450 motor spinning on it's own scores 440 I'm guessing I'm gonna have to return the motor?

I've also tried putting a tiewrap around it to isolate the light side and in a certain position its really much improved but I have no way of being able to add anything to it to balance it since theres barely a mm clearance between the can and the frame sides. :-( apart from that I'm not sure I'd trust whatever I did manage to attach not to come off at 30,000 rpm.
D

[VOLT]

any balancing is done inside the can " ON BIG MOTORS", use plastic steel "2 Part Putty" ive used it with success to hold stripped spark plugs in so it can handle the heat no problem...if you have an Iphone/pad you can download any seismometer app and it will work ..just use a bigger cable tie or even 2 to find the spot where the motor runs smoothly and open the motor and put some plastic steel putty in between the magnets in the same spot you found with the cable ties "LIKE IN THE VID"

you can get it really smooth!

Have Fun!

do it with the pinion on for better dynamic balancing

[helimadness]

I have tried to track down vibes before and was told by the vbar experts tHat motor vibes are was above the analyzers range so just show up as grass at the bottom of the page. So if the grass is tall motor vibes are bad. My 500 will spool up without moving on the bench.
Milly0812 when you say strapping down the sensor do you mean the main vbar unit or the small remote sensor. I watched mr mels vids on vibes and he strapped down the main unit not the remote sensor in his test. Makes me think the gyro sensors must be in the remote unit but the accelerometers in the main unit?
Cheers

[maddog7]

Volt,
I did actually try the tie wrap thing but I didn't know about putting plastic steel INSIDE the can. I even have some already in the garage.What a good idea. There would not have been enough clearance to put anything on the outside and looking as best I could without disassembling the motor, at the drum the gaps between the magnets didn't look very big and it took a large tiewrap and a half to get it somewhere close.

I actually have a similar but different method I've used up to now to balance motors. It's a little more elaborate but probably not as good as the phone method!

I bolt the motor to the end of a piece of hardwood approx 18"x1"x1" with a mirror at 90 degrees to the motor on the same end, then put the other end in a vice attached to my desk. I put a Laser level on a box pointing at the mirror and where the reflection hits the wall I stick a piece of white paper. Mark 6 points on the motor, use the tie wrap and try each point. the length of the blur of the reflected pointer shows the level of vibes. It significantly reduced the vibration in the video I got from my tricopter.

Can't help feeling the phone method will be even more accurate!

Anyways, I was so concerned with the violence of the vibes, I sent the motor back to FL. I Hope they'll be cool as normal.

[maddog7]

I have tried to track down vibes before and was told by the vbar experts tHat motor vibes are was above the analyzers range so just show up as grass at the bottom of the page. So if the grass is tall motor vibes are bad. My 500 will spool up without moving on the bench.

helimadness,
Thanks for the help. I thought it a little weird that the motor was 3700 kv and on 3s the highest the vbar analyser went to was 30,000 rpm with no load. I presume that's what the Vbar dudes mean?

Thing is, in my attached piccie, the only thing moving in the whole heli was the motor so everything on the analyser was caused by the motor.
:-)
D