Motor Balance Methods?

[Busher]

Originally Posted by A VIKING

Just a photo of the arrangement I have on my motor for dynamic balancing of the motor can.
The epoxy drops were placed on the can with a tooth pick that had been cut cleanly in two then dipped in the epoxy for the application to the can.
The tooth pick allowed consistent application and would also allow an easy increase or decrease of the applied epoxy.
The center drop has been applied to the metal of the can with the paint removed to see if it would stick longer or maybe for a shorter period of use.
So far so good, we'll see how long it can hang on.
Motor vibe levels still holding at a low level.

Just a thought here, some of the devcon epoxies are metal types and are silver in colour, these epoxies are rated at much higher temps and really stick quite well to metal. Perhaps these would work better for the heat generated on the motor can if the 5 min epoxy does not work.

I also like the wired motor bolts they remind of the bikes that were prepared for production racing in my younger days, but on that point is it possible that the wire itself could set up a harmonic vibration rather like a guitar string and in fact increase the amount of vibration you have?

[TBur]

Gona share this , hopefully successful story, as I've been in the vibey motor doldrums all too often in the past and didn't see a way forward.

Got a bran new motor for my 6hv from a HF member. Was showing vibes around 3 on bench with no gear train . Tried taping but the vibes were not even close to consistent from one spool to the next. Ordered 2 abec7 bocas, ($24) put em in, vibes now around 5, but responding as one would expect to taping

Rainy Saturday and inspired by others here in the forum I decided it was time to step beyond taping and put epoxy inside the can to balance it. (I will order the putty for next time, no doubt..).

Here is the results running on bench with full drive train (no blades) @ 2150 headspeed.


update: looked at 6 flight vibe logs, at worst I got ~ 2 at motor frequency

[A VIKING]

Originally Posted by Busher

Just a thought here, some of the devcon epoxies are metal types and are silver in colour, these epoxies are rated at much higher temps and really stick quite well to metal. Perhaps these would work better for the heat generated on the motor can if the 5 min epoxy does not work.

I also like the wired motor bolts they remind of the bikes that were prepared for production racing in my younger days, but on that point is it possible that the wire itself could set up a harmonic vibration rather like a guitar string and in fact increase the amount of vibration you have?

So far so good with the 5 min epoxy.

...and that would be no on the safety wire causing the harmonic.
I had the harmonic before converting to safety wire.
It didn't change after the safety wire addition.

[Busher]

Good news all round then

[A VIKING]

The motor vibs are still low and the epoxy weights are still holding fast.
This after 10 flights with 135 degree motor temps.
My fingers are still crossed.

[A VIKING]

Just some Gee Whizz info on the 5 min. epoxy used for balancing my motor can.
Just passed through 30 flights and the three drops of epoxy are still stuck fast to the can. They may last much longer than I thought.

Anyway greetings to Omer and Georgi, I am happily flying the SK720BE and reviewing my logs, all vibs remain low.

[georgi UK]

=] Greetings also Martin! is it a state of paranoia to keep checking the epoxy?!

[A VIKING]

Originally Posted by georgi UK

=] Greetings also Martin! is it a state of paranoia to keep checking the epoxy?!

Not at all Georgi!
It's a state of curiosity.

[georgi UK]

Originally Posted by A VIKING

Not at all Georgi!
It's a state of curiosity.

=] same thing, different way to say it!!!!

[omerco]

Martin you sure enjoy the whole package

[A VIKING]

Yes I do, every bit of the SK720BE is a useful tool.
I enjoy it all.
It just takes a little imagination on how it can improve your ship and flying abilities.

[rs2k]

Once I found the sweet spot for a single zip tie, I put a second one on to fine tune it. You slowly rotate them in opposite directions at equal distances from the sweet spot until you get the smoothest action from your motor. I found that much easier than trying to add or remove weight.

I ran up the motor 10 times at about 5 seconds each with the two zip ties in different spots and recorded the distance of each zip tie from center then checked the SK720 logs. I set the zip ties to the run that came out the smoothest. Just under 1 for me on my wobbly 600MX motor.

Now if only getting the rest of the vibes out my my heli were that easy.

[A VIKING]

Originally Posted by rs2k

Once I found the sweet spot for a single zip tie, I put a second one on to fine tune it. You slowly rotate them in opposite directions at equal distances from the sweet spot until you get the smoothest action from your motor. I found that much easier than trying to add or remove weight.

I ran up the motor 10 times with the two zip ties in different spots and recorded the distance of each zip tie from center then checked the SK720 logs. I set the zip ties to the run that came out the smoothest. Just under 1 for me on my 600MX motor.

I was impressed with my epoxy drops hanging on at 21,000 RPM.
The zip tie thing warps my mind.
Do you have a photo?

[rs2k]

The light spot on the motor is in between the two zip ties. One zip tie wasn't enough and two were too much, so spreading two apart has the same result as lowering the weight on that one spot.

[A VIKING]

Originally Posted by rs2k

The light spot on the motor is in between the two zip ties. One zip tie wasn't enough and two were too much, so spreading two apart has the same result as lowering the weight on that one spot.

That's awesome. Thanks!

[A VIKING]

Just a last follow up note with my experimenting with 5 min. epoxy drops applied to the motor can for balance.
The epoxy is still holding strong after 50 flights with motor temps ranging from 120 to 150 degrees. Motor vibes remain low and unchanging.
See post 30 for a photo of what I did.
To start, a small square of clear packing tape is applied to the can to determine the balance point as indicated by the SK720BE followed by removal of the tape and cleaning of the can with rubbing alcohol then apply the 5 min. epoxy one drop at a time at the same location as the tape until balance is achieved.
Use a wood tooth pick cut in half and use the flat end to apply the epoxy. Make sure you lay the ship on it's side to apply the epoxy which will prevent the epoxy from running down the side of the motor can before it can harden. This technique will create a smooth perfect shape to the epoxy as in the photo.

I will only update this post again if the epoxy does sling off one day but it looks like that may never happen.

[CZorzella]

Thanks for sharing your experiment.

[A VIKING]

Originally Posted by A VIKING

Just a photo of the arrangement I have on my motor for dynamic balancing of the motor can.
The epoxy drops were placed on the can with a tooth pick that had been cut cleanly in two then dipped in the epoxy for the application to the can.
The tooth pick allowed consistent application and would also allow an easy increase or decrease of the applied epoxy.
The center drop has been applied to the metal of the can with the paint removed to see if it would stick longer or maybe for a shorter period of use.
So far so good, we'll see how long it can hang on.
Motor vibe levels still holding at a low level.

Back on post 30 of this thread I did an experiment using 5 min epoxy as weight for balancing a small vibration with my motor.
I am happy to say the epoxy is still hanging on, a little bit yellow in color now but stuck fast.
So after scores of flights and 150 degree engine temps the epoxy is being very impressive.
Motor vibes continue to be low.

[Busher]

Thanks for keeping us up to date,

As a side note I now take more notice of motor vibes and now have at least 2 methods of balancing them. It's all good Info..

[CZorzella]

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