A few of you may have seen my post about the vibration problems that I'm having with my Assault 700 in an other thread.

Here's a video how the vibration. The only thing spinning is the Align 700MX, the main gear has been removed.

Assault 700 Vibration Issue (0 min 42 sec)

I guess my question is how much vibration is normal from just the motor? Does it look like I bought a bad motor?

Any input would be greatly appreciated.

Align motors can be problematic and out of balance new, but its impossible to tell what is really going on on without the capability to log different vibe frequencies in flight. Some high end FBL controllers can do this and the particular frequency tells us exactly what part has the vibe.

With that being said, I noticed the FBL wires appear to be bundled and zip tied close to the unit. This is a non no, and will transmit high frequency vibes into the unit. You want the wires leaving the unit to be loose and free for an inch or so with nothing touching them. Servo wire covering can make this issue really bad, especially if used all the way up against the plug as it makes the wires more rigid

Also note that your motor is turning much higher RPM in that demo than it ever would in flight. Once fitted against the gear and with blades on, the vibe frequency will be dampened and changed completely. The mass of the blades completely changes the vibe frequency. This means that what you are experiencing while doing this demo test means nothing, as it wont be the same while in flight. Doing any run up with the heli sitting on a solid object will also pass high frequency vibes back up through the skids into the frame and will change things.

Start with the basics, and make sure the main and tail blades are properly balanced. Its not good enough to just have the same weight. They must be static and dynamically balanced with the same COG. Cheap blades may be the same weight, but have the weight distributed in different places along the blade, and his will cause vibration.

Low grade bearings with poor tolerances can also cause high frequency vibrations where they fit the main shaft and anywhere else spinning on the heli with more slop than they should have. You will never be able to feel this by hand spinning them, but they will appear at high RPM. Some FBL units are vibe tolerant and can deal with this, but others not so much and the lower quality fitment of things will come though. These are the things that cant be seen and may not be noticed, but wreak havoc on the moving parts like a high frequency dental tool. This difference in tolerances is why some clone parts that appear to be nice pieces will sometimes fail early or in flight for no reason compared to higher spec stuff.

Align PU gel or the green Zeal gel is the best stuff for isolating vibes from a FBL unit, although its always best to find the source rather than just isolate the FBL unit from it. FBL units may also be bothered by one frequency of vibe, but not so much another frequency. You can put a heavier metal material plate between the gyro and the heli, and this mass will change the frequency reaching the FBL unit or filter it out all together. Skookum sells a couple mm steel plate for this exact application, or you could fab something up yourself. http://www.helidirect.com/skookum-an...it-p-22097.hdx

I saw in your other post that you say the heli tail was bobbing up and down. Note that this is also a sign of head speed being too low, or main blades too tight. Rigid head dampeners or lack of grease on the head dampeners can also cause this, so there are a few easy mechanical things to check to see if this solves the bobbing issue.

Good luck

The tail bobbing up and down is probably the tail shaft . On my 700 brand new , the shaft was slightly bent . I thought they were the tail blades out of balance but they were perfect . Slow turning the tail shaft showed a slight wobble , replaced it and it was perfect after that .

I've had motors with the can out of balance, which I've been able to improve by adding weight, in the form of clear tape (Scotch "Magic" tape) That works well on a smooth can, but unfortunately your Align motor has cooling fins. Once I find the spot around the perimeter of the can that benefits from added weight, I mark it with a paint pen, which makes it easier to experiment with adding or reducing the weight to achieve the best balance. You might just be able to get tape to stick, otherwise you might sand or file down the cooling fins on the opposite side of the can. It's a tedious process, but you can reduce the motor vibes significantly. The high frequency vibes you get from an out of balance motor seem to be the ones that can cause bolts to back out. The imbalance is likely caused by variation in the amount of glue (epoxy) used to fix the magnets to the can.

As for the suggestion that your motor is running much faster unloaded than it will in the heli in flight - there isn't actually that much difference, usually only up to 15% or so.

Just balance the motor using the cable tie method. Put a cable tie on the motor and spin it up with the coin as you have done already. Move the cable tie around the can till you get the sweet spot where there is less vibration.
There is no point in putting tape on the can with the fins and also when is gets hot the tape can fly off.
If you do no want a cable tie on your motor still go ahead and use one to find where you need to put it, then take the can off and put some epoxy or hot glue or something between the can magnets on the inside to add weight at the same spot as the cable tie was.
I have done this to a similar 700 motor on an aerial rig and it ran really smooth after that. It also adds more life to your motor bearings. Look up motor balancing with cable tie or something like that on You Tube.
All this is a 10/15 minute job and should be done to EVERY motor. IMO!

Wish I'd hear of the cable tie method before I started fooling around with tape! although the tape works well on my 450 size motors....

I have tape on 6 of my Hex motors but the cans a smooth. I used the lazer pointer method which I find is more accurate. Sorry I forgot to mention that method in my other post! I also have used phone vibration apps but the lazer is better and a lot quicker.
Simply put the motor on a flexible mount like a long piece of wood or metal ( or in my case just leave it on the multicopters arm ). Then hard mount the lazer beside the motor and point it so is shines on a wall around 10 or so feet away. Spool it up and you will see the lazer dot vibrate. Add tape or cable tie and watch lazer. Move it around until the lazer becomes a red dot when motor spins which means it is balanced. I did this with the Hex and then added the props and balanced the props on the motor. Works great. A lazer pointer would be around 5 bucks on ebay.

gonna have to try that method too, it takes away the subjective aspect!

But it's laser - Light Amplification by Stimulated Emission of Radiation... someone must have spent hours thinking up that acronym!

Funny how I actually know what it stands for and I still could not spell it!

How about radio direction and ranging....

Originally Posted by Xrayted

Align motors can be problematic and out of balance new, but its impossible to tell what is really going on on without the capability to log different vibe frequencies in flight. Some high end FBL controllers can do this and the particular frequency tells us exactly what part has the vibe.

With that being said, I noticed the FBL wires appear to be bundled and zip tied close to the unit. This is a non no, and will transmit high frequency vibes into the unit. You want the wires leaving the unit to be loose and free for an inch or so with nothing touching them. Servo wire covering can make this issue really bad, especially if used all the way up against the plug as it makes the wires more rigid

Also note that your motor is turning much higher RPM in that demo than it ever would in flight. Once fitted against the gear and with blades on, the vibe frequency will be dampened and changed completely. The mass of the blades completely changes the vibe frequency. This means that what you are experiencing while doing this demo test means nothing, as it wont be the same while in flight. Doing any run up with the heli sitting on a solid object will also pass high frequency vibes back up through the skids into the frame and will change things.

Start with the basics, and make sure the main and tail blades are properly balanced. Its not good enough to just have the same weight. They must be static and dynamically balanced with the same COG. Cheap blades may be the same weight, but have the weight distributed in different places along the blade, and his will cause vibration.

Low grade bearings with poor tolerances can also cause high frequency vibrations where they fit the main shaft and anywhere else spinning on the heli with more slop than they should have. You will never be able to feel this by hand spinning them, but they will appear at high RPM. Some FBL units are vibe tolerant and can deal with this, but others not so much and the lower quality fitment of things will come though. These are the things that cant be seen and may not be noticed, but wreak havoc on the moving parts like a high frequency dental tool. This difference in tolerances is why some clone parts that appear to be nice pieces will sometimes fail early or in flight for no reason compared to higher spec stuff.

Align PU gel or the green Zeal gel is the best stuff for isolating vibes from a FBL unit, although its always best to find the source rather than just isolate the FBL unit from it. FBL units may also be bothered by one frequency of vibe, but not so much another frequency. You can put a heavier metal material plate between the gyro and the heli, and this mass will change the frequency reaching the FBL unit or filter it out all together. Skookum sells a couple mm steel plate for this exact application, or you could fab something up yourself. http://www.helidirect.com/skookum-an...it-p-22097.hdx

I saw in your other post that you say the heli tail was bobbing up and down. Note that this is also a sign of head speed being too low, or main blades too tight. Rigid head dampeners or lack of grease on the head dampeners can also cause this, so there are a few easy mechanical things to check to see if this solves the bobbing issue.

Good luck

The bundle of wires is just the esc wire, but it was resting on the other wires. I'll move it and see what happens. I probably went a little over board on wire covering as we'll. I used shrink wrap which does make the wires more rigid.

I'll work on the wires and see if it helps. Thanks for your input!

Originally Posted by The Valkman

Just balance the motor using the cable tie method. Put a cable tie on the motor and spin it up with the coin as you have done already. Move the cable tie around the can till you get the sweet spot where there is less vibration.
There is no point in putting tape on the can with the fins and also when is gets hot the tape can fly off.
If you do no want a cable tie on your motor still go ahead and use one to find where you need to put it, then take the can off and put some epoxy or hot glue or something between the can magnets on the inside to add weight at the same spot as the cable tie was.
I have done this to a similar 700 motor on an aerial rig and it ran really smooth after that. It also adds more life to your motor bearings. Look up motor balancing with cable tie or something like that on You Tube.
All this is a 10/15 minute job and should be done to EVERY motor. IMO!

Very good to know, thanks. I will try and let you all know my results.

I've been thinking about this and I feel I shouldn't have to balance the can. The reason I bought an align motor was because I wanted a high end motor. Guess I need to do more research and not trust just a name. I'm going to try to return this, for what the darn thing costs, it should already be balanced.

Originally Posted by kingair301hc

I've been thinking about this and I feel I shouldn't have to balance the can. The reason I bought an align motor was because I wanted a high end motor. Guess I need to do more research and not trust just a name. I'm going to try to return this, for what the darn thing costs, it should already be balanced.

Yeah, I don't know what is up with them as of late. . I bought two brand new Align 600MX 1220kv motors.. First one lasted about 20 flights and the magnets inside can came loose bringing heli to a screeching halt. . Second MX did not even give a full flight and same thing took place.
One was returned for 50% refund. . The other a full refund.



Unhappy Align Employees maybe.

I balance all motors/props and blades no matter who makes them. I'd say that was fun when the magnet came loose!!