Balancing motors

[HowDoIfly]

Can I easily balance my motors in-situ or do I have to strip down my build to isolate the ESC';s and motors? ie, can I just disconnect the ESC signal cables to all but the one motor I want to balance or do I also need to unsolder them from the PDB?

[Calomile]

You can do it by measuring the vibrations on the arm using a smartphone placed on the arm. It';s easier to take the motor apart and balance the bell housing on a decent prop balancer such as the DuBro model.

Using the smartphone you can then also dynamically balance the prop and motor while you';re at it!

[HowDoIfly]

Thanks for your input but with this build, removing the motors (to balance the bell housing) is not so easy lol.

So if it';s safe to use the method I suggested above, I';d sure appreciate confirmation... as much as I might be interested to see what magic smoke actually looks like, I don';t want to tempt it 

[HowDoIfly]

Never mind, I worked it out.   

[HowDoIfly]

Hmmm, another epic fail from HowDoIfly 

Whatever I tried, I could not get repeatable results so abandoned this attempt.

I was running up the motors (with props on) individually and using smartphone apps (three different ones due to inconsistencies) to show vibrations. But none of it was conclusive (imo). I added a tie-wrap and could get slight variations on the vibes according to position (using 30degree increments) but whenever changed the tie-wrap for selotape on the supposed "sweetspot", the vibes didn';t follow suit, regardless of how much weight I added.

[rsmith21]

Take the props off, 1, its dangerous 2, they should be balanced and will make no difference to the result.

Run the motors up and hold onto the end of the arm, feel each one in turn and you should be able to feel the vibrations worse in some that others ( hoping you have at least one that is fairly good ) use your tie wrap trick again to feel for the sweet spot. I use aluminium duct tape to balance mine it sticks like a very sticky thing :) and you add a little at a time feeling for the results.

For best results you should take the motors off, or find some way of powering the motors one at a time, if its an IFLY you can use the motor test tool to spin up each motor in turn and that way you can leave it on the quad.

Have you seen the videos of the guys using a laser pen and mirror, that method is much more indicative than the phone method, there is too much mass in the phone to get great results IMO.

[Ross]

Have you seen the videos of the guys using a laser pen and mirror, that method is much more indicative than the phone method, there is too much mass in the phone to get great results IMO.

No..but point us in the right direction...... please

[Cozp83]

here ya go ross
Flite Test - Laser Balancing Props - FLITE TIP

[guest325]

Interesting, I would guess by doing it that way motor out of balance would be eliminated as well because you are balancing the whole arm.

[Cozp83]

Thats the idea darrellw 

[HowDoIfly]

Plans have changed (see my latest http://www.multi-rotor.co.uk/index.php?topic=3451.0) but I did notice last night as I deconstructed my hex several possible reasons for my out of spec vibrations.

First off, despite me rounding off two allen keys ensuring the frame and motor screws were F-tight, most screws appeared to be not so tight on removal. They hadn';t backed out any but the torque required to undo them was significantly far less than the torque used tighten them (and trust me, if I have an experience, it';s nut and bolt spinning!). I have a theory that this may or may not be relative to a percieved poor alignment of my rctimer F550 clone kit.

Anyway, back to the motors. I spun them by hand last night and noticed three out of the remaining five had a noticeable wobble at the prop nut. I can imagine at least six possible reasons for this:

The prop nut is not symetrical.
It';s thread is ******.
The stud it scews onto is ******.
The shaft the stud sits over is ******.
The motor bearings are out of whack or
The bearing recesses are misaligned.

[guest325]

If you';ve got Rctimer motors nothing would surprise me, mine are not the best - just taken delivery of some HK motors that were cheaper and they are quite obviously better made (NTM Propdrive 2826 1100kv).
I think that if you want your model for photography / fpv you are better off looking at better quality motors - at the end of the day you will get what you pay for. I';ve got Hyperion and Axi motors that are 3 years old now and seen plenty of use, nowt wrong with them!

[rsmith21]

here ya go ross
Flite Test - Laser Balancing Props - FLITE TIP

BUT TAKE THE PROPS OFF, its too dangerous to do it with the props on, you balance the props on a prop balancer :)

The system works very well give it a try.

[HowDoIfly]

If you';ve got Rctimer motors nothing would surprise me, mine are not the best - just taken delivery of some HK motors that were cheaper and they are quite obviously better made (NTM Propdrive 2826 1100kv).
I think that if you want your model for photography / fpv you are better off looking at better quality motors - at the end of the day you will get what you pay for. I';ve got Hyperion and Axi motors that are 3 years old now and seen plenty of use, nowt wrong with them!

Yes, that';s the idea of trying cheap, see what works and what doesn';t.

I';ll be looking for recommendations for motors (that can handle 4s), matching props and better prop adapters than the scarey screw-on collet type! Plus a folding frame with detachable landing gear would be very convenient.

[guest325]

These are the ones that I have, they look very good:
http://www.hobbyking.com/hobbyking/store/__44465__NTM_Prop_Drive_Series_28_26_1100kv_300w_short_shaft_version_UK_Warehouse_.html
But I also like these, they are made on the same production line as Hacker motors - superb quality!
http://www.hobbyking.com/hobbyking/store/__38043__Turnigy_Aerodrive_SK3_3530_1150kv_Brushless_Outrunner_Motor_UK_Warehouse_.html

[guest325]

BUT TAKE THE PROPS OFF, its too dangerous to do it with the props on, you balance the props on a prop balancer :)

The system works very well give it a try.

The whole point of doing it with the props on is so that you are in effect balancing the whole of the rotating structure that said you need to restrain the model better than in the video.

[rsmith21]

Personally , I have to dis agree  , the process is for balancing the motor bodies, the props can get broken and your right back to the start point again.

If you balance the motors doing this, and the motors will always be ok. Balance new props when you get them and you can fit them on any appropriate motor.

There is more to it than that, but that';s enough. Honestly you have to treat them as separate items and balance both.

[Cozp83]

why is everyone so scared of props?!?

[powerlord]

Darrell how do you use the short shaft ones and what  is the benefit?

Sent from my HTC One using Tapatalk 4

[guest325]

Darrell how do you use the short shaft ones and what  is the benefit?

Sent from my HTC One using Tapatalk 4

With the short shaft motors you need the accessory kit which includes a screw on adapter to give you a screw on prop mount. Whether or not you use the cross mount depends on the construction of your model; this is much better than using collet mounts for your props - more positive.

[HowDoIfly]

I guess you more experienced flyers might have spotted it before but I made in interesting discovery last night while contemplating my next build.

Spinning the motor by hand I noticed the wobble at the prop nut again and studied it a bit closer to find it also occuring at the prop hub. Removing the prop nut and prop, I spun the motor again and saw a wobble from the top of adapter collet. Seems the top mating surface of the collet (where the prop hub sits) is skewed. I eyeballed the adapter stud but it seemed true so am blaming the collet at this point. Anyone else seen this?

EDIT: Oh, and p.s. The rctimer motor wiring is dire. It uses the same winding wires, very poorly protected. I had to add hot glue to the grommets as they were obviously very prone to the slightest movement and the only mechanical strength would be coming from the motor winding wires themselves.

[guest325]

I guess you more experienced flyers might have spotted it before but I made in interesting discovery last night while contemplating my next build.

Spinning the motor by hand I noticed the wobble at the prop nut again and studied it a bit closer to find it also occuring at the prop hub. Removing the prop nut and prop, I spun the motor again and saw a wobble from the top of adapter collet. Seems the top mating surface of the collet (where the prop hub sits) is skewed. I eyeballed the adapter stud but it seemed true so am blaming the collet at this point. Anyone else seen this?

EDIT: Oh, and p.s. The rctimer motor wiring is dire. It uses the same winding wires, very poorly protected. I had to add hot glue to the grommets as they were obviously very prone to the slightest movement and the only mechanical strength would be coming from the motor winding wires themselves.

Found the rctimer motors are not the best, my NT propdrive motors are cheaper and better made but HK SK3';s are in a different league altogether, being made on the same production line as Hacker motorsthey sshould be - I';m using a 750W 1000kv one atm and it';s superb.

[HowDoIfly]

Following my failure using the android apps and with the rotten weather stopping any flying test, I revisited the vibe problem and made some progress, this time with the props off.

I guess the placement of the phone to sense the vibes is critical as this time I could (initially) get repeatable results. However, I';ve not mastered the art of rectifying the vibes yet and results weren';t so repeatable as I progressed, as only one motor showed improvement. 

Frustrated with this, I looked to using the laser method and realised I had no suitable mirror and my laser batteries needed replacing. So, I';m off shopping again, bbl.

[HowDoIfly]

With the new frame and it';s landing gear, I';ve made a few untidy landings resulting in the props trying to dig in as it fell over. Broken a few doing this and on last inspection, have gained some more "wobbly" prop nuts.

I was looking to try different motors for the quad and decided to put an order in to HK for the NTM 28series which requires ordering seperate accessory pack of prop adapters. As they appear to be the same fitting as the rctimer motors, I ordered ten sets so I can get rid of the collect types that came with the rctimer motors.

I have my laser pointer and dentist mirror ready so when the order arrives I';ll be having a balancing bonanza day as I';ve also ordered a selection of different props to try.

[mutley2]

I think the phrase that';s needed is "dynamic balancing", you will only ever get a limited amount of balancing done on single components (that';s why your car tyre is balanced on your wheel not as a unit when made)  simples...

[HowDoIfly]

Well I tried balancing using the laser method (no props but prop nut and washer fitted) and failed to get repeatable results (this sounds familiar so it must be me doing something wrong)

Then I decided to remove the prop nut & washer and I made good headway... I managed to reduce the laser light show to a dot on all four motors. So what is it with the prop nut that throws everything out and why can';t I compensate this inbalance?

[Tony Campbell]

Sometimes the washers are crap and have been made off centre. It only takes a fraction of a mil to induce vibration at high rpm. Also, Prop nuts, or domed nuts that are supplied with motors, can be drilled and threaded badly. This causes them to be less than straight when fitted. Another thing to watch for is that you dont over tighten them. This causes the prop hub to deform which can give a less than level surface for the washer/nut combo to seat down onto. Also, can cause prop failures due to stresses in the hub. Replacing domed nuts with good quality Nylocs can sometimes give better results all round. Also, check that the washer hole is a good fit round the prop shaft. If its even a little bit of a sloppy fit, it will be slightly off centre. and will cause vibes

[dirtyharry]

I';ve fitted a little 4 way dip switch in line with all my esc signal leads so i can isolate all but one motor . I then stick it in auto level and power it up on the tx till its just about to lift that corner . I then balance the prop+nut+motor as one complete dynamic mass with nothing more than a bit of lecky tape and my hand to feel the vibes.

Have tried phone aps/mag balancers/mirrors/cable ties etc  etc and found this method to be the fastest and best . Once you get the hang of it you can balance a corner in under a minute.

However be careful  switching esc signal leads on and off like this can sometimes give a kick of power.


http://www.ebay.co.uk/itm/DIP-4-Switch-PCB-Key-Switch-Piano-4-Circuits-Way-Printed-Board-Switch-DIL-4-/180725910254?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item2a141a8aee

[rsmith21]

It came to me that there must be a way to automatically remove imbalance in our motor\prop assemblies, it turns out there is a device for cars and bikes that we could build a miniature version off. If it hadn';t been patented already I may have been able to start a business with this idea. Have a look guys, should I get into the workshop and build a miniature version.

Centramatic Wheel Balancer on Vimeo

[barneyg]

If you could build something like that 5mm center hole and about the size of the thick washer that sits above the prop that would be pretty cool ... question is can you put enough weight in something that small ?