How to Balance a EDF Impeller

[CHELLIE]

Hi Everyone I have not seen any Instructions or Advice here on Wattflyers on how to properly Balance a EDF Impeller, Sooooo I would like to Ask all of you EDF Gurus How you Balance your Impellers and what balancing tools you Use, That would be a great help for us that are not to well informed with EDF Impeller balancing, and will help to make our EDF Last longer, Thank you in Advance Fellow Wattheads , Take care and have fun, Chellie

PS Please leave videos, Links to tools, or whatever Information you think will be useful for others to use, This is your Thread

[CHELLIE]

small ducted fan balancing

[CHELLIE]

Found a nice EDF blade and prop balancer at Heads Up Rc

Magnetic Propeller Balancer
This Propeller Balancer can be used to balance propellers, spinners, spinner back plates, ducted fan blades, wheels, and even the rotor of an outrunner motor. It has a 3mm threaded shaft with two cones that screw into place, and one end of the shaft actually floats in a magnetic field as the other end of the pointed shaft rests against a magnet. This results in so little friction that even small rotors of outrunner motors can be balanced.

http://www.headsuprc.com/servlet/the...alancer/Detail

Magnetic Balancer.flv

#!

[CHELLIE]

http://www.google.com/products/catal...ed=0CCEQ8wIwAQ#

[CHELLIE]

Interesting idea from our friends at RCG

monkamarm2000
smug in granny panties




Join Date: Aug 2002
Location: NorCal Silicon Valley
Posts: 11,562


As of late I have been using silicone, it's easy to apply and then scoop out excess before its dry. Plus I cant prove it, but it seems to act more like a vibration dampner for the fan. I just did up my 750, and they are notriously out of whack, but with a smalle bead of silicone and a good blance it's as smooth as silk now.

Barry

[CHELLIE]

http://www.hobbycity.com/hobbycity/s...idProduct=7702
HK Balancer not recomended for EDF Impellers Due to Cones not being machined true as per post #11

http://www.aeromicro.com/DennisDeFevere_EDF50_Rotor.htm

[Turner]

Nice work Chellie.

[CHELLIE]

Originally Posted by Turner

Nice work Chellie.

Hi Turner I did some EDF Research and added it to this thread, and in doing so Learned a lot too I am No EDF Guru by no Means and I was looking for info on how to best balance a EDF Impeller, and could not find very much Information on Wattflyers, What I learned Here, I am just Passing on in hopes that it will Help others with Their EDF power system, If your into EDFs Turner and have learned a thing or two about them, Please post your findings Take care, and have fun, Chellie

[Turner]

I don't do EDF but need a prop balancer. Your work above has convinced me I can make a nice one myself. Thanks.

[cbatters]

Thanks for starting the thread and for all of the people that contributed. Definitely need to balance EDF blade to get rid of harmonics and vibrations in the Miglet 50mm 6 blade.

Clint

[4stripes]

I have the HK magnetic balancer. The design is great but the problem is the threaded cones are not machined true to the threaded part making balancing almost impossible! I wouldn't recommend this model unless you have a lathe and can re-machine the parts.
I add weight using 5 minute epoxy inside the hub. Works well and never lets go. If you happen to add to much you can just place a little on the opposite side. Takes one small batch of epoxy and less than 5 minutes to do (assuming you have a decent balancer).
Cheers
PS I've tried using small amounts of putty inside the hub but the centrifugal force trows it out.

[CHELLIE]

Originally Posted by cbatters

Thanks for starting the thread and for all of the people that contributed. Definitely need to balance EDF blade to get rid of harmonics and vibrations in the Miglet 50mm 6 blade.

Thats what its all about Clint, helping each other to succeed in this hobby

Clint

Originally Posted by 4stripes

I have the HK magnetic balancer. The design is great but the problem is the threaded cones are not machined true to the threaded part making balancing almost impossible! I wouldn't recommend this model unless you have a lathe and can re-machine the parts.
I add weight using 5 minute epoxy inside the hub. Works well and never lets go. If you happen to add to much you can just place a little on the opposite side. Takes one small batch of epoxy and less than 5 minutes to do (assuming you have a decent balancer).
Cheers
PS I've tried using small amounts of putty inside the hub but the centrifugal force trows it out.

Thank you for the heads up on the HK balancer, that will help others to be aware of that issue when balancing EDF impellers, I use JB weld a lot, and its good to know it can be used for balancing EDFs too Take care, Chellie

[4stripes]

JB weld is a great adhesive. I once used it to glue an inrunner motor into a shroud as it was cracking at the mounting area. Worked well and lasted over 50 flights (may have lasted longer but the plane crashed so I'll never know). It can take heat much better than regular epoxy. I even glued a spark plug into a stripped head on my old garden tractor (worked perfectly)!
Cheers

[Bill G]

Originally Posted by CHELLIE

http://www.hobbycity.com/hobbycity/s...idProduct=7702
HK Balancer not recomended for EDF Impellers Due to Cones not being machined true as per post #11

http://www.aeromicro.com/DennisDeFevere_EDF50_Rotor.htm

That's one of the problems, making adapters to center the rotor. I've made a few for different rotors, but my Kavan wheel balancer is only good for finding large out-of-balance conditions. The magnetic ones you showed would be much better. I've had to balance most with pure experimentation. The problem is that the weight needed may be so slight, that overshooting is a problem. Some of the pieces of tape that I've used to determine a light area, are almost microscopic. Balancing rotors can be a pain!
If I was rich, I'd buy a bunch of them, and just keep throwing them out until I found a good one.

Much overlooked is changing the position of the rotor on the adapter, and the position of the adapter on the motor shaft. No machining is dead perfect, and there is always some eccentricity. My current Saro project now has one of the smoothest running fans I've ever had. The tuning was done by rotating the rotor on the adapter, to get the blade tip clearances consistent. There was some eccentricity before, and the fan/ducting vibrated so bad that I thought they would explode. It's amazing how much a tiny adjustment can make. I may have also lucked out, and found a better position for the rotor/adapter to mount on the motor shaft. There is also some relationship between the rotating motor mass and the rotor.

[dkrhardy]

http://www.headsuprc.com/servlet/the...alancer/Detail


I watched the video ... does that bit of cello tape actually stay on? Amazing work there CHELLIE, nice finds!

[Bill G]

Originally Posted by dkrhardy

http://www.headsuprc.com/servlet/the...alancer/Detail


I watched the video ... does that bit of cello tape actually stay on? Amazing work there CHELLIE, nice finds!

Amazingly the small scraps of tape do stay on quite well. I've moved them around a number of times when doing trial and error balancing, before the stick is so shot that I use a new piece of tape. The difficult part is that you have to experiment with different sizes of tape pieces. Too small and you don't notice the effect. Too large and it will just make it worse by over shooting. I wouldn't trust a piece of tape to stay on, for long term use though. Once I find the the light area, I remove the tape and slowly add glue to the blade, testing for smooth operation. You can get a good guesstimate of the amount of glue, based on the size of the tape scrap.