stormexplorer

Hello All,

I made a simple magnetic prop balancing device this afternoon for less than $5.00. I bought a Great Planes Finger Tip Prop Balancer part number GPMQ5000. I then used 2 magnets I had, 2 pieces of 1 inch angle (each 14 inches long) and two clamps. The magnet stuck to the steel angle naturally and I clamped the angle to the work bench. I centered the props on the Great Planes fingertip balancer and slipped it between the magnets. Wholla a $5.00 magnet prop balancer. It spins without friction just like the $24 version I saw I the hobby shop.

I hope this helps if your in need of an inexpensive prop balancing device.

Thanks Brad

Dukester

My Feedback: (31)

Good thinking, I was looking at the magnetic one myself in the LHS but refused to pay the price. Any problems lining up the magnets so that the balancer sits straight?

Duke

stormexplorer

Hi Duke,

I didn't have any trouble. As you can see from the picture the magnets are the same size (I think this is important) and have the strongest attraction at the center of the magnet. You can buy matching magnets at a good hardware store for a couple of dollars if you don't already have them. Spread the angles just wide enough so the Great Planes prop balancer shaft just slides between the magnets at the center vertically and horizontally. The prop just hangs there with little if any friction. The angles can be moved out from the work bench for larger props.

Thanks Brad

Bill DCat

I've done almost the same thing. I put the magnets on either jaw of a bench vise and then used the Great Planes fingertip balancer between them. Works great. Being cheap and strapped for cash is the mother of most inventions...

Bill

DTB

My Feedback: (15)

Great idea... Looks very promising.

Jumpnjoe

Sorry for the ignorance. This is the 1st I've heard about a prop balancer. Does everyone need one of these? What's the purpose?

JimTrainor

There goes that revenue stream for Top Flite.

Dukester

My Feedback: (31)

Joe,

I wouldn't say that everyone absolutely has to have a prop balancer. Its a useful addition and you can pick a basic one up relatively cheap.

What the prop balancer does is exactly what its name implies. No matter how good the manufacturing process, every prop will be somewhat out of balance in that one of the blades will weigh slightly more than the other. This causes the center of mass of the prop to be out of line with the physical center of the prop. So when the prop spins, a vibration is induced as the center of the mass of the prop is spinning around the center of rotation on the crankshaft. In the long run, this causes increased engine wear and could possibly cause premature prop failure.

The prop balancer allows you the put the prop on it and balance the blades against each other. The heavy blades will fall to the bottom and the light blade goes up. You can reduce the weight of the heavy blade or increase the wight of the light blade by many methods (search rcuniverse or rcgroups for those methods and remember they vary by prop type). Once the blades will hang level you have them balanced and the props center of mass and rotation should now be lined up, reducing vibration.

Now as to whether you need one or not. Others will likely have something to say here also, but I would say that for general sport flying using plastic or composite props you could probably get away without balancing if you accept the long term risk of shortened engine life.

Duke

stormexplorer

Hello,

Since posting the original pictures of the home made magnetic prop balancer I made a more permanent design. The 1/4 inch threaded rod is provided to properly space the distance between the magnets. The shaft of the prop balancer is not actually touching the right magnet in the picture(1/32 inch gap). It's just suspended by the magnetic force.

I made a mpeg file showing an unbalanced prop coming to rest (47 sec. long). I don't know how to upload the file to RCUniverse but I would be glad to if someone can tell me how. Dukester has a very good narative on balancing props. I'm a new pilot and got tired of replacing props on my NexStar as I try to eliminate the bounce in my landings. That was the motivation of building the prop balancing device.

Thanks Brad

FatBoy123

Hello, I know this is an old thread but maybe someone can help me.

I wanted to make one of these, put the two wood sides seem to me like they are permanantly fixed to the base, so in this case what is the use of the threaded rod to adjust the distance, as it will not move.

Or maybe I am missing something.

Thanking you all in advance.

2slow2matter

My Feedback: (1)

fatboy
The only thing I can think of is that it's just to spread the wood apart--a little ways. This would put a lot of pressure on the joint, and it would eventually break if you tried to spread it too far. Not a real good setup if you need to balance props with lots of different sized hubs! You could attach the legs to the base with a bolt that runs through a slot that would allow the leg to move back and forth. Only one leg would have to be moveable. The other could be glued to the base!

tsands

My Feedback: (3)

IMHO the threaded rod is to keep the uprights perpindicular to the base so they don't squeeze on the rod and render useless the magnet.. there is no logical reason to need to move them in and out. looks like there is room to move the hub holders at LEAST 1/2 inch. unless of course you are flying giant scale then maybe you would need a different one. Besides the joints are dados so they should hold

Pilot Chad

My Feedback: (4)

I have a prop balancer too. It's a dual tool. Screwdriver and prop balancer..

bingo field

I used some scrap lumber and a couple of magnets from an old defunct computer hard drive. Fingertip balancer in the middle. The wood dowels are glued at one end, the other end slides back and forth on the dowels to get the distance you need for separation. And yes, the hard drive magnets are VERY powerful. (Trick to getting the cover off a hard drive.. Use the dremel with a cutting wheel to cut a straight slot in the very small torxs head screws and use a small screwdriver to get them out. Don't forget the one under the labels that say do not remove the label...)

CGRetired

My Feedback: (1)

If you can find someone that is throwing away a bad computer hard disk drive, grab it. The magnet in these devices is a strong STRONG magnet and works great as the magnets for prop balancing.

lrvest

I really like this one, I have looked at several and this one is the best,keep up the good work.

lrvest

The set screw at the bottom is to pull the sides in close for the shaft to fit close to the magnets, they wont move far enough to break anything.

lrvest

Small adjustment,will not break anything.

OzMo

My Feedback: (3)

NICE!
You may be able to enhance you balancers by placing a layer of thin hard plastic over the magnets to reduce friction. Possibly salvaged from a CD ROM case On mine only one side of the metal axel touches a magnet. The other side is suspended in the magnetic field. I know you guys know this but I am adding it for the benefit of others. And yours looks SO much better than mine!

speaker magnets are free BTW

Leroy Gardner

You guys have the right idea. I bought the Great Planes balancer which works fine for up to 13-14" props but now I have 22-23" props so I'm going to do what some of you did and build another one for large props. Anyway the little one will bairly support the bigger blades. Thanks for some good ideas Leroy