So, what device do you folks use for balancing a prop? I'm reading about an entra coat of paint on the tip to achieve balance!! That sounds like an extremely sensitive device is in use.

Also, if you're not adding paint to a prop, how do you balance it? Sanding? If so, where?

I'll appreciate any information and advice.

Frank

I use a high point balancer I bought years ago to baance ducted fan rotors.I lust sand the heavy blade with 400 grit paper.years ago we had to check props to make sure the hole was drilled perpindicular to the hub,I still have the special tool rhom air made for truing ip the hub.

http://www3.towerhobbies.com/cgi-bin...&I=LXHY61&P=ML

i don't paint them, and sand them on the heavy side with 400 grit paper.

I use the top flight power point prop balancer, it works great. If you don't want to paint the prop you can either sand it or put a few drops of CA on the face of the prop untill proper balance is acheived.

Austin

I have the Top Flight Prop Balancer.

I tend to sand wooden props and paint plastic props, plastic is a little tougher to sand down than wood.

A coat or two of some Testors model paint on the light end of a plastic prop will help bring it into balance. If it chips off after a few flights, it only takes a few seconds to repaint it.

http://www.troybuiltmodels.com/PropellerBalancer.htm

I use this balancer for all my props, I DON'T SAND because it can cause a change in thrust even though it should not. I use clear lacquer paint and lightly mist the back of the light side, spray enough where it is lightly heavy then when it dries it will be pretty close, it might take one or two more light coats and it is done. Once you graduate to props over 26 inches put a little Velcro on the light side of the prop hub then drip thin CA on it till it balances.

If the initial trial shows its completely whacked (which is often), then I start scraping the back of the heavy blade with a single edge razor blade. This removes a lot of material (relatively) fast. When I get closer, I go to the 400 grit sanding.

If the out-of-balance condition is very slight you can run a line of CA down the back side of the light blade.

i have a top flight balancer i sand the heavy side with sand paper on the back {motor} side

Well I am the odd ball. But not totally alone because I know that Minnflyer does the same that I do. I don't balance props and I've never had any problems. I will check a prop when I first get it, and as long as it's not extremely out of balance I will use it. If it is way out of whack I'll get rid of the prop and not use. I know that many think that this is crazy to not balance a prop, and I used to be one of those. But then I started watching the prop in use and realized that it's possible for a prop to get back out of balance the very first time you use it. Things like a prop strike, a pebble hitting the prop, even a prop running through grass can throw off that perfect balance that I used to spend a lot of time working on. So I quit wasting the time. If a prop in use get's a chunk taken out of it from rough use I simply put a new one one an keep flying. But small dings and dents don't worry me. I have several engine with 400+ flights on them without ever balancing a prop and they still run great.

I understand that there are those that prefer to balance a prop and I won't take anything away from them. By all means balance them. I am just adding a bit of counterpoint to the discussion here and putting out that most props these days don't need to be balanced like they used to. Most props these days will come out of the factory pretty close, well close enough at least!!

Ken

Ypu. If you want to spend the time balanceing, go right ahead. But even if you do, there's no need to get anal about it.

Case-in-point...

The Top Flite balancer is a very good one - it's very accurate and easy to use.

A few years ago I used to only smoke in my workshop, so often times I would go down there for a smoke even though I had no projects to work on. To kill the time while I was happily smoking away, I started to balance a prop - more just for fun and for something to do while I was sitting there.

And something I discovered was - Once the prop was (according to the balancer) PERFECTLY balanced, you could rotate the prop inside its holder and it would no longer hold a perfect balance.

So my advise is, if you want to do it, by all means, have at it. But don't feel that you can't fly your new trainer because you don't have a prop balancer.

BTW, I balanced that prop about 6 years ago, and that's the last time I used a balancer.

I must admit that most of the props I've bought lately, APC's, have not required any sort of balance. I was told that and accepted it. But, I too, had some time to waste (not by smoking, though.. ) and took out the Top Flight balancer. I played with about 8 or 9 props and sanded them a tad bit to make them balance. What I found was that not one was really in need of any sort of balance. I removed material, not much either, to find that it really, probably, was not necessary.

So, did it make a difference? Not that I noticed. Not at all. So, again, was it necessary? Probably not. As I said, every one was an APC, and every one of them was pretty much in balance right off the shelf.

CGr.

Hmmmnm..I bought my prop balancer a week or so ago. I've used it on ten props ( yes, I break a lot of props)..and all but one of them was off a bit. I use a small piece of cellophane tape on the back side of the heavy end. Some props take three pieces, most one or two. Easy, fast and they are in balance when I am done applying the tape. Rich

The tape will also get fuel residue on it and eventually come flying off at a very high rate of speed.

Do yourself (and anyone around your plane) a favor and remove it before someone gets hurt.

On glow engines, just put the heavy blade on the same side as the crankshaft counter-balance.

Besides, if you run a cheap plastic spinner, the prop balance is the last thing you should be worried about.

Why would you add tape to the back of the HEAVY side? That would add more weight to the heavy side.

As I said, very few of my APC's required balancing.

I agree. I have never balanced a prop and have never had any problems that could be blamed on out-of-balanced props.

WOW!! Thanks for all the input and advice, Guys. You've sure given me plenty to think about. Sounds as tho even if you don't actually balance a new prop some of you do check it's balance before using it. A balancer is probably next on my list of purchases. I will probably subscribe to the idea that within reason balancing is not required.

High Plains: Could you elaborate on your last comment concerning the "crankshaft counter-balance"? I've searched the forums here but didn't find any detailed information about it. Again, this is my first try at model airplanes, Kadet Mark II and Magnum XLS 46, as yet un-flown. Does this engine have a counter-balance and how would I find it?? Incidentally, since I've been following your advice about checking for the "bump" before starting with the electric starter, I've had no more problems with the prop loosening! Thanks for that.

Frank

Frank, The counter balance is on the opposite side of the crankshaft as the piston pin.

So when the piston is at TDC (Top Dead Center) the heavier side of the prop should face down (Providing the engine is upright)

Thanks, Mike. I think I got it. Pull the plug and with a wooden dowel inserted, find TDC? Seems like that's how we did it when I was playing with old Jaguar engines! But I still need a balancer to find the heavier side??

Yes and yes

As Minnflyer said, it is pretty easy to find TDC (top dead center). You don't have to be too exact on the position either, so I just roll the engine back and forth against compression to figure it out. As to a balancer, you can get close enough with a key or wire just stuck into the engine shaft hole in the prop to find a heavy blade. I do own a very expensive balancer, but rarely use it.

I'm glad you were able to try the bump method of preventing the prop from coming loose.

There are so many techniques to learn that make RC flying more enjoyable, and for those of us that have done this for decades, so much is a habit which makes it hard to remember to tell the newer modelers.

Well, I'm off to the LHS to see what kind of prop he carries, and probably a balancer.

Your help and that of MinnFlyer, RCKen, and all the other experienced modelers is greatly appreciated by me, and I'm sure, by all the other beginners here. It's also extremely valuable.

If there's something you've forgotten to tell us, I'm sure you'll have the answers when the questions arise!!

Thanks to All

Frank

I would bet that prop balancing is universal among competition fliers of all classes (except gliders?).

Believe me, we don't have all the answers. I get the opportunity to trouble shoot a lot of peoples models, and have done so for a long time. But every now and then I run across a problem that take lot’s of investigation to resolve, which are almost always engine related. While I know a bunch about 2 cycle engines, I am an absolute novice in regards to 4 cycle or gas setups.

Besides problems with power plants, setting up radio installations and trimming models is an area that is little understood by far too many. I am often surprised by how poorly some models fly, thus making their pilots feel like they are just not able to fly well enough to enjoy it, when just a few minor changes can make the problems go away.