Prop Balancers

If the prop is too heavy, it will fall off. Most props--even 13 inch 3-bladers work OK, however.

If the prop is too long, it won't be able to spin. You can, however, still balance it since it will "see-saw" and you are simply working for a horizontal balance.

This and the wheel type (can't rember the make)would probably be our recommended choices. The wheel type can support heavier props (or spinners, or whatever) and both can be lifted out and turned if you have too long of a 3-blade prop for the mechanism.

3-blade props on any balancer are more difficult than two bladers to balance.

For procedure, we jig the prop and either cut it to length on the bandsaw, or on the sander, making sure each blade is the same length. We then make sure that the blades are flat to the table (reworking the hub, if necessary). You want to ensure that the blades all rotate in the same plane. We than balance on the balancer and sand off the front (spinner) side of the offending blade until balance is achieved. With wooden props, we than give them a coat of Deftane and check for balance again.

Static balance is probably the only method available to the modeler as dynamic balance would demand a machine that could spin the prop and tell you (computer?) where the balance was off. I don't think the local Good Year tire shop would be too thrilled with putting our props on their tire balancer and I would be a little hesitant to add those lead weights to my prop, anyway.

Your sense of humor adds a lot to your responses! Goodyear Tires? Lead weights?

Now, what the heck is Deftane?

I was only half joking about the dynamic balancing. Imagine a balanced flywheel mounted on the shaft, a small string wrapped around the shaft, a small u-shaped tool to hold the shaft when you pull the string, and bingo! And then a felt tip marker mounted on a -- ahh, lets forget dynamic.

I'll get one.

Thanks, Larry F

Len is right about a dynamic balancer being expensive.... in a previous life, I had a pla who was creating turbine blades (very small ones) that spun at 45K rpm , mni. His plan was to use magnets as bearings so as to reduce moving parts and the like. He had a grant from $omeone, so he bought the hot-rod balancer.

The little wheels still came akimbo, but my kart tires were real smooth at 110 mph!

See Ya

Most people go through life quite sure the horizon is a flat horizontal line. CL fliers see it tilted 5 degrees or so. Those with imagination see it tilted a little more, maybe 7. You are at about 22 degrees, which is a compliment!

larry,i have a t/f mag balancer.it works great for me on 10-11" props,they still break though....jerry

While I'm sure you know, but this could be a bit confusing to others. We of course aren't aiming for it to remain level, but to have it stay at whatever initial position it's left. The only way it could stay level is if it was out-of-balance across the hub direction.

You are right in that either the High Point (Du-Bro wheel type) or the Top Flite is almost too good. It takes some judgment to tell when the rate at which it accelerates is low enough to call it done. And any airflow completely messes it up.

Balancing props is an interesting subject. Personally I do not like the magnetic balancers. One gent found that heavy props are not held and he is correct. After a while the rod becomes magnetised and forms a dead spot thereby making good props bad. I like the ones with the two wheels ate each end but only in the work shop. In a dry weather static can send a prop off. I have seen some modellers take two very light sanding cuts to get a prop "perfect" The i see them on the field with dirt and grass on the blades and wonder about their miss guided sicence.

Balancing three blades is easy. Find the heavy blade and have it hanging down then balance the other two. The high blade is the light blade. The balance the heavy blade to the other two.

How can I send a drawing of a simple prop balancer I use on fields? I can scan a drawing and what format is required?

Kind regards John Quigley down under where the gravity still sucks.