balance prop
 

Hi, is there any way I can balance a propeller with out using one of those fancy balancers like they sell at Tower. Can I just stick it on a screwdriver or something?

RE: balance prop
 

Sure, but it won't be as accurate. There are also plans for making a balancer. Takes some wood, a couple razor blades, and an appropriately sized piece of drill bit stock.

RE: balance prop
 

I made one of the razor blade balancers-use it all the time and its accurate-I upgraded mine slightly by adding 3 leveling screws on base and a level bubble epoxied on side. Also razor blades are installed using calipers and level to ensure they are level to each other and then epoxied in place. Mandrels can be made from smooth portion of various size carriage bolts, cut to length and polished smooth in drill press. This balancer costs almost nothing, its simple to make and is more heavy duty than most on market.

Drill holes in center cutout of balancer to store extra mandrels. A small ring of making tape can be used on a mandrel to size up for the occasional odd ball thread diameter.

One advantage of this design is that you can sit a prop on blades, determine the heavy side, reverse 180 degrees and the same blade should also indicate heavy, just a double check to make sure your balancer is consistent. Mine is 5 years old and going strong.

RE: balance prop
 

Actually if one side of the prop is slightly heavier, it can be used as engine balance. When mounting the prop, put the heavy side exactly 180 degrees from the piston when the piston is at TDC.

Ernie

RE: balance prop
 

You don't need a fancy balancer as I suspect many modelers never balance their props and just go on flying merrily. I use the Great Plances fingertip prop balancer which costs just $4.29 from Tower Hobbies: part no. LXK427. For advice on how to balance a prop see the tech info at www.masterairscrew.com/ For me the key point is that if your prop balances with a piece of masking tape no more than one inch long, it is a GO to fly. Don't need laboratory accuracy here given that your engine sure as heck isn't in balance.

RE: balance prop
 

Ditto, Unless you fly those super-fast extreme speed planes, slap a prop on and go flying.

RE: balance prop
 

I got in the prop balancing habit from boating. Having an off balance metal prop spinning at 25K RPMS on the end of a flexible shaft isn't a good thing. When I started flying I just naturally did the same for plane props. However, I'm significantly less fussy with my plane props. Most of the time I just check to confirm that it's sorta close. Sorta close is never good enough for the boat props.

If you want to determine the effects of an off balance prop, chuck one in a drill and see what the vibrations are like. Note to any Darwin award candidates, don't blame me if you mess up this experiment. :)

RE: balance prop
 

Well I have to say that the magnetic balancer is just so frictionless and fun that I wish I had thought of it before Great Planes did. I actually look foreward to using it. Granted, it may work "better than what we need" for sport flying, but it gives me a good feeling to know that my props are balanced.

Ernie

RE: balance prop
 

You can hang the prop (from the center hole) on a thin plastic wire... I do it with very nice results. Just do it indoors!!!

RE: balance prop
 

On the subject of balancing. I'm still not clear what material to take off a Nylon park flyer blade to balance it. I know balancing Heli blades, you find the center balance point of each blade, then add weight to this point to account for centrifugal force. Adding weight to the tip is not the same. I’m sure it doesn’t matter much with small props, so I may just remove material from the tip. Some of my blades are balanced as far as tip to tip, but the blade always settles horizontal, telling me it’s off side to side. Maybe a heavy spot in the hub area.

This is the kind of crap having a nice precision balancer will get you. It will drive you nuts :-)

RE: balance prop
 

Here's an example of a razor blade balancer I made back in the fifties took about five minutes, worked fine. I also might add I generally only balance my props for the high performance competition engines (that generally turn over 20 thousand static.

Another trick I sometimes do that does have an effect is if I have a prop with a known heavy blade its marked and mounted with the heavy blade opposite of the piston at top dead center. I don,t beleve any of our engines acheve perfect 100% balance due to crankcase room considerations.

John

RE: balance prop
 

Thank guys! I went ahead and ordered the top flite balancer anyway.

RE: balance prop
 

Way to go. You'll have a lot of fun with it whether your props need perfection or not. It's a real eye opener.

Ernie