crash and burn

My Feedback: (19)

Hello,

I own a BRISON 6.4 twin gasoline engine. I have been using a MENZ "Ultra" 26/12 wood prop and the occasional Carbon Fiber prop.

I noticed that after balancing the prop to sit level on the balancer horizontally, it will NOT stay still on the balancer when put in the vertical or diagonal positions.

I assume this means an out of balance hub???

I was told this is not a crucial part of the prop to balance because it is so close to the engine shaft.

However, if I choose to balance the hub, does anyone have a good technique???

I am sure the engine will run smoother with a fully balanced prop.

Thanks for any suggestions!!

Tom Graham - Seattle, Wa

majortom-RCU

My Feedback: (40)

You are absolutely correct, better balance means better running, less vibration, less wear & tear on rotating engine parts. Properly balanced prop should hold steady when set at horizontal, vertical, or any other angle. If it rotates to some other position, then the heavy part is at the 6 o'clock position wherever it comes to rest. If you set it vertical and it rotates to any other angle, the heavy part is most likely in or near the hub. Just hit the 6 o'clock position with your dremel sanding drum--this could be right in the hub, or somewhere out along the blade root. Just drop an eyeballed plumb line from hub center, and where it comes out of the prop is the heavy spot.

True, a gram of imbalance on the hub does less damage than a gram at the tip, but if you can see an imbalance, you should fix it.

crash and burn

My Feedback: (19)

Majortom,

Thanks, I think having a truly balanced prop is a very good idea.
In fact, I just finished balancing the hubs on a couple of my props and ran the engine. It ran smoother and I am sure without excessive vibration.

Thanks,

Tom

cubfan

Balancing the hub is a must in my book. I balance the blades first then check the hub. My method of balancing the hub is to find the lightest side of the hub mark it. Take the prop put it on my drill press, then drill a 1/8" hole in the face usually around a 1/4" deep. Then press a piece of 1/8 solder into the face. this adds weight to the light side without having to cut away the hub. Then I sand the solder flush with the prop. The prop washer will keep the solder from coming out. I have been doing this for a number of years with no problems. Cubfan