Give me some prop balancing education

[SHAWN DAVIS]

Whats the accepted method of balancing?
Where do you buy- or build your own?
How critical is it and what occurs with an unbalanced prop? I know on our big boats different ones seem to vibrate more than others, but it doesnt affect anything

[kookie_guy]

Accepted method of balancing involves using a magnetic balancing jig like this one....
http://www.offshoreelectrics.com/pro...prod=ose-80310

I built my own, because they were out of stock at the time, but for $19, why waste the time to build one.

First thing I do is file off any burrs not removed after the casting. Then I take the file, and on the back side of the prop (the nut side) I square the 2 thin edges of the blades. Then I sharpen the prop. When I do it, first I use a file to get it pretty sharp, then I use 1000 grit sand paper to get it razor sharp. Then it goes on the balancer. Give it a little spin, and when it settles, the heavier blade will dip down. The balancer I linked above is VERY precise. The blade that dips, you remove some material from the CONVEX side of the blade, which is the drive dog side. Never remove material from the concave side of the blade. Back on the balancer, check, and remove more material. You wanna get it to the point where when you give it a spin, it will always stop in a random position. Once balanced, I take some 2000gritt sand paper, and give it a polish with oil. After the polish, get all the oil off, and I mean ALL, and double check that you did not upset the balance. And that's all there is to it.

Pretty critical, because an unbalanced prop will cause vibration. Vibration will increase the side load on your bushings/bearings, potentially causing them to fail. It will also transfer the vibrations to the motor, which could potentially damage the motor.

[izcain]

Whats the accepted method of balancing?
Where do you buy- or build your own?
How critical is it and what occurs with an unbalanced prop? I know on our big boats different ones seem to vibrate more than others, but it doesnt affect anything

If you run it long enough it will affect your large boat! I can guarantee that. I have seen many gear failures in lower units due to prop issues.

[kookie_guy]

one thing I forgot to mention, when doing beryllium copper props, make sure you wear a respirator and gloves. Try to avoid any kind of exposure to the filings that come off the prop. Beryllium is a very dangerous and hazardous substance to get into your lungs.

[SHAWN DAVIS]

will do, I have heard the hazzards, thanks for the great explanation, its about how i dressed mine,
BTW I never balanced any big boat stuff, we been running these vibrating 4 blades for about 3 years and over 160 mph, I have never heard a bearing failure from vibration, but these are no. 6 drives also.
the 5 blades dont vibrate near as much, been good to 175

[BHChieftain]

one thing I forgot to mention, when doing beryllium copper props, make sure you wear a respirator and gloves. Try to avoid any kind of exposure to the filings that come off the prop. Beryllium is a very dangerous and hazardous substance to get into your lungs.

Yup, see below for more info
http://www.osha.gov/dts/hib/hib_data/hib19990902.html

Chief