Author Topic: Acceptable Prop Balance Limit  (Read 629 times)

Offline LSaupe

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Acceptable Prop Balance Limit
« on: December 14, 2021, 06:28:56 AM »
Is there an acceptable value out there for prop balance?  My current prop (62" w blade Powerfin) is showing a 101 in-g out of balance condition.  Is this a typical value or should I strive to improve?

Offline Aaron

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Re: Acceptable Prop Balance Limit
« Reply #1 on: December 19, 2021, 04:06:29 PM »
What rig are you using to balance your prop? I couldn't give you a torque value for out of balance but I can tell you what I did when I balanced the prop I carved. I had to make my own static balancer because I couldn't find/borrow one that fit my hub. I threw a pipe in a lathe and turned it down to fit into the hub (.008" less diameter than inner hub diameter). I also turned down the outside edges of the pipe to accept a couple of ball bearings I had laying around, to be placed on the outer edges of the tube sandwiching but not touching the prop. I then placed the bearings on some parallels and let the prop rotate to the heavy side, and sanded the heavy side until I could orient the prop in any 5 degree orientation (give or take) without the prop having any preference to rotate, in other words it wouldn't rotate no matter the orientation. Just a standard static balance procedure. I couldn't tell a difference between that prop or my culver prop vibration-wise. I might add that my culver prop is quite smooth, and this is wood, you will have a different procedure for adding or removing material for balancing a composite or metal prop.

Offline LSaupe

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Re: Acceptable Prop Balance Limit
« Reply #2 on: December 19, 2021, 05:47:25 PM »
I have a 3 blade prop.  Measured each blades mass and balance point, and then did a vector sum to find the resultant.  I then mounted the prop on a static balance rig much like you are using (I used roller bearing V blocks on a level surface).  Works very well.  The result was the same as the vector sum method.  I was able to obtain a good balance check by using a known mass and two sided VHB tape (well two in this case).  The numbers check out.  These are the V block I was using.  Very nice quality.

https://www.ebay.com/itm/192563722795


 

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