balanceing props

[jeff baham]

I have a stubborn prop here, I cant get it to balance out, I would file on the heavy side of the BLADE, it would just spin ,stop and roll back ,I know this is not balanced , I try sanding on back of blade, then I cleaned up the hub and still, spin ,stop, roll back, WHAT AM I DOING WRONG.

 

[Tony Drake]

Could be your balancer. Maybe your shaft isn't balanced

 

[Tom Foley]

Sometime large amounts of material have to be taken out of the hub by grinding or even spot drilling(shallow) .

 

[Mike Larson]

Alloys are mixtures of metals... its entirely possible, youve a factory error there.... I've had a bunch right outta the bag, not just from one man., that are close to junk.... use your caliper to check the prop all over, and see whats what.... bent balancer shaft?... I have drilled hubs before but only in a never ending horizontal balance scenario... keep at it... itll come around... Mike

 

[jeff baham]

ok guys thank for the info, it was the hub, sand and file for one hour, thanks again

 

[Michael Caruso]

ok guys thank for the info, it was the hub, sand and file for one hour, thanks again

Use a very small piece of modeling clay to find the light spot 180 degrees from the heavy spot.

 

[Derret]

At times I received props that had the center bore shifted away from true center of the prop- at times in two directions-

these props are LB's (little bastards) to balance- sometimes taking 4or5 work sessions to balance it & make both blades the same in profile/shape as I wanted it-

It sounds like this is the problem with your prop-

A good fit of the prop on the balance shaft makes balancing easier usually- I have a range of balancing shafts (10+?) that increase in size that I can try on the prop to find one that fits the prop bore snugly - making the final perfect balance easier- I use a blade type of balancer.

Slow work/going here- & for some outside the range of their workshop tools & taxing of their skills - I know-

There are different theories on how perfectly a prop needs to be balanced- I don't know what is right on that?

Hope this helps-

Dave

 

[Mike Larson]

The off center bore deal makes sense.... LB props...lol... I dont know how they cast them, but theyre cast, and sometimes you get... what you get.... idk... just keep filin'' mike

 

[John Beardslee]

The props are cast in a lost wax process, a quarts pin is in place for the bore but is undersized and the bores are sized afterwards using a reamer. I suspect the problems occur from using reamers after they are dull and carelessness from chip build up in the fixtures. Thus cocking the prop and getting an off center and on angle hole.

Thanks, John