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APC Propeller Hole Appear Off-Center?
One of the most important things most competitive
flyers have done for years is to make sure their props are
properly aligned with the crankshaft of their engine.
Some flyers have recently run across APC props with engine shaft
holes that appeared less than perfectly straight. Upon close
examination they discover the hole in the front of the prop hub
is sometimes slightly off, but the hole on the backside is
right-on.
This challenge
can be taken care of in a fairly straightforward way by using a
tapered reamer. Whereas regular drilling only adds to the
problem, a tapered reamer, when used properly, can ensure that
the engine shaft hole is both straight and properly centered.
The big plus when reaming APC props is the
precision engineering that goes into the design and molding.
Because the propeller hole position is created during the
molding process, the position of the hole is extremely precise
on the backside of the hub. Simply use the tapered reamer to
bore from the front side of the hub to enlarge the hole (see the
illustration below).
This is actually
the most accurate way to insure proper alignment of any prop,
even if the hole appears to be centered. When the prop washer
and prop nut are installed and tightened, the molded hole in the
back of the hub centers the prop and allows the back of the hub
to serve as the reference to seat flat against the drive washer
or spinner back plate.
This simple operation will provide one of the
most accurate methods of making sure the prop is perpendicular
to the crankshaft. Now the “tip tracking” will be as perfect as
you can get. Most contest flyers have been doing this for years.
If you have other technical questions specific to APC props, you
can contact them at 530-661-0399
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