On Dec 14, 3:18*am, Stealth Pilot
wrote:

for veedubber; the critical thing to find out with any balancer that
is home made is whether a very light weight added to a tip moves the
prop. I was amazed that mine moved with quarter of a post it note.
indeed experimentation has shown that balancing a prop in a room full
of still air is far more important than knife edges.
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On my 'back bench' (ie, the bench facing the lathe) I have a
machinist's steel tool box. It contains the high precision bits &
pieces every machinist accumulates over the years, such as my ten-k
mikes (ie, accurate to .0001"), broaches, reamers and so forth. In
the top right-hand drawer is a packet of Zig-Zag cigaret papers.
These are used as a gauge when making certain set-ups. But they also
serve as my 'test mass.' When a prop has been finished, I put a
cigarette paper on one of the blades to ensure the prop not only
drops, but on that side. The blade is then leveled and the test mass
is placed on the opposite limb. Some argue that I'm merely testing
the drag of my pivot and while pivot-drag is surely a factor, the
amount of TIME the blade takes to deflect by a certain amount, such as
down to the top of the bench, tells me if the prop is properly
balanced. That is, so long as each limb takes the same amount of time
to deflect for the same amount of distance, I know the balance is
equal on both sides of the prop.

Occasionally I get some guy in the shop who wants to argue that the
modern-day, all-electronic balancing is superior to my clumsy efforts,
especially with regard to TIME, in that the electronic balancers give
you an answer RIGHT NOW... and the answer is accurate to millionths of
a gram, or whatever.

Cost of such equipment is rarely mentioned :-)

This is another case of a newbie falling prey to some hi-tek
huckster. While it would be nice to have a balancer that gave such
precise results ( ie, four zeros preceding the significant digit ), in
the real world that degree of precision only applies to turbines ---
devices spinning at tens of thousands of revolutions per minute. If
you happen to have ACCESS to such a machine, you are lucky, but there
is simply no need for that degree of precision when you're dealing
with two-bladed props for Volkswagen engines.

After balancing the prop with the shiny-side out, I like to flip it
over and check the balance again. 'Shiny-side' = the prop is
finished with a good grade of VARNISH. After the varnish has cured,
the side of the prop facing the pilot [tractor installation assumed]
is given a light sprayed-on coat of FLAT BLACK paint, so as not to
reflect the sun into the cockpit.

-R.S.Hoover