Rundquist Propeller Tools, Inc.
of the 36" Gauge - Checking propeller pitch, rake,
tracking and diameter
the pitch of the propeller
propeller on the gauge shaft between the cones with the
pushing face of the propeller up. Slide the two
set collars provided on next, one will be used to hold
the prop down tight, the other will be used if need to
hold the indicator at a desired height.
pitch gauge to the radius that you wish to check by
sliding the gauge assembly along the horizontal
shaft. Each hole in the shaft corresponds to a
radius on the direct reading faceplate. Radius
"A" is closest to the faceplate.
(click on a photo for a larger view)
needle on the faceplate of the gauge to the correct
scale that corresponds to the radius being checked.
gauge to the trailing edge of the propeller and slowly
check the pitch down the blade to the leading edge. The
needle will show exactly what pitch the propeller has
and indicate right or left hand rotation. ALWAYS check
all three blades and mark the pitch and rotation
directly on the blade using a marker. Example: If the
propeller reads 18" pitch, right hand, mark the
Rake of the propeller to determine the correct rake angle.
the rake angle of a propeller, use the rake gauge. Slide
the rake assembly into the back of the 36''IND., Using
the machine handle lock on the flat of the 1/2'' shaft,
this locks the IND. on center of the shaft. Slide either
the 6'' or 12'' rake blade into the rake foot. Set the
blade on the propeller. Slide the blade out so that it
stays about 1" from the hub. Set the gauge
against the propeller and look for the straight line. At
first you may find it easier to use a 6" scale to
find the straight line, draw a pencil line along the
6" scale to find the straight line, draw a pencil
line along the 6" scale, then check the rake at
this point. ALWAYS check all blades.
of the blade can be read on the faceplate of the rake
gauge. This is the rake of the propeller. EX: Propeller
reads 16" AFT rake.
rake on the propeller behind the pitch and rotation.
18R16 - This shows the pitch block to use on the
The example above is how each pitch block is marked.
Pitch, rotation and rake. On most standard propeller
designs the straight line cuts through the shaft center.
parabolic rake - the straight line referred to will be
found to miss the center of the shaft from 1/4 to 10-1/2
inches. A propeller of this type can be thought of as
consisting of straight sections arranged tangent to a
short radius from the shaft center. This propeller, if
cut directly through the center will show a parabolic
curved section instead of the conventional straight
section. This is intended to produce a better stress
pattern in operation and also to add to the gripping
quality of the propeller. The Federal Equipoise
propeller is designed this way. To check the rake on
this type of propeller, loosen the machine handle that
is locked against the 1/2'' shaft this allows you to set
the rake blade off center to check the propeller. Once
you set the rake blade to the straight line, tighten the
machine handle. Check all blades to determine the rake.
Gauge and mark all propellers to be worked. This
eliminates the possibility of using the wrong pitch
block for the repair.
Check the tracking of the propeller
second set collar on the shaft so when the indicator is
placed on the shaft it will spin freely without hitting
the propeller. With the rake Ind. and shaft
removed insert one of the provided lasers in the top of
the hole pointing down.
second laser assemble to the body of the indicator.
the laser on the body of the indicator to point to 0 on the
scale that is on the base. Slide the indicator in so that the
second laser is pointing to the trailing edge of the
propeller, you will have to turn the propeller until the
laser shines on the trailing edge. Once this is set up,
you can then begin to rotate the indicator. On a three bladed
propeller each blade should be a 120 degrees
apart. Ideally, when
the laser on the body reaches 120 degrees the second
laser should be touching the trailing edge of the
Checking diameter of the propeller
rake assembly removed from the back of the indicator, insert
the laser into the top of the hole.
indicator out until the laser just makes contact with the
edge of the propeller.
set, you can then directly read the propeller radius
from the scale. The
measurement is read from the edge of the block. Multiply
the radius by 2 for propeller diameter.
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