Also available
are the optional PDR0085, a bolt-on replacement, which CNC
machined from a solid billet of 6061 aluminum.
We've had reports of
blades occasionally going out of track and have learned it's
usually related to excessive play in one of the Seesaw Arms. Check
for excess play before flying your model because the resulting
flutter can easily be strong enough to lead to a Spindle Shaft
bending. Fortunately, the shaft is a sacrificial part and is hence,
inexpensive and easy to replace.
The cause is usually
either the button head bolt(s) securing the AUD0048-2 Seesaw to the
AUD0005-2 Aluminum Center Hub have come loose (remove, clean with
acetone, and use threadlocker before snugging them back into
place), which is easy to find, or the M3x15 Allen
head bolts, which pass through the steel hat section (or
shaft), upon which the seesaw arm bearings piviot has backed
out of the AUD0048-2 Seesaw. Be careful tightening this bolt
as it bottoms on the steel hat section and is threaded into
the polymer seesaw and can be easily stripped out. However,
alternatively, there's excessive play, caused by a ganging of
tolerances, which is a fancy way of saying one of the hat sections
is slightly too long.
Checking for the
latter condition is actually pretty easy. First, grasp the
Seesaw Arm between your thumb and forefinger and give it a
side-to-side wiggle. Next, rotate the head around and check the
other Seesaw Arm the same way. If you've experienced blades going
out of track, then dollars to donuts there's more play in one
Seesaw Arm vs. the other!
You may be asking
yourself, "What's ganging of tolerances?" Simply this . . . it's
surely no surprise that two bearings with the same part number can
actually vary slightly in size, right? I.e. measure them using
instruments of sufficient precision and you'll almost always
discover that one can be slightly thinner than the other.
Similarly, the ID and the OD can vary slightly as well. The same
holds true for the shaft - such that it might be slightly longer
than others in the same parts bin. Ditto with the seesaw arm
itself, but nonetheless, these differences are within the +/-
tolerances of the design. Then during assembly; thinner bearings,
maybe a seesaw arm with a thinner ring gap, or perhaps a longer
shaft, when assembled result in slightly too much play in one of
the seesaw arms. It doesn't happen often but occasionally parts
(each in proper tolerance) when combined may result in an assembly
that's out of tolerance - in this case too loose!
First, just try
tightening the bolt. Be careful though since this bolt threads into
the plastic seesaw. Fortunately, if it's stripped, all's not lost
since plastic-type CA used as thread locker will have you back in
business because you can pretty much restore the threads using it.
If the damage is too bad, happily, seesaws are inexpensive so it's
not that big a deal.
If it's not loose,
then back the bolt out and look to see if the shaft itself (the one
the bearings ride on) isn't just a hair too long (you'll see it
sticking out past the inner race of the outer bearing of the seesaw
arm - it's pretty easy to discern). If this is the case, then file
a few thousanths (or however much is needed to make for a perfect
fit) off the end of the shaft.
That's how you remove the extra play and
the process is called "blue printing". Top pilots blue print every
assembly of a machine. Most of us aren't top pilots, but blue
printing an assembly is a simple, easy, and free modification. Best
of all, it may result in a tangibly better handling helicopter plus
it's fun to do - after all, it's called modeling for a reason!
While you're at it, check the mixing arms for excess play and blue
print them to perfection also!
We've had reports of
blades occasionally going out of track and have learned it's
usually related to excessive play in one of the Seesaw Arms. Check
for excess play before flying your model because the resulting
flutter can easily be strong enough to lead to a Spindle Shaft
bending. Fortunately, the shaft is a sacrificial part and is hence,
inexpensive and easy to replace.
The cause is usually
either the button head bolt(s) securing the AUD0048-2 Seesaw to the
AUD0005-2 Aluminum Center Hub have come loose (remove, clean with
acetone, and use threadlocker before snugging them back into
place), which is easy to find, or the M3x15 Allen
head bolts, which pass through the steel hat section (or
shaft), upon which the seesaw arm bearings piviot has backed
out of the AUD0048-2 Seesaw. Be careful tightening this bolt
as it bottoms on the steel hat section and is threaded into
the polymer seesaw and can be easily stripped out. However,
alternatively, there's excessive play, caused by a ganging of
tolerances, which is a fancy way of saying one of the hat sections
is slightly too long.
Checking for the
latter condition is actually pretty easy. First, grasp the
Seesaw Arm between your thumb and forefinger and give it a
side-to-side wiggle. Next, rotate the head around and check the
other Seesaw Arm the same way. If you've experienced blades going
out of track, then dollars to donuts there's more play in one
Seesaw Arm vs. the other!
You may be asking
yourself, "What's ganging of tolerances?" Simply this . . . it's
surely no surprise that two bearings with the same part number can
actually vary slightly in size, right? I.e. measure them using
instruments of sufficient precision and you'll almost always
discover that one can be slightly thinner than the other.
Similarly, the ID and the OD can vary slightly as well. The same
holds true for the shaft - such that it might be slightly longer
than others in the same parts bin. Ditto with the seesaw arm
itself, but nonetheless, these differences are within the +/-
tolerances of the design. Then during assembly; thinner bearings,
maybe a seesaw arm with a thinner ring gap, or perhaps a longer
shaft, when assembled result in slightly too much play in one of
the seesaw arms. It doesn't happen often but occasionally parts
(each in proper tolerance) when combined may result in an assembly
that's out of tolerance - in this case too loose!
First, just try
tightening the bolt. Be careful though since this bolt threads into
the plastic seesaw. Fortunately, if it's stripped, all's not lost
since plastic-type CA used as thread locker will have you back in
business because you can pretty much restore the threads using it.
If the damage is too bad, happily, seesaws are inexpensive so it's
not that big a deal.
If it's not loose,
then back the bolt out and look to see if the shaft itself (the one
the bearings ride on) isn't just a hair too long (you'll see it
sticking out past the inner race of the outer bearing of the seesaw
arm - it's pretty easy to discern). If this is the case, then file
a few thousanths (or however much is needed to make for a perfect
fit) off the end of the shaft.
That's how you remove the extra play and
the process is called "blue printing". Top pilots blue print every
assembly of a machine. Most of us aren't top pilots, but blue
printing an assembly is a simple, easy, and free modification. Best
of all, it may result in a tangibly better handling helicopter plus
it's fun to do - after all, it's called modeling for a reason!
While you're at it, check the mixing arms for excess play and blue
print them to perfection also!