tutelar-rc
Key Veteran
Location: Nobleton, Ontario - Canada
| Bent Main Shaft > How to straighten in a Blade CP Pro.
Note: This is intended as a supplement to the excellent work that has been done by Rob Moll at www.bladecprepair.com and SSG Scott at http://www.rcgroups.com/forums/showthread.php?t=494197. I credit both these guys with giving me the knowledge to be successful in this great hobby! If you have not read all the information at both of these sites, you should.
This method shows you how to straighten the main shaft in a Blade CP Pro, without the need to remove the main shaft and gear.
Symptoms
Signs of a bent main shaft range from any one, to multiple, of the following:
1. head wobble (although this is normally a bent main shaft),
2. loss of power,
3. helicopter seems difficult to control in a hover, moving around on its own.
Inspection
• Power up the helicopter and view the top of the rotor head.
• As the model is about to take off, the center of the screw on top of the head should form a small black round "hole" as seen in the picture above.
• I have also posted a video at (http://www.youtube.com/watch?v=TAoahiFXXYA).
• If the top of your rotor does not look like this then either:
1. the main shaft is bent, or
2. something is not balanced (see the note at the bottom of this post for the fix).
Note: Trying to hover or fly with a bent main shaft, or an out-of-balance condition will cause significant difficulty in controlling the model.
Repair
• Remove the entire head assembly and swashplate assembly from the main shaft by following the removal directions at (http://bladecprepair.com/man_mr_swashplate.html).
• The following picture shows where the main shaft on the Blade CP Pro normally bends:
1. Disconnect the tail motor, and power on the transmitter.
2. Connect your flight battery.
3. Advance the throttle just enough to start turning the main shaft.
4. Using a permanent marker and light pressure, touch the top of the main shaft:
For a video of this step, visit (http://youtube.com/watch?v=vlx1dCZYEps).
5. Power down the helicopter and unplug the flight battery.
6. The main shaft will have a red line part way around the shaft:
This photo shows the red line on the right hand side of the shaft, and no mark on the left hand side of the shaft.
For a video showing the red line mark a little better, visit (http://youtube.com/watch?v=RZX-dX0Sz7o).
7. Using a pair of pliers, gently bend the shaft away from the red line:
In this photo, the red mark is on the right hand side, so I am bending the shaft towards the left.
Note: do NOT try to get the shaft straight with the first bend. Use gentle pressure and multiple attempts to get the shaft straight.
8. Repeat steps 2 to 7 until the red line goes all the way around the main shaft:
This photo shows multiple attempts to bend the shaft straight, with the bottom line extending all the way around the shaft – indicating that the straightening is complete.
The lines will wipe off when completed, or if you need to make additional attempts.
The following video shows the completed repair, running at speed: (http://youtube.com/watch?v=16yR3kXOcVM). Note that you can also tell by the sound that the shaft is now straight.
9. Rebuild your helicopter by replacing the swashplate assembly and head assembly.
After completing any repair, I always rebalance my Blade CPP by following SSG Scott’s direction at: (http://www.rcgroups.com/forums/show...chmentid=812465). |
I have one suggestion though when spinning the heli up to check main shaft I take the main blades off so blade balance and tracking are not an issue and look at the head screw.
mild blade strike
