[Con]

I have at long last moved from glow to EDF with the HK Vampire and I want to check the fan balance. Can anyone tell me how to remove the nut that holds the fan on the shaft without turning the shaft at the same time. In other words, how do you stop the shaft from turning as you remove the nut. Its driving me mad

[Max]

is it that far off balance that you need to go through all the trouble to balance it?

I've seen 2 other HK vampires fly and their owners did nothing to it other than chuck a battery in it and toss it into the air.....

[Con]

Hi Max, It seems ok, but I just wanted to check the balance to be sure, that is when I thought, how the heck do you get the fan off the shaft, just curiosity I guess.

[Max]

I have 3 EDF's in my stable. I havent had the reason to pull one off yet....

It cant be that complicated, but it may mean you have to remove the entire fan assembly from the airframe before you (may) have access to the means to remove the fan from the motor.

The most common method of attaching a prop/fan to a motor shaft is either:

• Bolting directly to the motor;
• set screw onto the shaft;
• Collet

[Eric S.]

Static balancing that fan may not be necessary if it seems ok as is. If it is slightly out of balance it could be related to the shaft as well. There are a few threads in here by 4stripes about balancing and you can probably do it with out taking the impeller off the shaft, placing a small piece of duct tape on the spinner at different positions on the spinner using the clock method and throttling up a bit at each position until you find a spot that you notice less vibration.Check out 4stripes threads on this for more details. If your doing it just to check it for balance, you definitely don't need to take it out. If it's really loud (buzzing or groaning noise) & you feel heavy vibration through the plane when it's throttled up-it's out. if not it's fine. Most stock fans in the cheap HK planes are not balanced well at all. Yes they will usually fly without touching them but they are noisy and your losing efficiency and sometimes will eventually come apart at the worst possible time. If you really need to get the nut off the shaft and it's being a bugger, there's a few different ways.

Method #1: The easiest but lazy way is to grab the tip of the shaft with a pair of needle nose pliers and turn the nut with an open end wrench, but you will damage the threads a bit depending on how tight it is and will have to rethread them with the nut on its way off.

#2: The 2nd way that has worked for me is also a bit lazy but doesn't damage anything is to push down on the impeller when turning the nut to hold the shaft and try to turn the nut with a bit of a fast, snapping motion to break it loose. This way you can use a socket

#3:The third is a bit more time consuming but the best way. You need to file 2 flat spots at the top of the shaft on opposite sides so you can hold it with a small wrench while turning the nut.

I usually start with #2 and if that doesn't work I go to #1 and then do #3 after it's off to clean up what was damaged by doing #1. Yes, I'm lazy and lazy people do the most work.

[Con]

Thanks for your help Eric, its much appreciated.

[4stripes]

Another way is to dremel a slot into the end of the adapter so a flat screw driver can hold the shaft from turning. There is usually plenty of material to make a nice deep slot.

[Dutkoski]

I too find the slot method the best way, doesn't damage the threads at all on the adaptor. Easier to manipulate a screwdriver and wrench over using two wrenches.

[Eric S.]

Does the slot method not ruin the threaded hole for the screw that holds the spinner on?

[airbourne]

I use these:





Precision aluminum custom shaft adapter. Makes taking off the rotor/disassembling the fan a breeze, they are also a very snug fit and machined to high tolerances for easier balancing.