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Old Nov 04, 2012, 11:21 AM
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WhalleyB0Y's Avatar
Canada, BC, Surrey
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I picked up this magnetic balancer and had tried my hand at balancing a few props and rotors. It seems pretty easy to do and not as intimidating of a procedure as I had once thought. Unless I am doing it all wrong I anticipate great results with my new fans in the Raptor.

I am using this...

http://www.top-flite.com/accys/topq5700.html

...and by added tiny drops of medium CA to the back of the rotor hub on the lighter side I was able to get a true balance very easily.
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Old Nov 04, 2012, 12:30 PM
A-4 nut!!
skyhawk's Avatar
Vancouver B.C.
Joined Apr 2002
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WHY!!!!!

We told you already - the fans are balanced! and those things are not very good. They are notoriously out of wack. No good for fans and only barely good for props.

I think you just screwed yourself .
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Old Nov 04, 2012, 01:51 PM
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Woa, I haven't done anything yet Skyhawk. I have a replacement WeMo on its way with a new motor. The other fan is still already balanced and ready to go. I am just looking at way to be able to balance my own rotors and props in the future instead of paying extra to have it done.
How do you balance rotors and props? Thats too bad, I was really hoping this magnetic balancer was a good tool for the job.
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Old Nov 04, 2012, 01:54 PM
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Originally Posted by skyhawk View Post
WHY!!!!!

We told you already - the fans are balanced! and those things are not very good. They are notoriously out of wack. No good for fans and only barely good for props.

I think you just screwed yourself .
...and yes the previous fan had failed because I had mounted the rotor too close to the motor screws. They had rubbed and the motor worked itself loose and tilted the rotor against the shroud. I am listening to you guys, I am just not that good at communicating my thoughts.
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Old Nov 04, 2012, 03:04 PM
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I have been reading and watching various guides to dynamic balancing and here is the way I understand it:

Mounting the motor:
1. Install the adaptor on the motor shaft by applying heat to the adaptor. Firmly press the adaptor onto the motor shaft and tighten the grub screws with loctite on the flat spot of the motor shaft.
2. Wrap the motor with thin tape (foil tape) to ensure a snug fit into the stator. This step will keep motor centered in the stator.
3. Use loctite and tighten motor mount screws.
4. Place the rotor onto the adaptor shaft and rotate the motor gently by hand to listen for clicking sounds of the screws heads hitting the fan. The adaptor needs to be adjusted to allow clearance of the screws.

Balancing the fan:
1. Place the fan and motor into a stand that can protect you from debris should it blow apart. Mark a spot on the adaptor and the rotor to give position relation.
2. Run it up at half throttle on 3s, place a wand or a tool against the shroud to help feel for vibrations. If there are vibrations, rotate the fan 180* on the adaptor and try again.
3. Keep rotating the fan on the adaptor through 12 positions like the hours of clock until you reach the best balance as felt by your hand holding the wand against the shroud.
4. Attach the spinner to the fan and run it up at half throttle, feeling for imbalance. Rotate the spinner in 12 positions until you reach balance.

*Adding epoxy or CA to the lighter side can also can be done to help achieve balance. The glue should be added to the back side of the rotor near the hub.

Please let me know if I am missing an important step here or something should be changed. My only concern is my ability to feel the vibrations with the wand or my hand.
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Old Nov 04, 2012, 04:01 PM
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United Kingdom, England, Cobham
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Quote:
Originally Posted by WhalleyB0Y View Post
I have been reading and watching various guides to dynamic balancing and here is the way I understand it:

Mounting the motor:
1. Install the adaptor on the motor shaft by applying heat to the adaptor. Firmly press the adaptor onto the motor shaft and tighten the grub screws with loctite on the flat spot of the motor shaft.
2. Wrap the motor with thin tape (foil tape) to ensure a snug fit into the stator. This step will keep motor centered in the stator.
3. Use loctite and tighten motor mount screws.
4. Place the rotor onto the adaptor shaft and rotate the motor gently by hand to listen for clicking sounds of the screws heads hitting the fan. The adaptor needs to be adjusted to allow clearance of the screws.

Balancing the fan:
1. Place the fan and motor into a stand that can protect you from debris should it blow apart. Mark a spot on the adaptor and the rotor to give position relation.
2. Run it up at half throttle on 3s, place a wand or a tool against the shroud to help feel for vibrations. If there are vibrations, rotate the fan 180* on the adaptor and try again.
3. Keep rotating the fan on the adaptor through 12 positions like the hours of clock until you reach the best balance as felt by your hand holding the wand against the shroud.
4. Attach the spinner to the fan and run it up at half throttle, feeling for imbalance. Rotate the spinner in 12 positions until you reach balance.

*Adding epoxy or CA to the lighter side can also can be done to help achieve balance. The glue should be added to the back side of the rotor near the hub.

Please let me know if I am missing an important step here or something should be changed. My only concern is my ability to feel the vibrations with the wand or my hand.
That is basically it.

I have usually found that using the clock method on the rotor (and spinner in the case of a Wemo) is usually not enough and I've still needed to add weight at some position, particularly if the motor is out of balance. As you note, add some epoxy/CA - the way to find the lightest point is by using a square piece of insulation tape stuck to the blades (I typically use about 6mm squares). Move the tape from one blade to the next, running up the fan and listening/feeling the vibes each time (my ears seem to be better than my touch!). I then use some epoxy on the inside of the spinner hub at that position. Start with a blob and grind a bit away each time until the fan runs smooth. It takes a bit of time and some getting used to, but can be very satisfying when the fan runs smooth.

You've had some lousy setbacks, but your perseverance is admirable. Hope it all works out in the end!

One last point - be very careful of Loctite - it will eat your shroud! We've see this happen to people on this forum a number of times. You need to use the type that won't dissolve plastic, or make sure you get it INTO the screw hole in the motor only. You should not apply it through the hole in the shroud, rather apply it to the motor hole, wipe away excess and push the motor into the shroud. I'm actually wondering now if this what happened in your failed fan unit - can you confirm whether you used Loctite? If so, you may want to check your other fan for the same problem...

Jacques
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Last edited by Jacques.Eloff; Nov 04, 2012 at 04:24 PM.
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Old Nov 04, 2012, 08:02 PM
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I was tinkering with the canopy again tonight. I decided to cut up some thin ply and make a frame to hold the canopy in place. I little bit of sanding to get it to fit smooth with the body lines.

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Still a little unsure of which way to fasten it down for flight. I already have a few magnets on the fuse but I may not want to still use them.
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Old Nov 04, 2012, 08:09 PM
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Thanks Jacques,

Thats reassuring, I think now I will try to balance a few of the other junk fans I got sitting here just to practice the process. But that thing with the Loctite eating the plastic is probably what did in my fans. I drop a small bead of loctite on the threads of the screw, blow it off and then put the screw through the mount maybe smearing some on the shroud. Just another one little detail of all the many things that can go wrong with the assembly of an edf fan. Thanks for the tip.
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Old Nov 05, 2012, 02:21 PM
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Finally found some good material for thrust tube construction. It is sold in sheets as "Desktop protector" at Staples office supplies. $3.49 per large sheet. I don't know if it is milar or duralar but it looks just like it.

I also found translucent acrylic window tint and gloss acrylic thinner for use on my canopy for the scale tint. This was purchased at Michael's art supplies.
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Old Nov 07, 2012, 04:18 PM
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I had been experimenting with Rust-o-leum rattle can chrome and some orange acrylic translucent paint. Trying to achieve a scale look for the new canopy. I want to hide the fact that I now have an empty cockpit and there is a lipo sitting where a pilot should be. I had hoped a semi-opaque finish to the inside of the canopy would do the trick.

My experiments with the paint on a piece of scrap milar proved unsuccessful. When sprayed against on the milar for what would be the inner surface, the results on the outside were not chrome, not even shiny. Just a dull grey from behind the orange translucent. The chrome would work well if it was sprayed over the top of the canopy rather than from within it. I just don't think that is the way I want to paint it.

What I was trying to do:

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I will look at some other ideas including the possibility of just using a black tint.
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Old Nov 07, 2012, 04:24 PM
Wats the worst that can happen
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I am interested if you've found a decent place to fly in the lower mainland - considering the longer take-offs the jet requires. I am in the market for my first composite 90mm (or twin 70mm) jet and want to make sure there is somewhere convenient, safe and comfortably able to meet the space requirements.
I'm considering this jet, or the HK L-59 btw.

Sorry to read about all the bad luck you've been having. I feel for you. If I had more experience in the composite realm I'd offer my help.
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Old Nov 07, 2012, 05:55 PM
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United States, CA, Santa Clarita
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Tamiya spray for polycarbonate, # PS-31 "Smoke" works great for tinting the inside of canopies.
It's highly translucent, but the more coats you spray the darker it gets.

Hobby People:
http://www.hobbypeople.net/index.php...ray-paint.html

Tower:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXFFV0
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Old Nov 07, 2012, 07:55 PM
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Originally Posted by TheCure View Post
I am interested if you've found a decent place to fly in the lower mainland - considering the longer take-offs the jet requires. I am in the market for my first composite 90mm (or twin 70mm) jet and want to make sure there is somewhere convenient, safe and comfortably able to meet the space requirements.
I'm considering this jet, or the HK L-59 btw.

Sorry to read about all the bad luck you've been having. I feel for you. If I had more experience in the composite realm I'd offer my help.
Lol, I guess it does look like I've had a lot of bad luck and mishaps. This is probably because of this Raptor being my first build and I probably should have picked something less complicated and fussy. Edf jets are very finicky and a lot of things can go wrong. Most of my problems have stemmed from my lack of experience with the fans and motor mounting.

I certainly don't want to discourage you from this kit or anything similar. I am pretty sure anyone else would have had this plane built in a couple days. I bought this composite kit because I really like the "build" aspect of rc flying and I wanted something more than another foam edf. Unlike an arf foamie which can be assembled and ready in just moments, this kit has challenged me and kept me entertained in my shop for a long time. I wasn't planning on having so many problems and this should have been done ages ago but it keeps me tinkering and thats what I bought it for.

With that being said, I have not found a suitable place to fly composite jets of this size. If you want to use retracts and scale looking gear like I want to then you are going to have a tough time finding a place to go to. If your ok with bungee launching and belly landing your planes then it shouldn't be too hard to find a place. Most of the local clubs out here fly larger models with bigger wheels off of rough grass. I would fly this at my regular flying area with the retracts if only I was already comfortable about flying it. I just don't know how this is gonna fly and I would like to at least be at a Maac field when doing my shaker. I had joined a club in the States which is about an hour out of town from here and they have the smoothest grass runway I have seen. This seems to be my best chance to fly my jet with retracts... I will let you know how that goes when the time comes. Keep in touch!
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Old Nov 07, 2012, 07:56 PM
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Canada, BC, Surrey
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Quote:
Originally Posted by efflux RC View Post
Tamiya spray for polycarbonate, # PS-31 "Smoke" works great for tinting the inside of canopies.
It's highly translucent, but the more coats you spray the darker it gets.

Hobby People:
http://www.hobbypeople.net/index.php...ray-paint.html

Tower:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXFFV0
Thanks for the info, I am going to look into it!
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Old Nov 08, 2012, 03:02 AM
A-4 nut!!
skyhawk's Avatar
Vancouver B.C.
Joined Apr 2002
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Rit dye is the way to go.
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