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Old Jan 26, 2011, 09:35 PM
Ugly planes do not fly
_Sergey_'s Avatar
USA, GA, Alpharetta
Joined Mar 2007
1,689 Posts
Problem with motors

Motor mount screw holes are off center by almost 1mm. I can't mount second rotor -- it touches shroud. What should I do?
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Old Jan 26, 2011, 10:08 PM
Watts Up?
jet-ster's Avatar
USA, TX, Arlington
Joined Jun 2006
1,634 Posts
Man that is messed up! What motors are those?
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Old Jan 26, 2011, 10:46 PM
Ugly planes do not fly
_Sergey_'s Avatar
USA, GA, Alpharetta
Joined Mar 2007
1,689 Posts
Quote:
Originally Posted by jet-ster View Post
Man that is messed up! What motors are those?
HET 3W Typhoon. Not cheap ones either...
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Old Jan 26, 2011, 11:16 PM
"LiPo-Blaster"
RugFlyer's Avatar
Duluth, GA
Joined Apr 2009
932 Posts
Sergey...sorry to hear about this, sounds like some of my luck.

1. You could either send them back explaining the problem, that these motors are for a twin EDF and need to be Matched with the same mounting offsets.

2. Or ( I've done this before...) you could carefully drill out (enlarge a little at a time) the plastic EDF motor mount holes for the 3W motor that is different, so that you can center the motor using flat washers and or lock washers. Once you get the washers centered you can epoxy them so you motor will stay centered. Then fasten the motor down with locktite.

Let use know how you solve this minor setback!

-Rick
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Last edited by RugFlyer; Jan 26, 2011 at 11:25 PM.
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Old Jan 26, 2011, 11:21 PM
Ugly planes do not fly
_Sergey_'s Avatar
USA, GA, Alpharetta
Joined Mar 2007
1,689 Posts
How to reverse a servo

In 737 there is dedicated servo per elevator. One servo needs to be reversed either by using extra channel (no way!), separate reverser device (umm... no), programming a digital servo (too exotic and $$$) or by swapping two wires inside.

Here is how to reverse a servo in 20 minutes. And I am slow builder.

1. Swap two wires at the motor.
2. Swap two wires at the pot. Leave central wire. If it is hard to tell which wire is central use multimeter to measure resistance between each two pins. Two pins that have most resistance are end pins. Swap wires at those.
3. Mark reversed servo and as Doug says, admire your work

Here are two servos connected by Y splitter and moving in opposite directions.
http://www.youtube.com/watch?feature...&v=g5r7rL0rpWs
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Old Jan 27, 2011, 01:23 AM
Go FASST or go home...
Ben_E's Avatar
Bergen, Norway
Joined Nov 2002
3,123 Posts
Quote:
Originally Posted by _Sergey_ View Post
Motor mount screw holes are off center by almost 1mm. I can't mount second rotor -- it touches shroud. What should I do?
I guess quality motors are sold by serious vendors... E-mail them your pictures and ask them to ship you another motor - I'm sure they will do that.
Where did you get them from anyway?

Ben_E
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Old Jan 27, 2011, 09:30 AM
6 months to finish a rtf
pulsery2k1's Avatar
upstate ny
Joined Jun 2003
1,832 Posts
_Sergey

from your photo's it looks like the motor is fairly tight in the housing
it also looks like it an inrunner ,

what I alway's do is put o'rings on the motor case to not only
keep the motor centered but to keep the motor from twisting
under high power(rubbing blades) if you don't have o"rings
you can use electrical tape wraped very tightly around the motor.

that will centerthe motor - you have a caliper - remove the other
good motor and compair the hole's with the caliper - then
compair the fan housing's
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Old Jan 27, 2011, 10:59 AM
Ugly planes do not fly
_Sergey_'s Avatar
USA, GA, Alpharetta
Joined Mar 2007
1,689 Posts
Thank you Pulsery! Motors are inrunners and electrical tape sounds like a great idea to center them. Worst case I center motors and expand screw holes in the shroud. If motors are centered by o-rings I guess it's okay to leave screw holes in oval shape. Is this a safe assumption?

Where do you get 28mm o-rings? ACE Hardware?
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Old Jan 27, 2011, 11:27 AM
6 months to finish a rtf
pulsery2k1's Avatar
upstate ny
Joined Jun 2003
1,832 Posts
_Sergey_

I have an O-Ring Assortments , but mcmaster-carr sell them


http://www.mcmaster.com/#rubber-o-rings/=arvp8z

or your local hardware - plumming store .

the o'ring also dampen any vibrations caused by out of balance
rotors .
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Old Jan 27, 2011, 04:53 PM
Go FASST or go home...
Ben_E's Avatar
Bergen, Norway
Joined Nov 2002
3,123 Posts
Unpacking some more...

Thought I would show more of the box contents

Retracts and fans, motors, and again it's a bigie!

Looking very much forward to flying this bird!

Ben_E
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Old Jan 27, 2011, 06:53 PM
Aka: Tom Jenkins
ApexAero's Avatar
Palm Beach County, Fl.
Joined Aug 2008
4,396 Posts
Sergey, Stay away from electrical tape on those motors please, the heat will cause problems. Use a 1/4" strip of magazine cover wrapped around the end of the motor, wallow out the od screw hole and mount all centered up! I highly suggest getting a MPI finned heat sink, cut it in half for two motors with heat sink paste from Radio Shack
I've run that motor at 125 amps at 1680 watts in a lander 68mm fan and it has serious power.
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Old Jan 27, 2011, 07:06 PM
Ugly planes do not fly
_Sergey_'s Avatar
USA, GA, Alpharetta
Joined Mar 2007
1,689 Posts
Quote:
Originally Posted by ApexAero View Post
Sergey, Stay away from electrical tape on those motors please, the heat will cause problems. Use a 1/4" strip of magazine cover wrapped around the end of the motor, wallow out the od screw hole and mount all centered up! I highly suggest getting a MPI finned heat sink, cut it in half for two motors with heat sink paste from Radio Shack
I've run that motor at 125 amps at 1680 watts in a lander 68mm fan and it has serious power.
This is a great advice! Thank you! I've been thinking about MPI heat sink. It cost about $5 and good for two motors if cut in half. I will order it tomorrow.
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Old Jan 27, 2011, 11:36 PM
Ugly planes do not fly
_Sergey_'s Avatar
USA, GA, Alpharetta
Joined Mar 2007
1,689 Posts
Motor centering

I cut 1/4" strips of adhesive backed aluminum foil that is used in HVAC applications. Then rolled on the motor to make it tight insert into shroud can. This made a TREMENDOUS difference in EDF performance and sound! There is no more rotor touching shroud and vibrations 80% gone! The sound of the fan improved a lot. I will try to dynamically balance it anyway to see what I can get out of it.

Here are test runs. 4000mAh 25-50C 4S LiPo, unknown ESC

Motor 1: 28A, 406W, 770g thrust
Motor 2: 28.7A, 410W, 860g thrust

The difference in thrust I believe is because first fan is unbalanced when I scratched side of the shroud on the first test run. I'll rerun tests after balancing and new ESC arrive. Will play with timing too.

Anyway I think this is a perfect set up. Low amps and plenty of watts and thrust for scale flying. I am happy
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Old Jan 28, 2011, 01:03 AM
Aka: Tom Jenkins
ApexAero's Avatar
Palm Beach County, Fl.
Joined Aug 2008
4,396 Posts
I'd suggest low or no timing as the motor is hot enough, some minor vibs can be worked out by rotating the rotor on the adapter a tad, I'm sure you know. Nice neat work with the tape! Its amazing how things work with a little care ain't it?
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Old Jan 28, 2011, 01:41 PM
flying techy
NY
Joined Nov 2005
365 Posts
Quote:
Originally Posted by _Sergey_ View Post
I cut 1/4" strips of adhesive backed aluminum foil that is used in HVAC applications. Then rolled on the motor to make it tight insert into shroud can. This made a TREMENDOUS difference in EDF performance and sound! There is no more rotor touching shroud and vibrations 80% gone! The sound of the fan improved a lot. I will try to dynamically balance it anyway to see what I can get out of it.

Here are test runs. 4000mAh 25-50C 4S LiPo, unknown ESC

Motor 1: 28A, 406W, 770g thrust
Motor 2: 28.7A, 410W, 860g thrust

The difference in thrust I believe is because first fan is unbalanced when I scratched side of the shroud on the first test run. I'll rerun tests after balancing and new ESC arrive. Will play with timing too.

Anyway I think this is a perfect set up. Low amps and plenty of watts and thrust for scale flying. I am happy
touch the shroud? you mean the fan is off set to a side?

I noticed that with my ducted fans when i first get them. what i do is i run it slow to see where the problem is. If i see the blades touch the sides i use my hobby knife and i cut a tad off the tips just enough so it can spin freely.

Sometimes plastic comes that way with ducted fans. The thicker ducted units dont have that problem, the ones with thin plastic do.

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