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Jul 04, 2003, 06:43 PM
Thread OP

Dual CDrom Drive


Heres a CD rom motor I made up some time back but never had light enough cells to really test.

Its made from 2 identical cdrom motors back to back with a ballraced tube soldered onto double sided circuit board to hold it all together.

The Prop is a GWS 8 x 4.3 but it will spin alot bigger one. With what effiencey I do not know as yet. The spindle is a replacement GWS IPS one.

These motors are used directly out of the CDrom drive (no rewinding.

The battery pack used to drive them is 2 x 2 cell 700 mAH etechs (4 cells in series) but 1250s would not be to heavy. I have flown on 4 x 17670 sized laptop Li-Ions but at 152 grams it was way to heavy for the small plane I was testing.

The current draw is very low but at 14.8 volts the motors are working at a good voltage for the wind they have.

Not as much power to weight as a rewound single motor but this has to be very efficient and will power a significantly bigger plane.

The wires are soldered directly to the double sided board as they exit the motors and joined though the board. Voltage is applied to one pair of wires to line up the magnets in each cup and they are marked for assembly.

Controller I used is MGM compro TMM 18amp but the 8 amp version should work as well. The worry is at this higher voltage the BEC is derated considerably and could be blown if you put to much load on it. (i.e jammed powerful servo)
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Jul 08, 2003, 12:46 PM
Registered User
electron_head, I like you r dual CDROM. I started one last year using two identical drives as you are using. I was going to rewind
them, so they should give slightly more power to weight ratio. My
concern was the rewinding method to allow both motors to use
the same ESC. I have the mechanical part done, the layout is the
same as yours. I turned a one piece aluminum frame to hold both
rotors and the ball bearing supported shaft, with the center having a web for mounting. I have both coil stacks aligned to each
other, but I am not sure how to wind the coils, so the motors are
not fighting each other. Seeing your motor, gives me courage to
try to complete mine. Any ideas on this would be welcome. If you
are interested, I can get some pictures on what I have so far.
Thanks, Cecil Miami,FL [email protected]
Jul 08, 2003, 04:16 PM
Thread OP
The actual reason I made this one was I have more of this cdrom motor than any other type. After rewinding a couple and getting very poor results I tryed this.

Puting two together you half each phase resistance.
Theres a guy here connectiing the wires up Delta to achieve the same thing. I'm getting around 1.3 ohms which is still way to high compared to my rewound motors that are more around 0.7 ohm.

So to get a respectable current draw and total wattage I doubled the voltage.

The motor weighs almost double that of single cdrom motor.


I think where alot of people go wrong is they are expecting to get Speed 400 power at 1/3 rd the weight. They wind these motors with really hot winds and all that achieves is magnet saturation and high current draw. Only way to get the benefits of a hot wind is to have a ring magnet that matches. If your going to go to all that trouble why not just buy a Nippy or PJS. When the cdrom craze started these motors werent available.
Jul 08, 2003, 10:27 PM
Registered User

Dual CDROM Motor


I agree, but I like a challenge. They said it can not be done, but
we did not know that, so we did it anyway. I have a Nippy 280
and several larger outrunner motors that are very good. I have
a rewound CDROM motor that puts out good power for its weight
but does draw a lot of current. Some modelers like to fly and buy
ARFs, others like to build and not fly too much, I guess I love to
tinker and build. I want to see what this twin can be made to do.
Cecil Miami, FL
Jul 08, 2003, 10:40 PM
Thread OP
Ok Cecil we are of the same frame of mind.

Do your motors have a black or grey magnets?

If you want to build the best Cdrom motor without putting in replacements I have found the greys to be noticably stronger .

Heres a pic of 2 identical motors except for the magnet

The grey you can feel is stronger by putting a metallic object near (screwdriver) This becomes more obvious after you have wound a few. I dont bother winding black ones anymore. They work but you cant drive them as hard .
Jul 15, 2003, 07:13 PM
Registered User

dual cd-rom motor


electron_head, sorry I am late getting back on this, below you can get to two pictures of my project.My magnets are black, but are fairly strong. Weight with ball bearing without windings is 26.5
grams. cecil


[IMG][/IMG] [IMG][/IMG]
Jul 15, 2003, 08:44 PM
Thread OP
Looks good Cecil,

Looks like your bells are the same as on mine too. Don't worry too much about the magnets mine are black as well.

There must be some special wind but I havent taken the time to research it.

Good luck if you finally get round to winding your motor .
Nov 13, 2003, 10:18 AM
RPV builder & operator
Pierre Audette's Avatar
Just wanted to revive this thread, but on a different tangent. I got two motors of the same brand, OD at ~24mm. I doubled stacked the stator plates, minus 4, and ended up with a 10mm thickness. A piece of the stator mount was cut and stacked onto the other one. The brass fitting for the shaft was taken off the CD-ROM bell, and attached to a cut down housing from a S280. Just need to wire it up, and glue two rows of 5x5x1 magnets to get it going. Picts to follow later....
Nov 13, 2003, 06:58 PM
RPV builder & operator
Pierre Audette's Avatar
Pic of what I got done so far. Not sure if I should use a star or delta winding yet.
Nov 13, 2003, 10:47 PM
Thread OP
Hi Pierre,

I would experiment more but would have to get some rectangular magnets from overseas.

Have you seen this link its posted on ezone somewhere else but I saved the page for future reference.

http://slope-combat.de/aw/

Regards Garry.
Nov 14, 2003, 07:00 AM
Registered User
ssatoru's Avatar
Quote:
Originally posted by Pierre Audette
Pic of what I got done so far. Not sure if I should use a star or delta winding yet.
Nice motor, Pierre!

I am also trying similar but it is tough to allign two rows of magnet to have enough air gap. Wish I can get 10mm x 5mm x 1mm magnet and such.

Satoru
Nov 14, 2003, 11:16 AM
RPV builder & operator
Pierre Audette's Avatar
Thanks for that link Garry. It's a nice motor, but needs a lot machining than I was prepared to do. The thicker magnets should also make it more powerful.

One of the guys on the LRK Yahoo group mentioned that he used a single row of 5x5x1 magnets on a double stacked stator. It gave him more RPM's and ran cooler. Using ball bearings also lowered the amps.
Nov 14, 2003, 11:21 AM
Registered User
Kevin Murray's Avatar
TMM controller. So there CD Rom motors are brushless ?
Nov 14, 2003, 09:17 PM
RPV builder & operator
Pierre Audette's Avatar
Yes they are, three-phase motors just like the rest of them.
Nov 14, 2003, 10:30 PM
Registered User
Kevin Murray's Avatar
So I can just pull the botors out of an old cd rom drive and use it to power a micro indoor flyer ? This is great.


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