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Old Jan 10, 2004, 02:34 PM
Why not Delta?
rysium's Avatar
Sacramento, CA
Joined Jun 2003
1,714 Posts
Quote:
Originally posted by Acer
You should get more thrust and less amp draw when you change out the magnets. Mine went from turning a 4.75x4.75 prop at 15,000 r.p.m. at 9.7A to turning the same prop at 16,200 r.p.m. at 8.5A.
By giving stronger magnets you will have two things:

1 - when you have a stronger magnetic field on the rotor, you can have the same torque with less current on the stator = better efficiency

2. stronger magnets in rotor causes lower motor's rpm/V with the same power so if you run the same current you will get more torque. Using the same gearbox you can put bigger prop and have more static thrust using the same power (it's the same result as you put additional gearing.

RysiuM
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Old Jan 10, 2004, 02:40 PM
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galloping gimp's Avatar
Ohio, USA
Joined May 2002
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Cranky-

There are several ways to construct and mount a converted CD-ROM motor.

In some designs, the stator is mounted directly to a flat bulkhead or firewall. See post #202 above.

Some builders have even left the stator attached to its circuit board from the CD-ROM, then attached the circuit board to the airplane. See the first page of the original "One hour CD_ROM motor construction" thread.

In other designs, a tube of metal or other material is attached to the stator, and the tube is somehow affixed to a firewall or motor mount. See post #207 above. Depending on the materials involved, builders have used CA, epoxy, and other adhesives to attach the tube to the stator.

My choice was to retain the original brass stator hub and solder a short piece of brass tubing to it. See photo below. This resulted in a fairly heavy motor, but it was easy to do with minimal tools. I have yet to see how well it works in an airplane, but it generates at least as much thrust as an IPS.

Everyone's solution is a little different, based on their own skills and tools, the kind of plane they are flying, and the details of the CD-ROM components.

- Jeff
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Old Jan 10, 2004, 04:26 PM
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Hi Jeff,just wondering if you still get good performance with the motor you have pictured above with all the space between the magnets and stator heads.Nice looking motor.Matt
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Old Jan 10, 2004, 04:51 PM
RIP "Long Shadow Flyer"
crvogt's Avatar
Upstate New York-- Rochester, NY USA
Joined Oct 2001
732 Posts
Working on my first conversion, made a scrounging raid on the local ACE hardware, looking for someting aluminum to turn on a lathe or fashon into a motor mount.... In the specialty nuts and bolts drawers found " Weld Nuts" #10, 1/4... looks like it may do the trick. I plan on inserting a GWS bushing into the threads to help align the parts while the Epoxy sets, will coat the shaft with white lithium grease to prevent sticking... Will keep you posted on results and which size works best. These are a common item at ACE, Home Depot and Lowes. The shaft is one of the laser positioning slides, 3mm. neat!!!
Carl
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Old Jan 10, 2004, 05:06 PM
-plancks only-
Franck's Avatar
The Netherlands, UT, Benschop
Joined Oct 2001
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Acer,

What nr. of turns did you use ?

Jeff,

You have some mighty airgaps shown on the picture!

Regards,

Franck
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Old Jan 10, 2004, 07:26 PM
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INDEPENDENTLY POOR in OHIO
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t-turley

Quote....My tach indicates 3600 with the lights on, so I have to turn off all of the lights and try to get the readings by flashlight.

Tony, your tach is reading the 60 cycle flicker from the lights and is a good way to check the calibration of your meter

I set up the flashlight to shine through the prop and take my reading from the front

I also mount the prop as a pusher so that it does not fly off (anymore ) having been hit in the side once ( it cut me right through the shirt!! )

You mentioned small bearings, Where did you get them?

I have not yet found a CDR motor with bearings and I have disassembled nearly 60 motors so far

Roger aka GIFLYRC
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Old Jan 10, 2004, 07:32 PM
Hi Wattage Electrics - Cool
Rad Racer's Avatar
Jordan, Minnesota
Joined Jan 2004
618 Posts
My motor bell has room for (16) 5x5x1 magnets, will this work with a 9 pole motor?

Somewhere in this thread, I think I read that motor poles must be a multiple of 3, and magnets must be a multiple of 2....is this correct?
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Old Jan 10, 2004, 08:19 PM
Why not Delta?
rysium's Avatar
Sacramento, CA
Joined Jun 2003
1,714 Posts
Quote:
Originally posted by ROGER GANTZ
I have not yet found a CDR motor with bearings and I have disassembled nearly 60 motors so far
Out of 32 cd-roms types I found so far 8 types with BB.
Here is the list of CD-ROMS with BB. If shaft is 3mm, motor uses 3x6x2.5 BB, for shaft 2mm the B is 2x4x2

RysiuM
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Old Jan 10, 2004, 08:52 PM
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CrazEflyer's Avatar
olympia, Wa
Joined Sep 2003
199 Posts
Hi

I have a cd-rom motor that i have converted, and it shuters at half throtle and it all so gets very hot.

The cd-rom motor is a sony 56x with a thin gray magnet.
I put 16 turns of 22 or 24 guage wire Y wind on it and instaled ball bearings.

Do any of you know what i could do diffrent to fix it.
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Old Jan 10, 2004, 08:55 PM
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Here's a shot of my 2 latest rewind efforts: I finished rewinding the big 44mm guy just this afternoon, with 15T of #20. Pulls 11.5A from 7 cells on an APC 9x6 SF. I still haven't figured how to get good, consistent readings on my tach when using it indoors, but I did get a transient reading that said 12,000. That sounds too high to me, although it is clearly spinning the prop much faster than it did with 23T of #22.

The 22mm micro is wound with 10T of dual-strand #26. It screams like a banshee with the Gunther black 5x5, but doesn't like anything above about 3/4 power. I'm hoping the N45s will help change that. I ordered the 5 x 1.5 x 1mm magnets, to be installed in NN SS NN, etc pairs.

Tony Turley
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Old Jan 10, 2004, 09:02 PM
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Joined Mar 2001
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Quote:
Originally posted by ROGER GANTZ
t-turley

Quote....My tach indicates 3600 with the lights on, so I have to turn off all of the lights and try to get the readings by flashlight.

Tony, your tach is reading the 60 cycle flicker from the lights and is a good way to check the calibration of your meter

I set up the flashlight to shine through the prop and take my reading from the front

I also mount the prop as a pusher so that it does not fly off (anymore ) having been hit in the side once ( it cut me right through the shirt!! )

You mentioned small bearings, Where did you get them?

I have not yet found a CDR motor with bearings and I have disassembled nearly 60 motors so far

Roger aka GIFLYRC
Roger,

Thanks for the tip on the tach. As for the bearings, I've found a couple that had ball bearings in them; one was actually an ancient 4X drive, with a pair of really nice bearings - which I've since lost in 2 separate mishaps! My LHS can also order 3x6mm bearings for me.

Tony Turley
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Old Jan 10, 2004, 11:27 PM
Why not Delta?
rysium's Avatar
Sacramento, CA
Joined Jun 2003
1,714 Posts
Quote:
Originally posted by CrazEflyer
Hi

I have a cd-rom motor that i have converted, and it shuters at half throtle and it all so gets very hot.

The cd-rom motor is a sony 56x with a thin gray magnet.
I put 16 turns of 22 or 24 guage wire Y wind on it and instaled ball bearings.
I did almost the same - motor didn't run more than half throttle and was very hot - indicates short somewhere in winding.

I rewound it and was fine, but with 18T didn't run on 3 cells full throttle. When replaced magnets, it run without the problem.

So first - check if you have short somewhere before you do anything else. It's common that enamel on the wire gets broken and wire gets short to stator.
What I do, I paint with enamel all the stator's surface where the wire might touch it - it makes the surface smooths and soft, so it doesn't hurt the wire's insulation while you wind it.

RysiuM
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Old Jan 11, 2004, 12:15 AM
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olympia, Wa
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Thank you RysiuM i will try that.
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Old Jan 11, 2004, 12:48 AM
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ssatoru's Avatar
Chiba, Japan
Joined Jan 2002
1,044 Posts
Wing rules!

Quote:
Originally posted by Acer
You should get more thrust and less amp draw when you change out the magnets. Mine went from turning a 4.75x4.75 prop at 15,000 r.p.m. at 9.7A to turning the same prop at 16,200 r.p.m. at 8.5A.

-- Acer
http://speedwing.net
Conguratulation on CDROM motor, Acer. Nice mount. I have been flying my CDROM motor on a Depron small wing (MH60 airfoil, inspired by CLiC) for a while. I think wing is very suited for these powerful motors. Mine takes about 90-105W with ET1200 3S, can climb 218g vertical to out of sight in 15 seconds, can do 'active' knife edge.

Isn't your motor getting too hot? Mine got too hot to melt soldering with that wattage. You might want to try DoppelWhopper.

Satoru

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Old Jan 11, 2004, 03:18 AM
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galloping gimp's Avatar
Ohio, USA
Joined May 2002
1,623 Posts
Some of you asked about the apparent large gap between the magnets and stator in my CD-ROM conversion.

The gap is smaller than it appears from the photo I posted earlier in this thread. Something about the camera angle and lighting made the gap appear larger than it actually is. The photo below shows the actual gap, which is about 0.5mm.

Motor configuration:
stator diameter: 24mm
rotor outer diameter: 28.8mm
26 turns, #26 (~4mm) wire
winding: "star" (seeking torque rather than RPM)
prop shaft: 3mm GWS IPS
ball bearings: two 6x3mm (from IPS)
weight: 28g

Tested with:
GWS 9x7 prop (smallest prop I own)
370 mAH 8.4V NiMH battery packs (only battery packs I own)
Jeti 08-3P controller

The static performance measured so far:
With original ring magnet
3.5 ounces (~100g) thrust @ 4.5A

With 5x5x1 N45 magnets
4.9 ounces (~139g) thrust @ 4.3A

While running with the stock ring magnet, the motor got very hot and drew so much current that the battery pack voltage decreased to the low voltage cutoff point of the Jeti controller, which then shut down. After installing the N45 magnets, the current draw was reduced, the battery voltage stayed above the LVC point, and the motor got warm but not hot.

I'm sure it will do better with smaller props, which I do not have yet. I am considering:

GWS RS 8x4.3
GWS HD 8x4 or 9x5

Do you have any suggestions or other recommendations for props or anything else?

I know I am seriously stressing the battery packs, but they are all I own at this time. Li-Polys are probably the way to go.

- Jeff
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