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Old Jan 26, 2004, 12:50 PM
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and the HD one...
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Old Jan 26, 2004, 03:07 PM
RPV builder & operator
Pierre Audette's Avatar
Canada, QC, Gatineau
Joined Jan 2001
2,302 Posts
Re: 3 motors to rewind...

Quote:
Originally posted by sousap
1-may you guys recomend me how to achieve a working solution for both CDrom motors?
2-how to make a twin CDrom motor, ie wind both stators and use both bells? and about the magnets for it? may I use two 5x5x1 to make one 10x5x1?
3-about the HD motor, how to wind it?

1- I've had good success with 28 ga wire in delta and star winding patterns. Having two similar motors, you could try both and compare the results with various props.
2- I've done a double stacked motor with a modified speed 280 bell, with two rows of 5x5x1. Glue one row first and let it dry. Be careful to maintain matching polarity on the second row
3- Go LRK: http://www.torcman.de/peterslrk/Wickel_arten_eng.html
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Old Jan 26, 2004, 07:31 PM
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The stator was too big to fit in the bell with 6 x 3 x 1.5mm N45s, so I made a mandrel for my Dremel from a 3mm CD-ROM laser tray guide and an MPJ 3mm prop adapter. I spun the stator in the Dremel, using a sanding block with 150 grit paper to sloooooowly shave the stator until it fit with < 0.5mm clearance all around.

Tony Turley
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Old Jan 26, 2004, 07:34 PM
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While I'm sitting in front of the TV this evening, this will be my project:
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Old Jan 27, 2004, 02:52 PM
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Tucson Avra Valley, Arizona, United States
Joined Nov 2003
487 Posts
Ok, probably asked many times but this thread is so long that Im just going to ask again. What type of glue is used to secure the magnets in the bell? I have my magnets ready.. Thanks

Rick
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Old Jan 27, 2004, 03:00 PM
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galloping gimp's Avatar
Ohio, USA
Joined May 2002
1,623 Posts
Quote:
What type of glue is used to secure the magnets in the bell?
I used medium CA (gap-filling) to secure the magnets. I may spread a little epoxy on them for some additional strength.

- Jeff
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Old Jan 28, 2004, 10:16 AM
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ssatoru's Avatar
Chiba, Japan
Joined Jan 2002
1,044 Posts
Links to rewind AirCraft motor

Let me try to summarise rough steps. 900 messages of 'One hour CD_ROM motor construction' in a message.

1, Remove bell from motor
Open the end to remove stopper from shaft in any way.
http://www.rcgroups.com/forums/showt...77#post1314377
or
http://www.rcgroups.com/forums/showt...65#post1069665

2, Remove stator from mount
The brass stator mount is tightly pushed to stator and iron motor mount. Hammer it out.
http://www.rcgroups.com/forums/showt...22#post1089922

3, Rewind
Unwind removed stator, rewind as the following. I suggest to start with 0.3 mm 39T or 0.35mm 29T or so.
http://www.rcgroups.com/forums/showt...36#post1089936

Connect to star. Delta draws 1.7 times more current.
http://www.rcgroups.com/forums/showt...79#post1069679

Wire to your ESC with proper connector.

You can try to spin the motor at this stage. It is recommended to remagnet for better efficiency and stability.

4, Remove original ring magnet from bell
The ring magnet is glued to the bell metal.
Burn
http://www.rcgroups.com/forums/showt...50#post1274250
or crack it
http://www.rcgroups.com/forums/showt...63#post1362963

5, Glue 5x5x1 mm magnet to the bell
12 magnet in NSNS... order. Use CA.
http://www.rcgroups.com/forums/showt...59#post1279959

6, Rebuild motor
You need to prepare motor mount. See below for an idea.
http://www.rcgroups.com/forums/showt...50#post1089950

Put stator and bell to original brass stator mount. Note we do use any stopper for the shaft. Magnet force will keep it in place.

Use your idea mount prop. Mr. Shimizu use 5 mm plastic nut and works great with APC prop. I replaced original shaft with GWS IPS/EPS shaft as attached.
http://www.rcgroups.com/forums/showt...91#post1069691

That's all!

Satoru
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Old Jan 28, 2004, 11:30 AM
Why not Delta?
rysium's Avatar
Sacramento, CA
Joined Jun 2003
1,714 Posts
Re: Links to rewind AirCraft motor

Quote:
Originally posted by ssatoru
Put stator and bell to original brass stator mount. Note we do use any stopper for the shaft. Magnet force will keep it in place.
Not always . In my motor I measured the force that keeps the rotor. It's about 8oz. My motor can pull over 9oz when powered by 3 cell lipo. I tried it and the rottor flew away

It was OK from 2 lipos (static thrust is about 7.5oz).

RysiuM
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Old Jan 28, 2004, 12:02 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
The Netherlands, GE, Nijmegen
Joined Feb 2001
10,589 Posts
Frustrated ? You will be after this episode of cd-rom flight
http://www.bruessow.de/video/extrema.wmv (5.5MByte)
http://www.bruessow.de/video/mfk-muenster.wmv (16MByte)
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Old Jan 28, 2004, 01:04 PM
Foam Flyer
Depdog's Avatar
Stockbridge, Georgia, United States
Joined Jan 2003
2,931 Posts
I would love to see a short clip of the pilots thumbs (or fingers depending on the way they work the Radio Sticks) while doing some of thos rolling harrier circles.

That was cool

Glenn
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Old Jan 28, 2004, 01:17 PM
in persuit of low wing loading
Gordon Johnson's Avatar
Boston, Mass
Joined May 2001
6,428 Posts
Amazing.

Gordon
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Old Jan 28, 2004, 02:18 PM
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Joined Mar 2001
2,624 Posts
Re: Links to rewind AirCraft motor

Quote:
Originally posted by ssatoru
[B]4, Remove original ring magnet from bell
The ring magnet is glued to the bell metal.
Burn
http://www.rcgroups.com/forums/showt...50#post1274250
or crack it
http://www.rcgroups.com/forums/showt...63#post1362963
If you have a female in the house, steal some of her nail polish remover, and soak the bell in some of that for about an hour. The magnet will pop right out - or at least, mine did. I suppose some mfgs could use a glue that is impervious to NPR.

Tony Turley
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Old Jan 28, 2004, 03:00 PM
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mmormota's Avatar
Budapest
Joined Jul 2003
2,572 Posts
airgap

I measured the same stator with two slightly different bells.
Stator: 18 mm diameter, 5,5mm length.
Bells: both machined low carbon steel, 12 pcs 5*5*1,5mm N45 magnets.

The difference:
stator 1: 0,5 mm air gap
stator 2: 0,25 mm air gap
(I learnt to believe in the accuracy of a precision lathe...)

The measured parameters are improved a lot with the smaller airgap:

bell1:
Kv: 1740
Rm: 1,21
Io: 0,32

bell2:
Kv: 1470
Rm:1,167
Io: 0,31

The Rm and Io is almost the same, but Kv lowered from 1740 to 1470. You may think that's not a big deal, but it is!!!
The Rm is the same, so if I modify the motor with lower turn number, thicker wire to get the same Kv, Rm will be about (1470/1740)^2*1,167= 0,83 ohm.

It means more then 30% less copper loss, that is a big improvement in efficiency.

This result clearly shows, that we have to keep the airgap as low as possible. Unfortunately it needs a more accurate bell and better bearings.
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Old Jan 28, 2004, 04:28 PM
Why not Delta?
rysium's Avatar
Sacramento, CA
Joined Jun 2003
1,714 Posts
Re: airgap

Quote:
Originally posted by mmormota
The Rm and Io is almost the same, but Kv lowered from 1740 to 1470. You may think that's not a big deal, but it is!!!
The Rm is the same, so if I modify the motor with lower turn number, thicker wire to get the same Kv, Rm will be about (1470/1740)^2*1,167= 0,83 ohm.
I guess, a little less than that. This is the same result as putting stronger magnets.
But I noticed you have over 1 ohm resistanc. It's a lot. Imagine you put 5Amp through, the power poss in the copper will be I^2*R that is 5 * 5 *1 = 25W. That's the total power I'm putting throuh my motor.
In my motor, and I used 26G wire 24 turn, using 0.4m per pole, so I used total 1.2m per phase. In delta connection my Rm = 0.08 ohm. Now if I put 5 amps throuht I'm loosing 2W in copper (and over 10W in iron ).

B.T.W. I gave my plane with Razor300 to my son, and I'm flying exclusivly other one with CD-ROM motor in board. Powered by 3s1p 700 LiPo I have 12-15 minuts doing torque roll, full speed snaps and rolls, waterfalls, climbing flat spins (straight and inverted) and so on. It's my personal 3D trainer - much better than any flight simulator. Anyway, after over 12 minutes of such practice I can notice, that it doesn't pull from torque roll as hard as it should. It's my cue to land. Battery usually is draind over 80% as it takes around 600mAh on charger(out of 700 capacity).

I will post some videos soon.
For now here is a picture:


RysiuM
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Last edited by rysium; Jan 28, 2004 at 04:33 PM.
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Old Jan 28, 2004, 05:56 PM
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Joined Mar 2002
631 Posts
rcall (or ne1) how much does the taig lathe ...

weigh?

is it portable enough to haul back and forth between a table top and a closet on a daily basis?

my space is limited (no basements here in texas) so i would need it to go back into a closet quite frequently.

thanks,

jeff
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