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Apr 12, 2004, 04:50 PM
Dismembered Member...
arx_n_sparx's Avatar
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Brushless CD ROM motor surplus Part 3


Is continued on from here:

Part 2: https://www.rcgroups.com/forums/showthread.php?t=213932

Part 1:
Last edited by arx_n_sparx; Apr 12, 2004 at 04:56 PM.
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Apr 12, 2004, 05:07 PM
Registered User
Fishnut's Avatar
Hey, I got the first reply. Guess what fits perfectly on the prop adapter that comes with the Cobri shaft? Yup--EPS75 fan.

22T of 26 ga gave 16K rpm @ 5 amps, and that's not even a motor set up to turn a fan.

It's gonna be really cool when our BL sheet hits this fan .
Apr 12, 2004, 05:10 PM
DNA
DNA
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DNA's Avatar
"Is this the only good way to wind the stator? I tried this:
On each pole it is clockwise.
Starting from a pole, go counterclockwise skipping two."


skirtz,
That's how I wind mine. I tested it today using the original magnet ring
that came with the whole cd motor. I ruined the 12 Neo magnets by
trying to solder the shaft to the bell and overheated them. Don't do that!

I wound 18 turns 26gauge just as you described above. I first wired it as
a Delta config. I tried it with a pack of 7 nimhs and a Jeti 18-3p Esc. It
ran okay up to about 1/2 throttle then it stopped running. Throttle back and
restart and it ran ok then stopped again. I tried larger and smaller props,
but it did the same thing. It wouldn't run over 1/2 throttle.

Then I rewired it as a Star (Y) config. and retried it. It ran great and very
powerful up to full throttle. I then tried 8 nimhs with an 8x3.8 prop and it
again ran very powerfully up to full throttle. It was drawing 7.3 amps on the
8 nimhs and at full throttle it was starting to pull the bell off the motor so
I shut it down and glued a piece of heat shrink on the end of the shaft to
hold the bell on. Tried it again with the 8 nimhs and it has a lot of thrust with
just the original magnet ring. 5700rpm on an 8x3.8 Apc prop, barely gets warm.

Now I have to reorder some more Neo magnets and try it again.

Here's the winding diagram again. Start with red, then do green, then do blue.
Last edited by DNA; Apr 12, 2004 at 05:19 PM.
Apr 12, 2004, 05:27 PM
Foam Flyer
Depdog's Avatar
Wow, looking good

Glenn
Apr 12, 2004, 05:29 PM
Registered User
Fishnut's Avatar
The only time I had one croak out at half throttle, It traced out that I wound one phase going the wrong way. Brain fart.

This is the method I gleaned from picures of the original One Hour CD-ROM thread:

For this demonstaration it is assumed:

1. Teeth are numbered counterclockwise.

2. Wind the teeth clockwise, advance tooth to tooth counterclockwise.

Wind A phase CW on teeth 1, 4, and 7 then either make a pigtail (if you are using one wire) or change wire colors.

Begin winding the B phase CW on tooth 8 and continue to teeth 2 and 5 ending with a pigtail or change colors again.

Begin winding the C phase CW on tooth 6 and continue to 9 and 3.

You will end up with three wire pairs for delta:

The end of A and the beginning of B
The end of B and the beginning of C
The beginning of A and the end of C

Hey Ron: Does this sound OK? The motors seem to work fine. The wiring diagrams show beginning phases on 1, then 2 then, 3. But when I went off the pictures from the One Hour Thread, I started my phases on 1, then 8, then 6. Any difference?

Kurt
Last edited by Fishnut; Apr 12, 2004 at 05:35 PM.
Apr 12, 2004, 05:39 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
Correct Kurt. It does not matter where you start with phase B and C, as long as you skip two teeth.
Apr 12, 2004, 05:43 PM
high-speed freak
opualuan's Avatar
I'm sure this has been covered, but... general rule of thumb. in the same motor, teeth are wound with the same wire, same turns. same magnets, all else the same, except one stator is delta one is wye. in general what will be the performance difference (rpm/v, efficiency? etc)
Apr 12, 2004, 05:47 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
Delta Kv = sqrt(3) higher then Y Kv. Kt = sqrt(3) lower.

Groeten Ron
Apr 12, 2004, 06:03 PM
Sheesh...

Look, you guys are making this MORE DIFFICULT THAT IT IS! It doesn't matter how many winds, what gauge you use, how many turns, what strength magnets, or what direction you wind the arms...

IF YOU ARE CONSISTENT, YOUR MOTOR WILL RUN. All those pesky little details tailor the performance of the motor. If it's your FIRST MOTOR, don't worry about building some super-powerful, ultra-efficient, single stator that turns a 20" prop motor. If this is your first time, just build one that runs. That will teach you what you need to know to begin tailoring your motors to your planes.

Baby steps, guys, baby steps... I'm puzzled as to why I see these "I'm new to brushless, but how do I build a motor that will fly my Whosawhatsis. What do I do? Especially when there's COUNTLESS PAGES of information on this... I get emails saying "I saw all the posts about building cdrom motors, but it's up to 30 pages and i don't wanna have to read it all... how do I do it?"

Jeez... if you're not willing to read... Sorry, just venting some frustration.
Apr 12, 2004, 06:20 PM
T:W>1= :>)
rc-eflyer's Avatar
Quote:
Originally Posted by ScubaSteve
Sheesh...

Look, you guys are making this MORE DIFFICULT THAT IT IS! It doesn't matter how many winds, what gauge you use, how many turns, what strength magnets, or what direction you wind the arms...

IF YOU ARE CONSISTENT, YOUR MOTOR WILL RUN. All those pesky little details tailor the performance of the motor. If it's your FIRST MOTOR, don't worry about building some super-powerful, ultra-efficient, single stator that turns a 20" prop motor. If this is your first time, just build one that runs. That will teach you what you need to know to begin tailoring your motors to your planes.

Baby steps, guys, baby steps... I'm puzzled as to why I see these "I'm new to brushless, but how do I build a motor that will fly my Whosawhatsis. What do I do? Especially when there's COUNTLESS PAGES of information on this... I get emails saying "I saw all the posts about building cdrom motors, but it's up to 30 pages and i don't wanna have to read it all... how do I do it?"

Jeez... if you're not willing to read... Sorry, just venting some frustration.
We hear ya Steve Now take Valium and get back to work on those cans
Seriously, you will always have those that want YOU do do ALL the work
and make life easier for THEM. I hope THEY don't discourage you too much.
WE appreciated very much all your effort. THANK YOU

another STEVE
Apr 12, 2004, 06:34 PM
Registered User
OK, I have a dumb question since I am a CD-Rom newbie. In the Picture above of the Star Config. The 3 different color wires seem to terminate at the black dot, what is the black Dot? Is it just a pigtail where all the wire ends are soldered together?

P.S. - Are "Teeth" the same as "Poles"?

-Thanks-

Mike
Apr 12, 2004, 06:36 PM
Registered User
Steve,

The email situation has caused other motor providers to join the witness relocation program. Save yourself now and draw some boundries before people start saying, "What's up with Steve? It took him two days to respond to my email regarding my 12 dollar order " Just my 2C - Brian
Apr 12, 2004, 06:38 PM
Registered User
Teeth are on the stator, Poles are the magnets. The black dot is a pigtail where the 3 are soldered together - Brian
Apr 12, 2004, 06:42 PM
Registered User
Fishnut's Avatar
Quote:
Originally Posted by Ron van Sommeren
Correct Kurt. It does not matter where you start with phase B and C, as long as you skip two teeth.
Thanks Ron. I think I'll switch over to clockwise winds and clockwise numbering, beginning phases on teeth 1, 2, and 3. Sure simpler than the way I was doing it.

Here's a single 23T 26ga delta D (6.6:1) geared unit waiting for the Loctite to cure. Don't have a clue what she'll do, but I'll find out tomorrow.

I made one of the mounting holes an arched slot so I can change pinions w/o changing spurs. I also made the stator a good tight press fit so no loctite is needed. If I need to change stators, just yank the pinion, pull off the bell and shaft and unscrew (so to speak) the stator.

Oh, made my first flight today with a Gobrushless.com motor. Poor little Bird Dog went from sitting on grass to 100' in about 3 seconds .
Last edited by Fishnut; Apr 12, 2004 at 06:46 PM.
Apr 12, 2004, 07:03 PM
DNA
DNA
registered user
DNA's Avatar
Quote:
Originally Posted by opualuan
I'm sure this has been covered, but... general rule of thumb. in the same motor, teeth are wound with the same wire, same turns. same magnets, all else the same, except one stator is delta one is wye. in general what will be the performance difference (rpm/v, efficiency? etc)

Opualuan,

That's what I was trying to find out today in my testing. I used the same
stator/windings but just connected in either delta or star. It wouldn't run
past 1/2 throttle in delta, but ran fine full throttle in star, using the same stator.

It may have been due to the original ring magnet I was using. Maybe not
enough back emf to the controller. I'll try it again with some Neo magnets.

The weak point with these Diy cd motors is in attaching the bell to the shaft
securely and making certain it's on there straight so it doesn't rub on the
stator. Some bells I've seen have a brass insert in the middle which makes a
snug fit on the shaft. The bell that Steve is selling has a very small contact
area with the shaft, and can wobble. I thought I had it on the shaft securely
with CA, but when attaching the collet type prop adaptor, the CA broke and
the bell came loose, so the bell was spinning, but not the prop. I may try
JB Weld the next time.
Last edited by DNA; Apr 12, 2004 at 07:14 PM.


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