j.m.

Hey guys, I tore apart an old cd rom drive, and i am looking to make this motor as high performance as possible. Instead of the usual 16 turns, i am looking to do something more like 8(4 up and 4 back down). I am wondering if this will even work with how close the stator "teeth" are, and what size wire i should use. I was also wondering what size aluminum tubing i should buy, and what size bearings. I am looking to use a 1/8 or similar sized shaft. To hold the bearings in place, i want to get one size of tubing that the stator fits nicely over, and then put another inside of that slightly shorter, to hold the bearings apart. I was also wondering where and what type of magnets to get, and What should i bond them to the rotor with? Along with the stator to the bearing case? When i took the motor apart, i accidentally destroyed the bell (armature would it be called?) and i was wondering how i could purchase or make another one. I have no machining facilities or equipment, so to make it i am thinking about taking a large enough length or tubing, and atatching that to some sort of aluminum disk that i can then attach to the shaft. This motor might be used for a plane, but it also might be used for a 1/18 car, so i will probably need magnets stronger than n45. Can anyone help me?

j.m.

Oh, and i have a 20mm stator.

ron_van_sommeren

Don't use carbon, brass, aluminium, stainless steel, plastic, wood, glass, carbon for the flux ring, only iron will do.
Neodymium magnets:
www.gobrushless.com
www.engconcepts.net
www.aircraft-world.com
www.supermagnete.com


Excellent motor building articles by Brian Mulder, a must read:
http://www.southernsoaringclub.org.za/
-> Articles by SouthEasterners.
-> Electric Motors - part 1-5

Do-it-yourself motor homepages, manuals/tutorials, checks and tests in this motor builders tips and tricks thread. The checks and tests may save you from frying your controller or motor. Thread is active, bookmark it for future reference and subscribe to it:
http://www.rcgroups.com/forums/showthread.php?t=240993 (sticky thread, at top of subforum)


Vriendelijke groeten Ron van Sommeren
• diy brushless motor discussion group
• Drive Calculator download & discussion group
• int.electric fly-in & diy outrunner meet, Nijmegen, the Netherlands

j.m.

Flux ring?

jdetray

j.m. -

Ron has provided you with the info you need to get started, so I will add just a few additional comments.

Another good source of parts: [link=http://www.strongrcmotors.com/]Strong RC Motors[/link].

From the airplane perspective "high performance" does not necessarily mean fewer turns. It depends on the type of plane and type of flying. For example, for a slow flyer or a 3D plane where thrust is more important than speed, you would want to turn a fairly large prop at relatively low RPM. For this, you want plenty of torque, which translates to a relatively large number of turns.

On the other hand, for a fast-flying plane, where speed is more important than thrust, you want a smaller prop turning a higher RPM. A relatively low number of turns is more appropriate for this application.

Once you know how many turns you want, select a wire size that will pack as much copper as possible for the number of turns. This improves efficiency. In other words, for a low number of turns, use a larger wire size. For a high number of turns, use a smaller wire size. In all cases, pack as much wire as possible onto the stator.

If you have not built a motor before, I recommend starting with kit from GoBrushless or Strong RC Motors. These provide all the parts you need, along with instructions.

- Jeff

ron_van_sommeren

The part that holds the magnets, the bell without the endplate. Must be iron.

j.m.

I was thinking i could use very strong magnets(or maybe double them up) And at the same time use a low number of turns to aquirebothe torque and rpm. Is there a place where i could find n50+ magnets?

jdetray

Some of the vendors already mentioned by Ron and myself sell N50 magnets.

Motor building is always a compromise. Anything you do to increase torque will decrease RPM. Anything that increases RPM will reduce torque. Your job is to find the best compromise for your application.

Your first step must be to READ. Visit the links we have provided. Read the tutorials and forums. Check the stickies [link=http://www.rcgroups.com/electric-motor-design-and-construction-361/?daysprune=-1]here[/link]. With "no machining facilities or equipment" you'll be limited to buying off-the-shelf parts from the vendors we have suggested.

As I said before, an inexpensive kit is a great place to start -- the best place, in my opinion. Very few motor builders scavenge parts from CD-ROM drives any more. for example, GoBrushless will sell you a stator for $0.60 and a stock CD-ROM-type can for $1, so it's hardly worth it to tear apart drives.

- Jeff

j.m.

my dad is a computer whiz, so he had about 50 in his closet.

I have read a bunch of the tutorials, and i have a pretty good understanding of how to wind and pack the stators. I also heard about people using some type of glue to hold the parts together. If this is strong enough, i will be able to make the motor probably out of parts i have in my garage. On offshoreelectrics.com, they talked about this grey locktite, and they used it on their flexshafts (driveshafts) and it is easily strong enough to handle the power of a feigao 8xl on 36 cells. Does anybody know anything about this?

j.m.

I just looked at a floppy drive, and their motors are HUGE!!!! It must be at least 2 inches in diameter!!! I haven't taken it out however, so it might still have the same ole short stator teeth.

jdetray

I've never used the grey Loctite, but I often use JB Weld to hold motor parts together.

Here's a thread about using Floppy Drive motors:
[link=http://www.rcgroups.com/forums/showthread.php?t=242329]Floppy Motor Conversion Performance[/link]

Some streaming tape drives also have useful motors in them.

- Jeff

j.m.

I think the gray locktite is just for metal. Now, why exactly can't i use the magnets that come in the motor? Are they just not strong enough? Or is the large magnet ring just a single magnet with a north and south pole?

jdetray

You can build a working motor that uses the stock ring magnet, but it won't be very powerful. You don't need strong magnets in a motor that only has to spin a CD.

The ring magnet is divided into alternating north/south segments.

- Jeff

j.m.

Are there kits to build your own in-runners?

jdetray

I'm not aware of any. Perhaps Ron knows.

- Jeff

ron_van_sommeren

nope

j.m.

I saw a pic of a home-brewn in runner and it had the little magnets glued to the shaft, but i don't think that winding in runners would be very easy.

ron_van_sommeren

Do-it-yourself/diy inrunner links

Decent Swedish pictures
http://www.ppi.se/cjo/Slotless1.htm

More tricks for inrunners, by MGM and Christian Lucas :
http://www.rcgroups.com/forums/showt...17#post2003817
http://www.rcgroups.com/forums/showthread.php?t=151285
http://www.rcgroups.com/forums/showt...hreadid=168528
http://www.rcgroups.com/forums/showthread.php?t=70373
http://www.rcgroups.com/forums/showt...hreadid=176989

A discussion about diy slotless inrunners, contributions by a.o. Christian Lucas, Helmut Schenk and Thomas Asschenbrenner:
http://www.rclineforum.de/forum/thre...threadid=89559

Thomas' diy inrunner homepage, some very special coils (the same as the ones used in www.hb-motoren.de)
http://home.vrweb.de/thomas_aschenbrenner/

Inrunner using a Halbach magnet array (Klaus Halbach Jeff, not Edward Halbach )
http://goldeneye.ethz.ch/motoren/ele...unner/index_EN
http://goldeneye.ethz.ch/motoren/electric/inrunner/

Excellent English/Japanese site:
http://www.excite.co.jp/world/englis...co=excitejapan
http://www.excite.co.jp/world/englis...co=excitejapan
http://www.excite.co.jp/world/englis...co=excitejapan

LRK inrunner:
http://www.cenara.com/users/ce00359/LRK220.htm

A brushless inrunner from a cheap can motor:
http://www.rcgroups.com/forums/showt...hreadid=214136


From http://home.vr-web.de/~thomas_aschen...r/BL2/BL2.html

j.m.

Yup, just like i thought. That looks ALOT harder to wind.

ron_van_sommeren

Yes, because it's a slotless desig. The other designs use inrunner statorlaminations.

j.m.

ACTUALLY, forget what i said earlier. I don't have a 20mm stator, i have a 17.8mm stator. I couldn't find a metric ruler for the longest time, and i just found it tonight after i finished winding it. I used one of the online guides you pointed me to. Andi already soldered it up in wye configuration (because it might be used for a mini car, i need the torque). I also read some where that i could use one of the slider shafts as a motor shaft, and i can't believe that i didn't notice this before. I wound it 7 up, and 5 back down. (i couldn't fit 6). So where does the flux ring go? Does it go inside the endbell on top of the magnets? Or under them? And why do the go brushless gbx kits not have them? Do i really need one?

ron_van_sommeren

Fluxring IS the ring where you glue the magnets in, the bell without the endplate.

ron_van_sommeren

Slotless inrunner from http://www.ppi.se/cjo/Slotless1.htm

ron_van_sommeren

LRK slotted (stator) inrunner from http://www.cenara.com/users/ce00359/LRK220.htm

jdetray

Look at the [link=http://www.gobrushless.com/GBL_single_v2.pdf]GoBrushless tutorial[/link]. It has many excellent photos that show how a CD-ROM based motor goes together.

In a motor made from stock CD-ROM parts, the endbell/rotor/flux ring/can (it has many names) is one piece and is made of steel. In more advanced motors, the endbell may be aluminum and the flux ring is a separate piece made from iron or steel. You can see this in the GoBrushless [link=http://www.gobrushless.com/GBx_Tutorial_v1.pdf]GBx tutorial[/link].

In either design, the magnets are glued to the inside of the flux ring, facing the stator teeth.

- Jeff