Hard Drives for High RPM?

[budfly1]

Need Input!!! :?:

I'm just starting the game of Brushless Motors, and have striped 3 CD drives and 3 hard drives to look at there motors. Two of the CD motors ran very well with 6-3 props with no mods, flying a cheep 4ft foam kids glider.
But I want to do better.. a Conner 3gig HD supplied me with a BBed outrunner that has promise. I rewound it with 20t of #26 and filled the Stator(?)( it started with 70t #38 or smaller).

Question

To get more RPM should I go to a larger wire and less turns? I would like to stay under 10 amps. This setup was under 4 amps I think.

What is the relationship between turns and RPM and Amps?

Looking for input. :D

[ScubaSteve]

budfly,

Can you post of pic of this motor you're using? I've ripped apart so many hard drives my hands bleed and found the motor to be of little use since it's "hermetically sealed". When I finally did gut one (damaging it beyond use), the stator I found was your typical inrunner stator, where the stator arms face inward... :?

Steve

[Joel]

Less turns = more RPM = more load = more amps

When you use less turns, you can fit bigger wire to make it more efficient.

Also changing from star ("Y") to delta will give more RPM for the same # of turns.

Like ScubaSteve I have also taken apart several Hard Drives and didn't find a useable motor, I did find 2 12t stators but the rest of the motor isn't really useable, and the stators have very little room for wire. Your doing good if you found a useable hard drive motor.

Joel

[KreAture]

HD motors on OLD HDs often use double bearings. One on top and one bottom. They use a hollow shaft to connect the phases and they thus have NO rotating shaft. They are ment to run plates connected to the outside of the can, but often have screw holes on top edge wich are good for mounting a propsaver os some sorts.

They are unfortunately very heavy, and only good for very high rpm's with their sealed design. Their easies app is DD, so I think they are mostly a lost cause. Good souce of wiers stators LOL.

- KreAture

[budfly1]

Thanks for the replies,

here is a photo with the conners on the left, the CD motor top center, and a Segate in runner on the right.

http://images.ofoto.com/photos794/1/68/30/76/75/6/675763068103_0_ALB.jpg

also a pic of the back side of the conner motor a little out of focus.

http://images.ofoto.com/photos794/1/68/30/76/75/9/975763068103_0_ALB.jpg

Question How do you wind a Delta motor? Just around every 3ed pole - move to the next and around again - then one more time around? only end up with 2 wires. Or is it one lead from each start of a round with the last round connected to the start of the first. ??

this could become fun. :lol:[/img]

[jimbo]

the actual winding of Wye or Delta is the same, the difference is what you do with the ends of the 3 wires.
in a wye winding, the ends of the 3 wires are all twisted together and not attached to anything else. the start of those 3 wires all go to the speed controller.
In delta, (as with wye) you have 3 "starts" and 3 "ends" of wire, in sequence, start #1, start #2, start #3, end #1 end #2 and end #3.
connect start #3 to end #1, start #2 to end #3 and start #1 to end #2.
those 3 connections are then wired directly to the controller.
check the tutorial if I'm not being clear enough.

[budfly1]

Thankyou Jimbo,

Next question? will it make a difference if you wind in a clock wise dirrection on the pole or a CCW dirrection? Likewise the poles 1,4,7- CW or CCW around the stator?

This is getting Fun

[jimbo]

CW or CCW, I don't THINK it matters provided they are ALL wound in the same direction.
just for the sake of standardization, (and because it's the way all of the stators I've UNWOUND were...)
I wind them ClockWise, both around the pole and from pole to pole.

[Tubes]

Off the subject but funny signature JIMBO!

You are correct too. As long as you are consistant, it does not matter what direction you make your winds.

Reuben

[LBMiller5]

This thread has been inactive for a while, so I thought I would breath a little life into it. I too have taken apart more hard drives than I can count. Most of them have the motor built inside of the hub for the disk platters. Most of the older IDE drives as well as some of the newer drives have what I call a "Pancake" style motor. Very similar internally to a CD-ROM drive motor, but with a larger extended housing that incorporates a mounting flange. Here is a picture of one that I took out of an old Conners 420MB drive, around 1990 vintage. I forgot to lay a ruler in the photo for scale. The outer diameter of the mounting flange is 2.1 inches (53.5mm).

http://innov8tivedesigns.com/rcgroups/HD1.jpg

The bottom view shows the 3 spring contacts that mate with PC controller board from the hard drive. You can also see a 5mm shaft protruding from the center of the motor. This is the bearing shaft.

http://innov8tivedesigns.com/rcgroups/HD2.jpg

To open up this kind of motor, you need to lay the motor across the jaws of a vice, or over a board that has a hole drilled in it big enough to allow the rotor to clear. In the case of this motor, the rotor is 1.35" in diameter (34.5mm). Then you take a flat nosed drift punch that is a size smaller than the shaft and carefully tap it out. You could also use a bearing press if you have access to one.

After you get the stator & rotor assembly pressed out, it will look like this:

http://innov8tivedesigns.com/rcgroups/HD3.jpg

This particular motor had 2 ball bearings supporting the shaft that were 11x5x4mm. All hard drives turn at a very carefully controlled, consistant speed. For most of the IDE hard drives pre-1995 time frame it was 4200 RPM. At the end of the 90's the hard drive speed went up to 5400 RPM. Currently, most of the hard drives manufactured run at 7200 RPM. The bearings in these drives are very high quality, and if you can get them out without damaging them, could prove useful in motor construction projects for larger size motors.

The stator in these motors have fairly short poles, this is due to the larger center opening to accomodate the larger bearings. The stator from this drive has an OD of 23.7mm and an ID of 12.4mm. This photo shows the stator removed from the rotor assembly.

http://innov8tivedesigns.com/rcgroups/HD4.jpg

I have a couple dozen old hard drives that I can get parts from, but I am not sure if they are suitable for winding motors due to the short pole length.

Lucien

[budfly1]

Hi there,

I haven't found any more as good as the conner drive one. I have rewound that moter 4 times, the last time with 16t of #26 Y. It turned up 17K RPM at 18 amps then I think I over heated the magnets becouse the RPM droped to 12K at 17 Amps. ( 6X4 Prop) I need to get some new magnets and try again. Looking for speed. :) Think I'll try 18t of #24 Delta next. If I I can get over 15K without overheating I'll put it on a X29 fan fold.

[LBMiller5]

Hi Budfly1!

I noticed you are from Grand Rapids, MI. I am originally from Michigan myself. I grew up in Monroe, about 30 miles south of Detroit.

If you would like some more motors like these to experiment with, I have boxes full of old hard drives here, and I have a friend that owns a computer repair shop that said I could have as many old drives as I want to get them out of his shop. If you cover the shipping ($3.85 for Priority Mail) I can send you a few more. Just let me know if you are interested.

Lucien Miller

LBMiller5