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Old Jan 29, 2004, 02:41 PM
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never mind popped right off
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Old Jan 29, 2004, 04:59 PM
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Troms, Norway
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What specific models of CD-ROMs are recommended for this? They are really cheap right now and I wouldn't mind buying a CD-ROM just for the purpose of ripping out the motor (although I won't exactly be doing the environment a favour).

I disassembled an old DVD-ROM I have but the motor is useless, the bushing is too small to be replaced with bearings and the housing/magnet has a large flywheel which also acts as the shaft-grip and would need to me machined down.

I have lots of 7x3mm ball bearings from computer-fans. Could these be used in such a demanding workplace?


Tor Arne
Norway
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Old Jan 29, 2004, 07:45 PM
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Camas, Washington, USA
Joined Apr 2001
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Hitachi Model CDR-7930

Lynxman
That is a very good question! I tore a big pile of drives apart, it's amazing how many different configurations are out there for a drive that all do the same thing! I just happenedd to stumble across the cdr-7930, You can check this old thread, where I sold a few of these. These make wonderful conversions, they already have ball bearings and the stock magnet ring is very useable. I have yet to replace the magnet ring but I will try some N45's in one just to see if it's worth the trouble.

http://www.rcgroups.com/forums/showt...+you+own+cdrom

There is alot of good info here as well;
http://www.rcgroups.com/forums/showt...ighlight=cdrom

Also go to the power systems forum and you can read almost endless threads about conversions. Art
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Old Jan 29, 2004, 08:46 PM
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Upstate NY
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Are you guys adding any features (shoulders, spacer tubes, washers, snap rings etc...) to axially locate your shaft in the bearings? Or are you counting on the magnetic forces to do that?

I'm hoping to get time to make a conversion this weekend with a couple of 48x motors that look promising, 1/8 x 1/4 flanged ball bearings, and HPI racing gears (2mm bore).

Would there be a preference for Y or delta winding for a 2 cell lipo fixed pitch application? Gearing will be 12:1 or 9.6:1 and rotor speed would be ~1050 RPM.
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Old Jan 29, 2004, 10:40 PM
"Simplify, then add lightness"
Raleigh,NC
Joined Nov 2000
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I use a short spacer made from aluminum tubing that slips over the motor shaft behind the pinion gear and presses against the center of the bottom bearing. When I tighten the set screw on the pinion, it locks the shaft in, but I can take the shaft and magnet cup out by removing the pinion.

Mine works fine with a 14 turn "Y" winding. The "Y" winding supposedly gives more torque at lower RPM which is what you would want for a heli. 1050 RPM sounds a little low for a rotor speed. When I first did my HB, with the stock blades, I found that twisting pitch out of the blades gave more flying time, and also made it much more controllable.

Jeff
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Old Jan 29, 2004, 11:00 PM
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Camas, Washington, USA
Joined Apr 2001
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jeffs555,
That's how you are getting away with the low number of turns, Y configuration. Everything I've done so far (3 motors) has used Delta wiring.
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Old Jan 30, 2004, 08:30 PM
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Camas, Washington, USA
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some prop tests
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Old Jan 30, 2004, 08:31 PM
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Camas, Washington, USA
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thrust
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Old Jan 30, 2004, 08:32 PM
CD-ROM Junkie
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Camas, Washington, USA
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my new build, that's a nickel in the background
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Old Jan 31, 2004, 07:33 AM
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Troms, Norway
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My biggest problem is the magnets. I have no idea how to get the deodymium magnets that replace the magnet ring. Is your motor using the stock magnet ring, Art?
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Old Jan 31, 2004, 07:34 AM
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Upstate NY
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Thanks for the info Jeff! I'm off to the shop...
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Old Jan 31, 2004, 08:29 AM
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Camas, Washington, USA
Joined Apr 2001
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Lynxman,
Yes, I'm using stock magnets. If you are lucky, stock magnets are good enough, but so far the hitachi cdrom motors are the only ones I've tried that produce good power and motor runs smoothly. I plan on trying replacement magnets however, I have some N45's that I purchased from here;
http://www.engconcepts.net/Magnets/P...x_Magnets.html
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Old Jan 31, 2004, 01:10 PM
Spent too much already..
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East Yorkshire, England
Joined May 2001
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You fellows I have had a lot of success so far flying these things in my Pic (stock blade size) and Moth. They seem ideal for microhelis, good power to weight ratio.
The structure and bearings varies a lot between drives!
Some come with shaft size 2mm, some with 3mm which with a slight shim, will take an ECO-8 3.2mm pinion which is available down to 10 teeth.
I have found 15 turns Y winding to work well in the PIC on 8 nimh, and also the 1500rpm Moth on 3 x lipoly.
I use 12 of 5x5x1 neodym magnets so far, and Phoenix 10 controller works smoothly and well.
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Old Jan 31, 2004, 07:47 PM
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Troms, Norway
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Quote:
Originally posted by Art Newland
Lynxman,
Yes, I'm using stock magnets. If you are lucky, stock magnets are good enough, but so far the hitachi cdrom motors are the only ones I've tried that produce good power and motor runs smoothly. I plan on trying replacement magnets however, I have some N45's that I purchased from here;
http://www.engconcepts.net/Magnets/P...x_Magnets.html
Thanks, great site! I contacted them.
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Old Jan 31, 2004, 08:24 PM
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Upstate NY
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Today's Progress

My "collecting" has yielded two 48X motors and several lower speed variants. No two are the same. Today, I made up a mount/bearing housing, shaft, and spacer for my first try at brushless conversion.

Here are the parts...
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