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Old Nov 07, 2004, 11:40 AM
CD-ROM Junkie
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United States, WA, Bellingham
Joined Apr 2001
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El-Cheapo GBL Motor Mount

whaddayathink?
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Old Nov 07, 2004, 03:31 PM
CD-ROM Junkie
Art Newland's Avatar
United States, WA, Bellingham
Joined Apr 2001
13,962 Posts
Quote:
Originally Posted by rysium
Looks nice
What material is that?
How does it fit over 8mm tubes?
What price is that?
Where to buy?

RysiuM

Very hard rubber (neoprene maybe?)

Very tight fit over the GBL bearing tube, was hard to pull it back off. I think a drop of CA would hold it very well.

2 came in the package for about $3

Auto parts store.

weighs 3 grams
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Old Nov 11, 2004, 11:18 AM
homo ludens modellisticus
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The Netherlands, GE, Nijmegen
Joined Feb 2001
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Removing windings from old motors
http://www.eschmidt.de/galerie/wicklung/index.htm
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Old Nov 11, 2004, 12:04 PM
Why not Delta?
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Sacramento, CA
Joined Jun 2003
1,714 Posts
Quote:
Originally Posted by Ron van Sommeren
Removing windings from old motors
http://www.eschmidt.de/galerie/wicklung/index.htm
That reminded me the time I worked in small electrical shop rewinding electrical brushed motors (about 1kW). First I mounted the rotor on a lathe and cut (turned) the wires on bothe sides (all the way to the shaft), then I put the motor in a stove for about an hour (around 300F) to soften and burn the laquer. After that I punched out the wires from slots. It was a fun.

RysiuM
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Old Nov 21, 2004, 04:17 AM
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Joined Nov 2004
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Easy and clean removal of magnet ring from bell

CAUTION: chemicals mentioned in this tip are FLAMMABLE AND TOXIC.

Tip to remove internal magnet ring assembly from CDROM brushless motor "bell". People seem to have a lot of trouble with this...most seem to physically attack the ring, chipping at it, trying to pry it loose, etc.

I soaked my "bell" in acetone for about 4 hours, and the magnet ring just slid out in once piece. Easy, and the "bell" is sparkling clean. (I got the motor from a Toshiba manufactured CDRW drive). The reason I tried acetone, is that it is a solvent for cyanoacrylates. Other glues might respond better to xylene or MEK (liquid form, methyl ethyl ketone).

Escudo

(I soaked it in a small glass, with aluminum foil pressed over around the edge to help keep the acetone from evaporating too quickly. You could use a film developing tank, or anything else that won't get melted by the acetone. This trick probably won't work for all methods used to manufacture and attach the magnet ring, but hope it helps a few folks out.)
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Last edited by escudo; Nov 21, 2004 at 05:47 AM. Reason: title, clarify, and safety
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Old Nov 21, 2004, 05:17 AM
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Re: olmod Post Jun 15, 2004, 11:31 AM #3, "Want a Tight Fit?"
FOR SAFETY...Do this sizing BEFORE you grind the bit.

If you use fine sandpaper while rotating the shaft in the Dremel, you can reduce the diameter of this DIY bit by a VERY slight amount. This will provide a tighter press-fit, and gives you more room for error.
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Old Nov 21, 2004, 06:45 AM
4-D traveller
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Cheap GB motor mount

DC power socket cut; GB cf bearing tube glued in; Strengthened with tape.
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Old Nov 21, 2004, 06:50 AM
4-D traveller
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Lightened GB cans

I've lightened the GB cans, and thus made <20g main motor and <10g tail motor for my submicro heli.
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Old Nov 21, 2004, 07:14 AM
4-D traveller
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Interchangable can

Can with stanless tube inserted: 3mmOD and 2mm ID.
2mm shaft taken from a 250 brushed motor which has a brass stopper (can be pushed for space adjustment).
Rubber washer on top of the can, pinion with grub screw used as shaft collar.
The can spins freely on the shaft. The shaft collar and the brass stopper force the can to turn the shaft.
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Last edited by glxy; Nov 21, 2004 at 08:58 AM.
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Old Nov 22, 2004, 11:54 PM
Good Better Best quest.
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Australia, VIC, Cranbourne East
Joined Apr 2004
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Measuring the gap

some hobby shops have a K&S stand wich stock brass shim material ,when cut with scissors to 1/8"or smaller(tapered is good) width and removing any burr, make great non magnetic mini feeler guages to check the gap between stator poles and magnets.
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Old Nov 23, 2004, 04:47 AM
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Re: Power post of Jul 20, 2004, 04:21 PM #54

You might try modifying the nuts so the result is a cone-shape. Possible design advantages...The narrower end of the cones will slip slightly into the stator hole, further reducing the chance for any damage to the top/bottom of the stator, and they can be used on stators of different sizes and sized holes (up to a point...don't angle the cone shape too much) without having to worry about differences in protection overlay design variations. I'm uncertain if this has potential to encourage undesirable enlargement of the hole because of the soft laminate material of the stator core. Only way to see is to try it and let us know if it works.
Escudo
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Old Nov 24, 2004, 01:56 AM
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Scavenging Neodymium Magnets from CD/DVD/Disc Drives

I'm repeating my earlier finding here because I've not seen it anywhere else...but when you disassemble the CD/DVD/Disc drive, you can scavenge the rare-earth magnets that are hidden in the optical assembly. They are plated and come in a variety of sizes and strengths. (for example, I've found 2.9x2.95x1.12mm and 4.78x5.90x2.44mm (approx) magnets seem typical. The larger size mags were stronger than N45) Remember that you can stack magnets to increase field strength.

To match magnets for use in a given motor, you should compare them. To compare relative strength against themselves or known commercial magnets I've bought, I've tried 2 methods. Both seem adequate to the task. However, I'm also not all that satisfied with the consistency of strength ratings of commercial magnets, either, and I compare and match even the ones I buy.

A hand-held version of my tester in Method 1 can also be used to verify the polarity of your magnets in the bell/can before glueing them in place. This method doesn't risk dislodging a magnet by using another magnet to "test" the polarity. (one of my test tools consists of the Hall sensor mounted at the tip of an old pen tube. I just slide it next to each magnet. As I proceed around the ring the LED alternates On and Off verifying the magnet poles are installed properly)


Test jigs easily can be setup for either method.

Method 1:
Crude, fast, but adequate for magnets of similar size and geometry. I just set up a Hall-effect sensor to sense the magnetic field. In my case, this is a 9V battery, a resistor, an LED, and the Hall sensor. Comparable magnets provide the same response at the same distance. (since the distance from the sensor to the magnet is less in this method, this provides a bit less resolution than method 2, but still seems to yield adequate results. I solved a quality problem in a production environment when we needed an ultrafast and easy to use tester to verify magnet polarity and strength. Remember that rare-earth magnets (even plated ones) can rather easily weaken or lose their magnetism due to age, heat, moisture, and exposure to adverse EM fields.

Method 2:
Set a compass at a given distance from a known power magnet (ie; N45), and note the deflection as the magnet is moved toward and away from the compass. An unknown magnet of similar strength will result in the same deflection pattern. (I'm assuming the the magnets are of the same geometry and the size of the magnets is small compared to the distances involved, so field shape variations are minimal). (Note: if you measure the distances and deflections, you could come up with a way to quantify the strengths, but I'm satisfied with comparing.)

Escudo
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Last edited by escudo; Nov 24, 2004 at 03:43 AM. Reason: Add another tip for polarity detection
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Old Dec 01, 2004, 01:01 PM
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Magnet Sources and testing

I've been very happy overall in the past with "The Magnet Source" (aka Master Magnetics). UNFORTUNATELY, "The Magnet Source" does not provide anything over N35. A real downside for us in this application. When I used them, "The Magnet Source" had consistent very high quality plating and strength through hundreds of plated neos at a time with excellent shipping and customer responsiveness, and would execute small and large orders with equal consideration. Very important factors to me.

For a general list of manufactureres, see magnetassemblies.com as a start. Most of them, however, list lower strength, lower temp magnets.

I'm intrigued lately by mmcmagnetics.com for NdFeB magnets used in electric motors. They claim high field strength and high temperature resistance.

MMC is offering NdFeB's with "working temperature" ratings they specify as quite high. I'd like to get my hands on some and check them out in a really rigourous test. Something a bit more sophisticated then my previous post. MMC sells neos rated with a working temp from 80degC to 200degC (this is below the Curie point, but it apparently means the magnet can stand up to some length of prolonged heating will little or no ill effect. Something that could definitely benefit brushless motor assemblies. I'm waiting on some clarification from them now, and still wonder if this might be specmanship). Many available NdFeB's are rated at a "working temperature" of less than 100degC, and these higher ratings being available in these higher "N" ratings to the hobbyist is a new thing.

I also just found out about gobrushless.com, a small startup designed to help the CDROM motor conversion hobbyist. However, GB is not a magnet manufacturer, and they don't publish detailed specs (like plating info and mechanical tolerances) or supplier information. As you see from my prior post, plating is a big factor in Neo life-expectancy. GB resells neos appealing to the hobbyist motor builder in a limited number of sizes and strengths, and sells them in useful motor building quantities (15's, 50's, and 100's). Prices seem roughly competitive for the quantities involved. Although their web pages still show N45's they claim to carry strictly N50's from now on.

A test of GB's magnets would be very useful, however, they could change suppliers the next day and the test data would be valueless since they don't guarantee any peformance parameters.

I have no special interest in any of these companies.

escudo
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Last edited by escudo; Dec 07, 2004 at 03:00 AM. Reason: qualification on availability
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Old Dec 01, 2004, 09:33 PM
AKA Don
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United States, MI, Houghton Lake
Joined Dec 2002
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Quote:
Originally Posted by FRAMEDNLVS
One problem I have is that I order from slofly. Don't get me wrong, they are great. But they don't put down what "N" there magnets are. I'm afraid that i'm going to start mixing magnets that are different. I have ordered 24 and then I ordered 100. So now with 4 or 5 different motors laying aroud i'm going to get some mixed up. I'm probably going to throw a set away if one gets lost.

The other problem I still have is how to get the can and the shaft to stay together. I have two that are straight, but they will slip under load. JB weld doesn't seem to work. Solder didn't work. Any ideas on this?


Chris
Check out the setscrew hub cans available at www.strongrcmotors.com

I also buy magnets direct from the factory with strength and temperature specifications clearly shown.
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Last edited by bz1mcr; Dec 01, 2004 at 09:36 PM.
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Old Dec 01, 2004, 10:04 PM
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Edmonds Wa. (Seattle)
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OK
I guess I was miss-informed I guess I did not pay attention when we talk

on another note I have 3,000 bells that will fit the 20mm GB stators and N50 curved magnets that were made just for this bell,
The bell has a nice fat piece of brass in the center to press the shaft through and gives great support for the shaft.
I am selling off all these parts in groups of 10 or more.
PM me if interested
Scott
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