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        One hour CD ROM motor construction PART2

#1 Takao Shimizu Dec 01, 2003 08:19 PM

One hour CD ROM motor construction PART2
 
Over 500 posts are already in "One hour CD_ROM motor construction".

http://www.rcgroups.com/forums/showt...hreadid=127606

This is the new thread for continue.

Anyway, I am tring to have N52 magnets.
Some Japanese manufactures are available, so far.

#2 Trprhook Dec 01, 2003 09:01 PM

Hi All.. Part II ! Great
 
Need to thank you Takao for having started this thread.

I'm doing my first re-wind tonight.

I do have a comment though concerning the spacing of the magnet wire. Spacing is important! By having gaps and irregular winding reactance is introduced. Reactance means heat which means loss of power. Being somewhat of a purist on windings, (my mentor is a notable in the field of electromagnetics) I find it difficult to not eliminate the spaces. It takes just a few more minutes, and by then your fingers are so stiff they wont notice the few minutes.

I did take apart a few HDD motors.. argh!
The key seems to be driving the front housing off with a drift pin ( in my case a nail), you can then salvage bearings also.

I hope to post a few pics later this week, either of a succesful rewind or the local fire department responding..

Anyway.. thanks to all Zoners for their invaluable contributions here..
Hook

#3 GIFLYRC Dec 01, 2003 09:46 PM

PERFORMANCE & PROBLEM
 
My latest rewind got closer to my goal of 3K with a 1260 prop and also created the following problem

28 mm stator 30 turns # 26 wire

~= 2800 rpm with 1260 prop

~= 3 to 1 gear ratio with 22 tooth pinion & 64 tooth spur gears

current is 3.6 A AND 36 WATTS @ WOT

My problem is that I am unable to secure the stator so that it does not twist out of the mount. I have glued it to the mounting plate using 5 minuet epoxy and also GOOP, and also thin c/a with baking soda (not all at once ) Hmmmm, mabe I should try that!

I can get several min. of operation and then the bond fails due to heat and torque

So if you have any suggestions, or sketches of a gear box that I can make or tips to help me secure the stator, I would like to see them
Thanks, Roger aka GIFLYRC

#4 Jim Miller Dec 01, 2003 09:57 PM

Cure the Epoxy?
 
I find your post interesting because my first motor mount will be a Y of glassboard epoxied to the windings. My guess is that we'll need to use something other than 5 minute since it isn't very strong. I'd go with 30minute or more and heat cure it at 200F or so. Start the heat cure as soon at the epoxy is set but still green.

You could also try heat curing 5 min but I don't think it will do much good.

I've now got wire and my magnets. Need to go dumpster diving for CDROMS.

good luck

jtm

#5 ssatoru Dec 02, 2003 02:32 AM

Re: PERFORMANCE & PROBLEM
 
Quote:

Originally posted by ROGER GANTZ
My problem is that I am unable to secure the stator so that it does not twist out of the mount.
Congratulation on promising result, Roger!

How about using red Loctite? They are 150 deg C resistant. I use a little bit of CA to fix as stator is rather tight fit to the mount.

Satoru

#6 cwalsh Dec 02, 2003 06:55 AM

1 Attachment(s)
Hi,

Here is my new motor, 28 turns of double wire, sorry I dont know the size of the wire!

3mm carbon shaft, rare earth magnets, and prop adapter modified into a rather nice looking shaft saver, works very well indeed.

Mount is an 8mm aluminium tube, this can be shimmed to fit a PJS mount.

This prop is a 9*4.7 and she pully 4 Amps out of a 2 cell 1500 Kokam pack.

I am thinking that if I change to a 8*4.7 I could use 3 cells at around the same or slightly more Amps.

BR,

C.

#7 Jim Miller Dec 02, 2003 09:41 AM

Loctite versions
 
Red Loctite is a good idea. Loctite also has some primers that cause the Loctite to setup more quickly. I've used it on my telescope.

Loctite also makes versions specifically to gap fill. I've seen posts on the other thread indicating that Loctite can't be used to seat the magnets since it cures anaerobically. That seems inconsistent with a gap fill designation.

I'm going to try some test pieces (not magnets!) with some gap fill to see how well it works, esp w/ the primer to shorten magnet assembly time.

have fun

jtm

#8 Ron van Sommeren Dec 02, 2003 10:22 AM

The link to part I of this thread:
http://www.rcgroups.com/forums/showt...hreadid=127606

#9 Ron van Sommeren Dec 02, 2003 10:25 AM

Wait half an hour, one hour, until the oven temperature has settled. An initial tempature overshoot may kill the magnets.

Met vriendelijke groet ;) Ron van Sommeren
diy outrunner brushless e-motor discussion.
Electric fly-in & lrk meet, June 27th, 2004, Nijmegen, the Netherlands.

#10 Jim Miller Dec 02, 2003 10:37 AM

Ron
If you're referring to the curing of the epoxy in your post I don't think the bell/magnets need to be inserted into the stator housing during the cure of the mount

At least I'm not planning to do that!

tnx
jtm

#11 azfrench Dec 02, 2003 10:39 AM

cwalsh, I think I have the same motor as you. What are some numbers you are getting out of it? RPM, Thrust, ??? I have not replaced magnets or rewound it yet but it runs stock. I think it is going about 1000 rpm no load. Im using a cc25. Some of the stock magnet material broke off while getting the shaft out so this may be why the rpms are low. Til then.

Rick

#12 galloping gimp Dec 02, 2003 01:04 PM

1 Attachment(s)
Here is my CD-ROM conversion so far.

I used the original brass stator insert, then soldered a brass tube to it. An aluminum tube at the rear holds a 6mm GWS ball bearing. I swaged the .25" aluminum tube to fit the bearing. Another ball bearing is CAed into the brass stator insert at the front. A GWS 3mm shaft is press fitted and CAed to the bell. This motor is a bit heavy because of all the brass -- already more than 25g.

I have 5x5x1 N45 magnets which will replace the ring magnet.

I want to try this motor in my GWS Tiger Moth. I'm going to wind with #26 magnet wire (= 0.0159" ~ 0.4mm). Am I correct that a larger number of turns (20-25) and a Star connection will give me lower RPM and more torque than fewer turns and Delta connection?

Is it correct that lower RPM and more torque = ability to drive larger prop = better for slow flyer like the TM?

Does anyone have recommendations on where to obtain metric-dimensioned aluminum tubing in the U.S.? Would CF tubing also work?

Thanks,
Jeff

#13 Cody W Dec 02, 2003 06:10 PM

I'm gonna build a CD-ROM with dual stators, custom machined bell, and 20 5x5x2 N45 magnets. I know this has been done before; any links?

#14 Trprhook Dec 02, 2003 09:19 PM

EEhaaaaaaaaa.. it works!
 
Just fired up the first CDRom..
It was already wound "Y" but I disnantled it anyway, put longer leads on it and let 'er rip.

Jeez.. its so quiet I can't hear it. I was using a 8.4 Nimh with a CC Phnx 10.

9 Pole. Stock ring magnet. No prop.
I have a tach due in any day, and have a stack of NE45s.

Man a BL for under 6.00!

Will post a few pics and some data as I get it.
Also have a totally rewound I may try tonight. 9 pole 18 turns @ #26 wire.

Hook

#15 iva Dec 02, 2003 09:38 PM

I do not remember exactly when and where I read it but magnet wire and CA glues should be kept apart. Supposedly CA fumes will weaken or degrade insulation and that may lead to shorts.
That process is gradual and it may take some time for insulation to become useless.

Zoran


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