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Old Jul 02, 2005, 07:36 AM
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Ron van Sommeren's Avatar
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LRK and other larger homemade brushless motors, part II

Continued from part I:
http://www.rcgroups.com/forums/showthread.php?t=200588
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Old Jul 02, 2005, 09:32 AM
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Well ... I am still around watching this thread. At least I am not the person causing possible headaches this time. (LOL)

ProStreetRacer your motor does look interesting. From my experience gained here though, many people have built motors without a metal bell (used ali instead) only to discover a fair improvement when replacing the ali with ferrous material.

What you are saying is certainly going against the flow. Have you tried a metal bell yet for comparison?

Brian
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Old Jul 02, 2005, 12:28 PM
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PSR, Thanks for the info, would sure like to hear about current and the voltage you are using. A question about the multistrands of fine wire, does this help the motor to be better? Or are you using it for another reason? I've used 2 and 3 strands, usually because I needed larger wire than I had on hand, certainly found it easier than single of large gauge to wind.
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Old Jul 02, 2005, 07:04 PM
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Old Jul 05, 2005, 04:30 AM
Bigger is better:)
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Help

im building a very large motor and i have some questions. my first question is for the can of the motor i thought about using a coupler for copper pipe. i know that copper isn't magnetic but would it still work. maybe if i put a flux ring around the outside of it? anyway if it will work the ID of it is 55mm and i was planning on using 2mm thick magnets so i figure that i will need a stator that is about 48mm in diameter. that would give me about a .7mm airgap right. oh the copper coupler is 2mm thick. my second question is where can i get a stator that is 48mm in diameter and about 40 to 50mm tall? i think i might have a drill to rip apart tomarrow but i dont think the stator will be big enough in diameter. oh yeah im building this motor for an electric boat and im looking for something around 1000W maybe less im not sure right yet still working on the boat so idk how much thrust i need to get from the prop yet. any input or help would be greatly appreciated.
thanx in advance
Josh
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Old Jul 05, 2005, 04:49 AM
Good Better Best quest.
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Australia, VIC, Cranbourne East
Joined Apr 2004
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mmmm

Dont use the copper between the magnets and the flux ring ,it would be the same result if you were to increase the magnetic gap by the same thickness,to answer your other question regarding the need of a flux ring of iron,yes a motor will work without it, but it will be drawing more amps and much less efficient.
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Old Jul 05, 2005, 06:12 AM
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Josh: I think most guys work the motor the other way. You find the stator, THEN you worry about finding/making the bell........

Brad
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Old Jul 05, 2005, 07:07 AM
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Art,
I use 3 Li-po cells, @ 2100 mah and 12c, 21-25 amp draw continuous. As for the multi strands, I have always had good results using multi strands, even back in the old days of wiring up brushed motors. I do remember that the Kalt Helicopter used a motor that had one big wire in it and it was very efficient, lasted a long time on a charge and made good power. The helicopter was a piece of s#!t, but the motor was cool. And yes, you're right about winding the multi strands, they are much easier to wind !!!

Quote:
Originally Posted by Art Newland
PSR, Thanks for the info, would sure like to hear about current and the voltage you are using. A question about the multistrands of fine wire, does this help the motor to be better? Or are you using it for another reason? I've used 2 and 3 strands, usually because I needed larger wire than I had on hand, certainly found it easier than single of large gauge to wind.
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Old Jul 05, 2005, 08:02 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
The Netherlands, GE, Nijmegen
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Litze/multistranded wire has no advantage, see message 8764 "Litz wire revisited ":
http://groups.yahoo.com/group/lrk-to...64?viscount=30

And
http://www.torcman.de/peterslrk/Skin-Effekt.html
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Old Jul 05, 2005, 08:04 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
The Netherlands, GE, Nijmegen
Joined Feb 2001
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Quote:
Originally Posted by JoshT
im building a very large motor and i have some questions. my first question is for the can of the motor i thought about using a coupler for copper pipe ...
Iron. Not stainless steel, wood, carbon, epoxy, glass, copper, aluminium. Just plain iron. More tips and tricks, homepages, manuals. Tests and checks may save you from frying your controller. Thread is active, bookmark it for future refence and subscribe to it:
http://www.rcgroups.com/forums/showthread.php?t=240993

A 1000Watt diy motor:
http://www.rcgroups.com/forums/showthread.php?t=333317

Vriendelijke groeten Ron van Sommeren
e-motor building tips & tricks
diy outrunner discussion group
int. E fly-in & diy outrunner meet, August 28th, Nijmegen, the Netherlands
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Old Jul 18, 2005, 01:15 PM
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I have decided to have another crack at this motor from post 1 of the original thread. I've done a lot more reading, and have been encouraged by the success of the same motor on the Powerditto site. I don't quite understand some of the translation, though, in particular:

"Are interconnected the windings as with 2 successively wound 12N/14 P (with distributed coil) to be then parallel switched. That means:

AabBCcaABbcC AabBCcaABbcC

And then the red and the blue group of coils phasenweise parallel.
For the prevention of asymmetries and circle stream it empfielt itself to manufacture the parallel connection additionally also at each "jump" (Aa-aA)!"

I think I get the gist of the parallel connections, but what is the advantage? And what does the last sentence mean?

Tony Turley
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Old Jul 18, 2005, 08:07 PM
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Ron van Sommeren's Avatar
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To prevent circulating currents it is advised to make the parallel connections in more than one place.
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Old Jul 19, 2005, 03:41 PM
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Found something interesting the other day in an old compaq tapedrive machine of some sort. There were two large brushless motors of about 60mm - 70mm diameter and maybe 10mm in height, each have 18 teeth. What makes these different is that the teeth are arranged so that they point inward towards a circular magnet ring that is about 25-30mm in diameter. Essentially they're big inrunners similar in configuration to ones that I've found in small hard drives. I know that this is nothing ground breaking but I've never found any of this size before and was just wondering if anyone thinks that they might be useful.

Latrans
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Old Jul 19, 2005, 05:18 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
The Netherlands, GE, Nijmegen
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diy inrunner from hard-disk:
http://www.cenara.com/users/ce00359/LRK220.htm
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