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Old Jan 13, 2013, 10:11 PM
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United States, TX, Lubbock
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Originally Posted by efflux RC View Post
Hey Joe,
Someone once inquired about putting the JS 1400 into the Mach 70. It can be done, but at nearly 4000KV it's to high for this EDF for high power setups.
Gary, is that a custom standoff adapter mounting the big outrunner to the 28mm Mach fan?
I like the feelings in my head generated by a 36mm motor in that Mach.

Oh, and 4000kv would make a GREAT 5S setup! Why not??
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Old Jan 13, 2013, 10:28 PM
efflux RC's Avatar
United States, CA, Santa Clarita
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Originally Posted by PikeStaff View Post
This is good to know. Happy to hear that there is indeed a way to do it.
Since this is lees thread about his custom motors, I'm moving my off topic stuff to here.
http://www.rcgroups.com/forums/showt...6#post23807220
I commented there.
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Old Jan 13, 2013, 10:33 PM
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United States, CA, Santa Clarita
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Originally Posted by murdnunoc View Post
Gary, is that a custom standoff adapter mounting the big outrunner to the 28mm Mach fan?
I like the feelings in my head generated by a 36mm motor in that Mach.

Oh, and 4000kv would make a GREAT 5S setup! Why not??
Yes, It's the standoff that came with (Little Screamers) JS1400. I "turned down" the motor mounting flange with dremel to fit the motor housing of the mach fan. The motor "fairing" was a one quickie fiberglass one that I made.
The shaft on that motor was bent during a test with another fan years earlier. I never got a replacement shaft, and support from LS was no longer available.
The problem I see spinning outrunnners at 70+K.
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Last edited by efflux RC; Jan 13, 2013 at 10:53 PM. Reason: spelling
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Old Jan 13, 2013, 11:00 PM
Lee Liddle
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Carrollton, Tx
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Originally Posted by sneu View Post
Just because "thats the way it is done" does not make it good engineering practice



Steve


Well, there sure are plenty of fans out there with stand off motors. It seems that doing it wrong is working well in spite of itself.
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Old Jan 13, 2013, 11:03 PM
Lee Liddle
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Carrollton, Tx
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Originally Posted by sneu View Post

While we are discussing engineering--you don't have nearly thick enough iron behind the magnets--you can get away with less iron when you have high pole counts and small gaps between the poles but when the pole count goes down the steel needs to get thicker to close the magnetic path. I am guessing that your outer ring will have a lot of flux leakage. I would guess that you need at least double the steel and maybe more. Yes it will run---but you are not making the best use of the magnet strength.

Steve
I guess you are guessing wrong, because I don't have big gaps between the magnets. Sounds like you need to go back and read the whole thread.
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Old Jan 14, 2013, 03:05 AM
Life begins at transition
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Does a paperclip stick to the outside of the motor?
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Old Jan 14, 2013, 07:12 AM
Lee Liddle
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Originally Posted by Odysis View Post
Does a paperclip stick to the outside of the motor?
I don't know, I don't have any paperclips.
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Old Jan 14, 2013, 07:40 AM
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That's funny right there.
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Old Jan 14, 2013, 10:10 AM
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Originally Posted by Knife Liddle View Post
I guess you are guessing wrong, because I don't have big gaps between the magnets. Sounds like you need to go back and read the whole thread.

If your pictures are any indication-- you do have large gaps between the magnet poles. Try the paper clip test and see if they stick to the outside of the motor bell when assembled. If you can't find one then any small steel scrap will do.

The fewer the poles the more back iron that is needed. to close the magnetic paths. Don't have to take my word for it--take the design and check it using FEMM (http://www.femm.info/wiki/HomePage)

Steve
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Old Jan 14, 2013, 10:37 AM
Ginger or MaryAnn ??
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I myself do not know a whole lot about motor construction but I would like to know about paper clip sticking to can, I have a few outrunners that they do stick to, what does that mean?
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Old Jan 14, 2013, 11:11 AM
Lee Liddle
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It means they aren't perfect.
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Old Jan 14, 2013, 11:35 AM
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Originally Posted by fh64_lucky View Post
I myself do not know a whole lot about motor construction but I would like to know about paper clip sticking to can, I have a few outrunners that they do stick to, what does that mean?
It means that they have not done a good job in designing the magnetic components of the motor. It also means that the motor constants are not as good as they could be and that the efficiency is less than it could be.

Steve Neu
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Old Jan 14, 2013, 11:36 AM
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Well in order to be more efficient, could you get another bell or open ended piece of tube or pipe and just wrap it and glue it to get the additional metal?
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Old Jan 14, 2013, 11:39 AM
Ginger or MaryAnn ??
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Thank you for answers, learn something new alot on these threads....
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Old Jan 14, 2013, 11:55 AM
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Originally Posted by Michael Paxton View Post
Well in order to be more efficient, could you get another bell or open ended piece of tube or pipe and just wrap it and glue it to get the additional metal?
The goal is to get the right amount of steel to contain the flux. Another steel tube could be put over the bell--but it needs to be a tight fit with no gaps.

Steve Neu
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