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Author Topic: Anyone have any rpm figures for the common motors?  (Read 2193 times)

RipSlider

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Anyone have any rpm figures for the common motors?
« on: July 09, 2008, 09:45:26 PM »

Hello all.

Has anyone come across any roughly accurate figures for rpm/volt or rpm at a specific volt level for the common motors - i.e 540, 700, 700 bb, 380 etc.

I've asked a few people but not been sucsessful.

Note here - i'm looking for no-load figures rather than driving a big model with a big prop.


Thanks

Steve
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Martin [Admin]

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Eddy Matthews

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Re: Anyone have any rpm figures for the common motors?
« Reply #2 on: July 09, 2008, 09:56:08 PM »

Go to the Darlington & District MBC at:  http://homepage.ntlworld.com/edward.matthews/ddmbc.htm

Then click on "Electric Motors" - The last item in the left hand menu..... The figures for all the common Graupner and Mabuchi motors are there....

Regards
Eddy
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Shipmate60

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Re: Anyone have any rpm figures for the common motors?
« Reply #3 on: July 09, 2008, 10:24:01 PM »

Steve,
I test all my motors for rpm, voltage and current consumprion.
Unfortunately most motors that are used in model boating are produced for other uses so even the Generic 540 can have such diverse performance that unless they are produced to the same spec each motor needs individual testing.

Bob
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RipSlider

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Re: Anyone have any rpm figures for the common motors?
« Reply #4 on: July 09, 2008, 10:53:35 PM »

Eddy's figures are more than enough I think - I was looking for a motor producing > 10,000rpm - looks like there are a few that produce well over that.

Thank you sir - and others

Steve
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AlisterL

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Re: Anyone have any rpm figures for the common motors?
« Reply #5 on: July 11, 2008, 09:41:11 AM »

Bob,

At the risk of hijacking this thread, how do you measure rpm? Do you have a fancy tool or is there some cunning technique you can share?
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Alister

Martin [Admin]

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FullLeatherJacket

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Re: Anyone have any rpm figures for the common motors?
« Reply #7 on: July 11, 2008, 11:34:04 AM »

Found this one from a UK supplier:
http://www.sloughrc.com/asp/default.asp?itemid=L-MG602
FLJ
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Shipmate60

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Re: Anyone have any rpm figures for the common motors?
« Reply #8 on: July 11, 2008, 05:15:50 PM »

AlisterL,
I have an old friction hand held tacho.
As long as the coupling end is on the shaft it works fine.

Bob
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AlisterL

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Re: Anyone have any rpm figures for the common motors?
« Reply #9 on: July 12, 2008, 12:20:46 AM »

LOL - thanks guys. Looks like another item for the wish list then :)
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Alister

Captain Povey

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Re: Anyone have any rpm figures for the common motors?
« Reply #10 on: August 05, 2008, 03:42:20 PM »

At work we have a thing called a Vibratak. It is like a pencil with a wire sticking out of one end the other end is attached to a slider. You put the nose of the thing on the motor and slide the slider up and down until wire vibrates and then read the sacale marked in rpm. It works like a one legged tuning fork. Crude but effective, provided the motor is is not too well balanced. Graham.
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barry park

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Re: Anyone have any rpm figures for the common motors?
« Reply #11 on: August 08, 2008, 02:16:35 AM »

Hi Ripslider,
        You were looking for a motor with rpm about 10k.   (A long time since your post - I know)
Yes ,you did qualify that saying it would be lightly loaded when you were looking at the no-load revs as a guide.

 You obviously know something about how DC motors behave but even for a small fan or prop you couldn't ignore torque.....I'm guessing you've since found that out.

A while back I did this.........
I took a Johnson 540 out an old dust-buster..... it sounded like a turbine and has a no load rpm of about 40k @ 5 volts
I have Johnson 540's as supplied to the car industry (at over 3 x the torque constant of an RE540) with no load revs about 4k @ 5 volts.I rigged up both on the same shaft and small boat prop and the second one turned faster.
 
Barry
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debssnal

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Re: Anyone have any rpm figures for the common motors?
« Reply #12 on: August 16, 2008, 09:58:27 AM »

Hi Have a look at this link it my help
http://homepage.ntlworld.com/edward.matthews/ddmbc_files/motors/graupner.htm
it gives you all the rpm for graupner and mfa
regards
Alan
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