Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Default Anybody here using brushless RC motors?

I've been looking at the brushless motors used for RC planes and the
like. They are amazingly powerful for their size. And they really spin
up fast! One web site has kits you can buy to wind your own armatures.
Anyway, I have been wanting a rotary tool that is a cross between a
Dremel and an air powered tool I have. Something with an OD of about 1
inch. Like a Foredom handpiece. Faster than any of my Dremels but
slower than my small air powered hanpiece that spins at 80,000 rpm. So
I'm thinking one of the "inrunner" type motors might work. At 80,000
rpm the surface speed is about 2600 SFPM. Even though the speed drops
quickly as soon as the rotary tool contacts the work the speed is
still too high for carbide on steel and the burrs and rotary files
dull quickly, which makes them cut slower. On the other hand, the
Dremel and Foredom rotary tools are too slow and this ends up costing
time too. Something that spins about 40,000 rpm and maintains that
speed along with the smaller diameter would be great. In fact, a tool
that was .75 or even .625 diameter would be even better. I have a
dental handpiece that I use for some delicate work and it is just
under .5 diameter and is very easy to hold because of the small
diameter. If I could build an electric rotary tool with the torque of
a Dremel, 40,000 rpm, and 1/2 inch in diameter I would be very happy.
Even one that matched the Dremel torque and speed specs but was 5/8 or
1/2 inch diameter would please me greatly. So, anyone here play with
brushless RC motors?
Thanks,
Eric,

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Default Anybody here using brushless RC motors?

On Mon, 25 Nov 2013 18:20:47 -0800, etpm wrote:

I've been looking at the brushless motors used for RC planes and the
like. They are amazingly powerful for their size. And they really spin
up fast! One web site has kits you can buy to wind your own armatures.
Anyway, I have been wanting a rotary tool that is a cross between a
Dremel and an air powered tool I have. Something with an OD of about 1
inch. Like a Foredom handpiece. Faster than any of my Dremels but slower
than my small air powered hanpiece that spins at 80,000 rpm. So I'm
thinking one of the "inrunner" type motors might work. At 80,000 rpm the
surface speed is about 2600 SFPM. Even though the speed drops quickly as
soon as the rotary tool contacts the work the speed is still too high
for carbide on steel and the burrs and rotary files dull quickly, which
makes them cut slower. On the other hand, the Dremel and Foredom rotary
tools are too slow and this ends up costing time too. Something that
spins about 40,000 rpm and maintains that speed along with the smaller
diameter would be great. In fact, a tool that was .75 or even .625
diameter would be even better. I have a dental handpiece that I use for
some delicate work and it is just under .5 diameter and is very easy to
hold because of the small diameter. If I could build an electric rotary
tool with the torque of a Dremel, 40,000 rpm, and 1/2 inch in diameter I
would be very happy. Even one that matched the Dremel torque and speed
specs but was 5/8 or 1/2 inch diameter would please me greatly. So,
anyone here play with brushless RC motors?
Thanks,
Eric,


Not for what you're contemplating -- but I do have a couple of RC planes
that I fly with them.

It may work. I'd use an ESC with a helicopter "governor" mode for steady
speed. Make sure you have lots of fan cooling -- those motors get light
in part by being designed for steady airflow (they're AIRPLANE motors!!
). I wouldn't count on the motor bearings to hold up to much side-force,
so you'll have to provide support against that.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
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Default Anybody here using brushless RC motors?

On Mon, 25 Nov 2013 18:20:47 -0800, wrote:

I've been looking at the brushless motors used for RC planes and the
like. They are amazingly powerful for their size. And they really spin
up fast! One web site has kits you can buy to wind your own armatures.
Anyway, I have been wanting a rotary tool that is a cross between a
Dremel and an air powered tool I have. Something with an OD of about 1
inch. Like a Foredom handpiece. Faster than any of my Dremels but
slower than my small air powered hanpiece that spins at 80,000 rpm. So
I'm thinking one of the "inrunner" type motors might work. At 80,000
rpm the surface speed is about 2600 SFPM. Even though the speed drops
quickly as soon as the rotary tool contacts the work the speed is
still too high for carbide on steel and the burrs and rotary files
dull quickly, which makes them cut slower. On the other hand, the
Dremel and Foredom rotary tools are too slow and this ends up costing
time too. Something that spins about 40,000 rpm and maintains that
speed along with the smaller diameter would be great. In fact, a tool
that was .75 or even .625 diameter would be even better. I have a
dental handpiece that I use for some delicate work and it is just
under .5 diameter and is very easy to hold because of the small
diameter. If I could build an electric rotary tool with the torque of
a Dremel, 40,000 rpm, and 1/2 inch in diameter I would be very happy.
Even one that matched the Dremel torque and speed specs but was 5/8 or
1/2 inch diameter would please me greatly. So, anyone here play with
brushless RC motors?
Thanks,
Eric,


Then you dont..dont want to use air powered motors. They have little
torque in the grand scheme of things. Interesting idea about the RC
motors.


__
"A human being should be able to change a diaper, plan an invasion,
butcher a hog, conn a ship, design a building, write a sonnet,
balance accounts, build a wall, set a bone, comfort the dying,
take orders, give orders, cooperate, act alone, solve equations,
analyze a new problem, pitch manure, program a computer,
cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects."
- Heinlein

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Default Anybody here using brushless RC motors?

On Tue, 26 Nov 2013 00:15:06 -0600, Tim Wescott
wrote:

On Mon, 25 Nov 2013 18:20:47 -0800, etpm wrote:

I've been looking at the brushless motors used for RC planes and the
like. They are amazingly powerful for their size. And they really spin
up fast! One web site has kits you can buy to wind your own armatures.
Anyway, I have been wanting a rotary tool that is a cross between a
Dremel and an air powered tool I have. Something with an OD of about 1
inch. Like a Foredom handpiece. Faster than any of my Dremels but slower
than my small air powered hanpiece that spins at 80,000 rpm. So I'm
thinking one of the "inrunner" type motors might work. At 80,000 rpm the
surface speed is about 2600 SFPM. Even though the speed drops quickly as
soon as the rotary tool contacts the work the speed is still too high
for carbide on steel and the burrs and rotary files dull quickly, which
makes them cut slower. On the other hand, the Dremel and Foredom rotary
tools are too slow and this ends up costing time too. Something that
spins about 40,000 rpm and maintains that speed along with the smaller
diameter would be great. In fact, a tool that was .75 or even .625
diameter would be even better. I have a dental handpiece that I use for
some delicate work and it is just under .5 diameter and is very easy to
hold because of the small diameter. If I could build an electric rotary
tool with the torque of a Dremel, 40,000 rpm, and 1/2 inch in diameter I
would be very happy. Even one that matched the Dremel torque and speed
specs but was 5/8 or 1/2 inch diameter would please me greatly. So,
anyone here play with brushless RC motors?
Thanks,
Eric,


Not for what you're contemplating -- but I do have a couple of RC planes
that I fly with them.

It may work. I'd use an ESC with a helicopter "governor" mode for steady
speed. Make sure you have lots of fan cooling -- those motors get light
in part by being designed for steady airflow (they're AIRPLANE motors!!
). I wouldn't count on the motor bearings to hold up to much side-force,
so you'll have to provide support against that.

I of course would only be subjecting the motor to torque forces.
Robust ball bearings are needed to support the cutting tool. I didn't
know about the ESC "governor mode". Thanks for that.
Eric
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Default Anybody here using brushless RC motors?

On Monday, November 25, 2013 9:20:47 PM UTC-5, wrote:
I've been looking at the brushless motors used for RC planes and the

like. They are amazingly powerful for their size. And they really spin

up fast! One web site has kits you can buy to wind your own armatures.

Anyway, I have been wanting a rotary tool that is a cross between a

Dremel and an air powered tool I have. Something with an OD of about 1

inch. Like a Foredom handpiece. Faster than any of my Dremels but

slower than my small air powered hanpiece that spins at 80,000 rpm. So

I'm thinking one of the "inrunner" type motors might work. At 80,000

rpm the surface speed is about 2600 SFPM. Even though the speed drops

quickly as soon as the rotary tool contacts the work the speed is

still too high for carbide on steel and the burrs and rotary files

dull quickly, which makes them cut slower. On the other hand, the

Dremel and Foredom rotary tools are too slow and this ends up costing

time too. Something that spins about 40,000 rpm and maintains that

speed along with the smaller diameter would be great. In fact, a tool

that was .75 or even .625 diameter would be even better. I have a

dental handpiece that I use for some delicate work and it is just

under .5 diameter and is very easy to hold because of the small

diameter. If I could build an electric rotary tool with the torque of

a Dremel, 40,000 rpm, and 1/2 inch in diameter I would be very happy.

Even one that matched the Dremel torque and speed specs but was 5/8 or

1/2 inch diameter would please me greatly. So, anyone here play with

brushless RC motors?

Thanks,

Eric,


A real 'caution' is that most ESCs are sensitive to the lead length to the battery/power-source, long wire length tends to lead to damaged ESCs.
The fix is added capacitance at the ESC.
Not sure how much is required.

Lead length from ESC to motor is not normally an issue.

I run a few brushless outrunner powered planes, the power is amazing.


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Default Anybody here using brushless RC motors?

On Tue, 26 Nov 2013 09:06:18 -0800, etpm wrote:

On Tue, 26 Nov 2013 00:15:06 -0600, Tim Wescott
wrote:

On Mon, 25 Nov 2013 18:20:47 -0800, etpm wrote:

I've been looking at the brushless motors used for RC planes and the
like. They are amazingly powerful for their size. And they really spin
up fast! One web site has kits you can buy to wind your own armatures.
Anyway, I have been wanting a rotary tool that is a cross between a
Dremel and an air powered tool I have. Something with an OD of about 1
inch. Like a Foredom handpiece. Faster than any of my Dremels but
slower than my small air powered hanpiece that spins at 80,000 rpm. So
I'm thinking one of the "inrunner" type motors might work. At 80,000
rpm the surface speed is about 2600 SFPM. Even though the speed drops
quickly as soon as the rotary tool contacts the work the speed is
still too high for carbide on steel and the burrs and rotary files
dull quickly, which makes them cut slower. On the other hand, the
Dremel and Foredom rotary tools are too slow and this ends up costing
time too. Something that spins about 40,000 rpm and maintains that
speed along with the smaller diameter would be great. In fact, a tool
that was .75 or even .625 diameter would be even better. I have a
dental handpiece that I use for some delicate work and it is just
under .5 diameter and is very easy to hold because of the small
diameter. If I could build an electric rotary tool with the torque of
a Dremel, 40,000 rpm, and 1/2 inch in diameter I would be very happy.
Even one that matched the Dremel torque and speed specs but was 5/8 or
1/2 inch diameter would please me greatly. So, anyone here play with
brushless RC motors?
Thanks,
Eric,


Not for what you're contemplating -- but I do have a couple of RC planes
that I fly with them.

It may work. I'd use an ESC with a helicopter "governor" mode for
steady speed. Make sure you have lots of fan cooling -- those motors
get light in part by being designed for steady airflow (they're AIRPLANE
motors!! ). I wouldn't count on the motor bearings to hold up to much
side-force,
so you'll have to provide support against that.

I of course would only be subjecting the motor to torque forces. Robust
ball bearings are needed to support the cutting tool.


I never know what someone knows...

I didn't know
about the ESC "governor mode". Thanks for that.


Please submit a full report when you're done -- I think it's a cool idea.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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Default Anybody here using brushless RC motors?

wrote:
I've been looking at the brushless motors used for RC planes and the
like. They are amazingly powerful for their size. And they really spin
up fast! One web site has kits you can buy to wind your own armatures.
Anyway, I have been wanting a rotary tool that is a cross between a
Dremel and an air powered tool I have. Something with an OD of about 1
inch. Like a Foredom handpiece. Faster than any of my Dremels but
slower than my small air powered hanpiece that spins at 80,000 rpm. So
I'm thinking one of the "inrunner" type motors might work. At 80,000
rpm the surface speed is about 2600 SFPM. Even though the speed drops
quickly as soon as the rotary tool contacts the work the speed is
still too high for carbide on steel and the burrs and rotary files
dull quickly, which makes them cut slower. On the other hand, the
Dremel and Foredom rotary tools are too slow and this ends up costing
time too. Something that spins about 40,000 rpm and maintains that
speed along with the smaller diameter would be great. In fact, a tool
that was .75 or even .625 diameter would be even better. I have a
dental handpiece that I use for some delicate work and it is just
under .5 diameter and is very easy to hold because of the small
diameter. If I could build an electric rotary tool with the torque of
a Dremel, 40,000 rpm, and 1/2 inch in diameter I would be very happy.
Even one that matched the Dremel torque and speed specs but was 5/8 or
1/2 inch diameter would please me greatly. So, anyone here play with
brushless RC motors?
Thanks,
Eric,


you may have problems unless them motor has internal position sensors/
more than three fat power leads. They're mean to run fans or a gearbox
and a fan with no sudden load changes. Brushless fan controllers don't
tend to like loads other than air, or they get confused and lock up and do
other nutty stuff.

The RC controllers may be more tolerant of this, but again, if the motor
lacks position sensors, it's probably not meant for dealing with abrupt
load changes or putting out lots of torque at low speeds.



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Default Anybody here using brushless RC motors?

On Tue, 26 Nov 2013 18:20:54 +0000 (UTC), Cydrome Leader
wrote:

wrote:
I've been looking at the brushless motors used for RC planes and the
like. They are amazingly powerful for their size. And they really spin
up fast! One web site has kits you can buy to wind your own armatures.
Anyway, I have been wanting a rotary tool that is a cross between a
Dremel and an air powered tool I have. Something with an OD of about 1
inch. Like a Foredom handpiece. Faster than any of my Dremels but
slower than my small air powered hanpiece that spins at 80,000 rpm. So
I'm thinking one of the "inrunner" type motors might work. At 80,000
rpm the surface speed is about 2600 SFPM. Even though the speed drops
quickly as soon as the rotary tool contacts the work the speed is
still too high for carbide on steel and the burrs and rotary files
dull quickly, which makes them cut slower. On the other hand, the
Dremel and Foredom rotary tools are too slow and this ends up costing
time too. Something that spins about 40,000 rpm and maintains that
speed along with the smaller diameter would be great. In fact, a tool
that was .75 or even .625 diameter would be even better. I have a
dental handpiece that I use for some delicate work and it is just
under .5 diameter and is very easy to hold because of the small
diameter. If I could build an electric rotary tool with the torque of
a Dremel, 40,000 rpm, and 1/2 inch in diameter I would be very happy.
Even one that matched the Dremel torque and speed specs but was 5/8 or
1/2 inch diameter would please me greatly. So, anyone here play with
brushless RC motors?
Thanks,
Eric,


you may have problems unless them motor has internal position sensors/
more than three fat power leads. They're mean to run fans or a gearbox
and a fan with no sudden load changes. Brushless fan controllers don't
tend to like loads other than air, or they get confused and lock up and do
other nutty stuff.

The RC controllers may be more tolerant of this, but again, if the motor
lacks position sensors, it's probably not meant for dealing with abrupt
load changes or putting out lots of torque at low speeds.


A friend was using a super-duper RD brushless motor on a speed-record
attempt bicycle. Something like 45 HP out of a motor the size of a
baseball - WITH position sensors I believe. Last I heard was he was
going over 60mph working the bugs out. Then his (brain) cancer came
back, so I don't know if he's been able to go any farther
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Default Anybody here using brushless RC motors?

On Tuesday, November 26, 2013 1:20:54 PM UTC-5, Cydrome Leader wrote:
wrote:

I've been looking at the brushless motors used for RC planes and the


like. They are amazingly powerful for their size. And they really spin


up fast! One web site has kits you can buy to wind your own armatures.


Anyway, I have been wanting a rotary tool that is a cross between a


Dremel and an air powered tool I have. Something with an OD of about 1


inch. Like a Foredom handpiece. Faster than any of my Dremels but


slower than my small air powered hanpiece that spins at 80,000 rpm. So


I'm thinking one of the "inrunner" type motors might work. At 80,000


rpm the surface speed is about 2600 SFPM. Even though the speed drops


quickly as soon as the rotary tool contacts the work the speed is


still too high for carbide on steel and the burrs and rotary files


dull quickly, which makes them cut slower. On the other hand, the


Dremel and Foredom rotary tools are too slow and this ends up costing


time too. Something that spins about 40,000 rpm and maintains that


speed along with the smaller diameter would be great. In fact, a tool


that was .75 or even .625 diameter would be even better. I have a


dental handpiece that I use for some delicate work and it is just


under .5 diameter and is very easy to hold because of the small


diameter. If I could build an electric rotary tool with the torque of


a Dremel, 40,000 rpm, and 1/2 inch in diameter I would be very happy.


Even one that matched the Dremel torque and speed specs but was 5/8 or


1/2 inch diameter would please me greatly. So, anyone here play with


brushless RC motors?


Thanks,


Eric,




you may have problems unless them motor has internal position sensors/

more than three fat power leads. They're mean to run fans or a gearbox

and a fan with no sudden load changes. Brushless fan controllers don't

tend to like loads other than air, or they get confused and lock up and do

other nutty stuff.



The RC controllers may be more tolerant of this, but again, if the motor

lacks position sensors, it's probably not meant for dealing with abrupt

load changes or putting out lots of torque at low speeds.


Outrunners are pretty tolerant of what you describe (lotsa spinning mass), inrunners might be more sensitive, but as long as it's spinning fairly quickly it should work. With no prop I've put loads on my motors with my hand- at small throttle settings, heh.

This application would work best with 'low timing', that is, not a lot of advance. There are also settings for PWM frequency.

Neither outrunner nor inrunner will like starting with a large load (which shouldn't be an issue with this app).


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Default Anybody here using brushless RC motors?

On Tue, 26 Nov 2013 18:20:54 +0000 (UTC), Cydrome Leader
wrote:

wrote:
I've been looking at the brushless motors used for RC planes and the
like. They are amazingly powerful for their size. And they really spin
up fast! One web site has kits you can buy to wind your own armatures.
Anyway, I have been wanting a rotary tool that is a cross between a
Dremel and an air powered tool I have. Something with an OD of about 1
inch. Like a Foredom handpiece. Faster than any of my Dremels but
slower than my small air powered hanpiece that spins at 80,000 rpm. So
I'm thinking one of the "inrunner" type motors might work. At 80,000
rpm the surface speed is about 2600 SFPM. Even though the speed drops
quickly as soon as the rotary tool contacts the work the speed is
still too high for carbide on steel and the burrs and rotary files
dull quickly, which makes them cut slower. On the other hand, the
Dremel and Foredom rotary tools are too slow and this ends up costing
time too. Something that spins about 40,000 rpm and maintains that
speed along with the smaller diameter would be great. In fact, a tool
that was .75 or even .625 diameter would be even better. I have a
dental handpiece that I use for some delicate work and it is just
under .5 diameter and is very easy to hold because of the small
diameter. If I could build an electric rotary tool with the torque of
a Dremel, 40,000 rpm, and 1/2 inch in diameter I would be very happy.
Even one that matched the Dremel torque and speed specs but was 5/8 or
1/2 inch diameter would please me greatly. So, anyone here play with
brushless RC motors?
Thanks,
Eric,


you may have problems unless them motor has internal position sensors/
more than three fat power leads. They're mean to run fans or a gearbox
and a fan with no sudden load changes. Brushless fan controllers don't
tend to like loads other than air, or they get confused and lock up and do
other nutty stuff.

The RC controllers may be more tolerant of this, but again, if the motor
lacks position sensors, it's probably not meant for dealing with abrupt
load changes or putting out lots of torque at low speeds.


I don't know how well the RC controllers will work either. My feeling
is that since they can spool up the motors pretty fast they will
tolerate some speed fluctuations from loads. I'm hoping the torque
will be high enough to keepthe speed fairly constant.
Eric


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Default Anybody here using brushless RC motors?

On Tue, 26 Nov 2013 18:20:54 +0000 (UTC), Cydrome Leader
wrote:

The RC controllers may be more tolerant of this, but again, if the motor
lacks position sensors, it's probably not meant for dealing with abrupt
load changes or putting out lots of torque at low speeds.


Big and quick load changes is no problem at all. Have a look at this
electric helicopter:

http://www.youtube.com/watch?v=p8t41avFuCc

Position sensors are only needed when you need torque at zero speed,
such as in a car.
--
RoRo
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Default Anybody here using brushless RC motors?

On Tue, 26 Nov 2013 12:56:10 -0800, etpm wrote:

On Tue, 26 Nov 2013 18:20:54 +0000 (UTC), Cydrome Leader
wrote:

wrote:
I've been looking at the brushless motors used for RC planes and the
like. They are amazingly powerful for their size. And they really spin
up fast! One web site has kits you can buy to wind your own armatures.
Anyway, I have been wanting a rotary tool that is a cross between a
Dremel and an air powered tool I have. Something with an OD of about 1
inch. Like a Foredom handpiece. Faster than any of my Dremels but
slower than my small air powered hanpiece that spins at 80,000 rpm. So
I'm thinking one of the "inrunner" type motors might work. At 80,000
rpm the surface speed is about 2600 SFPM. Even though the speed drops
quickly as soon as the rotary tool contacts the work the speed is
still too high for carbide on steel and the burrs and rotary files
dull quickly, which makes them cut slower. On the other hand, the
Dremel and Foredom rotary tools are too slow and this ends up costing
time too. Something that spins about 40,000 rpm and maintains that
speed along with the smaller diameter would be great. In fact, a tool
that was .75 or even .625 diameter would be even better. I have a
dental handpiece that I use for some delicate work and it is just
under .5 diameter and is very easy to hold because of the small
diameter. If I could build an electric rotary tool with the torque of
a Dremel, 40,000 rpm, and 1/2 inch in diameter I would be very happy.
Even one that matched the Dremel torque and speed specs but was 5/8 or
1/2 inch diameter would please me greatly. So, anyone here play with
brushless RC motors?
Thanks,
Eric,


you may have problems unless them motor has internal position sensors/
more than three fat power leads. They're mean to run fans or a gearbox
and a fan with no sudden load changes. Brushless fan controllers don't
tend to like loads other than air, or they get confused and lock up and
do other nutty stuff.

The RC controllers may be more tolerant of this, but again, if the motor
lacks position sensors, it's probably not meant for dealing with abrupt
load changes or putting out lots of torque at low speeds.


I don't know how well the RC controllers will work either. My feeling is
that since they can spool up the motors pretty fast they will tolerate
some speed fluctuations from loads. I'm hoping the torque will be high
enough to keepthe speed fairly constant.
Eric


If not, the motors for RC cars have sensors. An RC car motor and ESC
combo should work down to zero speed, and not show the "nuttiness".

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
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Default Anybody here using brushless RC motors?

On Tue, 26 Nov 2013 18:20:54 +0000, Cydrome Leader wrote:

wrote:
I've been looking at the brushless motors used for RC planes and the
like. They are amazingly powerful for their size. And they really spin
up fast! One web site has kits you can buy to wind your own armatures.
Anyway, I have been wanting a rotary tool that is a cross between a
Dremel and an air powered tool I have. Something with an OD of about 1
inch. Like a Foredom handpiece. Faster than any of my Dremels but
slower than my small air powered hanpiece that spins at 80,000 rpm. So
I'm thinking one of the "inrunner" type motors might work. At 80,000
rpm the surface speed is about 2600 SFPM. Even though the speed drops
quickly as soon as the rotary tool contacts the work the speed is still
too high for carbide on steel and the burrs and rotary files dull
quickly, which makes them cut slower. On the other hand, the Dremel and
Foredom rotary tools are too slow and this ends up costing time too.
Something that spins about 40,000 rpm and maintains that speed along
with the smaller diameter would be great. In fact, a tool that was .75
or even .625 diameter would be even better. I have a dental handpiece
that I use for some delicate work and it is just under .5 diameter and
is very easy to hold because of the small diameter. If I could build an
electric rotary tool with the torque of a Dremel, 40,000 rpm, and 1/2
inch in diameter I would be very happy. Even one that matched the
Dremel torque and speed specs but was 5/8 or 1/2 inch diameter would
please me greatly. So, anyone here play with brushless RC motors?
Thanks,
Eric,


you may have problems unless them motor has internal position sensors/
more than three fat power leads. They're mean to run fans or a gearbox
and a fan with no sudden load changes. Brushless fan controllers don't
tend to like loads other than air, or they get confused and lock up and
do other nutty stuff.

The RC controllers may be more tolerant of this, but again, if the motor
lacks position sensors, it's probably not meant for dealing with abrupt
load changes or putting out lots of torque at low speeds.


Damn. I should have thought of that when I made my response. RC
airplane propellers are pretty much fans, as are (well, duh) ducted fans.

RC car motors have sensors, and come in a variety of sizes.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
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Default Anybody here using brushless RC motors?

quote:
wrote in message ...

I've been looking at the brushless motors used for RC planes and the
like. They are amazingly powerful for their size. And they really spin
up fast! One web site has kits you can buy to wind your own armatures.
Anyway, I have been wanting a rotary tool that is a cross between a
Dremel and an air powered tool I have. Something with an OD of about 1
inch. Like a Foredom handpiece. Faster than any of my Dremels but
slower than my small air powered hanpiece that spins at 80,000 rpm. So
I'm thinking one of the "inrunner" type motors might work. At 80,000
rpm the surface speed is about 2600 SFPM. Even though the speed drops
quickly as soon as the rotary tool contacts the work the speed is
still too high for carbide on steel and the burrs and rotary files
dull quickly, which makes them cut slower. On the other hand, the
Dremel and Foredom rotary tools are too slow and this ends up costing
time too. Something that spins about 40,000 rpm and maintains that
speed along with the smaller diameter would be great. In fact, a tool
that was .75 or even .625 diameter would be even better. I have a
dental handpiece that I use for some delicate work and it is just
under .5 diameter and is very easy to hold because of the small
diameter. If I could build an electric rotary tool with the torque of
a Dremel, 40,000 rpm, and 1/2 inch in diameter I would be very happy.
Even one that matched the Dremel torque and speed specs but was 5/8 or
1/2 inch diameter would please me greatly. So, anyone here play with
brushless RC motors?
Thanks,
Eric,
/quote


I wanted to try one of these as a cheap alternative to a conventional
brushless dc motor in a mechanism we were prototyping at work, so I grabbed
a couple with controllers off ebay to explore. Then I learned that the
control input needed to be a variable duty cycle digital signal, something
like (from old memory so I'm sure it's a little off) 10 or 15 ms period and
0-5 msec on time for 0-100% of motor speed, sigh. I used a signal generator
to fake it for the initial tests but it would have been a pain to drive it
with our controller if it had worked out (we were set up to output 0-5V for
0-100% motor speed). After getting the parts it was clear that the ESC and
the motor winding could handle some pretty hefty currents to make the hp
they claimed, but there was no way they could dissipate even 10% of the
resultant heat steady state. These were airplane motors and ESC's so they
were engineered to run for 1-2 minutes max, and then have many, many minutes
of cool down time while the battery pack was recharged or swapped out. The
motor bearings were pretty wimpy, too, so I was afraid that putting a pulley
on the motor shaft and having the lateral load from a belt would kill things
pretty quickly, but I never got that far since it was obvious that the
package wasn't what we needed. Hey, it was a fun experiment, anyway :-).
I'll dig one out Monday or Tuesday and see what rpm it's rated for, maybe
you could play with one.

-----
Regards,
Carl Ijames


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Default Anybody here using brushless RC motors?

On 12/1/2013 10:42 PM, Carl Ijames wrote:

I wanted to try one of these as a cheap alternative to a conventional
brushless dc motor in a mechanism we were prototyping at work, so I grabbed
a couple with controllers off ebay to explore. Then I learned that the
control input needed to be a variable duty cycle digital signal, something
like (from old memory so I'm sure it's a little off) 10 or 15 ms period and
0-5 msec on time for 0-100% of motor speed, sigh. I used a signal generator
to fake it for the initial tests but it would have been a pain to drive it
with our controller if it had worked out (we were set up to output 0-5V for
0-100% motor speed). After getting the parts it was clear that the ESC and
the motor winding could handle some pretty hefty currents to make the hp
they claimed, but there was no way they could dissipate even 10% of the
resultant heat steady state. These were airplane motors and ESC's so they
were engineered to run for 1-2 minutes max, and then have many, many minutes
of cool down time while the battery pack was recharged or swapped out. The
motor bearings were pretty wimpy, too, so I was afraid that putting a pulley
on the motor shaft and having the lateral load from a belt would kill things
pretty quickly, but I never got that far since it was obvious that the
package wasn't what we needed. Hey, it was a fun experiment, anyway :-).
I'll dig one out Monday or Tuesday and see what rpm it's rated for, maybe
you could play with one.

-----
Regards,
Carl Ijames



I don't know anything about your controller, Carl, but pulse width
modulation is really fairly trivial (these days!).

http://www.instructables.com/id/QuickStart-one-transistor-DC-motor-controller/



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Default Anybody here using brushless RC motors?

"Richard" wrote in message
m...

On 12/1/2013 10:42 PM, Carl Ijames wrote:

I wanted to try one of these as a cheap alternative to a conventional
brushless dc motor in a mechanism we were prototyping at work, so I
grabbed
a couple with controllers off ebay to explore. Then I learned that the
control input needed to be a variable duty cycle digital signal,
something
like (from old memory so I'm sure it's a little off) 10 or 15 ms period
and
0-5 msec on time for 0-100% of motor speed, sigh. I used a signal
generator
to fake it for the initial tests but it would have been a pain to drive
it
with our controller if it had worked out (we were set up to output 0-5V
for
0-100% motor speed). After getting the parts it was clear that the ESC
and
the motor winding could handle some pretty hefty currents to make the hp
they claimed, but there was no way they could dissipate even 10% of the
resultant heat steady state. These were airplane motors and ESC's so
they
were engineered to run for 1-2 minutes max, and then have many, many
minutes
of cool down time while the battery pack was recharged or swapped out.
The
motor bearings were pretty wimpy, too, so I was afraid that putting a
pulley
on the motor shaft and having the lateral load from a belt would kill
things
pretty quickly, but I never got that far since it was obvious that the
package wasn't what we needed. Hey, it was a fun experiment, anyway :-).
I'll dig one out Monday or Tuesday and see what rpm it's rated for, maybe
you could play with one.

-----
Regards,
Carl Ijames



I don't know anything about your controller, Carl, but pulse width
modulation is really fairly trivial (these days!).

http://www.instructables.com/id/QuickStart-one-transistor-DC-motor-controller/


The signal that a R/C brushless motor controller takes is a pulse
approximately every 20 milliseconds. The width of the pulse is what
determines the output, a 1 ms pulse would, or could be 0%, a 2 ms pulse is
100%, or, if it's reversible, a 1.5 ms pulse is 0%, 1 ms is 100% in one
direction, 2 ms is 100% in the opposite direction. Some of the speed
controls learn the settings as they power up, for example, on my planes, you
power up with the stick at low throttle, it learns whatever that pulse width
is as the low throttle setting, then you take it to full throttle, it pulses
the motor 2 times, once you go back to low throttle, it's ready to go. Some
R/C car setups use 70% travel forward throttle and 30% reverse, so the 0%
would be more around 1.3 ms. Microcontrollers like the Basic Stamp and
Arduino have commands to send a pulse to R/C servos.

The reason for the odd control is because old school transmitters
transmitted a 4.5 ms sync pulse, then a pulse for each channel ranging
between 1 - 2 ms, then it would start the frame over. The receiver
syncronized with the 4.5 ms pulse and then sent the first pulse to channel
1, 2nd pulse to channel 2, ...

RogerN


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Default Anybody here using brushless RC motors?

On 12/2/2013 5:48 AM, RogerN wrote:
"Richard" wrote in message
m...

On 12/1/2013 10:42 PM, Carl Ijames wrote:

I wanted to try one of these as a cheap alternative to a conventional
brushless dc motor in a mechanism we were prototyping at work, so I
grabbed
a couple with controllers off ebay to explore. Then I learned that the
control input needed to be a variable duty cycle digital signal,
something
like (from old memory so I'm sure it's a little off) 10 or 15 ms period
and
0-5 msec on time for 0-100% of motor speed, sigh. I used a signal
generator
to fake it for the initial tests but it would have been a pain to drive
it
with our controller if it had worked out (we were set up to output 0-5V
for
0-100% motor speed). After getting the parts it was clear that the ESC
and
the motor winding could handle some pretty hefty currents to make the hp
they claimed, but there was no way they could dissipate even 10% of the
resultant heat steady state. These were airplane motors and ESC's so
they
were engineered to run for 1-2 minutes max, and then have many, many
minutes
of cool down time while the battery pack was recharged or swapped out.
The
motor bearings were pretty wimpy, too, so I was afraid that putting a
pulley
on the motor shaft and having the lateral load from a belt would kill
things
pretty quickly, but I never got that far since it was obvious that the
package wasn't what we needed. Hey, it was a fun experiment, anyway :-).
I'll dig one out Monday or Tuesday and see what rpm it's rated for, maybe
you could play with one.

-----
Regards,
Carl Ijames



I don't know anything about your controller, Carl, but pulse width
modulation is really fairly trivial (these days!).

http://www.instructables.com/id/QuickStart-one-transistor-DC-motor-controller/


The signal that a R/C brushless motor controller takes is a pulse
approximately every 20 milliseconds. The width of the pulse is what
determines the output, a 1 ms pulse would, or could be 0%, a 2 ms pulse is
100%, or, if it's reversible, a 1.5 ms pulse is 0%, 1 ms is 100% in one
direction, 2 ms is 100% in the opposite direction. Some of the speed
controls learn the settings as they power up, for example, on my planes, you
power up with the stick at low throttle, it learns whatever that pulse width
is as the low throttle setting, then you take it to full throttle, it pulses
the motor 2 times, once you go back to low throttle, it's ready to go. Some
R/C car setups use 70% travel forward throttle and 30% reverse, so the 0%
would be more around 1.3 ms. Microcontrollers like the Basic Stamp and
Arduino have commands to send a pulse to R/C servos.

The reason for the odd control is because old school transmitters
transmitted a 4.5 ms sync pulse, then a pulse for each channel ranging
between 1 - 2 ms, then it would start the frame over. The receiver
syncronized with the 4.5 ms pulse and then sent the first pulse to channel
1, 2nd pulse to channel 2, ...

RogerN



All true, of course.
But I can't let the Arduino and Basic Stamp reference slide by so easily.
That example is my offering for a Propeller P32x8 microcontroller.
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Default Anybody here using brushless RC motors?

"Richard" wrote in message
m...

On 12/2/2013 5:48 AM, RogerN wrote:
"Richard" wrote in message
m...

snip
The reason for the odd control is because old school transmitters
transmitted a 4.5 ms sync pulse, then a pulse for each channel ranging
between 1 - 2 ms, then it would start the frame over. The receiver
syncronized with the 4.5 ms pulse and then sent the first pulse to
channel
1, 2nd pulse to channel 2, ...

RogerN



All true, of course.
But I can't let the Arduino and Basic Stamp reference slide by so easily.
That example is my offering for a Propeller P32x8 microcontroller.


I'm going to have to get a propeller microcontroller sometime! If I
understand correctly, they are like multiple microcontrollers that have
shared memory area. That would be awesome for processing sensor data,
control programming, and servo output all at the same time. I would like to
use a controller for R/C flight, using gyro & accelerometers + GPS to make
it capable of following programmed flight paths. I got a 6 axis gyro plus
accelerometer module for under $10, looking for bargain GPS.

RogerN


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On 12/2/2013 1:03 PM, RogerN wrote:
"Richard" wrote in message


All true, of course.
But I can't let the Arduino and Basic Stamp reference slide by so easily.
That example is my offering for a Propeller P32x8 microcontroller.


I'm going to have to get a propeller microcontroller sometime! If I
understand correctly, they are like multiple microcontrollers that have
shared memory area. That would be awesome for processing sensor data,
control programming, and servo output all at the same time. I would like to
use a controller for R/C flight, using gyro& accelerometers + GPS to make
it capable of following programmed flight paths. I got a 6 axis gyro plus
accelerometer module for under $10, looking for bargain GPS.

RogerN


Yeah. Eight independent processors (with independent RAM in each) around
a central hub (with more RAM - and ROM), PLUS some really
interesting counters (that can do many things, like produce VGA
or TV video). The individual processors are referred to as COGS.

There are no dedicated I/O circuits on board. Those are loaded as
software driven devices as desired.
Any COG can access any I/O pin (OR-ed writes)

The Parallax Object Exchange (OBEX) has hundreds of pre-written
drivers and aps.

And no interrupts! Perfectly determinate timing!

I'm not a big fan of (forced) indented structures the way SPIN
(the native programming language) uses, but it works fine - once
you wrap your mind around it.

And you will probably find drivers for the stuff you already have.

Pick up a QuickStart board at Radio Shack.
You'll have a ball with it, Roger.



Intro to model airplane autopilots:
http://www.instructables.com/id/Intr...ane-Autopilot/

http://electronicdesign.com/boards/h...ies-quadcopter
http://diydrones.com/profiles/blogs/...:BlogPost:6607

Or maybe the Hoverfly board??? It already has everthing you'd need!
http://www.parallaxsemiconductor.com/customer-success/hoverfly-technologies

Or Octopilot? (the eight thing again in corny names)
https://code.google.com/p/octopilot/
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Default Anybody here using brushless RC motors?

On 02/12/13 05:00, Richard wrote:
On 12/1/2013 10:42 PM, Carl Ijames wrote:

I wanted to try one of these as a cheap alternative to a conventional
brushless dc motor in a mechanism we were prototyping at work, so I
grabbed
a couple with controllers off ebay to explore. Then I learned that the
control input needed to be a variable duty cycle digital signal,
something
like (from old memory so I'm sure it's a little off) 10 or 15 ms
period and
0-5 msec on time for 0-100% of motor speed, sigh. I used a signal
generator
to fake it for the initial tests but it would have been a pain to
drive it
with our controller if it had worked out (we were set up to output
0-5V for
0-100% motor speed). After getting the parts it was clear that the
ESC and
the motor winding could handle some pretty hefty currents to make the hp
they claimed, but there was no way they could dissipate even 10% of the
resultant heat steady state. These were airplane motors and ESC's so
they
were engineered to run for 1-2 minutes max, and then have many, many
minutes
of cool down time while the battery pack was recharged or swapped
out. The
motor bearings were pretty wimpy, too, so I was afraid that putting a
pulley
on the motor shaft and having the lateral load from a belt would kill
things
pretty quickly, but I never got that far since it was obvious that the
package wasn't what we needed. Hey, it was a fun experiment, anyway
:-).
I'll dig one out Monday or Tuesday and see what rpm it's rated for,
maybe
you could play with one.

-----
Regards,
Carl Ijames



I don't know anything about your controller, Carl, but pulse width
modulation is really fairly trivial (these days!).

http://www.instructables.com/id/QuickStart-one-transistor-DC-motor-controller/


Probably a bit over the top for controlling a hand piece. I bought a
servo tester from Conrad while I was in Munich about 20 years ago and
they still do them, see http://www.conrad.com/ce/en/product/234915/ .
That'll give manual control on the PWM that can then be supplied to the
ESC. I don't know if Conrad have a US branch but some digging might
reveal the circuit diagram which from memory was quite simple and used a
common 4000 series CMOS chip. Looking in the downloadable documents
section and the first file shows the circuit diagram and it uses a 4001
and a few discrete components, simples!.


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Default Anybody here using brushless RC motors?


Richard wrote:

On 12/1/2013 10:42 PM, Carl Ijames wrote:

I wanted to try one of these as a cheap alternative to a conventional
brushless dc motor in a mechanism we were prototyping at work, so I grabbed
a couple with controllers off ebay to explore. Then I learned that the
control input needed to be a variable duty cycle digital signal, something
like (from old memory so I'm sure it's a little off) 10 or 15 ms period and
0-5 msec on time for 0-100% of motor speed, sigh. I used a signal generator
to fake it for the initial tests but it would have been a pain to drive it
with our controller if it had worked out (we were set up to output 0-5V for
0-100% motor speed). After getting the parts it was clear that the ESC and
the motor winding could handle some pretty hefty currents to make the hp
they claimed, but there was no way they could dissipate even 10% of the
resultant heat steady state. These were airplane motors and ESC's so they
were engineered to run for 1-2 minutes max, and then have many, many minutes
of cool down time while the battery pack was recharged or swapped out. The
motor bearings were pretty wimpy, too, so I was afraid that putting a pulley
on the motor shaft and having the lateral load from a belt would kill things
pretty quickly, but I never got that far since it was obvious that the
package wasn't what we needed. Hey, it was a fun experiment, anyway :-).
I'll dig one out Monday or Tuesday and see what rpm it's rated for, maybe
you could play with one.

-----
Regards,
Carl Ijames



I don't know anything about your controller, Carl, but pulse width
modulation is really fairly trivial (these days!).

http://www.instructables.com/id/QuickStart-one-transistor-DC-motor-controller/



A lot of C-band sat receivers used a 555 to control the servo in the
feedhorn.


Or you can spend $1.81 for one of these:

http://www.ebay.com/itm/Multi-RC-Hel...item5af7992397


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.
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Default Anybody here using brushless RC motors?

Yes, I know pwm is trivial these days and I've done it a few times in other
projects, but we had just finished making a board with a pic and spi 12 bit
dac to generate a 0-5v signal to drive the motor that we planned to use
because that's what that controller wanted, and I had hoped that the rc
motor and esc would drop into that without any extra fiddling. If the rc
motor had worked out as a lower cost alternative we would have redone the
board, but it didn't.

Thanks, Roger, for the explanation of why the odd timings. I knew I was
close but not quite right on the timings, but the point was to make sure
Eric knew what an rc esc needs to be fed for control so he wouldn't get the
same surprise I did after buying the motors, instead of before :-).

-----
Regards,
Carl Ijames
"Richard" wrote in message
m...

On 12/1/2013 10:42 PM, Carl Ijames wrote:

I wanted to try one of these as a cheap alternative to a conventional
brushless dc motor in a mechanism we were prototyping at work, so I
grabbed
a couple with controllers off ebay to explore. Then I learned that the
control input needed to be a variable duty cycle digital signal, something
like (from old memory so I'm sure it's a little off) 10 or 15 ms period
and
0-5 msec on time for 0-100% of motor speed, sigh. I used a signal
generator
to fake it for the initial tests but it would have been a pain to drive it
with our controller if it had worked out (we were set up to output 0-5V
for
0-100% motor speed). After getting the parts it was clear that the ESC
and
the motor winding could handle some pretty hefty currents to make the hp
they claimed, but there was no way they could dissipate even 10% of the
resultant heat steady state. These were airplane motors and ESC's so they
were engineered to run for 1-2 minutes max, and then have many, many
minutes
of cool down time while the battery pack was recharged or swapped out.
The
motor bearings were pretty wimpy, too, so I was afraid that putting a
pulley
on the motor shaft and having the lateral load from a belt would kill
things
pretty quickly, but I never got that far since it was obvious that the
package wasn't what we needed. Hey, it was a fun experiment, anyway :-).
I'll dig one out Monday or Tuesday and see what rpm it's rated for, maybe
you could play with one.

-----
Regards,
Carl Ijames



I don't know anything about your controller, Carl, but pulse width
modulation is really fairly trivial (these days!).

http://www.instructables.com/id/QuickStart-one-transistor-DC-motor-controller/


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Default Anybody here using brushless RC motors?

On Mon, 02 Dec 2013 19:27:33 +0000, David Billington
wrote:

On 02/12/13 05:00, Richard wrote:
On 12/1/2013 10:42 PM, Carl Ijames wrote:

I wanted to try one of these as a cheap alternative to a conventional
brushless dc motor in a mechanism we were prototyping at work, so I
grabbed
a couple with controllers off ebay to explore. Then I learned that the
control input needed to be a variable duty cycle digital signal,
something
like (from old memory so I'm sure it's a little off) 10 or 15 ms
period and
0-5 msec on time for 0-100% of motor speed, sigh. I used a signal
generator
to fake it for the initial tests but it would have been a pain to
drive it
with our controller if it had worked out (we were set up to output
0-5V for
0-100% motor speed). After getting the parts it was clear that the
ESC and
the motor winding could handle some pretty hefty currents to make the hp
they claimed, but there was no way they could dissipate even 10% of the
resultant heat steady state. These were airplane motors and ESC's so
they
were engineered to run for 1-2 minutes max, and then have many, many
minutes
of cool down time while the battery pack was recharged or swapped
out. The
motor bearings were pretty wimpy, too, so I was afraid that putting a
pulley
on the motor shaft and having the lateral load from a belt would kill
things
pretty quickly, but I never got that far since it was obvious that the
package wasn't what we needed. Hey, it was a fun experiment, anyway
:-).
I'll dig one out Monday or Tuesday and see what rpm it's rated for,
maybe
you could play with one.

-----
Regards,
Carl Ijames



I don't know anything about your controller, Carl, but pulse width
modulation is really fairly trivial (these days!).

http://www.instructables.com/id/QuickStart-one-transistor-DC-motor-controller/


Probably a bit over the top for controlling a hand piece. I bought a
servo tester from Conrad while I was in Munich about 20 years ago and
they still do them, see http://www.conrad.com/ce/en/product/234915/ .
That'll give manual control on the PWM that can then be supplied to the
ESC. I don't know if Conrad have a US branch but some digging might
reveal the circuit diagram which from memory was quite simple and used a
common 4000 series CMOS chip. Looking in the downloadable documents
section and the first file shows the circuit diagram and it uses a 4001
and a few discrete components, simples!.

It looks like Hobby King has a motor or two that will work. Along with
an ESC and a servo tester. I also found a circuit for building my own
servo tester. I could hook up my Basic Stamp too. But for 5 bucks I'll
get the one that comes in a box. Thanks everyone so far for the
replies. I know the inrunner motors will overheat if run at high
currents for too long. I will need to come up with some type of
cooling scheme. I am amazed by the power of these little motors. A
20mm diameter motor thats rated at 330 watts! Of course the motor
would melt if not kept cool. Maybe I should connect a coolant hose and
run LN2 from a thermos through the thing.
Eric
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wrote in message
...

A 20mm diameter motor thats rated at 330 watts! Of course the motor
would melt if not kept cool. Maybe I should connect a coolant hose
and
run LN2 from a thermos through the thing.
Eric


Coffee-cup-sized Segway motors can deliver something like 1 HP
continuously without air cooling. They are completely enclosed in a
tight space and lose heat only through their mounting flange.

http://forums.segwaychat.org/archive...hp/t-9400.html
Doug Field, near the bottom, was Segway's chief engineer. The factory
is isolated and it's unlikely an imposter would know that we were
outside flying planes at lunch.



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On 12/2/2013 6:18 PM, Jim Wilkins wrote:
wrote in message
...

A 20mm diameter motor thats rated at 330 watts! Of course the motor
would melt if not kept cool. Maybe I should connect a coolant hose
and
run LN2 from a thermos through the thing.
Eric


Coffee-cup-sized Segway motors can deliver something like 1 HP
continuously without air cooling. They are completely enclosed in a
tight space and lose heat only through their mounting flange.

http://forums.segwaychat.org/archive...hp/t-9400.html
Doug Field, near the bottom, was Segway's chief engineer. The factory
is isolated and it's unlikely an imposter would know that we were
outside flying planes at lunch.




Yeah right.
Like my vacuum cleaner really has a 5 HP motor.
It says so on the side!




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"Richard" wrote in message
m...
On 12/2/2013 6:18 PM, Jim Wilkins wrote:
wrote in message
...

A 20mm diameter motor thats rated at 330 watts! Of course the
motor
would melt if not kept cool. Maybe I should connect a coolant hose
and
run LN2 from a thermos through the thing.
Eric


Coffee-cup-sized Segway motors can deliver something like 1 HP
continuously without air cooling. They are completely enclosed in a
tight space and lose heat only through their mounting flange.

http://forums.segwaychat.org/archive...hp/t-9400.html
Doug Field, near the bottom, was Segway's chief engineer. The
factory
is isolated and it's unlikely an imposter would know that we were
outside flying planes at lunch.



Yeah right.
Like my vacuum cleaner really has a 5 HP motor.
It says so on the side!


Segway didn't advertise the power of their motors. They are adequate
for their task, with a good margin that we tested frequently on the
rough trails and railroad track along the river behind the factory.

We knew what their battery voltage and current limits were, though I
can't reveal details. Accept whatever Doug Field wrote.

I was an electronic tech working with the control boards, gyro and
batteries and never tested a motor on the dyno that was 20' from my
bench.



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