Stepper Motor Temperature

[Jeff DeTray]

Is it normal for a stepper motor to become hot to the touch after an hour of
continuous running?

I obtained a motor with a nice 30:1 gearbox that I plan to use on my barn-door
camera mount. While testing the motor with no load last night, I noticed it
became quite warm after an hour or so. While I will probably never run the
motor continuously for an hour in actual use, I'd like to know if it's normal
for a stepper to get fairly hot and if running it hot will damage the motor.

Jeff DeTray
je...@detray.com
http://www.detray.com/jeff

[David Rose]

Jeff,

Stepper motors do run warm.
Depending on the type of motor you have, I would say that if you can not hold your
hand on the motor you may have problems.
I use a small stepping motor for my focusing mount / CCD set up. The motor is
quite warm to touch.

Regards,

Dave Rose.
--
email: dave...@virgin.net
Visit my CCD Astronomy Web page at:-
http://freespace.virgin.net/dave.rose/index.htm
Oxfordshire
U.K.
--

[David Johnson]

In article <6lh6ch$94$1...@news.monad.net>, Jeff DeTray <je...@DeTray.com>
writes

>Is it normal for a stepper motor to become hot to the touch after an hour of
>continuous running?
>
>I obtained a motor with a nice 30:1 gearbox that I plan to use on my barn-door
>camera mount. While testing the motor with no load last night, I noticed it
>became quite warm after an hour or so. While I will probably never run the
>motor continuously for an hour in actual use, I'd like to know if it's normal
>for a stepper to get fairly hot and if running it hot will damage the motor.
>

Stepper motors do tend to run hot -they have continuous current passing
through their windings.

Dave
--
David Johnson - remove nojunk to reply
Dave's Astronomy Magazine:
http://www.astromag.demon.co.uk

[William...@nashville.com]

On 1998-06-08 je...@DeTray.com(JeffDeTray) said:

>Is it normal for a stepper motor to become hot to the touch after
>an hour of continuous running?
>I obtained a motor with a nice 30:1 gearbox that I plan to use on
>my barn-door camera mount. While testing the motor with no load
>last night, I noticed it became quite warm after an hour or so.
>While I will probably never run the motor continuously for an hour
>in actual use, I'd like to know if it's normal for a stepper to get
>fairly hot and if running it hot will damage the motor.

It is normal for any motor to warm up as it is not 100% efficient. If
it gets too hot to touch then it is too hot. If you want to be precise
about it read the specs and use a thermometer, but a fingertip is a good
indicator. Be sure your pulse timing, width, voltage, etc. are within
spec and the gears aren't binding.

[Olle Eriksson]

>Is it normal for a stepper motor to become hot to the touch after an hour
of
>continuous running?

I have built a tracking mount with a stepper motor and I noticed that it
became very hot by just letting it run for half an hour. It's almost too hot
to touch but I still haven't had any problems with the accuracy of the
speed. I made a test by projecting a laser spot on a wall and measuring how
it moved. Take a look at my homepage at
http://hem1.passagen.se/astrosci/etcm.htm for more information about the
test.

I don't think you have to worry.
Olle Eriksson

[Bob Rubendunst]

> Stepper motors do tend to run hot -they have continuous current

^^^^^^^^^^

Actually it's discontinuous, which is why they are called stepping
or stepper motors. They do get warm.

[Loren Coe]

In article <357F090...@softm.com>,

i would be surprised at any application that did not use a "hold"
current. this current, along with the lack of forced air circulation
accounts for most of the heat buildup in a typical application (AFAIK).

YMMV.

loren

[Peter Drumm]

In message <357F090...@softm.com> - Bob Rubendunst
<so...@softm.com>Wed, 10 Jun 1998 17:30:24 -0500 writes:
:->
:->> Stepper motors do tend to run hot -they have continuous current
:-> ^^^^^^^^^^
:->
:->Actually it's discontinuous, which is why they are called stepping
:->or stepper motors. They do get warm.

You're both right, in a way. While turning, the windings are fed
pulses by the controller. The 'off' time is a lot less than the 'on'
time, so there's more time spent creating heat than dissipating it.
When the controller is on but not turning the motor, one winding gets
the current continuously.

pdr...@dwave.net <http://www.dwave.net/~pdrumm>
Using OS/2 Warp 4!
Wausau, WI. 44d 58m 00s N x 89d 36m 45s W
All opinions are mine alone, you go get your own!

[el...@hal.com]

In article <Os7g1.884$bj2.4...@ptah.visi.com>,

pdr...@dwave.net wrote:
>
> In message <357F090...@softm.com> - Bob Rubendunst
> <so...@softm.com>Wed, 10 Jun 1998 17:30:24 -0500 writes:
> :->
> :->> Stepper motors do tend to run hot -they have continuous current
> :-> ^^^^^^^^^^
> :->
> :->Actually it's discontinuous, which is why they are called stepping
> :->or stepper motors. They do get warm.
>
> You're both right, in a way. While turning, the windings are fed
> pulses by the controller. The 'off' time is a lot less than the 'on'
> time, so there's more time spent creating heat than dissipating it.
> When the controller is on but not turning the motor, one winding gets
> the current continuously.
>
>

Hi
Actually, there are two kinds of stepper motors. Some have permanent
magnets in them and as long as one is using hole steps, these can
have their power turned off. One can tell this type because with
no power they seem to snap from position to position. Any system
that uses micro stepping or partial steps must maintain a minumum
coil current to hole position. In order to save on wasted power,
many stepper controllers for industrial applications use two levels
of current to the coils, one for stepping and a reduced one for
holding.
Dwight

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[Larry Bourdillon]

While I don't claim to be an expert in stepper motors, I have used then
extensively in my past work. Most of the comments made here, by several
posters, are true; but it's important to keep in mind that there are
several types of motor drives. Which one your system uses can make a
"big" difference in the available torque, slewing (acceleration) speeds,
and motor temperatures. These drive methods include square wave, sine
wave wave, micro-stepping, etc., etc. I won't clog up the newsgroup here
with the details unless specifically requested.

However, to answer the original poster's question -- in a properly
designed *consumer* system, the motor shouldn't get too hot (60-70 C) to
touch. Such consumer motors (Meade, etc.) typically use inexpensive
components (bearings and such) and the life of the motor unit can be
severely limited by higher temperatures. This is often true of the
bearing lubricants, which (there are tradeoffs here) cannot take the
continous high temperatures without polymerizing or breaking down.

...larry

Bob Rubendunst wrote:

> > Stepper motors do tend to run hot -they have continuous current

> ^^^^^^^^^^

>
> Actually it's discontinuous, which is why they are called stepping