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Hi guys,
I ran a test the other day to see how hot the stepper motors are
getting on my machine. After 30 minutes, they (3 of them) were all
at 150 degrees F.
The motors are 5 volt motors rated at 1.4 Amps, nema 17. I am
driving them at 30 volts and 1.4 amps. The driver chip is the
SLA7062M chip. This heat test was performed with the motors holding
their position as that is the best way I know to "push them" for
heat build up.
I know I could get another transformer and drop the voltage, but
would prefer to keep it at 30 volts for performance. I have a bit
of room where I could add some chunks of aluminum for heat sinking,
but not sure if that would get the temp down enough. I have no room
for fans so I am sort of pondering what directions I can go to deal
with this.
As always, I am open to any and all suggestions or ideas.
One interesting thing I heard from a very reliable source is that if
I switch from the SLA7062M based driver to a Gecko driver, the motor
heat would drop down significantly. However, I don't have the
budget for 3 Geckos on this little machine.
Chris
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Hi, yep good ole heat...i would look carefully at how and what they are
mounted to, you might be able to add a sheet of alum with finns off out of
the way. one of my machines i removed the steel part the motor was mounted
on and made a new one of alum. i simply epoxied a heat sink to the top of
the motor and that has helped alot. might be able to take a thin backed
heatsink, bend it to the shape of the od of the motor and epoxy it on, or
stainless pipe camps. even a small amount of heat sink will make a
difference. cul brian f.
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----- Original Message ----- From: "lcdpublishing" <lcdpublishing@...> To: <CAD_CAM_EDM_DRO@...> Sent: Wednesday, August 23, 2006 11:23 AM Subject: [CAD_CAM_EDM_DRO] How to deal with Stepper Motor heat - 150 degrees F Hi guys,
I ran a test the other day to see how hot the stepper motors are
getting on my machine. After 30 minutes, they (3 of them) were all
at 150 degrees F.
The motors are 5 volt motors rated at 1.4 Amps, nema 17. I am
driving them at 30 volts and 1.4 amps. The driver chip is the
SLA7062M chip. This heat test was performed with the motors holding
their position as that is the best way I know to "push them" for
heat build up.
I know I could get another transformer and drop the voltage, but
would prefer to keep it at 30 volts for performance. I have a bit
of room where I could add some chunks of aluminum for heat sinking,
but not sure if that would get the temp down enough. I have no room
for fans so I am sort of pondering what directions I can go to deal
with this.
As always, I am open to any and all suggestions or ideas.
One interesting thing I heard from a very reliable source is that if
I switch from the SLA7062M based driver to a Gecko driver, the motor
heat would drop down significantly. However, I don't have the
budget for 3 Geckos on this little machine.
Chris
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If you're driving lead screws with the motors there is no reason not to
reduce the current when not moving. I have a SLA7062M based system that can
do that automatically. Cheap. Full details on my web site.
--
Phil Mattison
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----- Original Message ----- From: lcdpublishing <lcdpublishing@...> To: <CAD_CAM_EDM_DRO@...> Sent: Wednesday, August 23, 2006 8:23 AM Subject: [CAD_CAM_EDM_DRO] How to deal with Stepper Motor heat - 150 degrees F Hi guys,
I ran a test the other day to see how hot the stepper motors are
getting on my machine. After 30 minutes, they (3 of them) were all
at 150 degrees F.
The motors are 5 volt motors rated at 1.4 Amps, nema 17. I am
driving them at 30 volts and 1.4 amps. The driver chip is the
SLA7062M chip. This heat test was performed with the motors holding
their position as that is the best way I know to "push them" for
heat build up.
I know I could get another transformer and drop the voltage, but
would prefer to keep it at 30 volts for performance. I have a bit
of room where I could add some chunks of aluminum for heat sinking,
but not sure if that would get the temp down enough. I have no room
for fans so I am sort of pondering what directions I can go to deal
with this.
As always, I am open to any and all suggestions or ideas.
One interesting thing I heard from a very reliable source is that if
I switch from the SLA7062M based driver to a Gecko driver, the motor
heat would drop down significantly. However, I don't have the
budget for 3 Geckos on this little machine.
Chris
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OFF Topic POSTS: General Machining
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DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........ bill
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List Owner
Yahoo! Groups Links
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lcdpublishing wrote: Hi guys,
I ran a test the other day to see how hot the stepper motors are getting on my machine. After 30 minutes, they (3 of them) were all at 150 degrees F.
The motors are 5 volt motors rated at 1.4 Amps, nema 17. I am driving them at 30 volts and 1.4 amps. The driver chip is the SLA7062M chip. This heat test was performed with the motors holding their position as that is the best way I know to "push them" for heat build up.
I know I could get another transformer and drop the voltage, but would prefer to keep it at 30 volts for performance. I have a bit of room where I could add some chunks of aluminum for heat sinking, but not sure if that would get the temp down enough. I have no room for fans so I am sort of pondering what directions I can go to deal with this.
What you might look into is a scheme to drop the current when the motor is standing still. Gecko drives drop to 1/3 current 1 second after motion stops, and back up to full current as quickly as possible when a step pulse comes in. The circuitry to do this is basically a one shot and a transistor to change the reference voltage to the dac that produces the microstep sine waves. A similar circuit that changes the current limit threshold should do what you need. Jon
|
--- In CAD_CAM_EDM_DRO@..., "lcdpublishing" <lcdpublishing@...> wrote:
Hi guys,
I ran a test the other day to see how hot the stepper motors are
getting on my machine. After 30 minutes, they (3 of them) were all
at 150 degrees F.
The motors are 5 volt motors rated at 1.4 Amps, nema 17. I am
driving them at 30 volts and 1.4 amps. The driver chip is the
SLA7062M chip. This heat test was performed with the motors holding
their position as that is the best way I know to "push them" for
heat build up.
I know I could get another transformer and drop the voltage, but
would prefer to keep it at 30 volts for performance. I have a bit
of room where I could add some chunks of aluminum for heat sinking,
but not sure if that would get the temp down enough. I have no room
for fans so I am sort of pondering what directions I can go to deal
with this.
As always, I am open to any and all suggestions or ideas.
One interesting thing I heard from a very reliable source is that if
I switch from the SLA7062M based driver to a Gecko driver, the motor
heat would drop down significantly. However, I don't have the
budget for 3 Geckos on this little machine.
Chris
You should be able to drop the current when the motor has nor received a step signal in some seconds. You can use a micro to monitor the steps and toggle the motor current setting. Dave
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Check the specs on your motors, many are rated to run up to at least
80 degrees Celsius, which is 176F, so you may be running them within
spec. Stepper motors get hot, and you're testing them in the worst
case scenerio, full current, no motion, so if they are staying with
the spec heat range in that situation you're probably ok.
Paul T.
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Motor losses really only come from a few places, windings (I2R),
hysteresis, eddy currents, and bearing friction. The voltage at your
PWM driver isn't really relevent until you get to a couple hundred
volts where insulators break down and arcing is an issue.
So unfortunately, your only option is to reduce the current, which can
only be done with the chopper or PWM.
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On 8/23/06, lcdpublishing <lcdpublishing@...> wrote: Hi guys,
I ran a test the other day to see how hot the stepper motors are
getting on my machine. After 30 minutes, they (3 of them) were all
at 150 degrees F.
The motors are 5 volt motors rated at 1.4 Amps, nema 17. I am
driving them at 30 volts and 1.4 amps. The driver chip is the
SLA7062M chip. This heat test was performed with the motors holding
their position as that is the best way I know to "push them" for
heat build up.
I know I could get another transformer and drop the voltage, but
would prefer to keep it at 30 volts for performance. I have a bit
of room where I could add some chunks of aluminum for heat sinking,
but not sure if that would get the temp down enough. I have no room
for fans so I am sort of pondering what directions I can go to deal
with this.
As always, I am open to any and all suggestions or ideas.
One interesting thing I heard from a very reliable source is that if
I switch from the SLA7062M based driver to a Gecko driver, the motor
heat would drop down significantly. However, I don't have the
budget for 3 Geckos on this little machine.
Chris
|
Chris, Our HobbyCNC PRO driver board kit offers idle current reduction at a very reasonable price. We have it in a 3 or 4 axis version. Also has driver chip protection in case of open or shorted stepper windings, something the 7062M lacks. Uses the very latest in Unipolar driver chips. The SLA7062M is already old technology and we're closing them out of our product line at very special prices. Dave Rigotti www.hobbycnc.com --- In CAD_CAM_EDM_DRO@..., "lcdpublishing" <lcdpublishing@...> wrote:
Hi guys,
I ran a test the other day to see how hot the stepper motors are
getting on my machine. After 30 minutes, they (3 of them) were
all at 150 degrees F.
The motors are 5 volt motors rated at 1.4 Amps, nema 17. I am
driving them at 30 volts and 1.4 amps. The driver chip is the
SLA7062M chip. This heat test was performed with the motors holding their position as that is the best way I know to "push them" for
heat build up.
I know I could get another transformer and drop the voltage, but
would prefer to keep it at 30 volts for performance. I have a bit
of room where I could add some chunks of aluminum for heat sinking, but not sure if that would get the temp down enough. I have no room for fans so I am sort of pondering what directions I can go to deal with this.
As always, I am open to any and all suggestions or ideas.
One interesting thing I heard from a very reliable source is that if I switch from the SLA7062M based driver to a Gecko driver, the motor heat would drop down significantly. However, I don't have the
budget for 3 Geckos on this little machine.
Chris
|
Thanks for the help and information guys. I will have to ponder this
one for a while to see what I can come up with.
Chris
|
A little late coming into this discussion, but just one more thing to
consider -- when the motors are holding their position, is one winding
energized, or both? If you have 1.4A flowing through one winding, it's quite
different from 1.4A flowing simultaneously through two. In fact, depending
on the ambient temperature, and how efficient the motor is at dissipating
heat, I think the temperature in one case can be close to twice that of the
other. At least theoretically that seems possible.
Vlad
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On 8/23/06, lcdpublishing <lcdpublishing@...> wrote:
Hi guys,
I ran a test the other day to see how hot the stepper motors are
getting on my machine. After 30 minutes, they (3 of them) were all
at 150 degrees F.
The motors are 5 volt motors rated at 1.4 Amps, nema 17. I am
driving them at 30 volts and 1.4 amps. The driver chip is the
SLA7062M chip. This heat test was performed with the motors holding
their position as that is the best way I know to "push them" for
heat build up.
I know I could get another transformer and drop the voltage, but
would prefer to keep it at 30 volts for performance. I have a bit
of room where I could add some chunks of aluminum for heat sinking,
but not sure if that would get the temp down enough. I have no room
for fans so I am sort of pondering what directions I can go to deal
with this.
As always, I am open to any and all suggestions or ideas.
One interesting thing I heard from a very reliable source is that if
I switch from the SLA7062M based driver to a Gecko driver, the motor
heat would drop down significantly. However, I don't have the
budget for 3 Geckos on this little machine.
Chris
Addresses:
FAQ:
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timg@...
Moderator: pentam@... indigo_red@... davemucha@...
[Moderators]
URL to this group:
OFF Topic POSTS: General Machining
If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it
if you have trouble.
I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING
THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
bill
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