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From: Jeremy L <getsearc...@gmail.com>
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Subject: Re: [tcmaker] Stepper motor problem solved
Date: Sun, 11 Nov 2012 14:47:50 -0600
In-Reply-To: <4369442210017119715@unknownmsgid>
To: tcmaker@googlegroups.com
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>> The heating problem arose because those motors have very low coil =
resistance and so pull a lot of current - which can supposedly be =
mitigated by turning the current-limiting potentiometer down. I haven't =
tested that theory yet because I switched to this motor which has 20 =
times the coil resistance but really needs 24V to operate reliably. I =
would like to find one that runs well on 12V and doesn't double as a =
space heater.
>>=20
> The other thing to look at is hold current. Typically, stepper motor =
controllers, when not moving the motor, will put the motors in a hold =
state with full current applied. This is normal and is done to provide =
maximum hold torque. Most drivers provide a way to adjust the hold =
current levels lower if you don't need that much hold torque.=20
<Jumping in without much background info>
If there's excessive heat, perhaps the motor is trying to "hold" the =
position of each step, fighting the momentum to turn faster? In the =
logic world, a stepper holds a series of discrete positions. In the =
mechanical world, it is either holding one position stationary, or it is =
moving a smooth linear motion with inertia. The signal to hold a =
position involves fighting momentum to turn beyond the step position, =
which I would expect to appear as heat.
Granted, this would be a detail that presumably the steeper driver =
already has worked out. But if the driver is just given a series of =
pulses, with no velocity information, then it has no way of knowing the =
intended motion, and might have to resort to discrete positions.
Just a theory.
Jeremy
On Nov 11, 2012, at 1:12 PM, John Scherer wrote:
>=20
>=20
> Sent from my iPhone
>=20
> On Nov 11, 2012, at 10:18 AM, Don French <dcfre...@gmail.com> wrote:
>=20
>> Kelly,
>>=20
>> I understand the steppers a bit better now and discovered that =
reversing the connection between A and A- or B and B- has only the =
effect of changing the direction the motor turns. Reverse pairs and =
there is no effect. But it has no effect on the heat problem or the =
stuttering of the motor.
>>=20
> Yep, that's normal
>=20
>=20
>=20
>> The heating problem arose because those motors have very low coil =
resistance and so pull a lot of current - which can supposedly be =
mitigated by turning the current-limiting potentiometer down. I haven't =
tested that theory yet because I switched to this motor which has 20 =
times the coil resistance but really needs 24V to operate reliably. I =
would like to find one that runs well on 12V and doesn't double as a =
space heater.
>>=20
> The other thing to look at is hold current. Typically, stepper motor =
controllers, when not moving the motor, will put the motors in a hold =
state with full current applied. This is normal and is done to provide =
maximum hold torque. Most drivers provide a way to adjust the hold =
current levels lower if you don't need that much hold torque.=20
>=20
>=20
>=20
>> The stuttering was due to the thermal protection repeatedly shutting =
it down.
>>=20
>> -- Don
>>=20
>>=20
>> On Thu, Nov 1, 2012 at 4:47 PM, Kelly Murphy <kmurphy...@gmail.com> =
wrote:
>> I was also looking closer at the schmetacics, chip layout and the =
picture of the BED on sparkfun=92s site. It looks like the order of the =
pinout is a, -a, -b, b.
>>=20
>> =20
>>=20
>> From: tcmaker@googlegroups.com [mailto:tcmaker@googlegroups.com] On =
Behalf Of Don French
>> Sent: Thursday, November 01, 2012 4:43 PM
>> To: tcmaker@googlegroups.com
>> Subject: Re: [tcmaker] Stepper motor problem solved
>>=20
>> =20
>>=20
>> Maybe but this thing is supposed to have thermal shut-down =
protection.
>>=20
>>=20
>> -- Don
>>=20
>>=20
>> On Thu, Nov 1, 2012 at 4:15 PM, Kelly Murphy <kmurphy...@gmail.com> =
wrote:
>>=20
>> Just hold on to it until next week and I=92ll get it from you then, I =
should be in on Wed.=20
>>=20
>> =20
>>=20
>> I=92m wondering, based on the heat generated, if the original board =
had a heatstroke and went bad. That 2x2x1/2=94 block of aluminum got =
really hot last night.
>>=20
>> =20
>>=20
>> From: tcmaker@googlegroups.com [mailto:tcmaker@googlegroups.com] On =
Behalf Of Don French
>> Sent: Thursday, November 01, 2012 2:03 PM
>> To: tcmaker@googlegroups.com
>> Subject: [tcmaker] Stepper motor problem solved
>>=20
>> =20
>>=20
>> Last night I was trying to get a stepper motor working with a Big =
Easy Driver board. Three people were there helping, Kelly, Dave =
(Wrdralac?) and Bill Ryder. I only have email addresses for Bill who I =
already wrote to. So to Kelly and Dave, I just wanted to tell you that =
the problem was apparently with the BED although I am not sure WHAT the =
problem is. Anyway, switching to a different board fixed it. Sucker =
still puts out some serious heat though and the heat sink is needed. On =
that subject, Kelly - I absent-mindedly walked off with your block of =
aluminum. Let me know how to best get it back to you. =20
>>=20
>> Sure is sweet watching that baby humming along nice and smooth!
>>=20
>>=20
>> -- Don
>>=20
>> =20
>>=20
>>=20
--Apple-Mail=_6304A832-F085-41A4-9232-3CC5AED0D3BB
Content-Transfer-Encoding: quoted-printable
Content-Type: text/html;
charset=windows-1252
<html><head></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space; =
"><div><br></div><blockquote type=3D"cite"><div dir=3D"auto"><blockquote =
type=3D"cite"><div>The heating problem arose because those motors have =
very low coil resistance and so pull a lot of current - which can =
supposedly be mitigated by turning the current-limiting potentiometer =
down. I haven't tested that theory yet because I switched =
to <a href=3D"https://www.sparkfun.com/products/9238">this =
motor</a> which has 20 times the coil resistance but really =
needs 24V to operate reliably. I would like to find one that runs =
well on 12V and doesn't double as a space =
heater.<br><br></div></blockquote><div>The other thing to look at is =
hold current. Typically, stepper motor controllers, when not =
moving the motor, will put the motors in a hold state with full current =
applied. This is normal and is done to provide maximum hold =
torque. Most drivers provide a way to adjust the hold current =
levels lower if you don't need that much hold =
torque. </div></div></blockquote><div><br></div><div><br></div><Ju=
mping in without much background info><div><br></div><div>If there's =
excessive heat, perhaps the motor is trying to "hold" the position of =
each step, fighting the momentum to turn faster? In the logic =
world, a stepper holds a series of discrete positions. In the =
mechanical world, it is either holding one position stationary, or it is =
moving a smooth linear motion with inertia. The signal to hold a =
position involves fighting momentum to turn beyond the step position, =
which I would expect to appear as =
heat.</div><div><br></div><div>Granted, this would be a detail that =
presumably the steeper driver already has worked out. But if the =
driver is just given a series of pulses, with no velocity information, =
then it has no way of knowing the intended motion, and might have to =
resort to discrete positions.</div><div><br></div><div>Just a =
theory.</div><div><br></div><div>Jeremy</div><div><br><div><br></div><br><=
div><div>On Nov 11, 2012, at 1:12 PM, John Scherer wrote:</div><br =
class=3D"Apple-interchange-newline"><blockquote type=3D"cite"><meta =
http-equiv=3D"content-type" content=3D"text/html; charset=3Dutf-8"><div =
dir=3D"auto"><div><br><br>Sent from my iPhone</div><div><br>On Nov 11, =
2012, at 10:18 AM, Don French <<a =
href=3D"mailto:dcfre...@gmail.com">dcfre...@gmail.com</a>> wrote:<br>
<br></div><blockquote type=3D"cite"><div>Kelly,<br><br>I understand the =
steppers a bit better now and discovered that reversing the connection =
between A and A- or B and B- has only the effect of changing the =
direction the motor turns. Reverse pairs and there is no =
effect. But it has no effect on the heat problem or the stuttering =
of the motor.<br>
<br></div></blockquote><div>Yep, that's =
normal</div><div><br></div><div><br></div><br><blockquote =
type=3D"cite"><div>The heating problem arose because those motors have =
very low coil resistance and so pull a lot of current - which can =
supposedly be mitigated by turning the current-limiting potentiometer =
down. I haven't tested that theory yet because I switched to <a =
href=3D"https://www.sparkfun.com/products/9238">this motor</a> which has =
20 times the coil resistance but really needs 24V to operate =
reliably. I would like to find one that runs well on 12V and =
doesn't double as a space heater.<br>
<br></div></blockquote><div>The other thing to look at is hold current. =
Typically, stepper motor controllers, when not moving the motor, =
will put the motors in a hold state with full current applied. =
This is normal and is done to provide maximum hold torque. =
Most drivers provide a way to adjust the hold current levels lower =
if you don't need that much hold torque. </div>
<div><br></div><div><br></div><br><blockquote type=3D"cite"><div>The =
stuttering was due to the thermal protection repeatedly shutting it =
down.<br><br clear=3D"all">-- Don<br>
<br><br><div class=3D"gmail_quote">On Thu, Nov 1, 2012 at 4:47 PM, Kelly =
Murphy <span dir=3D"ltr"><<a href=3D"mailto:kmurphy...@gmail.com" =
target=3D"_blank">kmurphy...@gmail.com</a>></span> =
wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 =
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div link=3D"blue" vlink=3D"purple" lang=3D"EN-US"><div><p =
class=3D"MsoNormal"><span =
style=3D"font-size:11.0pt;font-family:"Calibri","sans-serif=
";color:#1f497d">I was also looking closer at the schmetacics, chip =
layout and the picture of the BED on sparkfun=92s site. It looks =
like the order of the pinout is a, -a, -b, b. =
<u></u><u></u></span></p><p class=3D"MsoNormal"><span =
style=3D"font-size:11.0pt;font-family:"Calibri","sans-serif=
";color:#1f497d"><u></u> <u></u></span></p><p =
class=3D"MsoNormal"><b><span =
style=3D"font-size:11.0pt;font-family:"Calibri","sans-serif=
"">From:</span></b><span =
style=3D"font-size:11.0pt;font-family:"Calibri","sans-serif=
""> <a href=3D"mailto:tcmaker@googlegroups.com" =
target=3D"_blank">tcmaker@googlegroups.com</a> [mailto:<a =
href=3D"mailto:tcmaker@googlegroups.com" =
target=3D"_blank">tcmaker@googlegroups.com</a>] <b>On Behalf Of </b>Don =
French<br>
<b>Sent:</b> Thursday, November 01, 2012 4:43 PM<br><b>To:</b> <a =
href=3D"mailto:tcmaker@googlegroups.com" =
target=3D"_blank">tcmaker@googlegroups.com</a><br><b>Subject:</b> Re: =
[tcmaker] Stepper motor problem solved<u></u><u></u></span></p>
<div><div class=3D"h5"><p class=3D"MsoNormal"><u></u> <u></u></p><p =
class=3D"MsoNormal">Maybe but this thing is supposed to have thermal =
shut-down protection.<u></u><u></u></p><div><p class=3D"MsoNormal" =
style=3D"margin-bottom:12.0pt">
<br clear=3D"all">-- Don<br><br><u></u><u></u></p><div><p =
class=3D"MsoNormal">On Thu, Nov 1, 2012 at 4:15 PM, Kelly Murphy <<a =
href=3D"mailto:kmurphy...@gmail.com" =
target=3D"_blank">kmurphy...@gmail.com</a>> wrote:<u></u><u></u></p>
<blockquote style=3D"border:none;border-left:solid #cccccc =
1.0pt;padding:0in 0in 0in =
6.0pt;margin-left:4.8pt;margin-right:0in"><div><div><p =
class=3D"MsoNormal"><span =
style=3D"font-size:11.0pt;font-family:"Calibri","sans-serif=
";color:#1f497d">Just hold on to it until next week and I=92ll get =
it from you then, I should be in on Wed. =
</span><u></u><u></u></p><p class=3D"MsoNormal"><span =
style=3D"font-size:11.0pt;font-family:"Calibri","sans-serif=
";color:#1f497d"> </span><u></u><u></u></p><p =
class=3D"MsoNormal"><span =
style=3D"font-size:11.0pt;font-family:"Calibri","sans-serif=
";color:#1f497d">I=92m wondering, based on the heat generated, if =
the original board had a heatstroke and went bad. That 2x2x1/2=94 =
block of aluminum got really hot last night.</span><u></u><u></u></p><p =
class=3D"MsoNormal"><span =
style=3D"font-size:11.0pt;font-family:"Calibri","sans-serif=
";color:#1f497d"> </span><u></u><u></u></p><p =
class=3D"MsoNormal"><b><span =
style=3D"font-size:11.0pt;font-family:"Calibri","sans-serif=
"">From:</span></b><span =
style=3D"font-size:11.0pt;font-family:"Calibri","sans-serif=
""> <a href=3D"mailto:tcmaker@googlegroups.com" =
target=3D"_blank">tcmaker@googlegroups.com</a> [mailto:<a =
href=3D"mailto:tcmaker@googlegroups.com" =
target=3D"_blank">tcmaker@googlegroups.com</a>] <b>On Behalf Of </b>Don =
French<br>
<b>Sent:</b> Thursday, November 01, 2012 2:03 PM<br><b>To:</b> <a =
href=3D"mailto:tcmaker@googlegroups.com" =
target=3D"_blank">tcmaker@googlegroups.com</a><br><b>Subject:</b> =
[tcmaker] Stepper motor problem solved</span><u></u><u></u></p>
<div><p class=3D"MsoNormal"> <u></u><u></u></p><p =
class=3D"MsoNormal">Last night I was trying to get a stepper motor =
working with a Big Easy Driver board. Three people were there =
helping, Kelly, Dave (Wrdralac?) and Bill Ryder. I only have email =
addresses for Bill who I already wrote to. So to Kelly and Dave, I =
just wanted to tell you that the problem was apparently with the BED =
although I am not sure WHAT the problem is. Anyway, switching to a =
different board fixed it. Sucker still puts out some serious heat =
though and the heat sink is needed. On that subject, Kelly - I =
absent-mindedly walked off with your block of aluminum. Let me =
know how to best get it back to you. <br>
<br>Sure is sweet watching that baby humming along nice and =
smooth!<br><br><br clear=3D"all">-- =
Don<u></u><u></u></p></div></div></div></blockquote></div><p =
class=3D"MsoNormal"><u></u> <u></u></p></div></div></div></div></div>=
</blockquote></div><br>
</div></blockquote></div>
</blockquote></div><br></div></body></html>=
--Apple-Mail=_6304A832-F085-41A4-9232-3CC5AED0D3BB--
Message from discussion Stepper motor problem solved
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