On Wednesday 15 July 2020 08:29:55 Gene Heskett wrote:
> On Wednesday 15 July 2020 07:40:50 Gene Heskett wrote:
> > On Wednesday 15 July 2020 00:58:43 Gregg Eshelman via Emc-users
wrote:
> > > There are sine wave controllers that do various smoothing things
> > > to run steppers smooth and
On Wednesday 15 July 2020 07:40:50 Gene Heskett wrote:
> On Wednesday 15 July 2020 00:58:43 Gregg Eshelman via Emc-users wrote:
> > There are sine wave controllers that do various smoothing things to
> > run steppers smooth and silent. Trinamic calls it Spread Cycle and
> > Stealth Chop.
On Wednesday 15 July 2020 00:58:43 Gregg Eshelman via Emc-users wrote:
> There are sine wave controllers that do various smoothing things to
> run steppers smooth and silent. Trinamic calls it Spread Cycle and
> Stealth Chop. https://www.youtube.com/watch?v=Q0sJlGh9WNY On Tuesday,
> July 14,
There are sine wave controllers that do various smoothing things to run
steppers smooth and silent. Trinamic calls it Spread Cycle and Stealth Chop.
https://www.youtube.com/watch?v=Q0sJlGh9WNY
On Tuesday, July 14, 2020, 11:18:22 AM MDT, Todd Zuercher
wrote:
If you can hear it, it
This person makes basically comedy videos with one totally impossible robot
after another. The "robots" are props. He does not try to be serious. I
suspect the kid is the actor and others make the props. The background
sets are built and the lighting is certainly not what is found in a home
Hi Chris,
On 7/14/20 12:10 PM, Chris Albertson wrote:
On Tue, Jul 14, 2020 at 10:50 AM John Dammeyer
wrote:
https://youtu.be/tlMTksuOuZQ
Were you using LinuxCNC for this? Or did you write your own control
software?
This was done with Linux CNC. However, The purpose of me owning a mill
On 7/14/20 11:48 AM, John Dammeyer wrote:
-Original Message-
From: Chris Albertson [mailto:albertson.ch...@gmail.com]
Sent: July-14-20 2:49 AM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] off topic: pwm with a stepper driver/motor
Gene is correct when he wrote
On 07/14/2020 01:51 PM, andy pugh wrote:
On Fri, 10 Jul 2020 at 10:34, andy pugh wrote:
I don't see why there is any limit to the possible reduction of a belt
drive, if idlers are added to increase the wrap.
And here is an example:
https://youtu.be/7zBrbdU_y0s
OH MY! Some people REALLY
On Fri, 10 Jul 2020 at 10:34, andy pugh wrote:
> I don't see why there is any limit to the possible reduction of a belt
> drive, if idlers are added to increase the wrap.
And here is an example:
https://youtu.be/7zBrbdU_y0s
--
atp
"A motorcycle is a bicycle with a pandemonium attachment and
On Tue, Jul 14, 2020 at 10:50 AM John Dammeyer
wrote:
>
> > https://youtu.be/tlMTksuOuZQ
> >
> Were you using LinuxCNC for this? Or did you write your own control
> software?
>
This was done with Linux CNC. However, The purpose of me owning a mill is
for robotics. I have not yet figured how
> -Original Message-
> From: Chris Albertson [mailto:albertson.ch...@gmail.com]
> Sent: July-14-20 2:49 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] off topic: pwm with a stepper driver/motor
>
> Gene is correct when he wrote the precis
, July 14, 2020 9:39 AM
To: emc-users@lists.sourceforge.net
Subject: Re: [Emc-users] off topic: pwm with a stepper driver/motor
[EXTERNAL EMAIL] Be sure links are safe.
Hi Chris,
for the go to part I am not "too worried"about that possibly not being too
smooth, of course it is the
On 07/14/2020 04:49 AM, Chris Albertson wrote:
But what I wanted to add is that when you read the speed vs. torque curve
it is for FULL steps. The amount of holding torque is reduced with
microsteps. It makes sense too, full steps use full current that is
switched between coils just 100% on
Hi Chris,
for the go to part I am not "too worried"about that possibly not being
too smooth, of course it is the goal to do that, but
the point there is to get there.
The equatorial tracking indeed needs to be as smooth as possible. With
the hearing I have I think I can run the stepper
Gene is correct when he wrote the precision might be off when
micro-stepping.
Motors are mechanically built for 1.8 degree steps so that is likely to be
accurate but half steps depend on the driver.
But what I wanted to add is that when you read the speed vs. torque curve
it is for FULL steps.
Hello Gene,
On 7/14/20 12:49 AM, Gene Heskett wrote:
On Monday 13 July 2020 22:44:37 R C wrote:
well, I can calculate what the speed needs to be, also I can actually
"observe" it too.. by pointing the telescope at a star and see how
much the deviation is. I have encoder to check the
Hello Chris,
On 7/14/20 12:31 AM, Chris Albertson wrote:
On Mon, Jul 13, 2020 at 7:28 PM R C wrote:
Interesting,
but I already have the motors, and the gears are on their way. What
I was really looking for is how to drive the stepper-drivers, he DM542
series ones.
Do you have the
On Monday 13 July 2020 22:44:37 R C wrote:
> well, I can calculate what the speed needs to be, also I can actually
> "observe" it too.. by pointing the telescope at a star and see how
> much the deviation is. I have encoder to check the actual speed of a
> shaft.
>
> I found some information
On Mon, Jul 13, 2020 at 7:28 PM R C wrote:
> Interesting,
>
>
> but I already have the motors, and the gears are on their way. What
> I was really looking for is how to drive the stepper-drivers, he DM542
> series ones.
>
Do you have the user manual for the DM542? If not look at the top
yup exactly, actually in a way so I can point at things that you can't
really see but would need longer exposures for.
On 7/13/20 9:28 PM, Chris Albertson wrote:
On Mon, Jul 13, 2020 at 8:02 PM Dave Matthews wrote:
It may just be my age but wouldn't it be easier to just use a 555 (do
yeah that would be easiest, but I want to do something similar for
azimuth and altitude.
On 7/13/20 9:00 PM, Dave Matthews wrote:
It may just be my age but wouldn't it be easier to just use a 555 (do they
still make them) and a knob to tweak the pulse rate to match the star? Add
a slew
On Mon, Jul 13, 2020 at 8:02 PM Dave Matthews wrote:
> It may just be my age but wouldn't it be easier to just use a 555 (do they
> still make them) and a knob to tweak the pulse rate to match the star?
That would be easy but I think there is some plan to have a "go to"
ability where the
It may just be my age but wouldn't it be easier to just use a 555 (do they
still make them) and a knob to tweak the pulse rate to match the star? Add
a slew button to change the speed while the button is pushed and a
direction switch to toggle the direction pin on the driver. I guess I
don't see
well, I can calculate what the speed needs to be, also I can actually
"observe" it too.. by pointing the telescope at a star and see how
much the deviation is. I have encoder to check the actual speed of a shaft.
I found some information in a manual/tech-sheet that comes with the
drivers,
A fast control loop that drives each motor at a given speed and a second
slower control loop that figures out what that speed should be. The
second loop typically uses "PID" even if only in fact the "P" is used.
That can be used to drive any number of motors all at their correct speeds.
On
Interesting,
but I already have the motors, and the gears are on their way. What
I was really looking for is how to drive the stepper-drivers, he DM542
series ones.
Ron
On 7/13/20 7:53 PM, cogoman via Emc-users wrote:
I recently discovered geared stepper motors.
I recently discovered geared stepper motors.
http://www.zyltech.com/nema-17-stepper-motor-geared-planetary-gearbox-1-7-a-3-1-nm-435-ozin/
I've been happy with zyltech in the past. I bought one of these for
evluation, but the specs seem to be great for CNC. Low enough current to
work with a
. that is easy to do
-Original Message-
From: Chris Albertson [mailto:albertson.ch...@gmail.com]
Sent: Friday, July 10, 2020 10:14 PM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] off topic: pwm with a stepper driver/motor
Stepper motors are good for this. A stepper
[mailto:cjv...@gmail.com]
Sent: Friday, July 10, 2020 10:05 PM
To: emc-users@lists.sourceforge.net
Subject: Re: [Emc-users] off topic: pwm with a stepper driver/motor
yep.. true.. but it is also knd of what I do for a living...
I think it can be done, to build an equatorial platform
On 7/10/20 8:13 PM, Chris Albertson wrote:
Stepper motors are good for this. A stepper has the most torque at zero
RPM and the torque falls as speed increases while a DC brushed motor has
very little power when moving slowly. You need more gearing with the DC
motor.
that is exactly right,
On Friday 10 July 2020 22:26:12 Ken Strauss wrote:
> "You need more gearing with the DC motor." Correct and this could be
> considered an advantage since a very small DC motor + gearing
> (multiple planetary stages) would have sufficient torque to move the
> scope. I have no idea if a RPI can
Chris Albertson [mailto:albertson.ch...@gmail.com]
> Sent: Friday, July 10, 2020 10:14 PM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] off topic: pwm with a stepper driver/motor
>
> Stepper motors are good for this. A stepper has the most torque at zero
>
units? See
https://www.teknic.com/
> -Original Message-
> From: R C [mailto:cjv...@gmail.com]
> Sent: Friday, July 10, 2020 10:05 PM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] off topic: pwm with a stepper driver/motor
>
> yep.. true.. but it is
Stepper motors are good for this. A stepper has the most torque at zero
RPM and the torque falls as speed increases while a DC brushed motor has
very little power when moving slowly. You need more gearing with the DC
motor.
The problem is you need to generate precise pulses. If the pulse
et
Subject: Re: [Emc-users] off topic: pwm with a stepper driver/motor
I don't think anyone did, but I know that's how most do it...
But that's just too easy :)I would just like to see if I can do it,
killing time
On 7/10/20 7:39 PM, Ken Strauss wrote:
I haven't been following this close
R C [mailto:cjv...@gmail.com]
> Sent: Friday, July 10, 2020 9:43 PM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] off topic: pwm with a stepper driver/motor
>
> I don't think anyone did, but I know that's how most do it...
>
> But that's just too easy :)
I don't think anyone did, but I know that's how most do it...
But that's just too easy :) I would just like to see if I can do it,
killing time
On 7/10/20 7:39 PM, Ken Strauss wrote:
I haven't been following this closely but has anyone suggested that you use a
DC motor with an encoder?
I haven't been following this closely but has anyone suggested that you use a
DC motor with an encoder? With a PID loop and PWM power to the motor you could
run the motor continuously. DC motors with integrated encoder and planetary
gearbox are readily available for a few dollars. Just a
from what I understand, worm gears work really well and because of the
reduction, the motor needs to sping at a decent rpm, it doesn't have
tospin that slow. I am using steppers, because it is easy to count the
steps and then calibrate because of how much you're drifting.While with
a regular
On 7/10/20 1:12 PM, Chris Albertson wrote:
On Fri, Jul 10, 2020 at 10:33 AM andy pugh wrote:
Sprockets for T2.5 belts are available with 10 teeth, so that would be
a 2.3m table for the 300:1. Which is also probably too big. I suppose
that the design criterion is that one stepper step should
On Fri, 10 Jul 2020 at 20:14, Chris Albertson wrote:
> You need to move at 1/2 the resolution otherwise you can see the steps. So
> let's say each step would be 1/4 arc-second
I was going with one step per thingy, and then assuming microstepping
to get sub-thingy :-)
I will just mention:
On Fri, Jul 10, 2020 at 10:33 AM andy pugh wrote:
>
> Sprockets for T2.5 belts are available with 10 teeth, so that would be
> a 2.3m table for the 300:1. Which is also probably too big. I suppose
> that the design criterion is that one stepper step should be less than
> the angular resolution
On Fri, 10 Jul 2020 at 17:59, Chris Albertson wrote:
> There is also a minimum amount number of degrees of contact required with
> the small pulley. The pulley must be far enough away so the minimum number
> of teeth are engaged.
Or you can use idlers to modify the belt shape. This is done
Yes in theory one could design a 300:1 belt reduction in one stage. But
according to the belt manufacturer, you do need to have a minimum number of
belt teeth engaged. I think about 11 teeth. If only 180 degrees of the
small pulley is engaged with the belt then the minim pulley size is 22.
So
I had a friend that had a motorised telescope.
It had a DC motor, with a very high reduction ratio. I think one would see
fluctuations with a stepper motor.
Also, I wouldn't use a belt at all. Drive a smooth roller and use a
friction drive against a large disc. This also allows you to manually
On Friday 10 July 2020 05:34:58 andy pugh wrote:
> On Fri, 10 Jul 2020 at 02:00, Chris Albertson
wrote:
> > Belts can go to about 6:1 at best a double belt reduction only goes
> > to 36:1
>
> I don't see why there is any limit to the possible reduction of a belt
> drive, if idlers are added to
On Fri, 10 Jul 2020 at 02:00, Chris Albertson wrote:
> Belts can go to about 6:1 at best a double belt reduction only goes to 36:1
I don't see why there is any limit to the possible reduction of a belt
drive, if idlers are added to increase the wrap.
If I was doing this (and this particular
How to generate pulse at the exact rate you need...
First make a loop that runs as fast as you can make it run. The first
thing it does is "sleep" for a hundred or so microseconds. Then it checks
the time of day and to see if it is time yet to do the next pulse. If not
it fall to the end of
Stepper motors are called that because they move in steps. Usually they have
two coils. Both coils are powered when the motor is powered on, and this is
what holds the motor in position. Reversing the current to one of these coils
will advance the motor to the next step. The direction the motor
On 7/9/20 6:47 PM, Chris Albertson wrote:
OK, got it a "Dob, on a Ea, platform and the platform on an Az, El mount.
Yup.
Again PWM is "Pisle Width Modulation" Steppers and stepper drivers don't
use PWM. They use what we cal "Pulse/Direction"
I didn't know that, I read the product
On Thursday 09 July 2020 20:32:42 Gene Heskett wrote:
> > > Steppers aren't pwm driven, so ignore that. But a 48 volt supply
> > > is pushing the ratings of a DM542 which is 50 volts max, and you
> > > would be wise to adjust it a few volts lower. I have a pair of 7.5
> > > amp 48 volt supplies
Gene,
Belts are a good idea for the Ax and El axis but in the Eq axis he needs
something on the order of 100:1 reduction
The time tested traditional method is a synchronous AC moter and a VFD that
can do 60 Hz +/- about 5 percent. This axis turns only 1 rev per day but
the step need to be less
OK, got it a "Dob, on a Ea, platform and the platform on an Az, El mount.
Again PWM is "Pisle Width Modulation" Steppers and stepper drivers don't
use PWM. They use what we cal "Pulse/Direction"
PWM uses a constant square wave rate like that is always between 60 Hz and
maybe up to 1,000 Hz.
On Thursday 09 July 2020 19:05:45 R C wrote:
> Hello Gene,
>
>
> To start with the end of your reply, I actually am a mathematician
> :)
>
> On 7/9/20 4:24 PM, Gene Heskett wrote:
> > On Thursday 09 July 2020 14:23:57 R C wrote:
> >> Hello,
> >>
> >> this is (probably) off topic, been seen that
I am not using linux cnc, I am just 'driving' the stepper drivers
with a raspberry pi
I figured, same hardware (drivers, motors), "Linux CNC" can use it, so
thought I'd just ask here about the internals/specifics and how to use it.
On 7/9/20 1:44 PM, andy pugh wrote:
On Thu, 9 Jul
Hello Gene,
To start with the end of your reply, I actually am a mathematician :)
On 7/9/20 4:24 PM, Gene Heskett wrote:
On Thursday 09 July 2020 14:23:57 R C wrote:
Hello,
this is (probably) off topic, been seen that happen. If it is please
ignore it.
I am building a "motorized"
On 7/9/20 1:44 PM, andy pugh wrote:
On Thu, 9 Jul 2020 at 19:26, R C wrote:
The stepper motors I use with a stepper driver, those common DM542 ones,
the stepper motors themselves are 2A and 1.8 degrees per step.
...
As with PWM itself, I am probably just not too familiar with it.
Do you
On Thursday 09 July 2020 14:23:57 R C wrote:
> Hello,
>
> this is (probably) off topic, been seen that happen. If it is please
> ignore it.
>
>
> I am building a "motorized" telescope mount (dobsonian) with what is
> called an equatorial platform, it has 3 axis which I am going to drive
> with
there will be worm gears, and those will just gear all the axis/axes
down down.
On 7/9/20 1:23 PM, Chris Albertson wrote:
Telescopes are something I know a little about, What you don't tell us and
what matters quite a lot is the mechanical gearing. How are the
motors connected to the mount?
On Thu, Jul 9, 2020 at 12:47 PM andy pugh wrote:
> On Thu, 9 Jul 2020 at 19:26, R C wrote:
>
> > The stepper motors I use with a stepper driver, those common DM542 ones,
> > the stepper motors themselves are 2A and 1.8 degrees per step.
> ...
> > As with PWM itself, I am probably just not too
On Thu, 9 Jul 2020 at 19:26, R C wrote:
> The stepper motors I use with a stepper driver, those common DM542 ones,
> the stepper motors themselves are 2A and 1.8 degrees per step.
...
> As with PWM itself, I am probably just not too familiar with it.
Do you mean PWM?
Stepper drivers take step
Telescopes are something I know a little about, What you don't tell us and
what matters quite a lot is the mechanical gearing. How are the
motors connected to the mount?
If this is an equatorial mount what are there three motors? and why care
much about if declination moves smoothing as it is
Hello,
this is (probably) off topic, been seen that happen. If it is please
ignore it.
I am building a "motorized" telescope mount (dobsonian) with what is
called an equatorial platform, it has 3 axis which I am going to drive
with stepper motors.
The stepper motors I use with a
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