[Emc-users] Zeromq, as there have been discussions

[Nicklas SB Karlsson]

As there have been some discussions about zeromq information about the 
protocol may be interesting https://rfc.zeromq.org/



This information is also interesting. "In 2011, CERN 
 was investigating ways to unify 
middleware solutions used to operate CERN accelerators." 
https://en.wikipedia.org/wiki/ZeroMQ and 
https://indico.cern.ch/event/354137/contributions/1763290/subcontributions/153483/attachments/701686/963362/ZeroMQ-tCSC-Aram.pdf 
which make me believe zeromq is a very good choice provided it is 
suitable for the kind of communication it is used for in Linuxcnc which 
I guess it is.



As have been pointed out many times before it have already been 
implemented in Machinekit which if I get it correct is a fork of an 
older version. Have no time to spend on it myself except possible 
reading some details about the protocols at least for months.



Nicklas Karlsson



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Re: [Emc-users] [Emc-developers] chart of arrays

[Nicklas SB Karlsson]

Den 2021-05-02 kl. 03:06, skrev Jon Elson:

On 05/01/2021 12:35 AM, Nicklas SB Karlsson wrote:

Den 2021-05-01 kl. 04:52, skrev Jon Elson:

NML may send via TCP/IP if configured to, got more time then I was 
unemployed and have been looking into the configuration file and at 
least once tried. ZeroMQ may also among methods send via TCP/IP, 
reading fast they do not say anything about the protocol used then 
sending data.


My understanding is that NML has no understanding of the hierarchy of 
the structures inside the shared memory area.  So, as written, it can 
only have the WHOLE shared memory across the net.


Zero mq's sole purpose is to break up the sub-structures so that 
clients can subscribe to specific structures that they need, and then 
ONLY that structure is sent to that node.


Jon


I did not have any idea which waw better, guessed Zermq but did not find 
anything about the protocol and nml already there.



Searching for more information however found something interesting. "In 
2011, CERN  was investigating ways 
to unify middleware solutions used to operate CERN accelerators." 
https://en.wikipedia.org/wiki/ZeroMQ and 
https://indico.cern.ch/event/354137/contributions/1763290/subcontributions/153483/attachments/701686/963362/ZeroMQ-tCSC-Aram.pdf 
which make me believe zeromq is a very good choice provided it is 
suitable for the kind of communication it is used for in Linuxcnc which 
I guess it is.



Do not have any time to spend on implementing it myself at least for months.


Nicklas Karlsson


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Re: [Emc-users] Maybe a minimally printed harmonic drive?

[Gene Heskett]

On Saturday 01 May 2021 12:34:01 Chris Albertson wrote:

> Gene,
>
> I did a search on the part number to gave and, they look really good
> but cost $400 per axis vs about $60 for what I have.   Yes, they are
> much better.Did you find a better deal?
>
Egad, where are you looking? 6 months ago I bought 4 of them in two 
orders thru ebay, 3 3NM's and a 2NM, and paid about $130 USD per axis.



85$ copy, but $45 shipping.  So $130/axis, discounts for 3 or more.

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] Maybe a minimally printed harmonic drive?

[Gene Heskett]

On Saturday 01 May 2021 12:25:12 Kenneth Lerman wrote:

> Has anyone tried using polypropylene  for the flex component? I
> believe PP is used for live hinges.
>
If refering to whats commony called TPU, yes, abject failure as its too 
flexible and just folds up.  Its good for those squeeze it coin purses 
though, and I may make some bigger ones to see if they'll sell as the 
one I have in my pocket is bursting with less than 2 dollars in small 
change in it.

> Ken
> Kenneth Lerman
> 55 Main Street
> Newtown, CT 06470
>
> On Fri, Apr 30, 2021 at 11:26 PM  wrote:
> > I haven't been following your project recently but am intrigued by
> > "And it turns the armature easy enough the 3NM 3 phase motor (those
> > are magic folks,
> > running 50C cooler than 2 phase stuff) I'll use will not be a bit
> > overstressed." Where did you end up getting your motors and what are
> > you using for drivers?
> >
> > -Original Message-
> > From: Gene Heskett 
> > Sent: April 30, 2021 10:45 PM
> > To: emc-users@lists.sourceforge.net
> > Subject: Re: [Emc-users] Maybe a minimally printed harmonic drive?
> >
> > On Monday 22 March 2021 09:19:19 Sam Sokolik wrote:
> > > 202,200 for the outside spline and the flex gear is 200.  In this
> > > situation - the 202 tooth spline is stationary to the stepper. 
> > > The 200 tooth outside spline is mounted to the faceplate.  In this
> > > layout - the ratio apears to be 101:1
> > >
> > > In this situation the stepper motor and the face plate spin the
> > > same direction.
> > >
> > > With the same set of outside spines swapped - the ratio is 100:1
> > >
> > > I am sure Andy can explain it.  It doesn't make sense to me.
> > >
> > > Happy with runout...  https://www.youtube.com/watch?v=eLyP2YwdstQ
> > >
> > > sam
> >
> > I am running some behind you Sam, with my project, having printer
> > problems kills time and money. Finally settled on an ender 5 Plus,
> > which is working passably well but I've wasted $3k getting there.
> >
> > Any way, I changed the design some from yours, to a 30/1 because
> > those big spines print better, and by making my own bearings in
> > openscad, useing crosman bb's for balls. I put a huge one with over
> > 150 loose bb's directly on the outside of the moving spline, with
> > only the lip of the output coupling disc (printed of course)
> > interposed. And the floating spline has 3 more of those, sized for a
> > good friction fit inside that spline, with both the spline and the
> > bearings made as thin as practical to improve the flex life, and I
> > just took the eliptical armature off the build plate and wiggled
> > in into those 3 bearings inside the loose spline, so thats the
> > driver armature, no commercial ball bearings anyplace like yours. 
> > I've made the 8mm hole in the plastic for the motor shaft into a
> > prominent D-flat, and used a cbn wheel to make the flat much wider
> > on the motor shaft, and this armature will be driven onto the motor
> > shaft without any grub screws at all.
> > No clue how long it will run before it bores that hole out and I
> > have to make an alu inner for it. :(
> >
> > But I just now assembled it without the motor, turning the armature
> > by hand,
> > and it works, with no detectable backlash. And it turns the armature
> > easy enough the 3NM 3 phase motor (those are magic folks, running
> > 50C cooler than
> > 2 phase stuff) I'll use will not be a bit overstressed.  Those bb's
> > will pound the plastic smooth and get smoother with use.
> >
> > So now its time to finish the output shaft, and make the rest of the
> > housing. Which will be supported by the big bearing at the spline
> > end, and 4
> > of the printed bearings at the load end. I've got the motor end
> > gnawed out of some 1" stock I had, and I bought a foot of 3.125"
> > thick by 6" wide stuff
> > so I can make 2 output housings. That showed me the current price
> > for extruded alu, scary. I also bought enough rod to make about 4
> > output shafts,
> > over $200. And I've a spare 4" chuck from a TLM upgrade to a 5" to
> > use on it. Or better yet, buy another 5" from LMS.
> > So I'll get there, if I don't fall over first. At my age, thats
> > always a possibility.
> >
> > I'll try to get some pix of what I've got so far, put up on my web
> > page over
> > the weekend. Along with some of the openscad source files.
> >
> > As usual, this stuff keeps me alone, safe, and out of the bars. :-)
> >
> > Cheers, Gene Heskett
> > --
> > "There are four boxes to be used in defense of liberty:
> >  soap, ballot, jury, and ammo. Please use in that order."
> > -Ed Howdershelt (Author)
> > If we desire respect for the law, we must first make the law
> > respectable. - Louis D. Brandeis
> > Genes Web page 
> >
> >
> > ___
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> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
> >
> >
> > _

Re: [Emc-users] Maybe a minimally printed harmonic drive?

[andrew beck]

John.  I love the Chinese servos too.

And totally agree going direct to manafacture is much better.

I buy my servos with absolute encoders now.

130 ppr I think.  Or might be 13.

Just a basic 750w servo 220v servo drive plus motor costs me about $220 usd
last I checked.  (this is with just standard 2500ppr encoders)

I normally buy bigger ones like 3kw

Absolute encoders are a extra 50usd


And service is amazing.

Case in point I was setting up some kollmorgen servo star drives last
week.  Support was nothing like as good as the Chinese support lol.  (they
will do anything to help)

I'm thinking I Might bring in a pallet load to New Zealand and sell them
here as shipping by air is so expensive.

On Sun, 2 May 2021, 5:09 AM John Dammeyer,  wrote:

> > From: Chris Albertson [mailto:albertson.ch...@gmail.com]
> > To: Enhanced Machine Controller (EMC)
> > Gene,
> >
> > I did a search on the part number to gave and, they look really good but
> > cost $400 per axis vs about $60 for what I have.   Yes, they are much
> > better.Did you find a better deal?
> >
> > Question for the group:
> > Assuming that you need about 3NM holding torque, what will $400 get you
> if
> > you want to use a servo motor?   I'm thinking that these 3-phase closed
> > loop steppers are more comparable in performance and price to servos than
> > to cheap steppers.   Anyone have a link to a source of small-size Chinese
> > servos and matching drivers.
> >
>
> 
> Yes.  I've been raving about the Bergerda series of AC Servos for a year
> now.  I have a 1.8kW running the mill spindle and a 750W (2.39NM) running
> the knee (19mm shaft size) which cost just under $300.
> http://en.bergerda.com/
>
> I also cast a mount and tried one of the 400W (1.25NM) units on the X axis
> and it was flawless too.  But at the moment my cabinet won't fit the drives
> compared to the DC Servo HP_UHU drives and I didn't want to swerve in
> another direction until the mill was completely converted. When I change to
> ball screws I'll also replace the two DC Brushed motors which are huge in
> comparative size to the AC servos.
>
> They come in various flavours and sizes (ie frame/rpm/torque/shaft size)
> and all run on 220VAC.  Pricing out from
> https://www.automationtechnologiesinc.com/products-page/ac-servo-motors
>
> the same DC brushed servo setup that I have comes out way more expensive
> than the AC servos when you add the driver and encoder and cable and DC
> power supply with one caveat.
>
> https://www.automationtechnologiesinc.com/products-page/dc-servo-motor/nema34-1125ozin-dual-shaft-servo-motor
>
> Shipping.  Bergerda is not a aliexpress reseller but the actual
> manufacturer so payments go through Alibaba and they won't do slow mail
> deliver.  Must be FedEx tracked therefore one motor can be very expensive.
> A big enough order could be done surface for considerable savings.
>
> I've been trying to connect them up with a North American supplier but so
> far no luck.
>
> Anyway, I bought extra 400W units for the eventual conversion to ball
> screws and one to replace the stepper on the lathe.   The drives all run on
> 220VAC which can be an issue if you only have 110VAC available.
>
> Now why servos instead of close loop steppers?  First the steppers still
> can stall at higher RPM so like standard steppers they are oriented to
> direct drive and slower rpm which means no torque multiplication with
> reduction belt drive. That generally means using a larger motor but they
> are definitely stable.  I used a CANopen commercial unit a while back that
> was impressive although eventually we upgraded to a German J1939 controlled
> AC Servo.
>
> The biggest downside other than rpm is they are still stepper motors and
> noisy whereas the AC Servos are quiet.  Dead quiet.   And support has been
> excellent with one of their engineers even making an iPhone video of the
> button press sequences of the display to set up some parameters when I was
> having trouble.
>
> Oh one other thing that I did verify.  Most of the cheap Aliexpress AC
> servos out there use cheap encoders.  Bergerda made a point of mentioning
> the use high end Japanese encoders.  So I took the cover off the end of the
> motor and grabbed the part number and name.  Yes indeed.  Japanese
> manufacturer and in singles through Alibaba came in at 3x the price of the
> cheap Aliexpress encoders.   So with cheap you get what you pay for I guess.
>
> 
>
> John Dammeyer
>
>
> > Next idea...
> > I looked up Gene's part and the motor/controler is sold as a set.  I can
> > see why.   But I see I can buy a 3-phase stepper motor for about $100.
>  So
> > we pay quite a lot for the driver and encoder.   I can buy a 1000 line
> > encoder for under $20 and close the loop with a $4 microcontroller and
> > three h-bridges.  I've done this many times using DC brushed gear motors.
> >  (My use case is robotics but it's identical to a multi-axis mill.)
> >
> > On Sat, May 1, 2021 at 6:30 AM Gene 

Re: [Emc-users] Maybe a minimally printed harmonic drive?

[Kenneth Lerman]

Has anyone tried using polypropylene  for the flex component? I believe PP
is used for live hinges.

Ken
Kenneth Lerman
55 Main Street
Newtown, CT 06470



On Fri, Apr 30, 2021 at 11:26 PM  wrote:

> I haven't been following your project recently but am intrigued by "And it
> turns the armature easy enough the 3NM 3 phase motor (those are magic
> folks,
> running 50C cooler than 2 phase stuff) I'll use will not be a bit
> overstressed." Where did you end up getting your motors and what are you
> using for drivers?
>
> -Original Message-
> From: Gene Heskett 
> Sent: April 30, 2021 10:45 PM
> To: emc-users@lists.sourceforge.net
> Subject: Re: [Emc-users] Maybe a minimally printed harmonic drive?
>
> On Monday 22 March 2021 09:19:19 Sam Sokolik wrote:
>
> > 202,200 for the outside spline and the flex gear is 200.  In this
> > situation - the 202 tooth spline is stationary to the stepper.  The
> > 200 tooth outside spline is mounted to the faceplate.  In this layout
> > - the ratio apears to be 101:1
> >
> > In this situation the stepper motor and the face plate spin the same
> > direction.
> >
> > With the same set of outside spines swapped - the ratio is 100:1
> >
> > I am sure Andy can explain it.  It doesn't make sense to me.
> >
> > Happy with runout...  https://www.youtube.com/watch?v=eLyP2YwdstQ
> >
> > sam
> I am running some behind you Sam, with my project, having printer problems
> kills time and money. Finally settled on an ender 5 Plus, which is working
> passably well but I've wasted $3k getting there.
>
> Any way, I changed the design some from yours, to a 30/1 because those big
> spines print better, and by making my own bearings in openscad, useing
> crosman bb's for balls. I put a huge one with over 150 loose bb's directly
> on the outside of the moving spline, with only the lip of the output
> coupling disc (printed of course) interposed. And the floating spline has 3
> more of those, sized for a good friction fit inside that spline, with both
> the spline and the bearings made as thin as practical to improve the flex
> life, and I just took the eliptical armature off the build plate and
> wiggled
> in into those 3 bearings inside the loose spline, so thats the driver
> armature, no commercial ball bearings anyplace like yours.  I've made the
> 8mm hole in the plastic for the motor shaft into a prominent D-flat, and
> used a cbn wheel to make the flat much wider on the motor shaft, and this
> armature will be driven onto the motor shaft without any grub screws at
> all.
> No clue how long it will run before it bores that hole out and I have to
> make an alu inner for it. :(
>
> But I just now assembled it without the motor, turning the armature by
> hand,
> and it works, with no detectable backlash. And it turns the armature easy
> enough the 3NM 3 phase motor (those are magic folks, running 50C cooler
> than
> 2 phase stuff) I'll use will not be a bit overstressed.  Those bb's will
> pound the plastic smooth and get smoother with use.
>
> So now its time to finish the output shaft, and make the rest of the
> housing. Which will be supported by the big bearing at the spline end, and
> 4
> of the printed bearings at the load end. I've got the motor end gnawed out
> of some 1" stock I had, and I bought a foot of 3.125" thick by 6" wide
> stuff
> so I can make 2 output housings. That showed me the current price for
> extruded alu, scary. I also bought enough rod to make about 4 output
> shafts,
> over $200. And I've a spare 4" chuck from a TLM upgrade to a 5" to use on
> it. Or better yet, buy another 5" from LMS.
> So I'll get there, if I don't fall over first. At my age, thats always a
> possibility.
>
> I'll try to get some pix of what I've got so far, put up on my web page
> over
> the weekend. Along with some of the openscad source files.
>
> As usual, this stuff keeps me alone, safe, and out of the bars. :-)
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
> ___
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>
>
>
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Re: [Emc-users] Maybe a minimally printed harmonic drive?

[John Dammeyer]

> From: Chris Albertson [mailto:albertson.ch...@gmail.com]
> To: Enhanced Machine Controller (EMC)
> Gene,
> 
> I did a search on the part number to gave and, they look really good but
> cost $400 per axis vs about $60 for what I have.   Yes, they are much
> better.Did you find a better deal?
> 
> Question for the group:
> Assuming that you need about 3NM holding torque, what will $400 get you if
> you want to use a servo motor?   I'm thinking that these 3-phase closed
> loop steppers are more comparable in performance and price to servos than
> to cheap steppers.   Anyone have a link to a source of small-size Chinese
> servos and matching drivers.
> 


Yes.  I've been raving about the Bergerda series of AC Servos for a year now.  
I have a 1.8kW running the mill spindle and a 750W (2.39NM) running the knee 
(19mm shaft size) which cost just under $300.   
http://en.bergerda.com/

I also cast a mount and tried one of the 400W (1.25NM) units on the X axis and 
it was flawless too.  But at the moment my cabinet won't fit the drives 
compared to the DC Servo HP_UHU drives and I didn't want to swerve in another 
direction until the mill was completely converted. When I change to ball screws 
I'll also replace the two DC Brushed motors which are huge in comparative size 
to the AC servos.

They come in various flavours and sizes (ie frame/rpm/torque/shaft size) and 
all run on 220VAC.  Pricing out from 
https://www.automationtechnologiesinc.com/products-page/ac-servo-motors

the same DC brushed servo setup that I have comes out way more expensive than 
the AC servos when you add the driver and encoder and cable and DC power supply 
with one caveat.  
https://www.automationtechnologiesinc.com/products-page/dc-servo-motor/nema34-1125ozin-dual-shaft-servo-motor

Shipping.  Bergerda is not a aliexpress reseller but the actual manufacturer so 
payments go through Alibaba and they won't do slow mail deliver.  Must be FedEx 
tracked therefore one motor can be very expensive.  A big enough order could be 
done surface for considerable savings.

I've been trying to connect them up with a North American supplier but so far 
no luck.  

Anyway, I bought extra 400W units for the eventual conversion to ball screws 
and one to replace the stepper on the lathe.   The drives all run on 220VAC 
which can be an issue if you only have 110VAC available.

Now why servos instead of close loop steppers?  First the steppers still can 
stall at higher RPM so like standard steppers they are oriented to direct drive 
and slower rpm which means no torque multiplication with reduction belt drive. 
That generally means using a larger motor but they are definitely stable.  I 
used a CANopen commercial unit a while back that was impressive although 
eventually we upgraded to a German J1939 controlled AC Servo.

The biggest downside other than rpm is they are still stepper motors and noisy 
whereas the AC Servos are quiet.  Dead quiet.   And support has been excellent 
with one of their engineers even making an iPhone video of the button press 
sequences of the display to set up some parameters when I was having trouble.

Oh one other thing that I did verify.  Most of the cheap Aliexpress AC servos 
out there use cheap encoders.  Bergerda made a point of mentioning the use high 
end Japanese encoders.  So I took the cover off the end of the motor and 
grabbed the part number and name.  Yes indeed.  Japanese manufacturer and in 
singles through Alibaba came in at 3x the price of the cheap Aliexpress 
encoders.   So with cheap you get what you pay for I guess.



John Dammeyer


> Next idea...
> I looked up Gene's part and the motor/controler is sold as a set.  I can
> see why.   But I see I can buy a 3-phase stepper motor for about $100.   So
> we pay quite a lot for the driver and encoder.   I can buy a 1000 line
> encoder for under $20 and close the loop with a $4 microcontroller and
> three h-bridges.  I've done this many times using DC brushed gear motors.
>  (My use case is robotics but it's identical to a multi-axis mill.)
> 
> On Sat, May 1, 2021 at 6:30 AM Gene Heskett  wrote:
> 
> > On Saturday 01 May 2021 08:35:12 Thaddeus Waldner wrote:
> >
> > > So these are actual stepper motors and not 3-phase BLDC motors with
> > > step/direction input?
> >
> > yes, and while I said a step loss will stop them it has to exist for an
> > unspecified time frame. You can fasten them down, put a vice grip on the
> > shaft and turn them 1/4 turn before they error, they will resist
> > mightily and if you let go of the vice grips quick enough, they'll catch
> > up to a zero error and just keep on trucking. I can, creeping along with
> > my jog dials, run a carbide tipped tool into a stationary chuck jaw, and
> > when its found itself jammed, it shuts down the output drivers and
> > bounces about 10 thou clear of the chuck, all without damageing the chip
> > in the tool.  The machine will obviously need re-homed as I have the
> > volatile option set 

Re: [Emc-users] Maybe a minimally printed harmonic drive?

[Chris Albertson]

Gene,

I did a search on the part number to gave and, they look really good but
cost $400 per axis vs about $60 for what I have.   Yes, they are much
better.Did you find a better deal?

Question for the group:
Assuming that you need about 3NM holding torque, what will $400 get you if
you want to use a servo motor?   I'm thinking that these 3-phase closed
loop steppers are more comparable in performance and price to servos than
to cheap steppers.   Anyone have a link to a source of small-size Chinese
servos and matching drivers.

Next idea...
I looked up Gene's part and the motor/controler is sold as a set.  I can
see why.   But I see I can buy a 3-phase stepper motor for about $100.   So
we pay quite a lot for the driver and encoder.   I can buy a 1000 line
encoder for under $20 and close the loop with a $4 microcontroller and
three h-bridges.  I've done this many times using DC brushed gear motors.
 (My use case is robotics but it's identical to a multi-axis mill.)

On Sat, May 1, 2021 at 6:30 AM Gene Heskett  wrote:

> On Saturday 01 May 2021 08:35:12 Thaddeus Waldner wrote:
>
> > So these are actual stepper motors and not 3-phase BLDC motors with
> > step/direction input?
>
> yes, and while I said a step loss will stop them it has to exist for an
> unspecified time frame. You can fasten them down, put a vice grip on the
> shaft and turn them 1/4 turn before they error, they will resist
> mightily and if you let go of the vice grips quick enough, they'll catch
> up to a zero error and just keep on trucking. I can, creeping along with
> my jog dials, run a carbide tipped tool into a stationary chuck jaw, and
> when its found itself jammed, it shuts down the output drivers and
> bounces about 10 thou clear of the chuck, all without damageing the chip
> in the tool.  The machine will obviously need re-homed as I have the
> volatile option set in the .ini file.  Thats a 25mm z screw, but my x
> screw is only an 8mm, so while its wired I've deferred to the size of
> the screw and the possibility of damaging it, and not tested it
> similarly with its shorter, 2NM rated motor. That screw today seems to
> be made of pure unobtainium, its half of one of a triplet I bought from
> Stuart St. about 15 or more years ago to cnc the smallest hf mill.
>
> > I always assumed that it’s the latter, with the difference being lost
> > in translation.
>
> So did I, but installing one, replacing a stepper that ran burn you hand
> hot, and finding it stone cold after half an hour powered up but the
> only move was homing the axis was quite the eye opener, the motors
> holding current is determined by the encoder error.  No error=not enough
> holding currant to make feelable heat. You think its shut down, until
> you try to turn it...
>
> [...]
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] Maybe a minimally printed harmonic drive?

[Gene Heskett]

On Saturday 01 May 2021 08:35:12 Thaddeus Waldner wrote:

> So these are actual stepper motors and not 3-phase BLDC motors with
> step/direction input?

yes, and while I said a step loss will stop them it has to exist for an 
unspecified time frame. You can fasten them down, put a vice grip on the 
shaft and turn them 1/4 turn before they error, they will resist 
mightily and if you let go of the vice grips quick enough, they'll catch 
up to a zero error and just keep on trucking. I can, creeping along with 
my jog dials, run a carbide tipped tool into a stationary chuck jaw, and 
when its found itself jammed, it shuts down the output drivers and 
bounces about 10 thou clear of the chuck, all without damageing the chip 
in the tool.  The machine will obviously need re-homed as I have the 
volatile option set in the .ini file.  Thats a 25mm z screw, but my x 
screw is only an 8mm, so while its wired I've deferred to the size of 
the screw and the possibility of damaging it, and not tested it 
similarly with its shorter, 2NM rated motor. That screw today seems to 
be made of pure unobtainium, its half of one of a triplet I bought from 
Stuart St. about 15 or more years ago to cnc the smallest hf mill.

> I always assumed that it’s the latter, with the difference being lost
> in translation.

So did I, but installing one, replacing a stepper that ran burn you hand 
hot, and finding it stone cold after half an hour powered up but the 
only move was homing the axis was quite the eye opener, the motors 
holding current is determined by the encoder error.  No error=not enough 
holding currant to make feelable heat. You think its shut down, until 
you try to turn it...

[...]

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] Maybe a minimally printed harmonic drive?

[Thaddeus Waldner]

So these are actual stepper motors and not 3-phase BLDC motors with 
step/direction input?

I always assumed that it’s the latter, with the difference being lost in 
translation.


> On Apr 30, 2021, at 11:23 PM, Gene Heskett  wrote:
> 
> On Friday 30 April 2021 23:25:43 ken.stra...@gmail.com wrote:
> 
>> I haven't been following your project recently but am intrigued by
>> "And it turns the armature easy enough the 3NM 3 phase motor (those
>> are magic folks, running 50C cooler than 2 phase stuff) I'll use will
>> not be a bit overstressed." Where did you end up getting your motors
>> and what are you using for drivers?
>> 
> Ebay for all of them.  There are 2 phase with feedback but they work at 
> full motor currants all the time. The only driver that counts and really 
> is 3 phase is the LCDA357H although I expect it will grow bigger brother 
> versions as time goes by and folks become aware of them. The chinese are 
> not heavly advertizing that, the difference getting lost in the 
> translation or ???.
> 
> Motor wires are labeled UVW just like a vfd. And a full step is 1.2 
> degrees, not 1.8.
> 
> An encoder on the back of the motor talks to the driver, not to LCNC, and 
> you drive them exactly as you would any other stepper setup.
> 
> Step speeds are still limited by the input opto's to maybe 250 kilohertz. 
> It, the LCDA3576H driver is small, about the size of a 100 mil pack of 
> smokes, has no currant setting switches because the motor current is 
> determined by the magnitude of the error.  Makes it at least 5x more 
> efficient. Rated at 20-50 VDC input, there are 1,2, & 3 NM sizes that I 
> know of right now. Running my 11x54 Sheldon with rapids 2x faster than 
> the 2 phase stuff I took off, motor heating might be 5F. And if they 
> lose a step, they have an error out that can shut down LCNC with the 
> e-stop circuit.
> 
> Highly recommended by great, great, grandpa Gene as a genuine improvement 
> in stepper technology.
> 
>> -Original Message-
>> From: Gene Heskett 
>> Sent: April 30, 2021 10:45 PM
>> To: emc-users@lists.sourceforge.net
>> Subject: Re: [Emc-users] Maybe a minimally printed harmonic drive?
>> 
>>> On Monday 22 March 2021 09:19:19 Sam Sokolik wrote:
>>> 202,200 for the outside spline and the flex gear is 200.  In this
>>> situation - the 202 tooth spline is stationary to the stepper.  The
>>> 200 tooth outside spline is mounted to the faceplate.  In this
>>> layout - the ratio apears to be 101:1
>>> 
>>> In this situation the stepper motor and the face plate spin the same
>>> direction.
>>> 
>>> With the same set of outside spines swapped - the ratio is 100:1
>>> 
>>> I am sure Andy can explain it.  It doesn't make sense to me.
>>> 
>>> Happy with runout...  https://www.youtube.com/watch?v=eLyP2YwdstQ
>>> 
>>> sam
>> 
>> I am running some behind you Sam, with my project, having printer
>> problems kills time and money. Finally settled on an ender 5 Plus,
>> which is working passably well but I've wasted $3k getting there.
>> 
>> Any way, I changed the design some from yours, to a 30/1 because those
>> big spines print better, and by making my own bearings in openscad,
>> useing crosman bb's for balls. I put a huge one with over 150 loose
>> bb's directly on the outside of the moving spline, with only the lip
>> of the output coupling disc (printed of course) interposed. And the
>> floating spline has 3 more of those, sized for a good friction fit
>> inside that spline, with both the spline and the bearings made as thin
>> as practical to improve the flex life, and I just took the eliptical
>> armature off the build plate and wiggled in into those 3 bearings
>> inside the loose spline, so thats the driver armature, no commercial
>> ball bearings anyplace like yours.  I've made the 8mm hole in the
>> plastic for the motor shaft into a prominent D-flat, and used a cbn
>> wheel to make the flat much wider on the motor shaft, and this
>> armature will be driven onto the motor shaft without any grub screws
>> at all. No clue how long it will run before it bores that hole out and
>> I have to make an alu inner for it. :(
>> 
>> But I just now assembled it without the motor, turning the armature by
>> hand, and it works, with no detectable backlash. And it turns the
>> armature easy enough the 3NM 3 phase motor (those are magic folks,
>> running 50C cooler than 2 phase stuff) I'll use will not be a bit
>> overstressed.  Those bb's will pound the plastic smooth and get
>> smoother with use.
>> 
>> So now its time to finish the output shaft, and make the rest of the
>> housing. Which will be supported by the big bearing at the spline end,
>> and 4 of the printed bearings at the load end. I've got the motor end
>> gnawed out of some 1" stock I had, and I bought a foot of 3.125" thick
>> by 6" wide stuff so I can make 2 output housings. That showed me the
>> current price for extruded alu, scary. I also bought enough rod to
>> make about 4 output shafts, over $200. And I'