Re: [Emc-users] OT: Help with Harmonic wave reducer drives needed

[Jan de Kruyf]

are you on about this thing Viesturs?

http://en.wikipedia.org/wiki/Harmonic_drive

j.


On Sat, May 12, 2012 at 4:27 PM, Viesturs Lācis wrote:

> Hello, gentlemen!
>
> I would like to ask, if someone can point me to some source of
> information, how to design and calculate wave reducers.
>
> I am doing this for my school project. I have a book, which has all
> the formulas etc, but I am stuck with three errors already and I do
> not have any other source of this information to verify, if the error
> is in my brain or in the book.
>
> Few examples:
> 1) there is formula for involute function of pressure angle between
> gear hob and the gear (that is needed to calculate correction for
> flexible gear). One of the elements in that formula is correction
> ratio x_2;
> The formula for calculating x_2 is given as well. And guess what, one
> of elements in that formula is the involute function of pressure angle
> between gear hob and the gear.
> So there is magic circle, 2 unknown values depending each on other.
> But I managed to solve that.
> 2) there is some mysterious ratio in 2 formulas for wave generator
> profle parameters and correction ratio for internal gear without any
> explanation, what is it and how it is calculated.
> 3) the formula for efficiency ratio is doomed already before starting
> to calculate it: n=1/(1+a+2,2*10^5*u)
> a - not explained, what is that, but it is given that for flexible
> bearing a=0,14
> u - reduction ratio, u = 89
> It does not really matters, because 2,2*10^5 means that the efficiency
> is virtually non-existent.
> 4) Wave generator is elipse, expected ovality (d1 - d2)/2 should be
> around value of modulus of teeth, which in my case is 0,7, but I am
> getting 0,17, which just means that the gears will remain engaged all
> around their perimeters, which is failure.
>
> I have been trying to find something in the international databases we
> have available through school's library IT tools, but no luck.
> Googling just gives me total rubbish. Obviously I fail at choosing
> correct keywords.
>
> Can You point me to some place, where I could find, how to design and
> calculate wave reducer? All the flexible gears, flexible bearings etc.
>
> Thanks!
>
> Viesturs
>
>
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Re: [Emc-users] Not so custom

[Chris Morley]

> From: mjb1...@gmail.com
> Date: Wed, 16 May 2012 06:51:14 +0100
> To: emc-users@lists.sourceforge.net
> Subject: [Emc-users] Not so custom
> 
> Argh
> 
> StepConfig overwrites custom_postgui.hal with an empty file.  The name 
> 'custom' suggests it should not.
> 
> Mike
> 
>

In fact it should not do that without warning you first. and if it does it 
should rename the old one
to backup_postgui.hal

What version of linuxcnc are you using?

Chris M
  
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Re: [Emc-users] Not so custom

[Viesturs Lācis]

2012/5/16 Mike Bennett :
> Argh
>
> StepConfig overwrites custom_postgui.hal with an empty file.  The name 
> 'custom' suggests it should not.

StepConf overwrites any files it is set to create. And it is set to
create custom_postgui.hal, when new config is created.

You can always save that file with a different name not to lose its
contents and then change the reference in INI file to tell that Your
file has to be loaded.

-- 
Viesturs

If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto

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[Emc-users] Not so custom

[Mike Bennett]

Argh

StepConfig overwrites custom_postgui.hal with an empty file.  The name 'custom' 
suggests it should not.

Mike





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Re: [Emc-users] Debian with LinuxCNC

[Dave]

>>  Perry Mason would say.

Perry who ??  ;-)

Dave



On 5/15/2012 10:28 PM, N. Christopher Perry wrote:
> You're dating yourself, Kent. :))
>
> N.C.
>
> On 2012-May-15, at 16:11, Kent A. Reed wrote:
>
>
>> On 5/15/2012 4:00 PM, Kent A. Reed wrote:
>>  
>>> On 5/15/2012 2:05 PM, Tux Lab wrote:
>>> <...>
>>>
 Does the graphics card driver makes any difference on latency?   As I
 run glxgear, I notice the fps is pretty low and it's running software
 rendering.   If I switch over to radeon driver will latency improve?
 does kernel timer frequency have an effect on the latency?

 thanks,

 John

  
>>> Yes, graphics card drivers can affect the latency, some very badly,
>>> but the devil depends on the details of how they diddle with the
>>> machine. You say "radeon driver". Are you using the proprietary NVidia
>>> driver? As posted on the wiki,
>>>
>> Oops, sorry. I mixed up manufacturers here. Radeon is AMD, not NVidia.
>> "Move to strike," as Perry Mason would say.
>>
>> Regards,
>> Kent
>>
>>
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Re: [Emc-users] linux 10.04 install from usb

[N. Christopher Perry]

That's what I ended up doing.  In my case I was trying to make a bootable usb 
on a Mac.  Tried 3 - 4 different usb sticks without success.

First time I ran through the process on an older Win2000 machine, everything 
worked exactly as it should.  Now that particular USB is tucked away as the 
last resort tool.

N.C.

On 2012-May-15, at 16:48, Kent A. Reed wrote:

> On 5/15/2012 4:12 PM, dave wrote:
>> Hi,
>> Google is sometimes not my friend. Grump for an older guy. ;-)
> 
> Greetings from a fellow grump.
>> The idea is to install a linux from a live cd to at usb so I can get it
>> on a D510MO. Since this board has no ide the route I think makes sense
>> is:
>> Download live iso from .ro site (done)
>> Transfer iso to bootable usb.
>> Boot from usb and install on a SATA drive.
> 
> Ummm. Ubuntu 10.04LTS, at least, includes the ability to create a 
> bootable USB driver using Startup Disk Creator (look in  the 
> System/Administration menu). You can also search the pendrivelinux.com 
> site for their various recipes.
> 
>> The usb is a 4G Lexar. Fdisk doesn't like it. I have managed to drag
>> and drop at least most of the CD to the usb but that certainly doesn't
>> make it bootable.
>> 
>> There must be a reasonable way to do this from the command line.
>> 
>> Here is the first stumbling block.
>> 
>> dave@dsk:~$ cd /media
>> dave@dsk:/media$ chmod 0777 -v -R -f Lexar
>> mode of `Lexar' changed to 0777 (rwxrwxrwx)
>> dave@dsk:/media$ fdisk /media/Lexar
>> last_lba(): I don't know how to handle files with mode 40700
>> You will not be able to write the partition table.
>> 
>> cfdisk simply reports "no write perms".
> 
> Haven't run into this but then I've never had to chmod a USB stick. If 
> push comes to shove I suppose you could use a Windows system to reformat 
> the drive and then start again in Ubuntu, but that seems excessive.
> 
>> TIA
>> 
>> Dave
>> 
>> 
> 
> Good luck.
> 
> Regards,
> Kent
> 
> 
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Re: [Emc-users] Debian with LinuxCNC

[N. Christopher Perry]

You're dating yourself, Kent. :))

N.C.

On 2012-May-15, at 16:11, Kent A. Reed wrote:

> On 5/15/2012 4:00 PM, Kent A. Reed wrote:
>> On 5/15/2012 2:05 PM, Tux Lab wrote:
>> <...>
>>> Does the graphics card driver makes any difference on latency?   As I
>>> run glxgear, I notice the fps is pretty low and it's running software
>>> rendering.   If I switch over to radeon driver will latency improve?
>>> does kernel timer frequency have an effect on the latency?
>>> 
>>> thanks,
>>> 
>>> John
>>> 
>> 
>> Yes, graphics card drivers can affect the latency, some very badly, 
>> but the devil depends on the details of how they diddle with the 
>> machine. You say "radeon driver". Are you using the proprietary NVidia 
>> driver? As posted on the wiki, 
> 
> Oops, sorry. I mixed up manufacturers here. Radeon is AMD, not NVidia. 
> "Move to strike," as Perry Mason would say.
> 
> Regards,
> Kent
> 
> 
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Re: [Emc-users] Intel Board issues

[Terry Christophersen]

I forgot that it says  [xx.xxx] pnpbios: dev_node_info function not 
supported
    [xx.xxx] pnpbios: unable to get node 
info

Terry


- Original Message -
From: Terry Christophersen 
To: Enhanced Machine Controller ( EMC) 
Cc: 
Sent: Tuesday, May 15, 2012 8:20 PM
Subject: [Emc-users] Intel Board issues

Hi all
 
I am upgrading a motherboard to a Intel D525MW 
I am using a Live CD and I got these issues:
 
63.608618  dev_node_info function not supported
63.608666 unable to get node info
 
I am using a 32g solid state disc
 
I usually dont have any problems when I use the Live CD
 
Im sure you will need moer info but I will wait for someone
to tell me what to look for in the BIOS
 
Thanks 
Terry

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[Emc-users] Intel Board issues

[Terry Christophersen]

Hi all
 
I am upgrading a motherboard to a Intel D525MW 
I am using a Live CD and I got these issues:
 
63.608618  dev_node_info function not supported
63.608666 unable to get node info
 
I am using a 32g solid state disc
 
I usually dont have any problems when I use the Live CD
 
Im sure you will need moer info but I will wait for someone
to tell me what to look for in the BIOS
 
Thanks 
Terry

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Re: [Emc-users] linux 10.04 install from usb

[dave]

On Tue, 15 May 2012 14:09:03 -0700
Karl Cunningham  wrote:

> I used UNetBootin to create a live USB stick on a Linux desktop
> machine. It can use the ISO or live CD as the source for the image.

Ah! "The best laid plans of mice and men "

I'm not quite sure what they mean by uninstallable. ;-)

Since you only requested a single operation it is extremely likely that
the package is simply not installable and a bug report against
that package should be filed.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
  unetbootin: Depends: libqt4-network (>= 4.4.0) but it is not installable
  Depends: libqtcore4 (>= 4.4.0) but it is not installable
  Depends: libqtgui4 (>= 4.4.0) but it is not installable


In addition just after I sent the original message I thought: well
there isn't that much difference between a CF and a USB ... so I ran
the live install against the usb. It seemed to go fine but will not
boot. Boot partition is 800 Mb and the other partition takes up all the
rest of the 4G. 

I'm beginning to think the path of least resistance is to unplug my
drives on the desktop machine, boot against the live-CD and simply
install to the SATA drive I'm going to use with the D510. 

Dave

> Karl
> 
> On 05/15/2012 01:12 PM, dave wrote:
> > Hi,
> > Google is sometimes not my friend. Grump for an older guy. ;-)
> >
> > The idea is to install a linux from a live cd to at usb so I can
> > get it on a D510MO. Since this board has no ide the route I think
> > makes sense is:
> > Download live iso from .ro site (done)
> > Transfer iso to bootable usb.
> > Boot from usb and install on a SATA drive.
> >
> > The usb is a 4G Lexar. Fdisk doesn't like it. I have managed to drag
> > and drop at least most of the CD to the usb but that certainly
> > doesn't make it bootable.
> >
> > There must be a reasonable way to do this from the command line.
> >
> > Here is the first stumbling block.
> >
> > dave@dsk:~$ cd /media
> > dave@dsk:/media$ chmod 0777 -v -R -f Lexar
> > mode of `Lexar' changed to 0777 (rwxrwxrwx)
> > dave@dsk:/media$ fdisk /media/Lexar
> > last_lba(): I don't know how to handle files with mode 40700
> > You will not be able to write the partition table.
> >
> > cfdisk simply reports "no write perms".
> >
> > TIA
> >
> > Dave
> >
> >
> >
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> >
> 
> 
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Re: [Emc-users] Debian with LinuxCNC

[Tux Lab]

Once I got RTAI module compiled and working on Debian, installing
LinuxCNC was a lot easier.

After banging my head on the wall for the last couple days, I finally
downloaded the LinuxCNC LiveCD.  It install and runs fine.   Though
the odd thing is, I can run linuxcnc latency-test, I can't run rtai
testsuite's latency test.

The hardware I am using is an old P4 2.0Ghz 1GB  IBM intellistation M
desktops.   When running the rtai latency test under debian, lat max
is usually  < 20,000 when compiling linuxcnc, but has SMI spiking
issue.   I am hoping the latency spiking issue can solved because I
have 4 identical desktop that I can use for linuxcnc.

The Max Jitter with Ubuntu so far ~20,000 running glxgear and watching
linuxcnc videos on youtube.

I know, why go with Debian when Ubuntu works right out the box.
Hopefully I can get the Debian box to turn more smoothly using the
configuration from Ubuntu box.

I guess the next step is to buy the Mesa card.

thanks,

John


On Tue, May 15, 2012 at 1:00 PM, Kent A. Reed  wrote:
> On 5/15/2012 2:05 PM, Tux Lab wrote:
>> thanks for the link.  I've tried so many different way to compile
>> rtai, ie via debian's repository and downloading from original source
>> that I'm a bit lost right now.    However it good to know that at
>> least someone else is running EMC on debian, so it's a doable task :)
>>
>> Anyway, I just got the latency test to run, but it looks pretty bad.
>> ovl max at 174,383.    Now I have to figure out how I got RTAI to work
>> and duplicate it on another system.
>
> It's good to see you're making progress.
>
> Is this perhaps a laptop?
>
> By any chance, did you boot the LinuxCNC LiveCD on the same machine and
> run the latency test from there to see how the numbers compare?
>
> What is your hardware platform, actually?
>
>> Does the graphics card driver makes any difference on latency?   As I
>> run glxgear, I notice the fps is pretty low and it's running software
>> rendering.   If I switch over to radeon driver will latency improve?
>> does kernel timer frequency have an effect on the latency?
>>
>> thanks,
>>
>> John
>>
>
> Yes, graphics card drivers can affect the latency, some very badly, but
> the devil depends on the details of how they diddle with the machine.
> You say "radeon driver". Are you using the proprietary NVidia driver? As
> posted on the wiki, this driver has been reported in the past to break
> real-time constraints (although they keep releasing new versions and
> we've not been good at keeping straight which ones are bad). Try the
> "nv" or "vesa" drivers instead if you have Radeon graphics. You could
> also boot the LinuxCNC LiveCD on the system and see what driver Ubuntu
> chooses.
>
> By itself, software rendering itself is probably not the issue. For
> example, I have a copy of LinuxCNC2.4.6 running on an old Dell Pentium
> IV desktop system with an NVidia GeForce FX 5200 graphics card. Ubuntu
> detects the card and loads the "nouveau" driver. The combination does
> not support 3D acceleration in hardware and yields quite modest frame
> rates. However, I get reasonable latency numbers, about twice the
> numbers I and others get with Intel Atom boards and their built-in Intel
> GMA graphics, still good enough for software stepping.
>
> Regards,
> Kent
>
>
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Re: [Emc-users] linux 10.04 install from usb

[Karl Cunningham]

I used UNetBootin to create a live USB stick on a Linux desktop machine. 
It can use the ISO or live CD as the source for the image.

Karl

On 05/15/2012 01:12 PM, dave wrote:
> Hi,
> Google is sometimes not my friend. Grump for an older guy. ;-)
>
> The idea is to install a linux from a live cd to at usb so I can get it
> on a D510MO. Since this board has no ide the route I think makes sense
> is:
> Download live iso from .ro site (done)
> Transfer iso to bootable usb.
> Boot from usb and install on a SATA drive.
>
> The usb is a 4G Lexar. Fdisk doesn't like it. I have managed to drag
> and drop at least most of the CD to the usb but that certainly doesn't
> make it bootable.
>
> There must be a reasonable way to do this from the command line.
>
> Here is the first stumbling block.
>
> dave@dsk:~$ cd /media
> dave@dsk:/media$ chmod 0777 -v -R -f Lexar
> mode of `Lexar' changed to 0777 (rwxrwxrwx)
> dave@dsk:/media$ fdisk /media/Lexar
> last_lba(): I don't know how to handle files with mode 40700
> You will not be able to write the partition table.
>
> cfdisk simply reports "no write perms".
>
> TIA
>
> Dave
>
>
>
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Re: [Emc-users] linux 10.04 install from usb

[Eric H. Johnson]

Dave,

How about this:
https://help.ubuntu.com/community/Installation/FromUSBStick

You should be able to use the Linuxcnc LiveCD as the ISO image.

Failing that, install generic Ubuntu 10.04 to the USB, use it to install,
then run the Linuxcnc install script as described here under "If you prefer
to start with the distributed Ubuntu CD":
http://linuxcnc.org/index.php/english/download/21?task=view

HTH,
Eric


Google is sometimes not my friend. Grump for an older guy. ;-)

The idea is to install a linux from a live cd to at usb so I can get it on a
D510MO. Since this board has no ide the route I think makes sense
is:
Download live iso from .ro site (done)
Transfer iso to bootable usb.
Boot from usb and install on a SATA drive. 

The usb is a 4G Lexar. Fdisk doesn't like it. I have managed to drag and
drop at least most of the CD to the usb but that certainly doesn't make it
bootable. 

There must be a reasonable way to do this from the command line. 

Here is the first stumbling block. 

dave@dsk:~$ cd /media
dave@dsk:/media$ chmod 0777 -v -R -f Lexar mode of `Lexar' changed to 0777
(rwxrwxrwx) dave@dsk:/media$ fdisk /media/Lexar
last_lba(): I don't know how to handle files with mode 40700 You will not be
able to write the partition table.

cfdisk simply reports "no write perms". 


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Re: [Emc-users] linux 10.04 install from usb

[Kent A. Reed]

On 5/15/2012 4:12 PM, dave wrote:
> Hi,
> Google is sometimes not my friend. Grump for an older guy. ;-)

Greetings from a fellow grump.
> The idea is to install a linux from a live cd to at usb so I can get it
> on a D510MO. Since this board has no ide the route I think makes sense
> is:
> Download live iso from .ro site (done)
> Transfer iso to bootable usb.
> Boot from usb and install on a SATA drive.

Ummm. Ubuntu 10.04LTS, at least, includes the ability to create a 
bootable USB driver using Startup Disk Creator (look in  the 
System/Administration menu). You can also search the pendrivelinux.com 
site for their various recipes.

> The usb is a 4G Lexar. Fdisk doesn't like it. I have managed to drag
> and drop at least most of the CD to the usb but that certainly doesn't
> make it bootable.
>
> There must be a reasonable way to do this from the command line.
>
> Here is the first stumbling block.
>
> dave@dsk:~$ cd /media
> dave@dsk:/media$ chmod 0777 -v -R -f Lexar
> mode of `Lexar' changed to 0777 (rwxrwxrwx)
> dave@dsk:/media$ fdisk /media/Lexar
> last_lba(): I don't know how to handle files with mode 40700
> You will not be able to write the partition table.
>
> cfdisk simply reports "no write perms".

Haven't run into this but then I've never had to chmod a USB stick. If 
push comes to shove I suppose you could use a Windows system to reformat 
the drive and then start again in Ubuntu, but that seems excessive.

> TIA
>
> Dave
>
>

Good luck.

Regards,
Kent


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Re: [Emc-users] linux 10.04 install from usb

[Stephen Dubovsky]

I recently did this successfully, albeit from a windows machine.  I used
Linux Live USB creator (http://www.linuxliveusb.com/), pointed it to the
iso, and it made the USB stick bootable w/ the CD image.  It doesn't just
copy files.

You should be able to use Unetbootin from the linux command line to do the
same thing.  (http://unetbootin.sourceforge.net/)

Stephen

On Tue, May 15, 2012 at 4:12 PM, dave  wrote:

> Hi,
> Google is sometimes not my friend. Grump for an older guy. ;-)
>
> The idea is to install a linux from a live cd to at usb so I can get it
> on a D510MO. Since this board has no ide the route I think makes sense
> is:
> Download live iso from .ro site (done)
> Transfer iso to bootable usb.
> Boot from usb and install on a SATA drive.
>
> The usb is a 4G Lexar. Fdisk doesn't like it. I have managed to drag
> and drop at least most of the CD to the usb but that certainly doesn't
> make it bootable.
>
> There must be a reasonable way to do this from the command line.
>
> Here is the first stumbling block.
>
> dave@dsk:~$ cd /media
> dave@dsk:/media$ chmod 0777 -v -R -f Lexar
> mode of `Lexar' changed to 0777 (rwxrwxrwx)
> dave@dsk:/media$ fdisk /media/Lexar
> last_lba(): I don't know how to handle files with mode 40700
> You will not be able to write the partition table.
>
> cfdisk simply reports "no write perms".
>
> TIA
>
> Dave
>
>
>
>
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[Emc-users] linux 10.04 install from usb

[dave]

Hi, 
Google is sometimes not my friend. Grump for an older guy. ;-)

The idea is to install a linux from a live cd to at usb so I can get it
on a D510MO. Since this board has no ide the route I think makes sense
is:
Download live iso from .ro site (done)
Transfer iso to bootable usb.
Boot from usb and install on a SATA drive. 

The usb is a 4G Lexar. Fdisk doesn't like it. I have managed to drag
and drop at least most of the CD to the usb but that certainly doesn't
make it bootable. 

There must be a reasonable way to do this from the command line. 

Here is the first stumbling block. 

dave@dsk:~$ cd /media
dave@dsk:/media$ chmod 0777 -v -R -f Lexar
mode of `Lexar' changed to 0777 (rwxrwxrwx)
dave@dsk:/media$ fdisk /media/Lexar
last_lba(): I don't know how to handle files with mode 40700
You will not be able to write the partition table.

cfdisk simply reports "no write perms". 

TIA

Dave



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Re: [Emc-users] Debian with LinuxCNC

[Kent A. Reed]

On 5/15/2012 4:00 PM, Kent A. Reed wrote:
> On 5/15/2012 2:05 PM, Tux Lab wrote:
> <...>
>> Does the graphics card driver makes any difference on latency?   As I
>> run glxgear, I notice the fps is pretty low and it's running software
>> rendering.   If I switch over to radeon driver will latency improve?
>> does kernel timer frequency have an effect on the latency?
>>
>> thanks,
>>
>> John
>>
>
> Yes, graphics card drivers can affect the latency, some very badly, 
> but the devil depends on the details of how they diddle with the 
> machine. You say "radeon driver". Are you using the proprietary NVidia 
> driver? As posted on the wiki, 

Oops, sorry. I mixed up manufacturers here. Radeon is AMD, not NVidia. 
"Move to strike," as Perry Mason would say.

Regards,
Kent


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Re: [Emc-users] Debian with LinuxCNC

[Kent A. Reed]

On 5/15/2012 2:05 PM, Tux Lab wrote:
> thanks for the link.  I've tried so many different way to compile
> rtai, ie via debian's repository and downloading from original source
> that I'm a bit lost right now.However it good to know that at
> least someone else is running EMC on debian, so it's a doable task :)
>
> Anyway, I just got the latency test to run, but it looks pretty bad.
> ovl max at 174,383.Now I have to figure out how I got RTAI to work
> and duplicate it on another system.

It's good to see you're making progress.

Is this perhaps a laptop?

By any chance, did you boot the LinuxCNC LiveCD on the same machine and 
run the latency test from there to see how the numbers compare?

What is your hardware platform, actually?

> Does the graphics card driver makes any difference on latency?   As I
> run glxgear, I notice the fps is pretty low and it's running software
> rendering.   If I switch over to radeon driver will latency improve?
> does kernel timer frequency have an effect on the latency?
>
> thanks,
>
> John
>

Yes, graphics card drivers can affect the latency, some very badly, but 
the devil depends on the details of how they diddle with the machine. 
You say "radeon driver". Are you using the proprietary NVidia driver? As 
posted on the wiki, this driver has been reported in the past to break 
real-time constraints (although they keep releasing new versions and 
we've not been good at keeping straight which ones are bad). Try the 
"nv" or "vesa" drivers instead if you have Radeon graphics. You could 
also boot the LinuxCNC LiveCD on the system and see what driver Ubuntu 
chooses.

By itself, software rendering itself is probably not the issue. For 
example, I have a copy of LinuxCNC2.4.6 running on an old Dell Pentium 
IV desktop system with an NVidia GeForce FX 5200 graphics card. Ubuntu 
detects the card and loads the "nouveau" driver. The combination does 
not support 3D acceleration in hardware and yields quite modest frame 
rates. However, I get reasonable latency numbers, about twice the 
numbers I and others get with Intel Atom boards and their built-in Intel 
GMA graphics, still good enough for software stepping.

Regards,
Kent


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Re: [Emc-users] Debian with LinuxCNC

[Eric Keller]

On Tue, May 15, 2012 at 2:05 PM, Tux Lab  wrote:

> thanks for the link.  I've tried so many different way to compile
> rtai, ie via debian's repository and downloading from original source
> that I'm a bit lost right now.However it good to know that at
> least someone else is running EMC on debian, so it's a doable task :)
>
Of course it's doable, but even someone like me that has built many, many
running realtime systems has issues doing the job that take more patience
than I have right now.  I think Andy pinpointed your problem, but didn't
come right out and say it.  You need to d/l the linuxcnc source and build
it while the RTAI kernel you built is running the system.  That should get
you to the point where the bugs and crashes are really weird instead of the
obvious problems you are having now.
Good luck,
Eric
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Re: [Emc-users] Debian with LinuxCNC

[Tux Lab]

thanks for the link.  I've tried so many different way to compile
rtai, ie via debian's repository and downloading from original source
that I'm a bit lost right now.However it good to know that at
least someone else is running EMC on debian, so it's a doable task :)

Anyway, I just got the latency test to run, but it looks pretty bad.
ovl max at 174,383.Now I have to figure out how I got RTAI to work
and duplicate it on another system.

Does the graphics card driver makes any difference on latency?   As I
run glxgear, I notice the fps is pretty low and it's running software
rendering.   If I switch over to radeon driver will latency improve?
does kernel timer frequency have an effect on the latency?

thanks,

John

On Tue, May 15, 2012 at 6:19 AM, Schooner  wrote:
> Hi
>
> I have built 2.6.26 rtai kernels on Lenny and Squeeze.
> Still using Lenny on an older machine
>
> I used these instructions as a starting point and tailored for debian
> http://code.google.com/p/neo-technical/wiki/emc2ubuntu
>
> My notes suggest that tk/tcl8.4 bwidget and python-tk are not in the
> Lenny standard install and need fetching
> before emc will build.
>
> regards
>
> NB all references to emc do of course refer to another name that takes
> longer to type with 2 fingers
>
> On 15/05/12 04:24, emc-users-requ...@lists.sourceforge.net wrote:
>> Is there a more up to date tutorial on how to compile rtai with
>> Debian.    It took me a whole weekend to compile a kernel that will
>> boot but when I try the latency test, I get
>>
>> insmod: error inserting '/lib/modules/2.6.32-rtai/rtai/rtai_hal.ko':
>> -1 Invalid module format
>
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Re: [Emc-users] Debian with LinuxCNC

[andy pugh]

On 15 May 2012 17:02, Kent A. Reed  wrote:

> "insmod: error inserting Invalid module format" into your favorite
> search engine. Both Google and Bing point me to pages that discuss this
> message and its cause (mismatch of kernel and module).

Which asks the question, "Was the installed version of LinuxCNC
compiled with that particular kernel" (rtai_hal.ko is part of
LinuxCNC, not of RTAI)

I think I found problems in a similar situation to be caused by the
LinuxCNC makefile hard-coding kernel versions into
something

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Re: [Emc-users] Debian with LinuxCNC

[Kent A. Reed]

On 5/14/2012 4:00 PM, Tux Lab wrote:
> Is there a more up to date tutorial on how to compile rtai with
> Debian.It took me a whole weekend to compile a kernel that will
> boot but when I try the latency test, I get
>
> insmod: error inserting '/lib/modules/2.6.32-rtai/rtai/rtai_hal.ko':
> -1 Invalid module format
> ERROR: cannot load /lib/modules/2.6.32-rtai/rtai/rtai_hal.ko
> CANNOT INIT MASTER TASK
>
> Anyone else running LinuxCNC on Debian?   How did you get it to work?
>
> thanks,
>
> John
>
John:

This sounds like a variation of an old joke
 Patient: "Doctor, doctor, it hurts when I do this."
 Doctor: "So, stop doing do it."

Without a lot more details about which distribution of Debian, which 
kernel (2.6.32 from your message but is it one you built yourself?), 
which version of the RTAI distribution, etc., there's not much that can 
be said. Sometimes discretion is the better part of valor. In this case, 
discretion is exhibited by sticking with Ubuntu.

If you want to persist, the important message is the first. Try plugging 
"insmod: error inserting Invalid module format" into your favorite 
search engine. Both Google and Bing point me to pages that discuss this 
message and its cause (mismatch of kernel and module).

Try also looking at /var/log/messages and the output of dmesg for 
supporting details.

As always, when you find a working combination add it to the wiki.

Good luck.

Regards,
Kent


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Re: [Emc-users] Debian with LinuxCNC

[Schooner]

Hi

I have built 2.6.26 rtai kernels on Lenny and Squeeze.
Still using Lenny on an older machine

I used these instructions as a starting point and tailored for debian
http://code.google.com/p/neo-technical/wiki/emc2ubuntu

My notes suggest that tk/tcl8.4 bwidget and python-tk are not in the 
Lenny standard install and need fetching
before emc will build.

regards

NB all references to emc do of course refer to another name that takes 
longer to type with 2 fingers

On 15/05/12 04:24, emc-users-requ...@lists.sourceforge.net wrote:
> Is there a more up to date tutorial on how to compile rtai with
> Debian.It took me a whole weekend to compile a kernel that will
> boot but when I try the latency test, I get
>
> insmod: error inserting '/lib/modules/2.6.32-rtai/rtai/rtai_hal.ko':
> -1 Invalid module format

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Re: [Emc-users] simple conversational utility to cut off remnants

[Tom Easterday]

Thanks John and Sebastian, I will check out ngcgui.
-Tom

On May 15, 2012, at 7:27 AM, John Thornton wrote:

> Tom,
> 
> I use ngcgui and just fill in the blanks for length of cut. I have one 
> called x-trim that I just need speed and length and off I go.
> 
> Before ngcgui I just used a file called x-trim.ngc and edited the X and F.
> 
> x-trim.ngc
> G20 (Units: Inches)
> G40 (Cancel Cutter Comp)
> G90 (Absolute Mode)
> G64 P0.005 (Continuous mode + path tolerance)
> G92 X0 Y0
> o call [0.100] [0] [0.08] (Touchoff and start cutting)
> F70
> G1 X6
> M5 (Torch Off)
> G0 Z0.500
> X0.000
> G92.1 (Cancel offsets and set to zero)
> G0 Z0
> M2
> 
> touchoff.ngc
> o sub
> (#1 pierce height, #2 pierce delay, #3 cut height)
> F10
> G38.2 Z-1.75 (Probe to find the surface)
> G91
> G1 Z0.070 (Raise up to Z0)
> G90
> G92 Z0 (Set Z0)
> G1 Z#1
> M3 S1
> M66 P0 L1 Q5 (Wait for Arc OK from Torch)
> G4 P#2 (Pause for pierce delay)
> F25
> Z#3 (goto cut height)
> o endsub
> M2
> 
> John
> 
> On 5/14/2012 10:24 PM, Tom Easterday wrote:
>> Is there a simple conversational way in Linuxcnc (2.5) to cut a straight 
>> line or a simple pattern?  After cutting some parts on a large sheet with 
>> the plasma machine today we wanted to cut a straight line starting from a 
>> touch off point at a specific feed rate ending at a specific distance.  This 
>> was to cut off a remnant.  We also wanted to cut a simple pattern that went 
>> from touch off point to 24" in Y, then -5' in X, then 24" in Y and stop.  We 
>> need to set the feed rate and turn on the torch as well.  Other than whip up 
>> a quick g-code program (which works obviously), is there a utility that a 
>> more novice person could use to do this?
>> 
>> I see Sheetcam has a remnant function which is nice, but it would still be 
>> useful in the event you didn't set that up in advance
>> 
>> Tom
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Re: [Emc-users] Some advice needed

[andy pugh]

On 15 May 2012 13:28, Viesturs Lācis  wrote:

> No, those flexible bearings actually are _required_ to be flexed for
> normal operation . They even specify a range of min and max ovality -
> (D-d)/2 = 1,2...1.6mm (D and d - large and small diameters of elipse)
> for flexible bearing with inner diameter 90 mm and outer diameter =
> 120 mm.. They are not meant to be used "as they are" - as a round
> circle.

True, but the actual ovality is rather smaller than is shown in the animations.

> The thing is that there is extra play in the bearing, which decreases
> as the bearing is flexed, so even reducing the rings of normal bearing
> will not give a good flexible ring - the existing play in bearing will
> be not sufficient for it to flex to the extent I need.

Ordinary bearings are available in a range of clearance grades. Those
intended to be a tight press fit in the housing and on the shaft are
generally C4, and those rattle noticeably before installation.

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Re: [Emc-users] Some advice needed

[Viesturs Lācis]

2012/5/15 charles green :
> i dont see why to care what any part aside from the engagement area is doing, 
> except maybe at some resonance frequencies (grease it up good) and/or high 
> speeds (why use a reducer for high speed application?).
>

With 200:1 reduction ratio the input _has_ to go fast to get more than
few RPM on output. And robot arms need more than 2-3 RPM on output to
move a joint by 90 degrees in a second or two.

If only engagement area is controlled, then the rest of the profile is:
1) uncontrolled curve from
2) thin and
3) flexible material.
Every of these three factors contributes to unwanted warping of the
flexible gear and here they all are together.
Under load the flexible gear is not elipse anymore, but some kind of
strange geometric figure, becoming close to circle with segments on
opposite side cut off (and displacement of output flange relative to
input flange).
In text books they distinguish the wave gears:
1) free form wave gears:
wave generator is diametrically positioned rollers;
2) strained wave gears:
wave generator is either eccentric discs or elipse.

Please, do not tell me to reinvent the wheel - it is proven long time
ago - free form wave gears are not meant for pretty quick
applications, where stiffness is needed.

BTW "strain wave reducer" name is the name to describe whole wave gear
principle. And that is not a coincidence - free wave reducers simply
are not up to the task. There is a flex in the reducer, causing a
displacement, so encoder on the motor is useless for deriving the
actual joint position.

As I said and I do not want to repeat it again - forget about free
form wave gears in robotic application!!!


2012/5/15 andy pugh :
> On 15 May 2012 07:29, Viesturs Lācis  wrote:
>
>> If I cannot get the flexible bearings, then there is option of
>> eccentric discs as a wave generator.
>
> You could probably dismantle a normal bearing, machine down the races
> to make them much thinnner, and then press them onto an oval former.

No, those flexible bearings actually are _required_ to be flexed for
normal operation . They even specify a range of min and max ovality -
(D-d)/2 = 1,2...1.6mm (D and d - large and small diameters of elipse)
for flexible bearing with inner diameter 90 mm and outer diameter =
120 mm.. They are not meant to be used "as they are" - as a round
circle.
The thing is that there is extra play in the bearing, which decreases
as the bearing is flexed, so even reducing the rings of normal bearing
will not give a good flexible ring - the existing play in bearing will
be not sufficient for it to flex to the extent I need.

Viesturs

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Re: [Emc-users] psu for atom boards

[Erik Christiansen]

On 14.05.12 08:15, Ted Hyde wrote:
> I've noticed that the current online spec sheet for the standard
> PicoPSU says PG is acceptable between 10.5 and 13.5 vdc. It's not a
> "bold statement spec" - you have to hunt for it. However, I'd believe
> it in that if you fed 13.6, it would shut down.

No chance to put a 12v (charge to 13.8v?) battery in as a UPS, then.

The PDF spec-sheet for the PWR-PICOPSU-80-WI-32V that I'm using says in
its first 4 lines:

Input Requirements: 12-32V un-regulated, min=2A, max=10A (load dependent).

Max Input Voltage supported by TVS clamp=34V.
NOTE: Above 34V, the TVS protection diode will clamp and burn the input fuse.

I'm using one in my desktop PC as well. It allows me to put a pair of
12v batteries into the box, to serve as a UPS, without taking up extra
room.

Erik
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Re: [Emc-users] Commutating Reactor

[Dave]

Yes.   It appears that the Reactor is performing some useful function by 
removing a lot of noise.

I'd go for the generator and see what happens.

Dave

On 5/15/2012 7:29 AM, John Thornton wrote:
> Did you get a chance to look at the scope traces?
>
> I've secured a rather large 3 phase generator and power unit and will be
> hooking it up over the next few days for further testing.
>
> John
>
> On 5/13/2012 11:07 PM, Dave wrote:
>
 Do you know what the blue orb is on top of the commutating reactor is?
  
>> I don't know.  I could not find your exact part number for that reactor.. I 
>> got very close but not exact.
>>
>> Dave
>>
>>
>>
>> On 5/12/2012 8:25 AM, John Thornton wrote:
>>  
>>> I did replace all the caps in the infeed a while back...
>>>
>>> so my first test is to bypass the commutating reactor and see what that
>>> does.
>>>
>>> next rent a generator which will tell me if my phase converter is
>>> driving the simodrive 611 nuts or not.
>>>
>>> I do have another siemens drive but not a 611 on my Hardinge CHNC and it
>>> does not complain at all about running from my phase converter... I'm
>>> off to see if there is a reactor in that baby.
>>>
>>> I'll keep on the look out for a 3 phase generator... no natural gas
>>> here, we are lucky to have electricity lol.
>>>
>>> Do you know what the blue orb is on top of the commutating reactor is?
>>>
>>> John
>>>
>>> On 5/12/2012 6:59 AM, Dave wrote:
>>>
>>>
 Those are really good drives.. I wouldn't remove them.  If your infeed
 is bad you should be able to get it repaired or find a replacement.

 If you still have problems I'd try it with a good generator and see if
 your phase converter isn't driving the system nuts.

 The rental places around here rent trailer mounted units.

 Mid-sized older generators often go for not much money.

 I bought a natural gas driven 55 KW generator for $500 in very good
 shape which is not much more than its scrap value.
 It also runs off propane with a vaporizor added.
 If you have natural gas, it might be something to consider.

 Dave

 On 5/12/2012 7:28 AM, John Thornton wrote:

  
> I was looking at it yesterday and the infeed module (power supply) is
> tightly integrated with the spindle and axis modules with a flat data
> cable as well as a bunch of cables to the DX32 control. It would be a
> complete refit I believe to lose the infeed module from the system...
> but I might be wrong.
>
> The infeed module is on the left of the stack
>
> http://imagebin.org/212102
>
> Is there any detailed info on building a 600vdc power supply anywhere?
> That along with Linuxcnc might be the long run solution.
>
> John
>
> On 5/11/2012 7:24 PM, andy pugh wrote:
>
>
>
>> On 12 May 2012 01:18, Dave   wrote:
>>
>>
>>
>>  
>>> It sounds like the reactor is interacting with the capacitors on your
>>> phase converter (resonating).
>>>
>>>
>>>
>> Now that's an interesting idea.
>>
>>
>>
>>  
>>> Not having the reactor in the system may cause a lot of extra current
>>> through the capacitors on your phase converter.
>>>
>>>
>>>
>> I think the idea of making a single-phase DC bus supply and losing the
>> phase convertor had a lot of positives.
>>
>>
>>
>>  
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Re: [Emc-users] Some advice needed

[gene heskett]

On Tuesday, May 15, 2012 07:38:31 AM andy pugh did opine:

> On 15 May 2012 10:42, charles green  wrote:
> > the discreet spline teeth are also an approximation.  in fact,
> > anything made out of atoms is flexible and grainy.  why not construct
> > mechanisms from massless rigid rods and such?
> 
> I think Viesturs has a point about the sides being unconstrained in a
> twin-roller arrangement. The sides have the option of flapping like a
> drive belt.
> A combination roller/plain bearing might work, though, imagine a brass
> oval with rollers in the ends. There would be little load on the
> plain-bearing portions, but it would constrain the flex-spline.

I think that would work at elevated speeds only with sufficient liquid flow 
into the clearance to maintain hydrodynamic cushioning.  Metal to metal 
contact would likely hammer the brass out of shape, possibly contaminating 
the interior with particulates before they were expected.

Cheers, Gene
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Re: [Emc-users] Some advice needed

[gene heskett]

On Tuesday, May 15, 2012 07:32:44 AM charles green did opine:

> the discreet spline teeth are also an approximation.  in fact, anything
> made out of atoms is flexible and grainy.  why not construct mechanisms
> from massless rigid rods and such?
 
I have seen some drawings of such, from Marten-Marrietta back in the Titan 
1 glory days, 1961 or so, but the construction material was always 
specified as pure unobtainium.

;-)

Cheers, Gene
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My web page: 
I'm defending her honor, which is more than she ever did.

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Re: [Emc-users] Commutating Reactor

[John Thornton]

Did you get a chance to look at the scope traces?

I've secured a rather large 3 phase generator and power unit and will be 
hooking it up over the next few days for further testing.

John

On 5/13/2012 11:07 PM, Dave wrote:
>>> Do you know what the blue orb is on top of the commutating reactor is?
> I don't know.  I could not find your exact part number for that reactor.. I 
> got very close but not exact.
>
> Dave
>
>
>
> On 5/12/2012 8:25 AM, John Thornton wrote:
>> I did replace all the caps in the infeed a while back...
>>
>> so my first test is to bypass the commutating reactor and see what that
>> does.
>>
>> next rent a generator which will tell me if my phase converter is
>> driving the simodrive 611 nuts or not.
>>
>> I do have another siemens drive but not a 611 on my Hardinge CHNC and it
>> does not complain at all about running from my phase converter... I'm
>> off to see if there is a reactor in that baby.
>>
>> I'll keep on the look out for a 3 phase generator... no natural gas
>> here, we are lucky to have electricity lol.
>>
>> Do you know what the blue orb is on top of the commutating reactor is?
>>
>> John
>>
>> On 5/12/2012 6:59 AM, Dave wrote:
>>
>>> Those are really good drives.. I wouldn't remove them.  If your infeed
>>> is bad you should be able to get it repaired or find a replacement.
>>>
>>> If you still have problems I'd try it with a good generator and see if
>>> your phase converter isn't driving the system nuts.
>>>
>>> The rental places around here rent trailer mounted units.
>>>
>>> Mid-sized older generators often go for not much money.
>>>
>>> I bought a natural gas driven 55 KW generator for $500 in very good
>>> shape which is not much more than its scrap value.
>>> It also runs off propane with a vaporizor added.
>>> If you have natural gas, it might be something to consider.
>>>
>>> Dave
>>>
>>> On 5/12/2012 7:28 AM, John Thornton wrote:
>>>
 I was looking at it yesterday and the infeed module (power supply) is
 tightly integrated with the spindle and axis modules with a flat data
 cable as well as a bunch of cables to the DX32 control. It would be a
 complete refit I believe to lose the infeed module from the system...
 but I might be wrong.

 The infeed module is on the left of the stack

 http://imagebin.org/212102

 Is there any detailed info on building a 600vdc power supply anywhere?
 That along with Linuxcnc might be the long run solution.

 John

 On 5/11/2012 7:24 PM, andy pugh wrote:


> On 12 May 2012 01:18, Dave  wrote:
>
>
>
>> It sounds like the reactor is interacting with the capacitors on your
>> phase converter (resonating).
>>
>>
> Now that's an interesting idea.
>
>
>
>> Not having the reactor in the system may cause a lot of extra current
>> through the capacitors on your phase converter.
>>
>>
> I think the idea of making a single-phase DC bus supply and losing the
> phase convertor had a lot of positives.
>
>
>
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Re: [Emc-users] simple conversational utility to cut off remnants

[John Thornton]

Tom,

I use ngcgui and just fill in the blanks for length of cut. I have one 
called x-trim that I just need speed and length and off I go.

Before ngcgui I just used a file called x-trim.ngc and edited the X and F.

x-trim.ngc
G20 (Units: Inches)
G40 (Cancel Cutter Comp)
G90 (Absolute Mode)
G64 P0.005 (Continuous mode + path tolerance)
G92 X0 Y0
o call [0.100] [0] [0.08] (Touchoff and start cutting)
F70
G1 X6
M5 (Torch Off)
G0 Z0.500
X0.000
G92.1 (Cancel offsets and set to zero)
G0 Z0
M2

touchoff.ngc
o sub
(#1 pierce height, #2 pierce delay, #3 cut height)
F10
G38.2 Z-1.75 (Probe to find the surface)
G91
G1 Z0.070 (Raise up to Z0)
G90
G92 Z0 (Set Z0)
G1 Z#1
M3 S1
M66 P0 L1 Q5 (Wait for Arc OK from Torch)
G4 P#2 (Pause for pierce delay)
F25
Z#3 (goto cut height)
o endsub
M2

John

On 5/14/2012 10:24 PM, Tom Easterday wrote:
> Is there a simple conversational way in Linuxcnc (2.5) to cut a straight line 
> or a simple pattern?  After cutting some parts on a large sheet with the 
> plasma machine today we wanted to cut a straight line starting from a touch 
> off point at a specific feed rate ending at a specific distance.  This was to 
> cut off a remnant.  We also wanted to cut a simple pattern that went from 
> touch off point to 24" in Y, then -5' in X, then 24" in Y and stop.  We need 
> to set the feed rate and turn on the torch as well.  Other than whip up a 
> quick g-code program (which works obviously), is there a utility that a more 
> novice person could use to do this?
>
> I see Sheetcam has a remnant function which is nice, but it would still be 
> useful in the event you didn't set that up in advance
>
> Tom
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Re: [Emc-users] Some advice needed

[andy pugh]

On 15 May 2012 11:04, charles green  wrote:
> i dont see why to care what any part aside from the engagement area is doing

Now I think about it some more, I think you might be right.
The "cup" is probably a little stiffer with the edge fully restrained,
but I don't think the difference is as big as I originally thought.

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Re: [Emc-users] Some advice needed

[charles green]

i dont see why to care what any part aside from the engagement area is doing, 
except maybe at some resonance frequencies (grease it up good) and/or high 
speeds (why use a reducer for high speed application?).

--- On Tue, 5/15/12, andy pugh  wrote:

> From: andy pugh 
> Subject: Re: [Emc-users] Some advice needed
> To: "Enhanced Machine Controller (EMC)" 
> Date: Tuesday, May 15, 2012, 2:55 AM
> On 15 May 2012 10:42, charles green
> 
> wrote:
> > the discreet spline teeth are also an approximation.
>  in fact, anything made out of atoms is flexible and
> grainy.  why not construct mechanisms from massless rigid
> rods and such?
> 
> I think Viesturs has a point about the sides being
> unconstrained in a
> twin-roller arrangement. The sides have the option of
> flapping like a
> drive belt.
> A combination roller/plain bearing might work, though,
> imagine a brass
> oval with rollers in the ends. There would be little load on
> the
> plain-bearing portions, but it would constrain the
> flex-spline.
> 
> -- 
> atp
> If you can't fix it, you don't own it.
> http://www.ifixit.com/Manifesto
> 
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Re: [Emc-users] Some advice needed

[andy pugh]

On 12 May 2012 00:11, Viesturs Lācis  wrote:

> The problem is that they do not have the tools for 0,5 module,
> smallest they have is 0,7. But with ~124 mm pitch diameter the tooth
> count changes from 247 to 177, which significantly reduces the
> reduction ratio - from 123,5:1 to 88,5 (bigger is better; welding
> robot had total reduction ratio of 640:1 in shoulder and elbow
> joints).

You can get a 0.5mod hob from Arc Eurotrade, use that to make the
flex-spline, and also use it to make a shaving tool for the internal.
At least in theory.
In practice I don't think you need or want an actual involute form for
a harmonic drive.
If you have a milling machine with a slotting head and a rotary table
then you can single-point the internal gear. The tool could be ground
to any required profile. (Though I would suggest getting it
wire-eroded from HSS)


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Re: [Emc-users] Some advice needed

[andy pugh]

On 15 May 2012 10:42, charles green  wrote:
> the discreet spline teeth are also an approximation.  in fact, anything made 
> out of atoms is flexible and grainy.  why not construct mechanisms from 
> massless rigid rods and such?

I think Viesturs has a point about the sides being unconstrained in a
twin-roller arrangement. The sides have the option of flapping like a
drive belt.
A combination roller/plain bearing might work, though, imagine a brass
oval with rollers in the ends. There would be little load on the
plain-bearing portions, but it would constrain the flex-spline.

-- 
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Re: [Emc-users] Some advice needed

[charles green]

a loop of spring steel surrounding a layer of needle rollers, surrounding the 
cam form would be a workable prototyping path.  in the other direction, a pile 
of currency units can be converted into a stock drive product, or a close 
customization with a nominal lead time.  for example, very precise, durable, 
compact, stylish, and expensive mechanical clock modules can be had for only 
the asking of very large amounts of currency credits.


--- On Tue, 5/15/12, andy pugh  wrote:

> From: andy pugh 
> Subject: Re: [Emc-users] Some advice needed
> To: "Enhanced Machine Controller (EMC)" 
> Date: Tuesday, May 15, 2012, 2:37 AM
> On 15 May 2012 07:29, Viesturs Lācis
> 
> wrote:
> 
> > If I cannot get the flexible bearings, then there is
> option of
> > eccentric discs as a wave generator.
> 
> You could probably dismantle a normal bearing, machine down
> the races
> to make them much thinnner, and then press them onto an oval
> former.
> 
> CBN tooling will machine bearing races in their full-hard
> state.
> 
> -- 
> atp
> If you can't fix it, you don't own it.
> http://www.ifixit.com/Manifesto
> 
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Re: [Emc-users] Some advice needed

[charles green]

the discreet spline teeth are also an approximation.  in fact, anything made 
out of atoms is flexible and grainy.  why not construct mechanisms from 
massless rigid rods and such?


--- On Mon, 5/14/12, Viesturs Lācis  wrote:

> From: Viesturs Lācis 
> Subject: Re: [Emc-users] Some advice needed
> To: "Enhanced Machine Controller (EMC)" 
> Date: Monday, May 14, 2012, 11:29 PM
> 2012/5/14 charles green :
> > well, there's your spline form right there in the
> video.  screen capture.  the eliptical bearing is nice,
> but you can get away with a diametrically opposed pair of
> rollers for that function.
> >
> 
> No, diametrically opposed rollers is bad idea. Rollers
> determine only
> the large diameter of elipse and makes some teeth of
> flexible gear to
> engage the stiff gear. The remaining profile of elipse is
> not
> determined - it is free to flex as it wants under external
> load, so
> the stiffness of the reducer is considerably lower.
> Flexible bearing determines the shape of elipse thus
> flexible gear
> cannot take different shape under external load, so the
> reducer is
> much stiffer.
> 
> For robotic arms the stiffness is crucial.
> 
> Another problem with diametrically opposed rollers is that
> they
> require relatively low input speed, because of the same
> reason that
> they do not maintain overall shape of the elipse and at
> higher input
> speeds the flexible gear is not elipse any more, but
> something else,
> thus it hurts not only precision, but also the service life
> of the
> wave reducer.
> 
> If I cannot get the flexible bearings, then there is option
> of
> eccentric discs as a wave generator.
> 
> Viesturs
> 
> If you can't fix it, you don't own it.
> http://www.ifixit.com/Manifesto
> 
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Re: [Emc-users] Some advice needed

[andy pugh]

On 15 May 2012 07:29, Viesturs Lācis  wrote:

> If I cannot get the flexible bearings, then there is option of
> eccentric discs as a wave generator.

You could probably dismantle a normal bearing, machine down the races
to make them much thinnner, and then press them onto an oval former.

CBN tooling will machine bearing races in their full-hard state.

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