2012/7/15 Steve Blackmore st...@pilotltd.net:
On Sat, 14 Jul 2012 11:27:30 +0300, you wrote:
Yes, I actually did what Andy said - overlooked the mechanics, because
in all joints there are Nema42 stepper motors connected to Festo
cylinder with ballscrew inside. I do trust those 2 things a lot,
On 15 July 2012 02:56, Kasey Matejcek someo...@lkm.bz wrote:
No home made
With optical pickup
The problem with a single-channel encoder is that if you double-count
an edge then the apparent velocity appears to suddenly increase
massively.
Quadrature counting almost entirely eliminates this
Yes this is what I have 2 optical pickups setup n+1/2
The disk has 125 holes and appears to work right and fare as being able to
detect directions
And when I turn the spindle one rotation the encoder count moves 500 counts
-Original Message-
From: andy pugh [mailto:bodge...@gmail.com]
On 15 July 2012 13:39, Kasey Matejcek someo...@lkm.bz wrote:
The disk has 125 holes
And when I turn the spindle one rotation the encoder count moves 500 counts
Yes, that is normal. Encoder counters count every transition, so a 512
slot encoder is 2048ppr. But if you turn the spindle slowly
On Sunday 15 July 2012 08:32:08 andy pugh did opine:
On 15 July 2012 02:56, Kasey Matejcek someo...@lkm.bz wrote:
No home made
With optical pickup
The problem with a single-channel encoder is that if you double-count
an edge then the apparent velocity appears to suddenly increase
On 15 July 2012 14:45, Gene Heskett ghesk...@wdtv.com wrote:
But the internal calculations for velocity etc are done at the servo
threads granularity of nominally 1 millisecond. So there is no chance of
the figures being accurate when the count may be up to a millisecond old.
The counts
On Sunday 15 July 2012 10:32:13 andy pugh did opine:
On 15 July 2012 14:45, Gene Heskett ghesk...@wdtv.com wrote:
But the internal calculations for velocity etc are done at the servo
threads granularity of nominally 1 millisecond. So there is no chance
of the figures being accurate when
On Sunday 15 July 2012 11:10:43 andy pugh did opine:
On 15 July 2012 14:45, Gene Heskett ghesk...@wdtv.com wrote:
But the internal calculations for velocity etc are done at the servo
threads granularity of nominally 1 millisecond. So there is no chance
of the figures being accurate when
Kasey Matejcek wrote:
No home made
With optical pickup
Well, have you checked the quality of the signals, especially when the
spindle drive is running the motor? There may be some kind
of interference that is upsetting the encoder/counter circuit.
Probably examining the encoder velocity
andy pugh wrote:
Yes, that is normal. Encoder counters count every transition, so a 512
slot encoder is 2048ppr. But if you turn the spindle slowly you should
see them count up in ones.
How accurate is the 90 degree shift? Halscope might be able to tell
you at a slow steady speed (if the
Gene Heskett wrote:
But the internal calculations for velocity etc are done at the servo
threads granularity of nominally 1 millisecond. So there is no chance of
the figures being accurate when the count may be up to a millisecond old.
Perhaps with more resolution than my 39 cycle wheel,
andy pugh wrote:
On 15 July 2012 14:45, Gene Heskett ghesk...@wdtv.com wrote:
But the internal calculations for velocity etc are done at the servo
threads granularity of nominally 1 millisecond. So there is no chance of
the figures being accurate when the count may be up to a millisecond
Gene Heskett wrote:
But does it timestamp that data marking the last time it changed?
It is done in a different way, but it DOES work. It only keeps the
timestamp of the last
change, and the running timestamp clock. By comparing the two numbers,
you know
how long ago it has been since the last
It's been a harrowing two days after catastrophic failure of a rather old PC
PSU (of the Mach 3, not LinuxCNC host) generated sufficient mains transient
to cause subsequent failure of two low power transformers (one open circuit,
the other flashing over at primary line voltage despite normal
On Sunday 15 July 2012 16:45:27 Jon Elson did opine:
Gene Heskett wrote:
But the internal calculations for velocity etc are done at the servo
threads granularity of nominally 1 millisecond. So there is no chance
of the figures being accurate when the count may be up to a
millisecond
On Sunday 15 July 2012 17:01:22 Jon Elson did opine:
andy pugh wrote:
On 15 July 2012 14:45, Gene Heskett ghesk...@wdtv.com wrote:
But the internal calculations for velocity etc are done at the servo
threads granularity of nominally 1 millisecond. So there is no
chance of the figures
On Sunday 15 July 2012 17:15:06 Jon Elson did opine:
Gene Heskett wrote:
But does it timestamp that data marking the last time it changed?
It is done in a different way, but it DOES work. It only keeps the
timestamp of the last
change, and the running timestamp clock. By comparing the
On 15 July 2012 22:14, Gene Heskett ghesk...@wdtv.com wrote:
Sure there is Jon. Timestamp the last 4 edges so you can develop an
average speed over the total time period of those 4 stamps.
That's quite a lot like putting a lowpass on the velocity output.
I know you want a more satisfactory
On Sun, 15 Jul 2012 09:45:06 -0400, you wrote:
When cutting threads with the G76 canned cycle, with the spindle between 2
and 6 rps, it cuts great threads, but the racket as the z motor tries to
track this noise is similar to slowly dropping a shovel full of pea gravel
into a washtub. I
On Sunday 15 July 2012 20:51:58 andy pugh did opine:
On 15 July 2012 22:14, Gene Heskett ghesk...@wdtv.com wrote:
Sure there is Jon. Timestamp the last 4 edges so you can develop an
average speed over the total time period of those 4 stamps.
That's quite a lot like putting a lowpass on
On Sunday 15 July 2012 21:49:10 Steve Blackmore did opine:
Hi Steve, long time quiet it seems.
On Sun, 15 Jul 2012 09:45:06 -0400, you wrote:
When cutting threads with the G76 canned cycle, with the spindle
between 2 and 6 rps, it cuts great threads, but the racket as the z
motor tries to
I'll hook up a scope to it and check the phase on them
I've looked at one at a time so fare and there pretty clean on my 20mhz
scope
I'll get the 2 channel out and check both and the same time and phase
-Original Message-
From: Jon Elson [mailto:el...@pico-systems.com]
Sent: Sunday, July
Greetings all;
This need for a long allen set screw as the starting material for this
differential screw that Andy reminded me of is being a problem. fleabay
searches don't seen to be getting any hits tonight.
1. I am not enamored of the idea of heating up a piece of redi-thread and
Gene Heskett wrote:
Sure there is Jon. Timestamp the last 4 edges so you can develop an
average speed over the total time period of those 4 stamps.
Sounds great at first, but then you are basing the control loop on past
history, which makes
it even slower to respond to what is happening NOW.
Gene Heskett wrote:
On Sunday 15 July 2012 17:15:06 Jon Elson did opine:
All our boards use the parallel port, they don't use PCI slots. But,
right now only the
UPC has the encoder timestamp feature.
Jon
URL?
The overall one is :
Sure there is Jon. Timestamp the last 4 edges so you can develop an
average speed over the total time period of those 4 stamps. Then add the
last few digits for the position it is expected to be at the servo threads
time. The only thing to complicate that would be a motion reversal within
andy pugh wrote:
On 15 July 2012 22:14, Gene Heskett ghesk...@wdtv.com wrote:
Sure there is Jon. Timestamp the last 4 edges so you can develop an
average speed over the total time period of those 4 stamps.
That's quite a lot like putting a lowpass on the velocity output.
No,
Steve Blackmore wrote:
Same thing here too with G33. LinuxCNC is coats of paint better than
Mach at threading, but it's not right. Twitchy is the best description I
can give,
I have two CNC lathes, they are radically different with hardware but
both behave the same - they jitter really
Gene Heskett wrote:
I tried that too Andy, but the 'gain' had to be cranked into the .001 range
to get a value that only had the last 5% in it, and at that gain, the
settling time was many seconds. The basic problem there is that the last
value clocked in is 50% weighted. If the whole
On Sunday 15 July 2012 23:29:40 Jon Elson did opine:
Gene Heskett wrote:
Sure there is Jon. Timestamp the last 4 edges so you can develop an
average speed over the total time period of those 4 stamps.
Sounds great at first, but then you are basing the control loop on past
history, which
On Monday 16 July 2012 00:04:34 Jon Elson did opine:
Gene Heskett wrote:
On Sunday 15 July 2012 17:15:06 Jon Elson did opine:
All our boards use the parallel port, they don't use PCI slots. But,
right now only the
UPC has the encoder timestamp feature.
Jon
URL?
The overall
On Monday 16 July 2012 00:07:18 Peter C. Wallace did opine:
Sure there is Jon. Timestamp the last 4 edges so you can develop an
average speed over the total time period of those 4 stamps. Then add
the last few digits for the position it is expected to be at the
servo threads time. The
For that I would have to build a generator in order to send the proper
quadrature.
A single 74LS74 dual D-flip-flop can generate a perfect quadrature
waveform from a single channel square wave generator. If you need
a schematic for that I can sketch it out in the morning.
-- Ralph
On Sun, Jul 15, 2012 at 11:47 PM,
emc-users-requ...@lists.sourceforge.netwrote:
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