Colin K wrote:
> Anyway, I went down tonight and put a .0005" indicator on and homed it a few
> times to see what happened. The needle snapped back to precisely the center
> of the 0 line every time. I imagine it's possible that the zero point will
> drift over time as the mechanism ages, but these
On Dec 2, 2010, at 10:35 AM,
wrote:
> As I mentioned before - We home using 2 micro switches. one switch is on the
> linear slide and one is on the timing gear.
>
> http://www.electronicsam.com/images/KandT/homesw.jpeg
>
> the 2 switches are hooked in series. so when the linear closes the
Just as a random data point in all this, I have a little 7x toy lathe
currently running with Mach2 that I'm getting ready to switch over to EMC.
It homes using a single snap-action microswitch, the kind with no lever. I
don't know if this is different from EMC, but Mach homes by backing in until
th
andy pugh wrote:
> By the time you have found the 20 transistors and soldered them to a
> proto-board you have probably spent more money and a heap more time
> than using an Arduino from the start. And that is the expensive
> option.
>
A DIP flip flop of the 74HC74 type contain about 20 transist
On Thu, 2010-12-02 at 10:08 -0500, Tom Easterday wrote:
> I really appreciate all the input! I have to say I had no idea how
> much discussion this would generate. It makes me wonder what the EMC
> user base uses for homing, or perhaps makes me surprised that the EMC
> user base is just homing in
As I mentioned before - We home using 2 micro switches. one switch is on the
linear slide and one is on the timing gear.
http://www.electronicsam.com/images/KandT/homesw.jpeg
the 2 switches are hooked in series. so when the linear closes then it waits
for the one on the timing gear to close.
On 2 December 2010 15:08, Tom Easterday wrote:
> perhaps makes me surprised that the EMC user base is just homing inaccurately
> and warm and fuzzy in their ignorance.
There may be a bit of that. I know that it would be nice if my lathe
held diameter to better than 0.1mm through a restart, but I
I really appreciate all the input! I have to say I had no idea how much
discussion this would generate. It makes me wonder what the EMC user base uses
for homing, or perhaps makes me surprised that the EMC user base is just homing
inaccurately and warm and fuzzy in their ignorance. I know I w
Jon Elson wrote:
> Oh, REALLY, replace 20 transistors with a whole computer! How about a D
> FF, with the D connected to the home switch, and the Clock
> connected to the index pulse? This does also delay the release of the
> home switch until you pass the index again, but maybe that is OK, just
On 2 December 2010 04:10, Jon Elson wrote:
>> I haven't written out the actual logic, but I could sure do it with an
>> AVR :)
>>
> Oh, REALLY, replace 20 transistors with a whole computer!
By the time you have found the 20 transistors and soldered them to a
proto-board you have probably spent m
On Wed, Dec 01, 2010 at 10:22:27AM -0800, Kirk Wallace wrote:
> On Wed, 2010-12-01 at 12:59 -0500, Stephen Wille Padnos wrote:
> ... snip
> > What you really want is an edge detector that's controlled by the home
> > switch. When the switch output is 0, the output of the detector is 0.
> > When
Stephen Wille Padnos wrote:
> What you really want is an edge detector that's controlled by the home
> switch. When the switch output is 0, the output of the detector is 0.
> When the home switch is 1, the next rising edge of the encoder will set
> the detector output high until the home switc
On 1 December 2010 19:04, Kirk Wallace wrote:
> could be used to power the PC off (and on?) to get by the ACPI problem?
I don't think there is an ACPI problem with 10.04. My LiveCD
installation powers on and off perfectly.
--
atp
"Torque wrenches are for the obedience of fools and the guidanc
On Wed, 2010-12-01 at 12:59 -0500, Stephen Wille Padnos wrote:
... snip
> I haven't written out the actual logic, but I could sure do it with an
> AVR :)
>
> - Steve
Plus, it can be used for other things. I am working on using one for a
charge-pump sensor to keep drivers disabled until EMC2 boot
On Wed, 2010-12-01 at 18:16 +, andy pugh wrote:
... snip
> However, I think we are over-complicating this. If the p-port can't
> see the index then it can't see the encoder edges and this is all
> moot.
Good point, except, I think the system in question has the encoder
connected to a stepper c
andy pugh wrote:
> On 1 December 2010 17:59, Stephen Wille Padnos wrote:
>
>> And to add to the complications, you don't know where you'll get the
>> rising edge once the axis has tripped the limit switch.
>>
> A custom comp could watch the axis.N.home-state pin. Assuming that the
> axis
On Wed, 2010-12-01 at 12:59 -0500, Stephen Wille Padnos wrote:
... snip
> What you really want is an edge detector that's controlled by the home
> switch. When the switch output is 0, the output of the detector is 0.
> When the home switch is 1, the next rising edge of the encoder will set
> t
On 1 December 2010 17:59, Stephen Wille Padnos wrote:
> And to add to the complications, you don't know where you'll get the
> rising edge once the axis has tripped the limit switch.
A custom comp could watch the axis.N.home-state pin. Assuming that the
axis is set up for two-stage homing it cou
Kirk Wallace wrote:
> On Wed, 2010-12-01 at 08:44 -0800, Kirk Wallace wrote:
>
>> On Wed, 2010-12-01 at 12:03 +, andy pugh wrote:
>>
>>> On 1 December 2010 06:26, Jon Elson wrote:
>>>
>>>
The problem with anding home and index is then the home
signal becomes a VERY
On Wed, 2010-12-01 at 08:44 -0800, Kirk Wallace wrote:
> On Wed, 2010-12-01 at 12:03 +, andy pugh wrote:
> > On 1 December 2010 06:26, Jon Elson wrote:
> >
> > > The problem with anding home and index is then the home
> > > signal becomes a VERY narrow pulse,
>
> How about using a flip-flop
On Wed, 2010-12-01 at 12:03 +, andy pugh wrote:
> On 1 December 2010 06:26, Jon Elson wrote:
>
> > The problem with anding home and index is then the home
> > signal becomes a VERY narrow pulse,
How about using a flip-flop or latch chip? They are cheap and fast, but
would need to have EMC2 d
On 1 December 2010 06:26, Jon Elson wrote:
> The problem with anding home and index is then the home
> signal becomes a VERY narrow pulse,
I think the trick here would be to set the "index-enable" pin high at
some point in the homing sequence, then home on it going low.
The bldc driver works thi
Tom Easterday wrote:
> On Nov 30, 2010, at 2:28 PM, andy pugh wrote:
>
>> On 30 November 2010 19:22, Tom Easterday wrote:
>>
>>
>>> Also, Jeff mentioned moving at a snails pace...we will be moving slowly
>>> during homing. We would get near home, find index pulse while moving
>>> slowly
Tom Easterday wrote:
> Thanks Jeff and Stephen. We were thinking of using it for home. So, if the
> index pulse is going to be different each time, then how do physical limit
> switches work any better? It is a digital input, no?
>
> Also, Jeff mentioned moving at a snails pace...we will be
A proper home switch is closed from its trip point to one end of travel,
so there's no tiny pulse to miss like there is with an index pulse.
Jeff
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Tom Easterday wrote:
> Thanks Jeff and Stephen. We were thinking of using it for home. So, if the
> index pulse is going to be different each time, then how do physical limit
> switches work any better? It is a digital input, no?
>
Right - it will work just as well as a switch, but probabl
On Nov 30, 2010, at 2:28 PM, andy pugh wrote:
> On 30 November 2010 19:22, Tom Easterday wrote:
>
>> Also, Jeff mentioned moving at a snails pace...we will be moving slowly
>> during homing. We would get near home, find index pulse while moving slowly…
>
> You can probably synthesise a nice ac
On 30 November 2010 19:22, Tom Easterday wrote:
> Also, Jeff mentioned moving at a snails pace...we will be moving slowly
> during homing. We would get near home, find index pulse while moving slowly…
You can probably synthesise a nice accurate home signal by and-ing the
limit switch and index
Thanks Jeff and Stephen. We were thinking of using it for home. So, if the
index pulse is going to be different each time, then how do physical limit
switches work any better? It is a digital input, no?
Also, Jeff mentioned moving at a snails pace...we will be moving slowly during
homing.
Tom Easterday wrote:
> We are building a plasma/router table and are using Gecko 320X with servo
> motors. The Gecko's ignore the index pulse of the encoders and so we want to
> send the index pulse to EMC.We are using a D510 with parallel port and
> simple parallel break out board. How fa
oops, in my earlier message I think I wrote "us" several times where I
meant "ns". 30us (3ns) period and 12us (12000ns) are typical
base_periods and latencies.
... and for the purposes of registering a limit/home switch closure,
that is only read every servo-period, which is typically 1ms (10
If parport.read-all is in base-thread, then the port is read nominally
each base-thread period, but in real life the interval is not exactly
the period. Sometimes it's a little later, and sometimes it's a little
earlier, compared to the nominal period. For instance, if latency test
reports a jitt
We are building a plasma/router table and are using Gecko 320X with servo
motors. The Gecko's ignore the index pulse of the encoders and so we want to
send the index pulse to EMC.We are using a D510 with parallel port and
simple parallel break out board. How fast can EMC poll an input conn
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