On 5 July 2012 18:12, Jon Elson wrote:
>> I agree with your disagreement. The problem you describe is likely to
>> particularly acute in cases where someone has a 1:3 pulley ratio and
>> only bothers to type in the scale factor to as many significant
>> figures as they feel necessary.
>>
>>
> Nop
andy pugh wrote:
>
>
> I agree with your disagreement. The problem you describe is likely to
> particularly acute in cases where someone has a 1:3 pulley ratio and
> only bothers to type in the scale factor to as many significant
> figures as they feel necessary.
>
>
Nope, doesn't really make an
John Kasunich wrote:
>
> I respectfully disagree on this part. Counts are counts, and
> integers can be accumulated indefinitely with no error. Floating
> point math can be imprecise, and accumulating "counts times scale",
> where scale is a float, could result in accumulating errors.
>
>
On 5 July 2012 15:13, John Kasunich wrote:
>> It probably ought to add delta_counts *
>> scale to the position, not recalculate the position from total counts.
> I respectfully disagree on this part. Counts are counts, and
> integers can be accumulated indefinitely with no error. Floating
> po
On Thu, Jul 5, 2012, at 01:08 PM, andy pugh wrote:
> My initial impression is that the software encoder does not handle the
> wrap as well as it might. It probably ought to add delta_counts *
> scale to the position, not recalculate the position from total counts.
> The magic of twos-complement
On Thursday 05 July 2012 08:42:02 andy pugh did opine:
> On 5 July 2012 05:18, Jon Elson wrote:
> >> Rollover is a non-issue within the lifespan of most machines
> >
> > Not necessarily. Assume 3000 RPM and a 1000 cycle/rev encoder.
> > Typical 24-bit
> > encoder counters will roll over on a b
On 4 July 2012 22:08, andy pugh wrote:
> There is (somewhere) a config for aligning a milling spindle for tool
> change, so it's a solved problem. I just couldn't find it.
Ah, here it is. (Note that we currently have two almost-identical
threads on this subject)
http://www.linuxcnc.org/docs/html
On 5 July 2012 05:18, Jon Elson wrote:
>> Rollover is a non-issue within the lifespan of most machines
> Not necessarily. Assume 3000 RPM and a 1000 cycle/rev encoder. Typical
> 24-bit
> encoder counters will roll over on a bit over a minute (16 mil/12 mil).
> That gets overflowed to 32 bits,
andy pugh wrote:
> On 4 July 2012 21:37, Ralph Stirling wrote:
>
>
>> My thought is that it should use the C encoder all the time,
>> but with a velocity mode for normal turning, threading, and
>> CSS. Encoder rollover would be needed, but 64 bits should
>> handle an awful lot of revolutions o
Terry Christophersen wrote:
> I dont know how this is done on newer lathes but Ive seen
> older ones with an electric clutch on the spindle that engages
> and a seperate servo motor that does the milling or positioning moves
> then disenguages for normal lathe turing.
> Could an encoder be put on a
andy pugh wrote:
> Given that, I think it has got to the point where a custom HAL module
> is called for which mediates the position feedback.
Yes, that sounds right.
> The spindle doesn't have an f-error problem. I guess you could just
> ignore f-error on A too, and short-circuit the feedback.
>
On 4 July 2012 21:37, Ralph Stirling wrote:
> My thought is that it should use the C encoder all the time,
> but with a velocity mode for normal turning, threading, and
> CSS. Encoder rollover would be needed, but 64 bits should
> handle an awful lot of revolutions of the spindle.
Rollover is a
: Wednesday, July 04, 2012 1:15 PM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] A axis and spindle
On 4 July 2012 21:00, Jon Elson wrote:
> And, how to do this without causing a momentary huge following error
Ah, yes. Good point.
Given that, I think it has got to the point wher
- Original Message -
From: Jon Elson
To: Enhanced Machine Controller (EMC)
Cc:
Sent: Wednesday, July 4, 2012 3:00 PM
Subject: Re: [Emc-users] A axis and spindle
andy pugh wrote:
> The behaviour would then be that the axis would move in A-word control
> until an M3 or M4, at which point t
On 4 July 2012 21:00, Jon Elson wrote:
> And, how to do this without causing a momentary huge following error
Ah, yes. Good point.
Given that, I think it has got to the point where a custom HAL module
is called for which mediates the position feedback. (though another
mux to short-circuit the fe
andy pugh wrote:
> The behaviour would then be that the axis would move in A-word control
> until an M3 or M4, at which point the mux would direct the speed PID
> to the PWM generator. On M5 the mux would switch to the old A-axis
> position control, the oneshot would trigger, loading a "true" to th
On 4 July 2012 15:00, Kasey Matejcek wrote:
> I want to be able to turn down the part then change the tool to drimal type
> cutter tool and cut a pattern into the peace with one gcode file
>
> Is this possible?
It is possible. It isn't especially easy. It is probably easier with
servos than with
17 matches
Mail list logo
