Hi Tom,
So if I only want to monitor the spindle speed a 1-pulse solution would do if I read you reply correctly. As I have the drawbar in daylight so to speak I could print stripes and glue these on the shaft and probably get many pulse via optical reader or even readers to make a simple encoder with >8 stripes or something like that.
This is the way I have Mach3 reading the spindle rpm today but here I would not be needing minimum pulsewidth as with printerport/Mach3.
For tapping I have floating tapping heads so maybe above would do?
Will have to investigate and see what can be obtained from the VFD.
Cheers
Bengt
--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
> Hi Bengt,
> Â
> I think an encoder is required to do rigid tapping. With a single pulse there is no reliable way to tell when the motion has been reversed besides having an error of up to a full rev (a full thread). The only solution I could see would be if the VFD followed the commanded speed very accurately so you could use dead reckoning to predict where it should be based on your command combined with single pulse feedback to correct for long term drift. But this would be very complicated.
> Â
> Doesn't the VFD put out any information on how it is commutating the 3 phase motor?
> Â
> Regards
> TK
>
> From: Bengt Sjoelund <cnc@...>
> To: DynoMotion@yahoogroups.com
> Sent: Friday, February 10, 2012 1:07 PM
> Subject: [DynoMotion] My CombiMill is alive
>
>
> Â
> Hi Tom & all Kfloppers,
> At last I have some motion on all my axis, I have installed berak resistors to my VSD-XE servos and now I dont get errors/faults due to overcurrent. Still some details to tune inside VSD but I can see the light in the tunnel.
>
> Question for future, as I have 3-phase driven spindle motor controlled via VFD (0-10V)there is no feedback to Mach3/KMotionCNC. What is minimum needed as regards pulses from the main spindle shaft, is it doable with 1-pulse/rev just to monitor spindle rpm.
>
> If I want to do some rigid tapping what is the minimum needed for that?
>
> There is no easy way to put in an encoder as I have to dig deep into the spindle head shafts and enclosure to be able to attach suitable shaft extension for encoder.
>
> Interested to hear how you guys have solved this type of problem on retrofitting older CNC or manual milling machines to KFlop/Kanalog.
>
> Cheers from a freezing cold Sweden
> Bengt
>
