Servo as spindle for mini lathe

[Moriduri]

Hello, I'm currently retrofitting an old mini lathe to CNC using LinuxCNC as controller.
My goal is to understand how to setup a servo motor as a spindle and how to synchronize it with the Z carriage in order to do rigid tapping and plain threading (I probably won't ever do rigid tapping on this machine but for future projects it will certain come in handy knowing how to do it).
As far as I know for plain single point threading only the encoder index signal is needed, instead for tapping the encoder quadrature phase A and B are required too.
My current hardware is composed of: PCI express parport, a cheap chinese 5 axis breakout board with optoisolated inputs, Leadshine 57bl180d servo motor + ACS806 servo drive, one nema17 stepper for the X axis and one nema23 stepper for the Z axis.
The servo drive works with pulse/dir signals (I've tried to set it up as the X axis, using stepconf wizard to configure its parameters, and it works fine) and outputs the encoder differential quadrature phase A, B and index Z.
Unfortunately I've no experience at all with advanced HAL programming other than using the stepconf wizard so any advice and suggestions would be greatly appreciated!!

Thanks, Matteo

Similar Threads:

• My attempt at a servo spindle for my 7x14 mini lathe
• Need Help!- Spindle encoder Haas Mini lathe delivery
• Mini lathe and mini mill spindle?
• Mini lathe motor for spindle?
• Mini lathe headstock for Spindle

[Al_The_Man]

To give you an idea how it is done with more sophisticated systems is with the use of electronic gearing, where the servo axis is geared off of the relatively imprecise spindle encoder/axis.
AFAIK Linux has the ability to use a motion card, which may make it possible, the Galil cards I use can do it, the other alternative is the relatively imprecise 1pulse/rev method.
Al.

[Moriduri]

Setting the encoder's PPR to around 400 wouldn't allow the parport to handle it? I'd prefer to avoid extra cards if possible.

Matteo.

Inviato dal mio ASUS_Z00AD utilizzando Tapatalk

[PCW_MESA]

Setting the encoder's PPR to around 400 wouldn't allow the parport to handle it? I'd prefer to avoid extra cards if possible.

Matteo.

Inviato dal mio ASUS_Z00AD utilizzando Tapatalk

Absolutely, LinuxCNC can do anything a fancy motion card can do with only a (or a couple) parallel port(s),
if you accept the limits of lower maximum pulse rate and lower encoder resolution

Since your drive outputs A/B/Index it should be straight forward to configure LinuxCNC for threading and rigid tapping
(as long as you have direct drive so you get 1 index per turn)

[Moriduri]

Absolutely, LinuxCNC can do anything a fancy motion card can do with only a (or a couple) parallel port(s),
if you accept the limits of lower maximum pulse rate and lower encoder resolution

Since your drive outputs A/B/Index it should be straight forward to configure LinuxCNC for threading and rigid tapping
(as long as you have direct drive so you get 1 index per turn)

I can lower the PPR even more if needed (4000 default divided by 255 max), stepgen limits and therefore lower RPM max isn't that big of a problem cause for now i'm just interested in know how to make it work so that is useable.

Matteo.

Inviato dal mio ASUS_Z00AD utilizzando Tapatalk

[Moriduri]

Any ideas on how to implement those funtions in HAL?

Matteo.

Inviato dal mio ASUS_Z00AD utilizzando Tapatalk