How to dynamically switch one ethercat servo motor from spindle to axis ?

Aciera wrote:

I gather that traditionally there is a motor with belt drive for the spindle mode and a different motor on a worm gear that is mechanically engaged for the rotary mode. Although I would be somewhat surprised if that was still the case on modern machines.

That's what I'm familiar with, although I've only seen spur and helical gears - not worm gears on the C-axis aux motor.

I think the 2nd motor for C-axis is still common, perhaps becoming less so as integral spindle motors with very high-res encoders become more frequent.

OP-
Although my lathe project has lately stalled (outside time pressures), I am using a custom component originally written by Andy Pugh to dynamically switch between spindle mode and C-axis mode.  A search for my posts over the past year should uncover some tedious fiddling I've gone through.  Perhaps more important to you, my (non-Ethercat) configs were posted a number of times.

Simplified, Andy's component treats the spindle as a C-axis which has a spindle mode.  This means that at rest the C-axis is locked.  And when the spindle mode is stopped (M5), the C-axis takes over automatically returns to the last position  - within 360 degrees - before spindle mode was engaged.

Unlike the motor configuration Aciera & I discussed above, my lathe has a single servo motor performing double-duty.  With a 1.5:1 belt ratio, I do not expect it to be stiff enough to handle any sort of 'real' milling.  But engraving, light milling, threadmilling, and orientation for drill/tap should be fine.  A 2:1 ratio would have been better, but since it's a small diameter (5C) lathe I valued higher speeds for small diameter work vs. low-end torque and C-axis holding power.

-S

Thank you ,though too profesional for a rookie like me ,I will take some time to digest this content.

timaer wrote:

Thank you ,though too profesional for a rookie like me ,I will take some time to digest this content.
 

I'm at the point where I (probably) understand the basics, but there's a whole universe of 'backstage' coding that escapes me.  Maybe I (and others here) can help you jump-start your LCNC education.

Let me know if you've got questions or don't understand something.  LCNC has a steep learning curve, and digesting the jargon can take some time.

Thanks,spumco.I quite agree that "LCNC has a steep learning curve".I'm been learning the linuxcnc about 2-3 months,so far by now,I can only configure a simple lathe or a simple mill machine,knowing a little about the hal ,maybe able to connect the general hardware by writing hal,using qtvcp to write a custom UI ,and invoke the linuxcnc 's action with python.

But for the advanced configuration such like making one servo motor both as spindle and C-axis,I've no clear map about this.I've read many topics related to this ,but due to the lacking of the strong basic knowledge,I can only understand some.Generally ,the solution seemed to use the spindle orient component to achive it (of couse,need to using other component like encoder/abs/mux2 etc.) ,it's a little complex for and the key barrior for me is that I can only controll or configure the hardware using Ethercat, and the solution seems not workable for Ethercat servo motor.but some hardware using PWM or VFD,which is unfamilar to me .

So,at the current stage,considering my poor basic knowledge about the linuxcnc.it's better to have a solution using Ethercat controlled servo motor,which can let me switch the mode from spindle to C-axis or from C-axis to Spindle ,at least I 've not found it yet . If there is a workable and mature PWM or VFD solution ,I'll also have a try .I head of that using spindle and C-axis as one is very simple in Mach3,I dont know if it is true because I never used Mach3, hope to find a good solution in linuxcnc to achive this functionality.

I don't really know how LCNC and Ethercat work behind the scenes, but I suspect it doesn't matter if you use analog, step/dir, or Ethercat to command the spindle/C-axis.

Have you done any testing yet?  If not, maybe you should have a go at it - just a single Ethercat servo on the bench to fiddle with.

I've not done any test yet .I'm still looking for a mature and workable solution for it .I'll have a try for each possible ways.