Acorn suitability for small 4 axis lathe.

[JoNo]

Good day,
I have spent some time digging through MANY forum posts but I think the best way to understand is to ask the questions...
I am making a small high speed CNC lathe. It is progressing well and I am looking at CNC controllers that can do the following:
Normal X/Y axis control X and Y are driven by Clearpath SDSK-3432S-ELN servos
Main spindle Speed control and C axis ( main Spindle) angular position control - the spindle is driven by a Clearpath SDHP-N1433A-ELN 3phase servo
The main spindle is a 5C collet spindle.
The spindle servo is a 2KW servo, 2700RPM with good torque, and is driven by step/direction control, with 0.02deg positional resolution.
So the Spindle must be a step pulse train from 0 to around 300000 Hz for normal turning, and then angular control using a spindle 4096 pulse encoder, with a Z ( index) pulse.

I then have a small ( 800watt) spindle to be used as a 'live' spindle for milling parts in the main spindle.
So, I need 4 axis control for all this.
What I would also like:
X and Y axis handwheels ( MPG's) - manual handwheels like on a manual lathe..so need 2 additional encoder inputs to the controller.

The toolchanger will be managed via PLC.

I am not sure if the Acorn is suitable - it does not seem to cater for more than one encoder input? But does seem to be able to handle the rest?

I would really like to use the ALLin1DC or the OAK-CNC controllers, but they do not seem capable of step/direction control, only DC or AC servos - is this correct?

Attached some photos of the lathe's progress for interest.
Any advice appreciated!

Regards
Joe

[tblough]

If you want to use manual handwheels, you won't be able to use an Acorn. You'll have to move up to the Oak and servos to get more than 1 encoder input. If you want to stay with the Acorn, then the wireless MPG is your best bet. You won't be able to move both axis at the same time, but you will be able to select either axis (actually any of the four) and use the MPG to move that axis.

[JoNo]

Thanks for your response. Since I already have all the Clearpath servo's (step/dir inputs) - I need the controller to be able to do step and dir axis control which if I am correct, precludes the use of the Allin1 and OAK controllers?
The Clearpath motors are really good, and not 'inexpensive', so don't wish to waste that investment!

More important than dual handwheels is the Acorn's ability to control the main spindle in two different, independant modes - normal spindle speed mode, using step and direction control, OR angular position control, ie, a true C axis, also with step and direction control. Where can I find out if the Acorn is able to do this?
Joe

[tblough]

A lot of people have tried running a stepper as a spindle drive. No one has posted a success story that I remember. Use the forum search function to see the previous posts.

[JoNo]

Its not a stepper per se; it is driven by step/dir signals, but it is a CLOSED LOOP AC, brushless servo - with internal drive electronics and 32000 count encoder - it is fully programmable, auto-tune PID loop control software runs to tune it in situ, etc. It makes a perfect spindle motor.

How or where do I ask questions that Centroid would answer? I am keen to get the Acorn, but really need to know if it can drive the spindle as an AXIS for pure spindle, and as C for angular axis. I simply want to do with spindle and C as the OAK, etc boards do, but using the Acorn.

[martyscncgarage]

Its not a stepper per se; it is driven by step/dir signals, but it is a CLOSED LOOP AC, brushless servo - with internal drive electronics and 32000 count encoder - it is fully programmable, auto-tune PID loop control software runs to tune it in situ, etc. It makes a perfect spindle motor.

How or where do I ask questions that Centroid would answer? I am keen to get the Acorn, but really need to know if it can drive the spindle as an AXIS for pure spindle, and as C for angular axis. I simply want to do with spindle and C as the OAK, etc boards do, but using the Acorn.

You are asking for a lot really.
You want POSITIONAL Accuracy and you want the same servo to act as a spindle motor.
You would need a drive that can take 0-10VDC input or PWM input (Version 4.6 will be able to control a spindle drive with PWM) and have reasonably accurate spindle control but then you want it to be positional, basically turning it into a C axis, then you need the pulse train to control it as an axis.

Marty

[tblough]

Its not a stepper per se;

As far as Acorn is concerned, it's a stepper. Acorn doesn't care what is downstream as long as it accepts step and direction inputs. Acorn's step and direction signals can be connected directly to a stepper motor, or a stepper compatible motor driver like your Clearpaths.

[Gary Campbell]

You will be able to achieve positional and position based rotational motion of a rotary axis using step and direction signals.

Like others have said, you will not be likely to achieve pure rotational motion for turning. You need a different type of motor. (Like Clear path MVMC control)

[GBCues]

You are in the right place to get answers from Centroid, but it IS a holiday weekend, and a long weekend for most.

[JoNo]

[/quote]

You are asking for a lot really.
You want POSITIONAL Accuracy and you want the same servo to act as a spindle motor.
You would need a drive that can take 0-10VDC input or PWM input (Version 4.6 will be able to control a spindle drive with PWM) and have reasonably accurate spindle control but then you want it to be positional, basically turning it into a C axis, then you need the pulse train to control it as an axis.

Marty
[/quote]

Hi Marty.
Thanks for your response Marty, but please can you explain - I don't understand why I am asking a lot...
The servo motor I am referencing can do all that - it can be programmed to, for example, rotate 0.029degrees ( closed loop, so it moves that amount with 0.006degrees repeatability, with a 30NM load) per step, or to move 1degree per step, or whatever you program it to move.
If set up for 6800 steps/rev = 0.052deg/step, and then you feed the motor with a 280KHz pulse train, the servo motor will spin at 2500 RPM, closed loop control, full motor torque available, etc. It does not lose steps, it autotunes its internal PID for stability in situ, etc.
This motor is fully capable of positional control and normal spindle motor duty.
The motor is the CPM-SDHP-N1433A-ELN from Teknic.

What is in question is can the Acorn switch these modes of operation on a step pulse output-
1) A variable frequency drive from 0 to some hundred KHz for spindle duty
2) A simple step pulse train for rotary axis duty.
and do this under normal G/M code control?

In essence - instead of somehow switching the 'normal' VFD driven spindle out mechanically and switching in a servo to implement a C spindle axis ( with gears, clutches, whatever), with PLC macros, etc , as the same motor can do both tasks, I just want to electronically switch the signal type function from the Acorn to the motor ( from a variable frequency pulse train, to an angle-per-step pulse train). That should not be rocket science?

Thank You
Joe

The Servo motor specs: