What do I need for a C-axis?

[DocsMachine]

I have an older Acorn build, built off a Logan 11" lathe. It works, and fairly well, though some of my design choices maybe weren't ideal.

I eventually upgraded to an OmniTurn since I needed more of a true production machine capable of running flood coolant, but I still use the Logan on occasion, mainly for longer bits that require the use of a tailstock.

I have one project in the works which needs some cross-drilling. One solution to that, especially since it's going to be one of those aforementioned longer parts, is a C-axis with a small live tool that can hold a drill.

Doing a little searching around the board, I see I'll need to upgrade my "Pro" license to the "ultimate" (or 'digitizing', anyway) and of course I'll need a servo big enough to use as a spindle motor, and a driver of some sort for it.

My current setup is a first-gen Acorn (circa 2017?) with the expansion board. I'm behind on my software updates- I have no idea which version I'm on, but I know I haven't updated it in probably three years. My current drive is a 3-Phase 2HP 3450 motor on a WEG VFD. I have CSS and of course start/stop enabled, etc.

So, my questions:

2HP is about 1.5Kw. Would a servo that big be sufficient, or should I bump that up to a full two or even three?

Can anyone recommend a good servo and matching driver, especially one that's compatible with the step/direction Acorn signals?

I'm given to understand said servo will need a brake, is that correct? What would 'trigger' the brake?

What do I need to do to my current Acorn setup to enable a C-axis?

And does anyone have a... tutorial, I guess, on wiring one?

Bonus Q: Anyone have a good recommendation for a small "drill head"? I'd prefer electric rather than air or cable drive, something with maybe a built-in ER-11 collet nose? It'd only have to handle maybe up to a 1/8" drill.

Doc.

[suntravel]

First I would at least update the software.

I assume the Logan have a V-Belt driven spindle without a Gearbox?

Crossdrilling with small bits needs not that much holding torque. A servo with 2-3 kw would be good for this job, but it should drive the spindle with a HTD belt, or a Poly-V belt. The driver must be able to to switch with a input from speed to position mode.

An other way is to keep the spindle motor and attach a Nema 34 Stepper with a smaller HTD belt to the spindle running a clutch on the stepper shaft and use the stepper for C-axis

Both needs at least some macro programming.

Production quality boring units:

https://spindles.suhner-machining.com/e ... illmaster/

Or build one yourself with a small servo if you want to control the speed with 4. axis on the Acorn.

Uwe

[cnckeith]

example of what you can do with c axis video is here. https://www.centroidcnc.com/cnc_c_axis_lathe.html

[suntravel]

Would be cool to ad G17 G18 G19 to the lathe software ...

Uwe

[cnckeith]

Would be cool to ad G17 G18 G19 to the lathe software ...

Uwe

what are those functions to you?

[suntravel]

With G17 I can mill with Y Axis, but only have X and C physically:



It is called Polyform with Traub CNC

Uwe