Hardinge Lathe CNC Retrofit/Conversion

[Chaz]

Hi Gary,

In my case, probably 2 factors.

The first was I had no DC controller for the motor, at least, not what I could see in the 2 machines I bought. There is meant to be a controller / drive in the 2nd machine's cabinet however the way the machine is placed means I cant open the cabinet and I cannot move / access the machine (long story).

The second was due to single phase only, when I ordered I had assumed that it would be a single phase drive, unfortunately some misunderstanding and it turned out to be 3 phase but I do run it from another VFD and it works, albeit that Ive needed to slow the ramp down time else I trip the feeding drive.

Thanks

[glbreil]

Thanks Chaz, I need to do some more study but I have two complete machines and the spindle runs and operates on both now, I assume without knowing for certain that the control probably just provides a run signal to the original spindle drive probably like a 0-10 commonly used on a VFD. Not sure I understand how the encoder plays into that for the lathe to know the spindle location, but it’s good to know that the original spindle motor and controls might be an option. That seems like it could be one of the bigger costs. Thanks Gary

[glbreil]

Just one more question, if you were doing this again would you stay with the same control and components from SZGH or would you use something different?

Thanks again Gary

[Chaz]

Thanks Chaz, I need to do some more study but I have two complete machines and the spindle runs and operates on both now, I assume without knowing for certain that the control probably just provides a run signal to the original spindle drive probably like a 0-10 commonly used on a VFD. Not sure I understand how the encoder plays into that for the lathe to know the spindle location, but it’s good to know that the original spindle motor and controls might be an option. That seems like it could be one of the bigger costs. Thanks Gary

Yep, would be good to validate, I would assume this but would need to be checked.

[Chaz]

Just one more question, if you were doing this again would you stay with the same control and components from SZGH or would you use something different?

Thanks again Gary

Interesting questions. The SZGH controller eliminates the PC stability / compatibility issue. The downside is that it feels like you are missing some flexibility and configuration options. It's all still there but not as easy / pretty. I think from a stability point of view, its great.

The only other controller Id consider at this stage is using Centroid as I have used on other machines (Mill and Lathes before). Each has its own benefits but Id never run Mach and/or CS Labs again personally.

[glbreil]

Thanks, I have what has become an older CNC mill 1997 that was built new with a Centroid M400 control. It was my first CNC anything and I found it easy to learn and operate and the few times I have had trouble I have been able to figure out the issues and repair myself, so I definitely have been looking at that as an option.

Thanks Again Gary

[Chaz]

Yep, Centroid is nice and mature and the conversational options are good too.

[glbreil]

So after doing some research it looks like I would have to replace the axis motors to go with Centroid. They have a pretty nice system that only works with AC servos, but the encoders are on the motor.

Currently the CHNC 11 has the encoders on the ball screws and there is a belt between the motor and the ball screw.

What is your feeling about the effect on accuracy if the encoders were on the motor with a belt driving the screws?

Thanks Gary

[Muzzer]

My Tree CNC lathe had encoders on the ballscrews rather than the motor, with a toothed belt between them. I replaced the brushed DC motors with LiChaun AC servos (ie encoders within the motor) and Centroid Acorn. Works fine.

I don't see any big distinction between the 2 arrangements. You still have some backlash between the ballscrew and the table / toolpost and within the slides themselves.

The next step beyond encoders on the ballscrews or motors) would be closed loop control using linear encoders (usually glass or magnetic scales). Centroid have just released the "Hickory" and "Acornsix" controllers which build on the Acorn system by catering for encoder position feedback. That might be an option if your finances permit.
https://shopcentroidcnc.com/hickory-cnc-controller/
https://shopcentroidcnc.com/acornsix-cnc-controller/

The main difference seems to be that the Hickory uses ethercat - Acornsix is probably more appropriate for the likes of us.

[glbreil]

Thanks my only real concern is that the CHNC II is billed as a super precision lathe, not that I am doing anything super precision, but I hate to introduce any additional error if it isn't necessary. When emailing with Centroid, the recommended the Hickory system and the Leadshine EL7 AC servos. If having the encoders on the motor is an ok option, it appears to be a pretty simple retrofit solution. The only other issue to overcome is that I want to use the Fanuc AC Spindle Drive and Motor, but looking at the Centroid retrofit manual, it looks like that would work as well.

I did ask them if they have a motor that will work with the Hickory controller that has a separate encoder so it could be mounted on the screw, but I haven't heard back from them yet. There are only certain motors that will work with Hickory at this time. I am not sure what is required to get the Leadshine motors mounted in place of the Siemens DC servos yet. Still looking for a drawing of the motors.

Thanks for the thoughts, Gary