Spindle Positioning (no C-Axis option?) Super Kia Turn 21 (SKT21)/Fanuc 0i-TC

Sparky961 · Jan 7, 2017

What are the differences between a machine with the C axis option and one that just has spindle orientation? What does it take to convert the latter to the former? How do I know whether this machine has everything (mechanical and electronic) for the C axis? Are there some half-solutions that will give useful arbitrary spindle positioning?

More detail:
Control is Fanuc 0i-TC, and there are the buttons on the front panel for the C-axis and such. Nothing related to the C axis works though, so I'm trying to figure out what's missing, wrongly configured, or what I can cobble together.

In executing the spindle orientation (M19) command, I originally thought this might just be a lock or an index sensor but the way the chuck holds is certainly using PID to hold the position of the spindle (described elsewhere as "spongy"). So, this tells me there's a pretty decent encoder and control system there but so far I've been unable to make the spindle do anything but hold this single (repeatable) position.

There's a similar thread that gave a tip regarding the use of an "S" or "B" parameter following the M19 to specify an angle. I'll be trying this after the weekend but I'm skeptical because going through the parameters related to spindle orientation and positioning (in the machine) I found that only M18 (release) and M19 (orient) were specified - not the others that specify speed, angle increments, etc.

I can provide lots more information regarding the machine config if there's someone willing to work with me back and forth to try things.

yardbird · Jan 7, 2017

You are wanting to change the orientation position?

Brent

Sparky961 · Jan 7, 2017

yardbird said:
You are wanting to change the orientation position?

Brent

Well, if that's all that's possible - then yes, and it would be more than I can do now. However, I'm looking to have a bit more control from within a program as to where I can orient the spindle. Ideally I'd have it run as a C axis with full contouring but I don't know if that's possible given what I have.

yardbird · Jan 7, 2017

Here's a thread I started a while back, have a read. The post by jashley73 will describe the process to change the orientation position. You may be able to use the information provided by Bill to create a macro to achieve something like your wanting to do?

Brent

http://www.practicalmachinist.com/v...i-td-m19-spindle-orientation-question-312095/

yardbird · Jan 7, 2017

No I don't believe you will have a full "C" axis regardless of what you do?

We have a johnsford with a "C" axis. It has M codes to activate the spindle as the "C". Then your able to hand wheel rotate, position, feed, as a separate axis. I could be wrong but I don't believe you'll be able to do this on your machine.

Brent

Sparky961 · Jan 7, 2017

yardbird said:
No I don't believe you will have a full "C" axis regardless of what you do?

We have a johnsford with a "C" axis. It has M codes to activate the spindle as the "C". Then your able to hand wheel rotate, position, feed, as a separate axis. I could be wrong but I don't believe you'll be able to do this on your machine.

Brent

I think you're probably right, but I'm interested in getting to the bottom of the "why" a bit more. Is this actual missing hardware in the machine, or is this one of those things where you pay for an option just to have someone with the "protected knowledge" come and enable a parameter bit for a large sum of money?

The way I'm seeing things at present, and not having full knowledge of the machine internals, is that there is control and feedback on the spindle so why can't I control it through the program/panel?

Sparky961 · Jan 7, 2017

yardbird said:
Here's a thread I started a while back, have a read. The post by jashley73 will describe the process to change the orientation position. You may be able to use the information provided by Bill to create a macro to achieve something like your wanting to do?

Brent

http://www.practicalmachinist.com/v...i-td-m19-spindle-orientation-question-312095/

Interesting, and very applicable to what I'm trying to implement. As I mentioned, I've not yet tried adding an angle along with the M19 so that's going to be the next step. I tried setting up an M code for half-fixed positioning. It didn't alarm out, but it didn't do anything else either. I'm wondering now if I had the spindle rotating first and followed with an M5 if that might be the key. I shall try on Monday.

If that doesn't work out, the macro idea for a timed slow rotation (if I've understood the concept correctly) may give me more than I have, but isn't completely what I'm after either. At the very least it does expand the way I'm thinking about the problem though.

yardbird · Jan 7, 2017

Might try calling the manufacturer they may be able to tell you if it's a simple parameter change or more then that?

Brent

aj · Jan 7, 2017

Is the C-Axis displayed on the position screen? Does your Kia have live tooling? If not, then what would be the point in being able to program the C-Axis?

As far as converting it, you're looking at a considerable effort, both in hardware and ladder re-programming. Not to mention it's going to be expensive. Fanuc stuff ain't cheap.

Is it something you just want to fool with, or do you have the work flow for it? If you have the work for it you might want to keep an eye out for a used 4th axis machine. It'd be cheaper and a lot easier than trying to add a 4th axis to your machine.

Just for fun, try giving it a M91 in MDI mode. If it engages, you have a programmable C-Axis. If you get an error, then you don't. And just in case it does work, M41 releases the C-Axis.

Sparky961 · Jan 7, 2017

aj said:
Is the C-Axis displayed on the position screen? Does your Kia have live tooling? If not, then what would be the point in being able to program the C-Axis?

No live tooling but there are other reasons for wanting to be able to position and/or program the spindle position if you're able to think outside the box a little.

aj said:
As far as converting it, you're looking at a considerable effort, both in hardware and ladder re-programming. Not to mention it's going to be expensive. Fanuc stuff ain't cheap.

I imagine that if there are physical components missing, then this is true. If it's just something that needs to be enabled then it could be quite simple with the correct information. So far your answer is only speculation, as no one has told me what the actual difference is.

aj said:
Is it something you just want to fool with, or do you have the work flow for it? If you have the work for it you might want to keep an eye out for a used 4th axis machine. It'd be cheaper and a lot easier than trying to add a 4th axis to your machine.

This is the typical answer that I'd expect. However, I'm not the typical guy that accepts things at face value until I've evaluated the validity of the facts at hand.

aj said:
Just for fun, try giving it a M91 in MDI mode. If it engages, you have a programmable C-Axis. If you get an error, then you don't. And just in case it does work, M41 releases the C-Axis.

I'll certainly try, but I'm doubtful that in the machine's current state anything will happen. It does not display a "C" axis on the screen and the list of M codes for the machine don't list anything for it. That's not to say the machine isn't capable though. That's what this thread is all about.

Oldwrench · Jan 7, 2017

Have four of those machines with both Oi-TC and Oi-TD controls. Sorry, but unless your TCs have live tools and a Y axis, M19 has one single position and it's only good for changing chuck jaws. Incidentally when you command it in MDI you don't want to have your hands in there because sometimes it will spin a couple revolutions before coming to position. On a Haas VMC, M19 is an option that lets you specify angular position as xxx.xxx degrees, so when I saw M19 on that Fanuc I immediately thought of slotting splines. No such luck.

Sparky961 · Jan 7, 2017

Oldwrench said:
Have four of those machines with both Oi-TC and Oi-TD controls. Sorry, but unless your TCs have live tools and a Y axis, M19 has one single position and it's only good for changing chuck jaws. Incidentally when you command it in MDI you don't want to have your hands in there because sometimes it will spin a couple revolutions before coming to position. On a Haas VMC, M19 is an option that lets you specify angular position as xxx.xxx degrees, so when I saw M19 on that Fanuc I immediately thought of slotting splines. No such luck.

Now here's a guy that's able to think outside the box.

Yup, you guessed at least one of the sorts of things I had in mind if I could get the spindle positioning working.

So, you've given some confirmation that it doesn't work as provided but the question still remains what the machine is missing to make it work. Seems like it's unnecessarily crippled to me.

It's sort of like traction control on cars that uses the ABS sensors to detect wheel spin and shuts down the spark on a few cylinders to cut the engine torque to limit the spin. The physical components are already there and it's just a few lines of code in the engine controller to make it work. Oh, and they of course charge you another $500 on the price of the car for this excellent safety "option". [And no, I don't think it's a great feature, just an example to compare to]

P.S. Initially when I started using the machine I thought it would be great for changing chuck jaws too, but it turns out I just use a dead-blow hammer on the Allen wrench and let the chuck spin freely. It's easier because you can turn it to access each jaw the same way.

aj · Jan 7, 2017

Sparky961 said:
So, you've given some confirmation that it doesn't work as provided but the question still remains what the machine is missing to make it work. Seems like it's unnecessarily crippled to me.

No, it's not "crippled". As the man says, 'it is what it is'. Did you buy a machine with 4th axis capabilities? Are you upset that it isn't a vertical mill as well?

Sparky961 said:
It's sort of like traction control on cars that uses the ABS sensors to detect wheel spin and shuts down the spark on a few cylinders to cut the engine torque to limit the spin. The physical components are already there and it's just a few lines of code in the engine controller to make it work.

How hard do you think it would be to change your car with traction control into a 4 wheel drive vehicle? What some of us are trying to tell you is the hardware isn't there. Machine tool builders usually don't add an extra $10,000-$12,000 worth of hardware and software "just in case".

Vancbiker · Jan 7, 2017

It has been a few years since I looked closely at C axis lathes so the following may be a bit dated.....

Most machine builders implement some kind of servo motor and gear drive mechanism for true C axis (ability to contour mill with the rotary axis) lathes. In turning mode the servo motor gear drive is mechanically disengaged. When the M code to switch to milling mode is read, the gear drive engages, the axis is reference returned and then positioned to the commanded position. In many configurations a brake mechanism is included too.

There are some machines that do not incorporate a servo motor and gear drive and just use the spindle motor to index to programmed positions and then lock the spindle with a brake. Best for drilling or milling keyways and such. In small turning machines like swiss types, that style is often rigid enough to allow contour milling. In larger machines that style are typically not very good at contour milling. As motor and motor control technology evolves I expect the ability to direct drive a contouring C axis will become common.

Sparky961 · Jan 7, 2017

Vancbiker said:
It has been a few years since I looked closely at C axis lathes so the following may be a bit dated.....

Most machine builders implement some kind of servo motor and gear drive mechanism for true C axis (ability to contour mill with the rotary axis) lathes. In turning mode the servo motor gear drive is mechanically disengaged. When the M code to switch to milling mode is read, the gear drive engages, the axis is reference returned and then positioned to the commanded position. In many configurations a brake mechanism is included too.

There are some machines that do not incorporate a servo motor and gear drive and just use the spindle motor to index to programmed positions and then lock the spindle with a brake. Best for drilling or milling keyways and such. In small turning machines like swiss types, that style is often rigid enough to allow contour milling. In larger machines that style are typically not very good at contour milling. As motor and motor control technology evolves I expect the ability to direct drive a contouring C axis will become common.

Ok, so almost certainly (barring a physical check) I do not have a separate geared servo one would properly call a "C" axis. This sounds like one of the differences I was originally looking for. It doesn't explain why I can't position the spindle to a specific position though. It can do one position and hold it with feedback from an encoder, so why not anywhere else on that encoder? I know there's an encoder because there's a separate toothed belt off back of the spindle going to a Fanuc encoder. That's all the feedback control needs to do a variety of nice things.

I know this is the reverse of my traction control example - as if you had a car without traction control and wanted to add it because it has ABS and electronic ignition. But the difference is that car companies don't give you access to the internals of the car's PCM. Whereas just about all of a CNC machine can be easily tweaked, configured, and completely screwed up pretty darn easily. You just need to have the right information.

Sparky961 · Jan 7, 2017

aj said:
No, it's not "crippled". As the man says, 'it is what it is'. Did you buy a machine with 4th axis capabilities? Are you upset that it isn't a vertical mill as well?

Not useful.

aj said:
How hard do you think it would be to change your car with traction control into a 4 wheel drive vehicle? What some of us are trying to tell you is the hardware isn't there. Machine tool builders usually don't add an extra $10,000-$12,000 worth of hardware and software "just in case".

Hardly a good comparison.

aj · Jan 7, 2017

Vancbiker said:
In turning mode the servo motor gear drive is mechanically disengaged. When the M code to switch to milling mode is read, the gear drive engages, the axis is reference returned and then positioned to the commanded position.

I run a Nakamura WT-250 twin spindle that works this way.

I also run two WT-150s that work the other way you describe, with direct drive on the C axis. I'm guessing it takes a lot more control of the spindle motor to do it that way.

I posted a vid on YouTube a while back of some plastic parts I was running if you want to see it.

WT 15 Live Tooling - YouTube

machtool · Jan 8, 2017

Sparky961 said:
P.S. Initially when I started using the machine I thought it would be great for changing chuck jaws too, but it turns out I just use a dead-blow hammer on the Allen wrench and let the chuck spin freely. It's easier because you can turn it to access each jaw the same way.

Try and get out of that train of thinking. You will end up getting hurt. Assuming you got it to work with a C Axis or M19, You mentioned it at post #6

is that there is control and feedback on the spindle so why can't I control it through the program/panel?

Over come the in-position window of the feed back, and its likely to do any thing up to full motor current, to try to get back to position. Up to and including doing a full turn to pick up orientation again. Not exclusive, some will fault on current or position. Others will try to rip your arms off, or throw the allen key at you.

Regards Phil.

Tonytn36 · Jan 8, 2017

machtool said:
Try and get out of that train of thinking. You will end up getting hurt. Assuming you got it to work with a C Axis or M19, You mentioned it at post #6Over come the in-position window of the feed back, and its likely to do any thing up to full motor current, to try to get back to position. Up to and including doing a full turn to pick up orientation again. Not exclusive, some will fault on current or position. Others will try to rip your arms off, or throw the allen key at you.

Regards Phil.

NEVER EVER EVER use the M19 to hold the spindle to remove chuck jaws!!!!!!! Use a strap wrench! Using M19 to hold the spindle to remove bolts can get your hands / arms ripped off or worse.....

Tonytn36 · Jan 8, 2017

Sparky,

A machine with a C axis and no separate servo motor / gear train will have a very different servo drive for the spindle than a normal lathe. If the angle command doesn't work on your machine it's because the servo drive installed has only 1 orient position available and is set by parameter. One could still probably make that work if you can edit the PMC and write some code, depending on whether the Fanuc control outputs the angle command variable from the NC to something the PMC can actually use. You could modify the value of the parameter for orient via PMC calculation from the command value in the NC. However, this is still system dependent as some controls will require a reboot to re-read some of the parameter list items.

Some parameter items are modifiable on the fly, others are only loaded at control boot. If spindle orient offset correction is only loaded at boot, you are out of luck without purchasing the entire option, which most likely would include a different spindle motor, servo drive (and both will be more expensive than the OEM parts as they are more advanced versions) and the option package for the control (which Fanuc will probably break one off in you for).

Spindle Positioning (no C-Axis option?) Super Kia Turn 21 (SKT21)/Fanuc 0i-TC

Cast Iron

Titanium

Cast Iron

Titanium

Titanium

Cast Iron

Cast Iron

Titanium

Hot Rolled

Cast Iron

Titanium

Cast Iron

Hot Rolled

Diamond

Cast Iron

Cast Iron

Hot Rolled

Diamond

Diamond

Diamond

Similar threads