Cutting long stock on CNC Lathe

[WakelessFoil]

Here is an update on the work holding scheme.

I switched to the collet chuck and advanced the tailstock. This is a much more rigid setup but the new issue has to do with space. As you can see in the images, there is a lot more obstacles that I need to make sure my program weaves around. I cannot even index the turret at the home position, I am sure I can work around each of these obstacles but they have turned this into a several day experiment for me. If anyone has advice or clever ways to simplify this operation, or prevent crashing, I greatly appreciate your input!

Thanks,
Justin

 

[cngbrick]

The university I am attending has only one machinist, and the engineering department is poorly outfitted IMO. I guess the bureaucrats up top think the arts are more important.

I have worked in a machine shop (manual and CNC) for over three years now. I never had a professional machinist as an instructor but I am surrounded by guys who have worked in related technical trades via a metalworking society here in Virginia. I have worked on dozens of projects almost all of which were completed without loss of quality or limb (knock on wood). I would argue that my knowledge of soft jaws is not a perfect metric for measuring my experience with metalworking in general. Regardless, I still consider myself a beginner seeking knowledge in a hobby I wish to pursue.

And I would tell the machinist where to put his voltmeter, on the basis that if I do not, he would do it anyway without guidance because he still has a job to do. I would share my experience and knowledge, rather then engaging in an internet ego battle.

-Justin

Justin,

We all have to start from somewhere, I think you would benefit from training. We are all trying to help you and several members have brought up the safety aspect. I suggest you refrain from interpreting this as a debate or "ego battle", that is not productive.

A bit of background: one of my supplier's electricians put a standard voltmeter on a high voltage generator. He did not use a high-voltage probe and was not wearing any high-voltage gloves or face shield. The voltmeter arced and blew up, causing 2nd and 3rd degree burns to all exposed skin including his face. He was an electrician but had not trained in an industrial environment with high voltage machinery.

It's not just a question of telling someone where to put the probes or how to chuck a part in a CNC lathe, the person also has to understand the implications of what they are doing. Please take the time to find someone who can look over your shoulder when you are doing your setup.

RT

 

[angelw]

I would argue that my knowledge of soft jaws is not a perfect metric for measuring my experience with metalworking in general. Regardless, I still consider myself a beginner seeking knowledge in a hobby I wish to pursue.

And I would tell the machinist where to put his voltmeter, on the basis that if I do not, he would do it anyway without guidance because he still has a job to do. I would share my experience and knowledge, rather then engaging in an internet ego battle.

Hello Justin,
If anything, the ego battle is coming from your side, the members of this Forum are simply pointing out your shortcomings when you seem reluctant to accept it.

Actually, your lack of understanding of the use of soft jaws is a fairly good measure of your experience in the machining sphere of metalworking. Soft Jaws have been employed in all types of machining operations, milling and turning, manual and automated, since day dot. But moreover, your comments in this and particularly another Thread on the use of Multi-repetitive Cycles, where you used other than the Centre Line of the machine and Work-piece as X Zero, is a clear indicator of your lack of experience in using a lathe, Manual or CNC.

With regards to your latest setup question, its unusual for there not to be clearance with a tailstock when the Turret is at the X Axis Reference Return position, but if that is the case, you simply find an area where a tool change can be carried out without interference with the Tailstock or any other part of the machine or Work-piece and designate that as your Tool Change position for your current job. Its also somewhat usual when using a Tailstock, that the Tool Change location is at the X Reference Return position and forward of the Tailstock in Z. The approach to the Workpiece after the Tool Change would be to the Z coordinate first, followed by a move to the X coordinate. To return to the Tool Change position, would be to the X location first, followed by the move to the Z location. It's the same for Manual Lathe operation when a Tailstock is involved, you simply take the Tool Post to a safe area to perform an index. All basic stuff and all to be found in books if you weren't so reluctant to read more on the subject.

Regards,

Bill

 

[angelw]

I cannot even index the turret at the home position,

And why is that? Your machine is a Nakamura Slant JR that has a swing over the saddle of 11.01".

As I mentioned in my previous Post, "its unusual for there not to be clearance with a tailstock when the Turret is at the X Axis Reference Return" and looking at the picture of your machine in your last Post, I'd estimate the flat on the top of the tailstock body to be at a diameter of circa 6", so you should have a heap of clearance to index the turret. Further, it would be incredible for the machine designers at Nakamura to be so stupid as to design a lathe where the turret couldn't be indexed over the Tailstock. Accordingly, I'll have to call BS on you again, or it's another example of your lack of experience preventing you from being able to work it out.

With regards to setting up a safe Tool Change Position, your machine is likely to have a 2nd Reference Return feature, G30. The G30 location is set by registering a value in parameters of the Incremental Distance you want the Tool Change Position to be from the G28 Reference Return Position. The value for the X Axis will be Zero and the value for Z will be a minus value from the G28 Z Reference Return Position a distance that will put the Turret at a safe location, forward of the Tailstock.

At the start and end of each Tool Operation, you should include the following code:

G30 U0.0
G30 W0.0
-------------
-------------
Program Code
-------------
-------------
G30 U0.0
G30 W0.0
M01

Regards,

Bill

 

[WakelessFoil]

And why is that? Your machine is a Nakamura Slant JR that has a swing over the saddle of 11.01".

As I mentioned in my previous Post, "its unusual for there not to be clearance with a tailstock when the Turret is at the X Axis Reference Return" and looking at the picture of your machine in your last Post, I'd estimate the flat on the top of the tailstock body to be at a diameter of circa 6", so you should have a heap of clearance to index the turret. Further, it would be incredible for the machine designers at Nakamura to be so stupid as to design a lathe where the turret couldn't be indexed over the Tailstock. Accordingly, I'll have to call BS on you again, or it's another example of your lack of experience preventing you from being able to work it out.

With regards to setting up a safe Tool Change Position, your machine is likely to have a 2nd Reference Return feature, G30. The G30 location is set by registering a value in parameters of the Incremental Distance you want the Tool Change Position to be from the G28 Reference Return Position. The value for the X Axis will be Zero and the value for Z will be a minus value from the G28 Z Reference Return Position a distance that will put the Turret at a safe location, forward of the Tailstock.

At the start and end of each Tool Operation, you should include the following code:

G30 U0.0
G30 W0.0
-------------
-------------
Program Code
-------------
-------------
G30 U0.0
G30 W0.0
M01

Regards,

Bill

I lined things up and it appears that the turret will clear the tailstock but only just and with certain tools, not with a heap of clearance. We have a relatively large 35 degree tool that came with the machine and sticks out too far to clear the edge of the tailstock. As I would rather be safe then sorry, I did change the tool change position manually in the file, and made sure it was advancing towards the spindle first in Z then in X. I am working to figure out how to set this in Fusion. I made the test cut and it all worked out. I'll try to post an update later this week.

Thanks,
-Justin

 

[cngbrick]

Difficult to tell from the picture but it looks like the tool you show may be too thick to line up with the spindle centerline when compared with the smaller one shown below so length is not the only issue unless you have a different tool holder that would accommodate it. Although it could be modified to fit it looks like the lathe is designed for smaller tools (assuming the turret is properly homed and in the X tool change location).

 

[Garwood]

Difficult to tell from the picture but it looks like the tool you show may be too thick to line up with the spindle centerline when compared with the smaller one shown below so length is not the only issue unless you have a different tool holder that would accommodate it. Although it could be modified to fit it looks like the lathe is designed for smaller tools (assuming the turret is properly homed and in the X tool change location).

Looks like he's holding a 1" stick tool that's already been milled down to 3/4" thick to fit the machine. Could probably mill off some more to suck it back in the turret further if needed.

 

[cngbrick]

Looks like he's holding a 1" stick tool that's already been milled down to 3/4" thick to fit the machine. Could probably mill off some more to suck it back in the turret further if needed.

Good observation, if the height is ok then shorten the shank so the tool clears the tailstock.