Mill to lathe transition - learning resources?

rx8pilot · Nov 20, 2018

Hello all.....looking for some reseources to help me move from milling to turning.
I just got a new job that starts next week. I will be managing the metalworking department at an aerospace engineering firm. This includes all the usual suspects - CNC mills/lathes, EDM, etc.

I am coming from 12 years owning a small design/engineering shop that only did 3/4/5 axis milling of complex parts. My milling skills are very sharp and can easily cope with complexity and tight tolerances. The new job will need me to add turning to my skillset including live tools and mill-turn. I don't need to be an overnight expert, but I do need to dive in and learn as fast as I can absorb. There are some experienced lathe machinists already in the group that can help at a practical level, but I need to be in in a better position to understand the process myself if I expect to be effective as a manager.

I am familiar with all the lathe basics after farming out turned parts for years and working with other machinsts shoulder-to-shoulder, but never actually programmed, setup, and run a turning machine myself. I have studied the various tooling and workholding options at an academic level. I have studied the geometry and kinematics of common machines over the past few years, so I have at least a working knowledge of the fundementals.

If anyone has suggestions for learning turning machines (safely), I would be grateful. YouTube, online courses, books.....anything.

Finegrain · Nov 20, 2018

My only advise is that the CNC lathe has way more inertia than the CNC mill, what with a 60# (or maybe even much more) chuck spinning at a couple or few thousand RPM. If you run the turret into the chuck, it will make a big kaboom.

Also, don't be tempted to run a long bar out the back end of the spindle without a proper barfeed support -- there are some entertaining YouTube videos of what can happen.

Regards.

Mike

D.D.Machine · Nov 20, 2018

cnc control set up milling and turning and cnc programming handbook by Peter smid are great … I am also a mill guy that has to work on lathes some … well I hate lathe work those two books have made it a lot better for me … FYI I finger cam lathe parts.

rx8pilot · Nov 20, 2018

Finegrain said:
My only advise is that the CNC lathe has way more inertia than the CNC mill, what with a 60# (or maybe even much more) chuck spinning at a couple or few thousand RPM. If you run the turret into the chuck, it will make a big kaboom.

Also, don't be tempted to run a long bar out the back end of the spindle without a proper barfeed support -- there are some entertaining YouTube videos of what can happen.

Regards.

Mike

Rule#1: Don't break yourself
Rule#2: Don't break the machine

Perhaps those are good rules to live by, lol.

One of my first orders of business is to learn the techniques and tricks to avoid the tools/headstock from getting tangled up in the chuck. In 12 years, I have not crashed a machine and I do not want to start now. 5 axis mill work provides a lot of opportunity to smash things - but I have always been bug-eyed when wathching lathes work so close to the chuck jaws.

litlerob1 · Nov 20, 2018

Seems to me there are some basic Mathematical formulas that you should memorize.

Pythagorean theorem.

L/D ratio for bars Steel=4-1 Carbide=6-1 Devibe=10-1 the rest is voodoo.

Understand SFM, not just the formula, but understand it.

Understand Toolholder nomenclature when you are dealing with indexable Tools it's important to know, it's more than just a 3 or 4 fluter.

Collision of the Turret with the rotating Chuck is NOT allowed, under any circumstances. If you are half aware, it won't happen. But the result is catastrophic, not just oops get a new holder and start over.

Clean everything, jaws, masters, collets, holders, Insert pockets, Inserts, bushings.

Programming is a snap.

When dealing with a C-Axis, everything needs to be as close to Zero as you can get it.

Understand Runout, Total Runout, Cylindricity and Perpendicularity.

Turning is much more Spiritual than Milling.

Robert

DMF_TomB · Nov 21, 2018

rx8pilot said:
Hello all.....looking for some reseources to help me move from milling to turning.
I just got a new job that starts next week. I will be managing the metalworking department at an aerospace engineering firm. This includes all the usual suspects - CNC mills/lathes, EDM, etc.

I am coming from 12 years owning a small design/engineering shop that only did 3/4/5 axis milling of complex parts. My milling skills are very sharp and can easily cope with complexity and tight tolerances. The new job will need me to add turning to my skillset including live tools and mill-turn. I don't need to be an overnight expert, but I do need to dive in and learn as fast as I can absorb. There are some experienced lathe machinists already in the group that can help at a practical level, but I need to be in in a better position to understand the process myself if I expect to be effective as a manager.

I am familiar with all the lathe basics after farming out turned parts for years and working with other machinsts shoulder-to-shoulder, but never actually programmed, setup, and run a turning machine myself. I have studied the various tooling and workholding options at an academic level. I have studied the geometry and kinematics of common machines over the past few years, so I have at least a working knowledge of the fundementals.

If anyone has suggestions for learning turning machines (safely), I would be grateful. YouTube, online courses, books.....anything.

.
cam software like mastercam has lathe tutorial books from emastercam
.
they will mention approach point like anything you approach from safe angle and distance.
.
many lathes have backlash. they dont like direction reversal. often you cut in X direction and Z dia direction separately. that it cut toward chuck OR cut in notching mode to smaller dia. some conversational will refuse to program both with same cutter. hard to describe. if you wanted to program a ball shape or spherical, backlash will cause a out of round error. obviously some machines have more backlash problems than others
.
chips not breaking up and wrapping around a part can be a real problem. most inserts made for specific feeds and speeds and doc
.
i would start with the manuals for your machine. many machines are different cannot always program same way cause of the machine being used and its parameter settings

rx8pilot · Nov 22, 2018

I have used CAMworks (sucked beyond comprehension), Mastercam (10yrs and would say it doesn't totally suck) , and most recently Fusion360.

Shockingly, Fusion360 is rather good. I have used it for some rather complex parts and it was easy to manage. For aerospace, it's a non-starter since it is cloud based data.

My new job currently has Gibbs CAM which I don't have any opinion formed. I am sure it is fine overall but I REALLY want the CAM solution to be integrated into Solidworks like I had with CAMworks and Mastercam.

With all that said, I doubt software will be much of a learning curve compared to learning tools, tool holding, chucks/workholding, and the endless secrets hiding in the lathe process. Long boring bars chattering and other mysteries of the lathe. Perhaps after setting up a few practice jobs, some of the mystery will be lifted.

At the moment, I am looking at the tool holders, insert geometries, different chucks, soft jaws, tail stocks.

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Spruewell · Nov 22, 2018

What stands out the most for me is that programming lathes is in many ways simpler, but the tooling is far more involved. In the mill you spend a lot of time focusing on setting up the part, in the lathe you must focus more on setting up the tooling.

rx8pilot · Nov 24, 2018

I spend an enormous amount of time tooling for milling. Is lathe tooling any more challenging? Very different, but looking from the outside it does not appear to be more complicated or difficult.

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litlerob1 · Nov 25, 2018

rx8pilot said:
I spend an enormous amount of time tooling for milling. Is lathe tooling any more challenging? Very different, but looking from the outside it does not appear to be more complicated or difficult.

I don't understand spending a lot of time tooling for a Mill. If you Drill a hole, if you Profile, if you Tap, if you Mill a slot. Do you mean that you spend a lot of time figuring out the most ideal Tool for the job? I Drill holes with Drills. But that's just me.

Turning is the most basic and productive form of Machining. It all depends on the parts you are making and the quantity. And the Machine itself. So what are those things?

R

Finegrain · Nov 25, 2018

rx8pilot said:
I spend an enormous amount of time tooling for milling. Is lathe tooling any more challenging? Very different, but looking from the outside it does not appear to be more complicated or difficult.

Most of my lathe OD toolpaths are done with a small # of tools -- 431 and 432 WNMG, NG3xxx groove tool for cleaning corners or thread reliefs, threading tool, and a parting tool.
The ID work is where it gets complicated. Multiple boring bar sizes and lengths, insert drills, multiple size and style grooving tools, threading, etc.

Regards.

Mike

rx8pilot · Dec 7, 2018

Spruewell said:
What stands out the most for me is that programming lathes is in many ways simpler, but the tooling is far more involved. In the mill you spend a lot of time focusing on setting up the part, in the lathe you must focus more on setting up the tooling.

After a week of lathe exercises - I can understand this comment a lot better.
The number of insert types is over the top. The boring bars, face slotting, badass insert drills, etc, etc, has me overwhelmed.

I spent some time digging through Kennametal and Sandvick online resources and catalogs tryng to get a handle on the important basics. It did not feel like I learned much becuase it is hard to tell the difference between the super special tools and the 'everyday' tools. For the most part, I can academically understand the geometry (positive/negative/neutral) (chipbreakers) (IC, edge corner radius) - but I have little confidence that I can choose the best holder/insert for a particular cut.

Hell, I am still trying to figure out how to properly load/unload the screwless inserts from cutoff/slotting holders.

Workholding is also a wild ride. The machines I have are configured with a variety of chucks ranging from 3 jaw standards to Royal collets to S type colet pads. When learning the sub-spindle transfer, I could immeadiately see that the sub spindle needs a dead length collet but I still cannot visually identify the difference. After searching for resources related to modern workholding on a CNC lathe, the best I could find was a Haas YouTube video [not exactly a comprehensive education].

guest · Dec 7, 2018

rx8pilot said:
...I could immeadiately see that the sub spindle needs a dead length collet but I still cannot visually identify the difference.

That's because there is no difference in the collets.

A "standard" collet chuck pulls the collet into a taper.

A dead-length collet chuck has the taper in a moving sleeve that slides over the collet. The collet doesn't move, so it doesn't pull the work in when it clamps.

rx8pilot · Dec 7, 2018

guest said:
That's because there is no difference in the collets.

A "standard" collet chuck pulls the collet into a taper.

A dead-length collet chuck has the taper in a moving sleeve that slides over the collet. The collet doesn't move, so it doesn't pull the work in when it clamps.

In case I was vague.....

Lathes are new to me. That is the reason I started this thread.
I do not know what I don't know. That limits the questions that I am inclined to ask.
What I am after - by any means available - are resources to tap that will help with the learning curve.

Where/How can I get a good, solid understanding of CNC lathe workholding options?
Where/How can I gain some ground on modern inserts and tool holders?
Those two topics are broad, complicated, and seemingly hard to find information on.

I am not a beginner to machining, just turning. That means I have a solid 13-year foundation in the art and science of metal cutting very precise parts with complicated geometry cut on 5 axis machines. Turning is another animal in so many ways, but I plan to attack my limitations as hard and fast as I mill parts.

Coadster32 · Dec 10, 2018

The good thing is that you are respectful of the new parameters that turning presents. Truly learning them will take time. In some essence, every turning tool is like a fly cutter...single edge cutting at whatever diameter you are turning, mostly without interrupted cutting action. That leaves chips to deal with, and where tooling selection and strategy come into play. This is where chip-breakers and CCS come into play. You may already have what you need to learn in the shop that you are already at, and may need to look no further. You may have a senior guy already in that department, and that might be the best way for you to learn. I'd start there. Yes, the Peter Smid book are good also, but you might be able to form a good bond with one of the guys in the department, while learning on the jobs that you need to get done. There truly is no better way. Good luck to you.

litlerob1 · Dec 10, 2018

rx8pilot said:
Where/How can I get a good, solid understanding of CNC lathe workholding options? In a Machine shop that has a Lathe, that you need to make parts on.
Where/How can I gain some ground on modern inserts and tool holders? Catalogues, experience, trial and error, asking about specific processes.
Those two topics are broad, complicated, and seemingly hard to find information on. That's because it's too broad, like asking "how many stars are there?"

Try making a part, when it gets confusing and you're not sure what to do next or what Tool to use, start a new Thread.

rx8pilot · Dec 10, 2018

Well, I loaded up the Doosan Puma 2000SY today and put together some test parts and programs. Taught myself how to use the tool presetter (Q Setter), and ran the programs with no parts. My post is working reasonably well, all the tool paths appeared to be correct. I ran a test with all axis, including a spindle transfer. At the moment, I cannot do that with a real part because of a problem with the live tooling and I don't have the sub-spindle configured with the correct chuck.

Tomorrow, I will put in the material and slowly work through the simpler program.

Pretty happy with progress. I have spent an enormous amount of time buried in the Fanuc and Doosan documentation, tool catalogs, and scouring the bowels of the internet. It's now time to make some chips.

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