[m-cglade]

Hi,

I am learning about CNC machines and can't seem to find this question answered anywhere.

Why can't a milling machine do lathe work? i.e if you have a 20mm aluminum bar and you wanted it 18mm, couldnt the milling machine just cut around the 18mm path?

Is it because of the finish or time?

Any help would be appreciated?

[Tkamsker]

It could be done but would have limitations and Most important it will be conic
As longer the shaft and smaller the Mill ,..


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[m-cglade]

Thanks for the reply!

If it was combined with the a 4th axis would this remove the limitation of shaft length?

Is it possible for a 4th axis to spin at speeds suitable to cut say aluminum? Then you could just lock the tool holder and use a lathe cutting tool on it?

Basically i'm considering buying a cnc mill to replace my manual mill and lathe, but I'm not sure if I need both cnc mill and lathe or if the mill can do the lathe work.

The lathe work is not complicated mainly reducing diameters,boring and tapping.

[Radcon91]

I know a few of the bigger name manufacturers build what are called "mill-turn" machines. They're basically live tooled lathes on steroids. I haven't done much research on them and my only knowledge of them comes from a few really cool videos on Youtube and tours through a couple of larger shops. So you should do some research on your own via google (it's your friend )

Hope this helps.

Josh

[awerby]

With a 4th axis mounted on a mill, you can make some parts that would normally be done on a lathe. But it's a lot slower, takes more expensive tooling, and doesn't provide the same kind of finish. On the other hand, you can make parts you never could make on a lathe.

[alexlee]

Hi,This is alex from China.
I am not sure the problem you have.You want cut 18mm from the 20mm thickness aluminum,right?
It is very easy,you can design the line for make the 18mm milling,what is the problem?

[m-cglade]

Yea I found those machines already radcon91, there called multi tasking machines (from my research anyway) I've seen the youtube videos aswell, they look awesome but something Id never consider right now. I'm looking more down the personal route like the tormach pcnc 1100. I know you can buy add on lathe parts like for example the tormach's duality lathe but I cant really see the point in it if the mill can just cut around the circular path anyway.

That's what I thought would be the reason awerby, too slow and would give a weird swirled finish? Do you know of what sort of tooling would be needed for this sort of job?

alexlee, correct, that is that idea.

So basically it sounds like it can be done but its time consuming and wont give a great finish. I think this should be okay for me as I'm doing mostly prototypes so aesthetics isn't the biggest issue and if it's slow I'll just have to factor that time in.

Thanks for the replies guys. Much appreciated.

[amish_rabbi]

google "tormach mill turn" and that should show you how to use a mill as a lathe. (alternately, it also works the other way around to use a lathe as a mill)

[awerby]

That's what I thought would be the reason awerby, too slow and would give a weird swirled finish? Do you know of what sort of tooling would be needed for this sort of job?

Since a normal rotary table isn't spinning anywhere near the speeds that lathes revolve at, you generally use endmills to cut with, not a single-pointed tool like you'd use for lathe work. Some "use your mill as a lathe" workflows do it the other way, and put the workpiece in the mill spindle (be careful not to go too fast - you want hundreds, not thousands of RPMs or things can go south in a hurry). In that case, you can mount a lathe tool to the bed of the mill and use the Z and Y axes to control it (sort of like a lathe). But this is only good for short pieces, since you can't support the end of the part with a center, like on a real lathe.

[m-cglade]

Since a normal rotary table isn't spinning anywhere near the speeds that lathes revolve at, you generally use endmills to cut with, not a single-pointed tool like you'd use for lathe work. Some "use your mill as a lathe" workflows do it the other way, and put the workpiece in the mill spindle (be careful not to go too fast - you want hundreds, not thousands of RPMs or things can go south in a hurry). In that case, you can mount a lathe tool to the bed of the mill and use the Z and Y axes to control it (sort of like a lathe). But this is only good for short pieces, since you can't support the end of the part with a center, like on a real lathe.

Ah I see, this sounds like the most plausable plan for me then as I don't really need the a centre as I work with bar no longer than 100mm.

I'm guessing this could be complicated to compute on the CNC software? Do you or anyone else on here recommend an "easy learning curve" software to make the G-code? I've heard dolphinCAM and MeshCAM are really simple but they look quite basic, i.e couldn't do the above task?

I use Autodesk Inventor for my models and looked at inventorCAM. I downloaded the demo version which is relatively easy to get to grips with but I've got a feeling it's a £5000+ software, something I can't really afford.

[awerby]

It could be calculated on any CAM software set up for running lathes. You'd have to either use the X axis for moving the tool in and out or substitute Y for X in the G-code. You might find that even a 100mm rod will have problems with deflection without end support, depending on how well it's held and how thin it is. (Wear a face shield, in case it works its way out of the spindle chuck.) And of course, you won't be able to do operations like tailstock drilling and boring, which are usual on a real lathe. Really, unless this is purely hobbyist experimentation, you're better off getting a lathe to do lathe work; even a cheap one will work much better than this.

[amish_rabbi]

It could be calculated on any CAM software set up for running lathes. You'd have to either use the X axis for moving the tool in and out or substitute Y for X in the G-code. You might find that even a 100mm rod will have problems with deflection without end support, depending on how well it's held and how thin it is. (Wear a face shield, in case it works its way out of the spindle chuck.) And of course, you won't be able to do operations like tailstock drilling and boring, which are usual on a real lathe. Really, unless this is purely hobbyist experimentation, you're better off getting a lathe to do lathe work; even a cheap one will work much better than this.

sure you can do tailstock drilling and boring, provided you have enough z you simply mount them pointing up in a fixture.

really, I would hand code this stuff though

[m-cglade]

Yeah I have now found a few videos that show the work piece in the spindle and the lathe tool in the bed, seems to work quite well.

Yeah well I am probably doing 50/50 lathe/mill work, mainly prototypes and very small production and I do have a manual lathe but would like to get away from using a manual one to free up time, Hence why I want to buy a CNC mill. But was just wondering if i could get away with doing lathe work on the mill as I can't afford both CNC mill and lathe and the CNC mill seemed more likely to be able to do lathe work as opposed to a lathe doing mill work.

like amish_rabbi says could you not do the boring just as usual with the material mounted upright in the bed and use the Z axis like normal?

Thanks for the help guys

[amish_rabbi]

not quite what I ment, you leave the material in the spindle and then just mount your lathe tools straight up. same as tailstock work

[Tkamsker]

I have a cnc lathe (factory retrofit ) which also has an cnc able Milling head ... because i also du r n d and prototyping ...

[roundman]

Each machine has it's strengths. They are different and it is true sometimes it is easy to cut round ops on a mill instead of a lathe. If one thinks it is much better to use a mill that may be true in some cases yet most of the time if it proves to be be better and more efficiently done on a mill I propose that one big reason that may seem the case is that it was not made using "best methods" on the lathe. That is inexperience in that instance. Now another thing that happens (there can be a lot of factors) is capacity meaning if your lathes are swamped one may just put a item on the mill instead which is smart. For lathe parts there is no better way to do them than on a lathe in my opinion because it is the nature of the beast that a lathe makes nice round parts with contours and radius included.

[Dodgedis]

Hi Guys,

I'm new around here and to the world of CNC machines and lathes. I have what might be a very green and obvious question. Say I have a stainless steel rod that is 50mm in diameter and 12 inches in length. The part that I intend to make will only be 1/2 in length. What is the best practice to follow before I start milling my part? Common sense tells me I should cut down the length somehow. The thing I'm asking is how do you guys go about doing this? Bandsaw, etc., etc.,? Even if this has been discussed in another section I'd love the help in pointing out its location.

Thank you guys. Your thoughts are much appreciated.

[bgriggs]

This video may be helpful.

[hoffmannm]

You want 20mm round stock --> 18mm round stock? We could do that on a mill, but if you have access to a lathe its simply the smarter way to do it.