'lo Xcuze me for the newbie's strange question of the day : Can a lathe be replaced by a milling machine for quite all metalworking? In another terms, a milling machine is more universal than a lathe or not? (It's for me : buying first lathe or milling machine?)
I am sure you will get plenty of responses to this frequent question, and the usual answer is: Buy a lathe first.
A lathe is the more versatile machine. You can do some milling on a lathe, but a mill makes a very poor lathe.
If you have a specific purpose that absolutely requires a mill, the priority could change. For example, if your typical project requires drilling and slotting pieces of 1/4" plate you would want the mill first.
I'm a newbie but I would say the basic question is whether you are going to be working with cylinderical shapes or rectangular shapes. If you plan to primarily work with rectangular shapes then you ought to start with a mill. If cylinderical shapes then you ought to start with a lathe. Neither a mill nor a lathe can really substitute for the other.
The answer depends on what sort of things you plan to build. Most of the electronics companies I've worked for didn't have or need a lathe.
I've found the lathe most useful for making power transmission components such as axles, bearings, shaft couplers and adapters, etc. However these are often easier to buy than to make, unlike structural components.
A mill can machine framework parts and drill accurate mounting holes, so if you plan to buy the shafts and bearings the mill is enough.
Segway has a good machine shop with CNC lathe and mill but so far I've been able to make everything I need here with the drill press, bandsaw and belt sander -- to 0.1mm accuracy.
Neither machine is a substitute for the other except for very simple jobs you could do almost as well with hand tools (and practice).
There's a Smithy Granite combo lathe/mill here in the shop that no one likes. I'm told it is a very awkward milling machine and the plastic gears break.
Personally I could live with a mill drill and 3"-6" mini lathe for occasional light machining. Sherlines are just too small for my home projects (log splitter, bucket loader, sawmill, etc) but I did use an old 6" Sears lathe to drill pivot pin grease passages for the hydraulic bucket loader and probably could have turned and threaded the pressure relief valve with it.
"Gil HASH" wrote in message news:42fa2239$0$926$ firstname.lastname@example.org...
The primary limitation of using a mill for turning (i.e., lathe work) is the size of piece you could handle. On a small vertical mill you might be able to handle a piece about 7" diameter and 12" long. On a small horizontal mill you might be able to do 20" diameter x 3" long. A typical home shop lathe (e.g., a 9" South Bend) can handle 9" diameter by 30" long. Conversely, a similar lathe used in milling could handle about a 6" x 5" work piece without moving the work between cuts. While turning on a mill is doable, it is a pain to set-up .. I only do it on those rare occassions when I have to turn something big diameter and relatively thin. As for which to get first .. I strongly disagree with the idea of getting a mill first if you expect to do mostly milling. The lathe is inherently more versatile. Also, milling attachments and fixtures for lathes abound. The reverse for mills doesn't hold. Another serious limitation of using a mill is the difficulty of mounting the work .. indeed, if a chuck can be mounted on the mill spindle at all. Most likely, you'd have to machine some adapters for face plates or chucks.. for which you would need a lathe. I've yet to find chuck commercially available adapters for small mills -- beyond a wimpy 3 jaw chuck like you'd find on a drill press. that is, wimpy compared to the typical chuck you find on a lathe. By the time you've tooled up the adapters you need to mount a chuck, you've already heavy into lathe work .. tapers, threads, boring, turning, etc.
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While each of the two machines can be adapted in a make-shift way to perform some of the functions of the other, they are each designed for different purposes and should be used appropriately if optimum results are wanted.
For example, in my case I have a 10" lathe (capable of rotating a 10" diameter workpiece) and a small horizontal milling machine. If I needed to turn the outside diameter ("OD") of a workpiece that was larger than
10" I *could* mount the workpiece in place of the arbor in my milling machine and then mount a cutting bit to the table, feeding it by moving the table. It would work but it would not give optimal results compared to a lathe of appropriate capacity for the job.
I could also get a milling attachment for my lathe which is mounted to the cross-slide (usually in place of the top-slide) of the lathe and provides a means of positioning a workpiece vertically. An end mill is inserted in the lathe's spindle (using a collet) and the workpiece, being clamped to the milling attachment is fed into the end mill using the carriage, etc. feeds. This arrangement is notoriously lacking in rigidity and severely limited in workpiece size capacity compared to even the smallest milling machines. For very simple operations this setup can achieve satisfactory results, but most people are disappointed by their performance.
If you study various machines you will see that they are composed primarily of cylindrical parts. Shafts, pulleys, pins, bolts, cranks, pistons and cylinders, etc. This is what lathes are designed to make best, so statistically, lathes are put to use more often than other machine tools when fabricating or repairing other machines. It depends on what you want to make with your machine shop, but I think in general you will find more use in a lathe than you will in a milling machine.
I know, for myself, my first machine tool purchase was a lathe, and once I had gotten enough tooling (accessories, specialized cutters, etc.) it kept me occupied for years before I finally bought a milling machine. It was on the lathe that I learned about the different cutting characteristics of different materials; speeds and feeds, tool geometry, etc. This vital knowledge and experience was directly transferable to use on the milling machine when I got around to buying it.
Threading is definitely possible on a mill, just not with a single point tool like on a lathe. Tapping heads for mills are a common item and many CNC mills support rigid tapping. That takes care of internal threading, external threading is less common on a mill, but can be done to a limited extent for smaller parts using a suitable die stock, or on a CNC mill via thread milling.
Conical parts can be done on a mill with a tilting rotary table although it's far from an ideal way to do it.
Generally a mill is a more versatile machine than a lathe although it will not fully replace one. If I had to decide which to buy first I'd go for the mill and try to add the lathe ASAP.
To do limited lathe type work on a mill, you would not place a lathe type chuck on the mills spindle to turn the work piece. What you do is use a rotary table or dividing head to hold and turn the work piece and use conventional milling cutters to do the work. This is why a lathe type chuck to go in a mill spindle does not exist and numerous rotary tables and dividing heads do exist.
Milling on a lathe is at least as awkward as lathing on a mill, and the mill is still the more versatile machine to have. There are certainly parts that you can make on a lathe that you can't make on a mill, and vice versa, however for typical home shop projects the mill will be able to accomplish more of the tasks.
Much of what you can't do on the mill is shafts and bushings that can be readily purchased, and in fact with a boring head you can make most of those bushings on the mill as well.
Either way, a proper shop should have both a mill and a lathe along with the proper tooling for both, which will cost more than the base machines. But start with the mill.
What holds all those cylindrical parts together? Parts that were milled mostly, and while you can inexpensively purchase shafts, pulleys, pins and bolts off the shelf, you can not purchase the pieces to hold it all together.
How often do you make your own bolts anyway vs. purchase quality bolts like perhaps grade 8 which would be difficult to produce yourself?
I have both a lathe and a mill, and the mill gets more use by a 5:1 factor or better.
Although I have done just that on a cnc mill, with great success, but on a manual mill you are correct, it is silly
I bought a lathe first, and while your argument is persuasive, I think that most 'hobbyist' mill operations can be done to some extent with a angle grinder or a file, the same is not true for turning operations. The stuff even an amateur needs [boring a bushing] is more easily done correctly, with less tooling cost, on a lathe.
In the end I say : Neither
Buy one of those old Bridgeport BOSS stepper machines and put a pc control on it
I've used my Bridgeport and a rotary table to "turn" the outside of a
30" diameter x 1/2" think piece. Also drilled a bolt circle and a few other features. I rough cut the piece to about 31" dia with a jig saw first.
Never chucked a shaft in your electric drill and gone at it with a file? Sucks, but is comparable to milling with a grinder and file.
Boring head and a pair of disposable soft jaws for the milling vice. close the vice and drill/bore the jaws to fit the bushing OD and then use the vice to hold the bushing while you bore the ID. Not ideal certainly, but quick and workable.
If you can find one. I keep hearing how they're everywhere and cheap, but I haven't seen one cheap. If you know of one let me know since I'd like to buy one. I have a 1J right now.