What makes a good quality lathe?

I'm a novice home machinist that recently purchased a fairly new Bridgeport 9x48 lathe and a Victor 1440G lathe. I also do a fair amount of woodworking and have a Oneway 2436 lathe for woodturning. I'm confident that the Oneway lathe is well built and screams quality compared to other woodturning lathes I've seen and used. It's hard to put into words what makes the Oneway a quality machine but it's very obvious to me. That can't be said for the Victor. Somehow it seems to fall short of giving me the feeling that a lot of care went into manufacturing it. As a result I'll probably replace it with something hopefully better. So, toward that end what makes a good quality metal working lathe?

Rigidity. Rigidity. Rigidity.

beeser said:

...So, toward that end what makes a good quality metal working lathe?

Click to expand...

The same thing that makes a good quality woodworking lathe.

Just remember that a metal lathe is probably 10X more complicated than a wood working lathe. It will have many more parts
and is required to work to much more precise dimensions than a woodworking lathe. A $2000 woodworking lathe will be a
pretty nice machine--you're not going to get much of a metalworking lathe for two grand. If you take that two grand, however,
and multiply it by 10 then you're going to be looking at a much better machine. Even at that, to get a real quality lathe you
probably need to double the amount again...

As teachmeplease has said, rigidity but also how carefully the pieces and parts are finished and fit together. How smooth the controls are. Reputation from those that have used them. How quiet they are and availability of spare parts. What goes hand in hand is cost.

For instance, the old design South Bend lathes may not be the most rugged, accurate, powerful machines but they are popular because of a wide verity of parts and user knowledge. For what they are and what they are used for, they are a very good machine. On the other hand, there hasn't been the accumulated knowledge about the new ones.

You should make a list of the good and bad points of the machines you just acquired. Next what do you want to do with them. Are they big enough and heavy enough for the job you want to do? One item that BP's get down graded for is the R8 spindle. Is that good enough or do you need to upgrade to a 30 or 40 taper machine.

One of the biggest problems with import machines is the availability of parts. A lot of and maybe most of the Taiwanese machines are made by company XYZ who is never mentioned. The name on the machine is whoever sold the machine, and even if they still exist, they may not be able or willing to say who actually made the machine.

Other can and will chime in on this and hopefully cast more light than I can.

Tom

Eyes, ears, hands are your best tools to judge quality.

Example:
With your eyes closed..
Open and close the drivers door on a ten year old Mercedes.
Open and close the drivers door on a five year old Chevrolet or Ford.

Quality is not necessarily reflected in price. Trust your senses, you have already answered your own question.

For a repair shop situation, inch/metric thread cutting changeover in < 5 seconds is mandatory on at least one machine in the shop. So the completeness of the quick change feed box thread selection is important.

Also, the distance between the bed and the chip pan is important. The dinky toy lathes never provide enough room because the chip snarls don't know what kind of lathe they're supposed to fit into

Rigidity is fairly proportional to swing: you're not going to get the rigidity of a 20" lathe in a 12" lathe, but they are generally suited to the size of work that they will hold. The 'beasts' out there, while capable of heavy cutting are also beasts to operate manually because they have heavy carriages and tailstocks. I don't mind a 19" swing lathe, probably a 16" would be ok, too. The bigger the swing, the better the capacity through the chuck and spindle. A 3 or 4" spindle bore comes in real handy. A 10" or 12" chuck has a reasonable amount of chucking capacity without the jaws hanging out dangerously far. But the chuck needs a fairly good size through bore to be really handy as well. Like a 12" chuck with a 2" through bore is quite restrictive, but if your machine has a tiny spindle, then the chuck has to be made to fit.

Lathes require lots of speed variation when cutting metal. In straight gear head lathes, I haven't seen many that are superb to shift. Then, some makes of lathes will have you stopping to change the direction of the feed, whereas another will let you do that without stopping. So yeah, when you're running a metal lathe, there are plenty of mechanics to attend to in order to run the machine, compared to a wood lathe with a mere On button, and a gouge in hand, you're away.

beeser said:

That can't be said for the Victor. Somehow it seems to fall short of giving me the feeling that a lot of care went into manufacturing it.

Click to expand...

You should see some of the other stuff that's out there. Victor is actually a middle of the road machine (IMHO). There are a few better and a lot worse. There are not nearly as many high end engine lathe makers as there used to be.
JR

HuFlungDung said:

Rigidity is fairly proportional to swing: you're not going to get the rigidity of a 20" lathe in a 12" lathe

Click to expand...

have to disagree there, two of the best examples, Monarch 10EE, and anything by Dean, Smith, and Grace. agree with the other points of yours however.

cyanidekid said:

have to disagree there, two of the best examples, Monarch 10EE, and anything by Dean, Smith, and Grace. agree with the other points of yours however.

Click to expand...

True, some of those old pigs were heavy, but the average joe isn't hogging heavy all day long. I used to make a jest back in the day when I heard one of my 'modest' lathes really grunting with a heavy cut: "Either, there is somebody who knows what they are doing, or they just fucked up their part!". Usually, it was the latter. However, the lathe didn't care, it just turned.

It's important to consider quality in light of what you want to do with the machine. A Monarch 10EE is the paragon of quality, yet would be poorly suited to my needs. Too short. The right Southbend is perfectly suited to many jobs, yet doesn't qualify as a toolroom lathe (at least according to many) in terms of precision. A Hardinge HLV is a very fine machine, until you have to slide the tailstock a lot, or have the tailstock maintain alignment while sliding. Horses for courses.

I would include precision in there somewhere.

Rigidity. Precision. Rigidity

or

Precision, Rigidity. Rigidity.

Beyond that I look for the features that I know I will use and ignore ones that I won't.

TeachMePlease said:

Rigidity. Rigidity. Rigidity.

Click to expand...

EPAIII said:

I would include precision in there somewhere.

Rigidity. Precision. Rigidity

or

Precision, Rigidity. Rigidity.

Beyond that I look for the features that I know I will use and ignore ones that I won't.

Click to expand...

Maybe just precision (under load). The rigidity is there to get precision.

PeteM said:

Maybe just precision (under load). The rigidity is there to get precision.

Click to expand...

well, yes, BUT there is the factor of VIBRATION, related to HARMONICS, and cutting forces, and mass, and dynamic interaction of all the above.

this affects cutting, and it is different from a 1 to 1 relationship between load and positional accuracy. it is a bit complex in actual conditions, but generally, mass, particularly of cast iron, dampens harmonic vibration.

being able to adjust speed infinitely helps, and is one reason why VFD's are so handy.

anyone who has parted off on a small SB knows all about harmonic vibration...

Suppose we could quibble about definitions - but precision applied to a lathe (at least to me) means the lathe's ability to hold accuracy over all -- not in just one or two of the contributing factors (lead screw, cross feed, gibs, insert seats, bearing clearances, etc.) of positional accuracy. Got a .0001" tolerance to meet- bang, you've got it.

As for resonances, harmonics, and vibration on, say, the aforementioned small SB - rigidity just moves the fundamental frequency up. The main contribution of lots of cast iron, beyond rigidity, is damping.

So many things.

Rigidity. Control layout and feel (do your hands naturally fall to the controls?), materials of construction (hardened surfaces and high quality steel/iron), user serviceability, robust design (heavy castings, broad contact surfaces), speed range (if we're talkin fixed speed heads), accuracy of the components (nicely engraved dials and accurately ground lead screws), feed/threading range.

Go spend two hours on a Summit then spend two hours on a Monarch/Hendey/Lodge/etc. The quality becomes apparent.

Sent from my SM-G930R4 using Tapatalk

yup! just what I was sayin' moves the fundamental up.. the confluence of machining and music.. mass is key.. frictional losses contribute, as in a wound bass string..

cyanidekid said:

well, yes, BUT there is the factor of VIBRATION, related to HARMONICS, and cutting forces, and mass, and dynamic interaction of all the above.

this affects cutting, and it is different from a 1 to 1 relationship between load and positional accuracy. it is a bit complex in actual conditions, but generally, mass, particularly of cast iron, dampens harmonic vibration.

being able to adjust speed infinitely helps, and is one reason why VFD's are so handy.

anyone who has parted off on a small SB knows all about harmonic vibration...

Click to expand...

I was disappointed years ago when I tried heavier cuts on my "28 inch swing Hungarian lathe". It is quite a bit heavier than my 19" Summits, and has 25 hp instead of 10. When turning a decent size shaft with tailstock support, I found I could not take significantly heavier cuts without having a slowly building crescendo of low frequency vibration.So I had to back off. This might be due to the way carbide inserts form chips, or the lead angle I was using. But .25" off the diameter became my standard roughing depth, at about .015 ipr feed. That is basically what I use all the time. Taking heavier cuts also tends to have more serious consequences if the insert blows up more frequently, or the work is more likely to start to push or slip through the chuck, then disturbing the position of the center hole.

I seldom have to rough any shaft for longer than a few minutes, I don't produce mountains of chips.

All of the points brought up by the other responders are very valid, but the one point most valuable to you as a hobbyist is not so much the rigidity or power the machine has. You don't do production work. You won't push the machine or your cutting tools very hard. You have time and you're not making money. So, for you, versatility and space consumption will be at the top of your list. How many threads will the machine cut? How many spindle speeds does it have? Do you have a taper attachment? Metric change gears? 3,4,6 jaw chucks? Collets? Steady rest and follower rest? Oil cooling system? These are the most important attributes for you. I too am a hobbyist, but I have 3 lathes and 4 mills, because no machine does everything well, but most hobbyists don't have the space luxury for so many machines.

beeser said:

I'm a novice home machinist that recently purchased a fairly new Bridgeport 9x48 lathe and a Victor 1440G lathe. I also do a fair amount of woodworking and have a Oneway 2436 lathe for woodturning. I'm confident that the Oneway lathe is well built and screams quality compared to other woodturning lathes I've seen and used. It's hard to put into words what makes the Oneway a quality machine but it's very obvious to me. That can't be said for the Victor. Somehow it seems to fall short of giving me the feeling that a lot of care went into manufacturing it. As a result I'll probably replace it with something hopefully better. So, toward that end what makes a good quality metal working lathe?

Click to expand...

Store-bought, current production, ALL MANUAL lathe that is "better" than a Victor and does NOT need a rebuild?

South Korean Webb/Hwacheon.

Price may cause you to think the Victor ain't such a bad deal, after all.

Only a few old-line manual makers survive AT ALL, and they have largely migrated to CNC or "CNC assisted" lathes.

Not selling these, but here is where the mostly identical castings and other parts that used to be all-manual HBX-360 Cazeneuve lathes are earning their crust in the present era:

CAZENEUVE - Optica Siemens English - YouTube

A good quality Machinist to make it Turn.