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256

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#1
I always wanted a nice used lathe to learn pipe threading and tapering etc. I am new to machining but know the basics.My employer has a good full machine shop to make drill pipe. What smaller but not too small used rig would you recommend for me to buy??. It needs to be automated only to the extent that the tool carriage and the chuck
are synced and move with each other.For making threads. I would guess most of them do that much.I want to spend about 5-800$.Dont care if its beat looking..
I want to start with plastic and learn and then move to steel. I want to learn first threading pipes and tapering and go from there..
 

tweinke

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#2
I think to do pipe threads you would also need a taper attachment.
 

mmcmdl

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It needs to be automated only to the extent that the tool carriage and the chuck
are synced and move with each other.For making threads. I would guess most of them do that much
As stated above . You would need either a taper attachment , tracer attachment OR a cnc machine for taper pipe threads . Also , if you plan on doing any kind of true ( large ) pipe threading , you should go with at least a 15" swing with a big thru spindle bore . JMI .
 

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As above, firstly what size pipe do you want to work on? you will need to get a lathe that will accept that size through the spindle bore so could be a quite large machine. Unless you simply want to learn the threading process on short pieces of pipe, that can be fitted into the chuck,then a smaller machine would work.

Also, as mentioned above you will need a taper attachment if you want to make taper threads, they are not usually cheap. however again if you are really only wanting to learn the process of thread cutting on a lathe then any lathe with a leadscrew and suitable change gears or gearbox will suffice.
Good luck, and have fun.
 

256

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what specific machines would you look for?
 

Bob Korves

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If it is just threading pipe that you are interested in, then I would buy a pipe threading machine. Tapered pipe threads on a lathe can be done with a taper attachment, but setting it up properly takes too long unless you will be doing larger quantities, which brings us back to a pipe threading machine, or if you are a hobbyist and time is not an issue. You can also use dies for cutting pipe threads in the lathe, but often to less than perfect pipe threads. A lot of it depends on whether the threads will be used for holding pressure or not. If not, there are more options for methods that will work adequately.

Of course, a good lathe can do lots of different jobs, not just cutting threads on pipe.
 

Bob Korves

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what specific machines would you look for?
Some lathes will not be equipped up from the factory to do some pipe threads, like 11 1/2 and 27 TPI. If the threads need to be tapered, then a taper attachment will be needed. The hole through the spindle must be capable of letting the size pipe you want to cut through it. The lathe must be in good condition and properly set up if the threads will need to hold pressure, which requires accuracy to ANSI/ASME standard B1.20.1, that would be if you want to sell them commercially.
 

P. Waller

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I have found turning taper pipe threads on a manual lathe with a conventional taper attachment to be about as slow and annoying as lathe work gets.

I suspect that there are oil field lathes with provisions for doing such work on a production level that are not NC.

However if you have many parts of different sizes to produce a NC lathe wins.
 

Bi11Hudson

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Pipe thread is tapered. It must be cut with a taper attachment, the compound won't work. Conduit thread on the other hand, is not tapered. It can be cut on any machine that that will cut the particular thread. And, pipe thread in the smaller sizes is sometimes fractional or an odd number, as noted.

For cutting pipe(tapered) thread, a die is probably the better choice. Unless it is for a spaceship or something of that nature. A pressure connection should be run in under fairly heavy torque anyway, so accuracy of the thread is usually not a big issue. Optionally, an insert from a pipe die could be set into the tool holder if the particular thread were available to use. That would cut the tapered thread, but would be a heavy load on most any machine unless you made multiple passes.

Conduit(straight) thread is permitted, by the electrical code to be cut with a pipe die. I usually loosen(?) the cutters a fuzz so it cuts a little oversize, but that's optional. So long as the fitting will pass over the thread. There are places where the conduit thread must be a couple of inches longer than pipe thread, so part of it ends up straight anyway.

Further, as noted, the pipe should be able to pass through the headstock for any usable length. For anything over 1/2" pipe, that involves a full sized machine. Over 3/4", you're talking big bucks. The only exception there(literally) is for a short(close) nipple. What must be kept in mind here is that the 1/2" is nominal ID and requires almost a 7/8" hole to pass through. I use a Craftsman 12X36 with a MT-3 taper and my passthrough is limited to 3/4", too small for 3/4" pipe. So, you're talking a large machine from the git-go.

Bill Hudson​
 
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Bob Korves

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What must be kept in mind here is that the 1/2" is nominal ID and requires almost a 5/8" hole to pass through.
Bill, 1/2" NPT is .840" nominal O.D., larger than 3/4".
 

Bi11Hudson

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ayeah, I hit the wrong key, 5 over 7. And you caught it before I could get back to edit. Thanks though.
 

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Member 256 has asked our advice and maniy of us have asked him for more information, but he has not come back to us with that info so we are really just guessing as to what his purpose is.
 

Bi11Hudson

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Actually, he was pretty clear (from the perspective of an old school electrician) in what he wanted. Basicaly, with little practical knowledge of machine work, he wants to learn machining. Like most of us, he wants to start with something he has an understanding of. That's always a good starting point.

I got into the electrical field because I wanted to make my model trains run better. That branched out to become an electrical engineer and provided a lifetime of employment. See www.hudsontelcom.com in a paper about home shop electrics. It has been clipped short for liability purposes. Ya got to restrain those lawyers, ya know. But at 50 pages, still an extensive read. But worth it, if you want to understand the nuts and bolts of how your machine works. And written by a man that has little formal schooling. (I did finish the 7th grade)

The machining came much later, but also to work on my trains. And do smaller, and finer, work. And bigger models, although at that size, 1/5 scale, they aren't considered models anymore, they're minatures. Any time you start something new, find a known reference point and go from there. You never know where you'll end up.

Bill Hudson​
 

256

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#14
I will learn the lathe if I can find a good cheap machine...i will never spend much money on it..
 

Bi11Hudson

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Your stipulation of the linking of the toolpost to the spindle means thread cutting capability. Most of the machines of any size today have that, to one extent or another. Most any machine from 6 inch or more will have it. Buying used puts you on your own. Whatever you buy, you would find support for it here. Buying new would get costly real fast but also get some support from the manufacturer.

At the low end (less than $2000) would be (in ascending order) Harbor Freight, Grizzly, and any number of discount tool suppliers. A little further up the scale would be LMS, Little Machine Shop, another well known on-line supplier. It goes up from there. As a rule of thumb, most machines today (and all the cheap ones) will have been made in China. There are a few that are made in Europe, but while good, they get real expensive, real fast.

Again, buying used will usually be cheaper. Good for learning, such a machine will lack many specialty devices but can be written off in its' entirity once you know a little about what you're doing. The big problem is with the seller, who often knows little, or nothing, about machine shop equipment. Or what goes bad on a used one. One option there is to find recommendations from someone that can physically look at the machine and judge whether or not the machine is really worth the asking price.

The big issue here is your stated desire to learn from a given reference point. Pipe threading means a fairly big machine. It will get real expensive, real fast. And takes a lot of space. The one advantage is that most specialty tooling can be passed down to a "keeper" machine. Again, you're on your own there.

My advice, such as it is, is locate something really cheap and learn what you must know. Then take it from there. Beyond that, advice is much like ***holes, everybody has one and most of them smell pretty bad. I'm not a machinist so most of my opinion should be taken with quite a lot (as opposed to a grain) of salt. At your stage, Harbor Freight is as good as any. Their 6X12 does cut threads, but with plastic gears. About all it has going for it is that it fits within your budget. You seldom find them used, most people put it up on a shelf or throw it out when they acquire a bigger one. Whatever you buy, make sure you get the loose gears with it. They are real important.

Bill Hudson​
 

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I will learn the lathe if I can find a good cheap machine...i will never spend much money on it..
I always remember some sage advice "good aint cheap, and cheap aint good"

But whatever you choose to do, good luck with it.

Can you talk to your employer about your desire to learn machining threads, is it possible he could help, some instruction perhaps, or even the use of his machines, and or some advice on second hand machines he may know of. Are you wanting to learn thread cutting so as to be of more use to your employer or just curiosity. If you show some enthusiasm for thread cutting would he be prepared to train you and put you to work on the threading jobs.
 

MrWhoopee

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I will learn the lathe if I can find a good cheap machine...i will never spend much money on it..
Metalworking is expensive. You might pick up a cheap machine, but it either will not do what you have in mind or it will be expensive to move, repair and tool. Either your budget or your expectations must change.
 

Chuck K

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#18
If you're first objective is to learn threading, I would shy away from the little imports and focus on something with some rigidity. South Bend, Logan, Leblond, ect. Just my opinion.
 

P. Waller

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Simple really.
If one desires to single point Tapered Pipe Threads then buy a machine capable of doing so on the pipe sizes required.
There is no magic here simply the limitations of the machine itself.

Single pointing such threads requires much less power when cutting and far less work holding force. One of the problems with tapping and die cutting pipe threads is holding the work in a traditional engine lathe chuck, the part will spin in the chuck well before you develop enough force to break the tool in pipe over 1 1/2 NPT.

I do a recurring job for the local Municipal water treatment plant, normally 2-4 parts per month. They are 2 1/2 NPT threads on each end, they supply the material, 304 SS in 24-60" lengths. I use a common Rigid die head with SS specific inserts held in a 24" 3 Jaw chuck on a W&S turret lathe that is 5" through the spindle and has a 25 HP spindle motor. This setup produces excellent threads but will easily spin the part in the chuck. If you want to die cut pipe threads purchase a pipe chuck for this purpose.

The limiting factor for any lathe is the spindle bore therefore choose a machine with the minimum spindle bore that your parts require.
This makes the decision very simple.
Look for "Oil Field" lathes, these are exactly what you want (-:
 

256

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#20
can I get a mini lathe used for 300$ that is good for training on 1-2 inch pipe??Maybe 30 inch capacity..
 

MrWhoopee

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Bob Korves

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can I get a mini lathe used for 300$ that is good for training on 1-2 inch pipe??Maybe 30 inch capacity..
Cutting threads on 1-2" pipe with a mini lathe will mostly be an exercise in futility. Not enough power or rigidity. 1" perhaps, but still not without nursing it along, especially as a beginner. The pipe will want to slip in the chuck as well. It will not fit through the spindle. The threads will also not be tapered. The mini lathe can, however, help you learn how to use a lathe, and for making other parts. For threading pipe, nothing beats a pipe threading machine. Making pipe threads at home by hand with dies works pretty well, but a good, solidly mounted vise with pipe jaws, or preferably a pipe vise, is needed for 1" and larger pipe. A much larger standard machinists lathe will be more suitable for working with pipe, but is still not close to ideal for the job.
 

256

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#23
what would you buy for a used pipe threader manual or auto and what price?? the RIGID ones are 1000 new ...way too much..
 

Bob Korves

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what would you buy for a used pipe threader manual or auto and what price?? the RIGID ones are 1000 new ...way too much..
Sorry, I do not know much about pipe threaders, never used one, have watched them in operation a few times. Hopefully someone else can answer your question.
 

MrWhoopee

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what would you buy for a used pipe threader manual or auto and what price?? the RIGID ones are 1000 new ...way too much..
I've kind of been watching them on CL, they're generally $500+ depending on condition, capacity and dies. If you can get work for them, they'll make you a lot of money. You won't learn much operating one, though.
 
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