What to look for in a lathe

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I was thinking about picking up a lathe, but I don't know anything about them really.  What are some of the key things I need to look for?  What should I avoid?  Any useful pointers would be appreciated.The Lord has declared, "This is my work and my glory--to bring to pass the immortality and eternal life of man"  Moses 1:39Link: My name is John, and I am a member of The Church of Jesus Christ of Latter-Day Saints.-- ColdCreekWorks.com --
Reply:Stupid question, but wood or metal?Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:Originally Posted by GambleStupid question, but wood or metal?
Reply:Look at they ways if it is a used lathe. Make sure they are in good shape. Make sure there isnt much slop in the cross slide. Watch the numbers or thousandths hash marks on the handle that moves the cross slide, turn it to the right several turns and stop. Then slowly turn it to the left until you feel the carrige start to move. A little slack is normal .003-.004. To much could mean wear. Does everything work? Does the feed engange and disengage easily? Put a peice of round stock in it that is a long as possible. Needs to be a larger diameter peice so you wont get flex in the metal. Make several light cuts the full length of the metal. Measure both ends, if it is larger at one end you can normally take up the difference by centering the tail stock if the center is larger or smaller then there could be exessive wear in the carrige and takes someone that knows how to adjust the carrige to get it out, if it can be gotten out. Find out if the lathe is single phase or three phase (which will require a phase converter, more money) and is it 110, 220, or 440 These are just some of the things to look for in a used lathe. Finally the most important thing to look for is the size of the machine. Try and decide the biggest thing you might have to turn and get a machine that is bigger than that. Good luck.Last edited by bhardy501; 02-27-2012 at 01:55 PM.
Reply:It all starts with the bed. Inaccurate bed = inaccurate machine, no two ways about it. If you are looking at one on-site, there are a few tricks you can try to check bed wear. The first is visual. Look for wear ridges where the carriage rides on the bed vs the area it does not make contact with. Usually, they'll be more wear near the headstock of the machine. Another trick is to run the carriage all the way up to the headstock. Set the carriage lock so it is just barely dragging, but the carriage still travels pretty free. Start moving the carriage towards the tailstock. If the bed is worn, it will start tightening up as you get closer to the tailstock. Obviously, about the BEST way is to take a test cut, but many times this isn't an option when you are just "checking one out" that popped up in the classifieds. If the bed truly is worn extensively, there are very few options. One is to let it be, and take what accuracy you can get. Lots of people do this, and some of them can work around it and still turn out pretty darn good parts. The other is to have it re-ground/re-scraped. You most likely do not want to mess with this. Having one re-scraped or re-ground could easily exceed what you paid for it in the first place, especially if you have to have everything turcited and refitted or shifted down to compensate for the loss of thickness.Next, you move on to the headstock. The headstock should run free, and shouldn't make any odd noises. Make sure not to confuse any gear noises with noises coming from the headstock. Any clicking noises could indicate loose rollers in bearings, if it indeed has roller bearings. Obviously, you can grab the spindle with your hand. It shouldn't have any radial play that you can feel by hand. If it has play in the thrust, that may not necessarily be a show stopper. If it's a conventional bearing machine, you can almost certainly adjust the thrust back to an acceptable level. It's designed to be adjusted. If it's a tapered roller bearing head, you can probably re-set the bearing pre-load and take the thrust out, too. Now on to the cross slide and compound rest. As suggested bhardy501, check them over the extents of their travel. They could adjust the gibs such that they are nice and snug in their most frequently used range of motion. If this is true, they will turn free until you start to get to either extent, where they will start to bind and tighten up. Backlash is not really a big deal like people make it out to be. It can be a bit tedious to work around, but it generally doesn't affect accuracy much, if at all. And on top of that, it can usually be remedied with simple parts swaps (as long as you can find part.)Next, check out the gearbox (if it has one) and the leadscrew, as well as the half-nut and power feeds (if any). Try changing gears on the gearbox, make sure it engages. Make sure the forward and back works if it is has a reversible gear box. Also look at the leadscrew. It will most likely be an ACME thread. which is more of a rectangular thread, which means the major diameter of the thread will be flat, not pointed like a regular thread. If it is pointed, it might have a lot of wear. Lock in the feed for threading (which engages on the leadscrew). Once engaged, see much you can move the carriage back and forth. It will move soon, but if it moves a lot, the half nut probably has a lot of wear. To be honest, half-nut wear usually isn't a big deal, as long as it engages good and stays that way. Half-nut wear is better than lead-screw wear. Some machines have independent power feed and feed for threading so you don't wear your leadscrew and halfnut when you don't need it. Check them both if they are there. Now have a look at the tailstock. Make sure the quill feeds in and out nicely and smooth. Make sure it doesn't have any noticeable radial play, especially when only extended a few inches or so. Run your finger inside the quill and feel for dings, nicks, etc, on the morse taper on the inside. Make sure the lock works. Check out the drive system. Look for nicked teeth on gears, old worn out belts, etc. See what voltage requirements it needs. If it's a geared head, try all the the gears out, and make sure they run smooth. Don't worry if it makes a little more noise running in reverse than forward, all gear head machines do this. I'm sure I left some stuff out. If I think of it I'll add it. Have fun!!
Reply:If you want to learn about lathe operations, buy new. If you have the money, your life will be easier. If you are the type that likes tearing into a complete overhaul, solving puzzles, and learning Life's Lessons in a hands on fastion, often the hard (i.e. expensive) way, buy used and just have fun. Some prior experience like engine rebuilding can be helpful here. Bed condition has been mentioned. Another basic item of any lathe is the spindle. As you rotate the spindle slowly by hand, if there are any consistent "tight spots" during rotations, it is bent or otherwise damaged.Here's a fun site to explore http://www.mermac.com/index.htmlI'd suggest a small lathe, as a learning experience. The only lathe I've ever operated in my life was a big LeBlond while a graduate student at Cal, and that was decades ago. Such a lathe can do everything you could possibly need, but takes up a fair amount of space, is quite heavy, and simply outside my experience level and needs and, most importantly, my budget. I'm not a machinist nor will I ever be. So last Fall I bought a running, albeit "well used", Atlas 618 with a bunch of tooling off CL which had sat in a shed unloved collecting dust for the past 20 years for not much money. I hope to have it semi-operational in another 3-4 months. Sure, I won't be contracting with NASA to produce parts for the shuttle, but that's not my ambition. With it, I hope never to be without those special tools, parts, and fixes, all of which seem to made from Unobtainium, but are simply fabricated on a lathe for the work at hand. A lathe is the only tool that can construct a copy of itself.Last edited by wirehead; 02-27-2012 at 08:05 PM.Reason: link updatedXMT304 (school)SP125+ (home)HF 4x6 BandsawGood judgement comes from experience and much of that comes from bad judgement.
Reply:some lathes some smaller home sized ones come with either a quick change gear box,or  just a pile of extra gears that you have to change out manually...These different gears are used to cut different thread pitches..But can also control the automatic feed ..First off try to find a lathe with a quick change gear box,its kind of like a lever you just shift , instead of manually unbolting the gear and putting on a different one..If its a manual change gear one ,make sure all the (loose) gears are included,and not damaged..gears are horribly expensive..I got a small 10" lathe with about 15 of the change gears missing ,I wrongfully assumed gears cant cost much.wrong ,looking on ebay at used lathe change gears,the few ones i can find at least ,are 35-100$ each ..Get one that comes with as much stuff as possible..This will be your first lathe you'll want better ones once  you get hooked..Get the biggest one you can find..they are not bad to move..bigger = heavier = better finishes ,deeper cuts..youll be amazed at what you can do with a latheLast edited by ak4130; 03-01-2012 at 01:52 AM.
Reply:Originally Posted by jdh239I was thinking about picking up a lathe, but I don't know anything about them really.  What are some of the key things I need to look for?
Reply:Originally Posted by jdh239I was thinking about picking up a lathe, but I don't know anything about them really.  What are some of the key things I need to look for?  What should I avoid?  Any useful pointers would be appreciated.
Reply:What do you guys think of this?http://www.smithy.com/midas/pricing/ltdThe Lord has declared, "This is my work and my glory--to bring to pass the immortality and eternal life of man"  Moses 1:39Link: My name is John, and I am a member of The Church of Jesus Christ of Latter-Day Saints.-- ColdCreekWorks.com --
Reply:hmmm... noticing a lot of people don't like the combo machines.... and particularly the mill portion of a smithyThe Lord has declared, "This is my work and my glory--to bring to pass the immortality and eternal life of man"  Moses 1:39Link: My name is John, and I am a member of The Church of Jesus Christ of Latter-Day Saints.-- ColdCreekWorks.com --
Reply:Originally Posted by jdh239What do you guys think of this?http://www.smithy.com/midas/pricing/ltd
Reply:If you don't know what to look for in a lathe, maybe you shouldn't be buying one?
Reply:Originally Posted by Tat2dHandzIf you don't know what to look for in a lathe, maybe you shouldn't be buying one?
Reply:Everyone has to buy their first lathe and everyone has to buy their first welder.
Reply:Originally Posted by Tat2dHandzIf you don't know what to look for in a lathe, maybe you shouldn't be buying one?
Reply:Originally Posted by jdh239hmmm... noticing a lot of people don't like the combo machines.... and particularly the mill portion of a smithy
Reply:I agree, everyone starts somewhere. I'm in the same boat, I want one but have no experience with one. This thread is very helpful. ThanksMiller diversion 165Miller mig 211Hypertherm pm 30Milwaukee 6230 14 inch chop sawMd 45 mag drill (RIP; fell on its head)New MD 45! Thanks to the esposa!Finally got an O/A setup