Question regarding buying lathes...

[Mike Walsh]

I've been perusing the lathe market for a little while now. Have passed up a few good ones. Sheldon ESQWP (or something like that) with all the goodies for $1200... A South Bend 9" x 36" for $600... All missed by a day or so. Got screwed over on the SB, but it is what it is.

That being said, I'm somewhat apprehensive about going to see a lathe prior to purchase.

What should I be looking for? What tools should I bring to inspect?

I'm aware that I should be looking for play in the mechanisms, but what is allowable? What is an appropriate setup for inspecting these numbers?

I'd like to pick up a decent lathe that I can get going on my steam engine with. Gets old having to take a field trip to the railroad to do any machining.

Thanks,
Mike Walsh

[SteveM]

I would start with these:
http://www.mermac.com/advice.html
http://www.mermac.com/klunker2.html

Remember that the tool bit is on center, and dropping the toolbit by a thou has a much smaller effect on the diameter of the part, so a little bed wear is not a big issue.

I would disagree with Dave Ficken and say that you should bring a mag base and indicator. Put the base on the carriage and the tip on the bed and see what wear there is. Also check spindle runout. If you extend the tailstock part way out and indicate the ram from the carriage, you can see if the ram is in line.

Check every gear for missing teeth. Bring a mirror so that you can look under the QC box for broken gears.

Steve

Steve

[Glenn Brooks]

Mike, one thing I've found on my lathe is that wear and tear on a lathe manifests itself everywhere on the machine. For example, worn ways in front of the chuck usually means an equivalent amount of wear on the bearing surface of the tailstock - where it mates with raised "v" of the bed. And worn ways also means equivalent wear of the gear teeth in side the headstock. Sometimes people will try to fix one thing, but often can't replace gears, or fix tailstock vertical alignment issues.

So I've come to conclude that the three components are in essence, proxies for each other.

So, First thing I would do is operate the headstock through all of the gear ranges. The lower speeds are usually worked the most. If one or two speeds growl and makes noises the other speed ranges don't - then you know the teeth on that gear are worn into little dragon teeth inside the machine. The noise is from the teeth clashing with each other when then turn round. Same thing when looking for excessive play, or run out, on the hand wheels on the carriage- if it's sloppy and has play, the bevel gears inside the machine are worn down, maybe worn out - causing the excess gear lash.

One thing I failed to notice on my lathe, when I inspected it, was that the bottom of my tailstock was deeply worn and Groved where it had contact with the bed. Over time, I've mapped my ways out with an indicator and found two distinct peaks and "troughs" in the ways, places on the ways where he tailstock and saddle were subjected to making a LOT of parts for the Canadian Military - wearing the bed into an undulating series of Miniature waves like the ocean in micro scale- but nevertheless making it troublesome and complex to make uniform cuts along the length of the bed - such as turning between centers. The ways are hardened. The mating surfaces of the tailstock and saddle are not - they show the wear the most. It's easy to move the tailstock partly off the bed and inspect the bottom. If it is smooth and not groved or worn in the center, the lathe probably hasn't been worked to hard and maybe in good shape.

Iam looking for another lathe now, and always inspect the bottom of the tailstock for wear - use your fingernail to detect ridges of wear as small as .010" on the edges.

Also very easy to run the saddle back and forth along the bed. If it binds up, or gets tight towards the tailstock - the lathe is worn out - everywhere!

And, I wouldn't be bashful at all about putting a 4' straight edge along the ways and looking for slit of light coming underneath the edge - even an aluminum carpenters level will quickly show you if the ways are severely worn in front of the chuck. A blue silver of light means wear of around 3 to 6 tenths (.0003-.0006). White light shows up just over 9 tenths (.0009). A nice bright slot of light could mean .025" wear - which is a lot - probably way to much wear! An indicator can help, but the saddle is going to slant down hill with as it runs along the way, and if the rate of change is constant, - it might not tell you anything!

Finally, run the tailstock quill all the way out, then put it up next to the headstock. Then put a 6" machinist rule between the centers. If the rule slants towards the tailstock, You Will know that the tailstock center is significantly lower than the headstock - if so, the bed is worn down to much (and the gear train and other parts are tired and beat up) and probably you should just walk away and keep on looking.

Regards
Glenn B.

[SteveHGraham]

Best thing to take with you: an experienced machinist.

Not always available, sadly.

[liveaboard]

I wish I'd read this before I bought my lathe...
It's as loose as a... Never mind.

[ryanjones2150]

Glad I stumbled upon this forum and this post particularly. I'm new here...Ryan Jones, Beaumont, TX. Glad to meet you gents...

I too am in the market for some small machinery. I have a small welding and fab shop out back and am investigating the possibility of doing my own machine work instead of farming it out. I know diddly squat about machine work, but that never stopped me before.

My biggest concern in looking at used equipment is that I will have no clue if its in serviceable condition or if its even all there. Could we expand this wealth of feedback about inspecting the lathe to inspecting a small mill as well?

I had once considered a 3 in 1 machine, but after lurking on here and reading up about them, I think I may be after separate machines. I have read on many forums and seems like this one is least likely of all to have responses that attack a guy over his lack of experience or knowledge or means to buy a southbend and a bridgeport. Didn't mean to interrupt to OP's question, this is good stuff...

[redneckalbertan]

Welcome to the forum! There are a great bunch of folks on the site, as it seems you have already found out. Adding your location to your profile will show that information under your name beside each of your posts. This can be done by click on 'User Control Panel' in the upper right corner of the page. Then click on 'Profile' in the left hand pane of the window. Enter the information in the appropiate field, then click on 'Submit, at the bottom of the page. If your location is included in your profile and another user is close to you, they may offer more assistance than just words of advice.