How To Inspect A Used Metal Lathe or Vertical Milling Machine Before Buying

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#1
Here ya go folks, hope this helps and keeps folks from spending their money on clapped out (machinist's term for used and abuses, rode hard and put away wet machine shop equipment) lathes and mills.


What to Look For When Buying A Used Metal Lathe Or Milling Machine

Don’t buy a pig in a poke!
If you can’t examine the lathe or mill in person, or can’t find someone who knows how to examine them to go look at it for you, DON’T BUY IT!

There are just too many things that can be wrong with either machine that only in person, visual and mechanical checking will find.
Here’s a few things to check on a metal lathe when contemplating buying a used one.
Quick inspection for anyone to perform-
First thing, if it is in a commercial machine shop, you should do is ask to see the service records/reports from when the techs were in to service it, if any. This can give you a good idea about how well it was maintained as well as identify ongoing problems that you may inherit if you buy the machine.
1. Hold your hand on all the axes X, Y, Z etc. one at a time and move them. Keep your hand on the casting and move them, slow in both directions, then fast in both directions.
2. Feel to see if it transitions smoothly, also check at a stopped position to see if there's some oscillation. If possible grab onto the ball screw for each axis at a stopped position to fell for this oscillation after moving a little bit. Listen for low growl or any abnormal noise when moving in rapid fashion. This could mean there's either bad bearings, ball screw, worn ways and even possibly little or no turcite or meehanite left.
3. Check the spindle. Run the spindle at all possible RPMS , listen for odd sounds., If it’s in a commercial shop, ask to come listen when its quieter in the shop like at the start of the day, close of business, or lunch time. Try to run it at its highest speed for 15 minutes nonstop, to listen for a change in sound.
4. Inspect the ways for chips, dents, dings, missing pieces, etc. Look to see if it has grooves or pitted. Could mean the turcite or meehanite is gone, or that the ways were not kept properly lubricated.
5. .
6. ASK the owner what material are they cutting most. If its Cast iron- I would say run away, because the dust gets into everything, wears down hard surfaces and bearings in areas you can’t see.
7. But if you don't, here’s what to expect. It gets into everything and turns into a solid rusted mass which you need a chisel and hammer literally to chip away. It can cause a lot of coolant drainage areas to plug up, for example backing up coolant into bearings, guides, motor, switches etc. It also works its way under way wipers, way covers and more and acts like an abrasive.
8. Is the metal around the tool posts or the mounting surface of a tool holder distorted Run an indicator on a few pockets to see how straight they are. You may see a gradual incline or decline which tells you it’s out of alignment. Only being out of alignment is no worry, you can realign it , IF you know how. The important thing is to make sure its gradual and there are no high spots.
9. Turn a Test Bar if you can, to check for vibration, chatter, and the alignment of the head stock both vertically and horizontally with the tail stock. You will need to have a good mag mount and dial indicator with you for this one, and a piece of mild steel bar stock between 1” and 1.5” in Ø and just a few inches shorter than the distance between centers on the lathe.
10. Open the covers if you an and inspect the wiring and relays and switches, look for worn wiring, signs of arcing, wires chewed on by bugs or rodents, relays or switches that show signs of arcing, etc.
11. Check all the belts for signs of cracking, and wear or miss-alignment with the pulleys they ride on.
12. Check the oil levels in all the reservoirs (head stock, carriage, gear box, etc.) and see if the oil looks clean, or old and burned and full of chips.
13. Take a good level and check to see if the ways are level (not twisted from the head stock to the tail stock). If twisted and setting and used for long periods, the twist will likely be permanent, and you will never be able to get it out, or do truly accurate work on the lathe.
14. Tighten the carriage lock nut with the carriage near the headstock just enough that it slides with a bit of hand pressure on carriage wheel, and then try to slide it towards the tail stock end of the ways. If it moves smoothly all the way to the tail stock end of the ways, the ways are in pretty good shape, but if it binds after about 12 inches or so, that says that the majority of the work on the lathe was done close to the headstock and the ways are heavily worn there.
15. Check the ways close to the headstock for chips and other damage if the above test fails, sometimes it will be just some loose swarf binding things up, but most likely it will be extreme wear on the ways.
16. Lift and operate all control levers and other controls on the lathe, do they move smoothly? And do the functions they control operate properly? They should move freely, but not sloppily.
17. Engage the lead screw nuts and see if the saddle moves up or down the ways with you just pushing on the carriage saddle. It should not, if it does, it means the lead screw half nuts need to be replaced, and possibly the lead screw as well.
18. If the lathe is set up for screw cutting, do all the screw cutting positions in the gear box work? They should.
19. Check the cross-slide lead screw for too much back lash, and examine the ways it rides on for damage as you did with the saddle/carriage ways. If you find a lot of backlash, ask why it has not been adjusted out, it’s easy to do, and if the operator hasn’t done it, it may be because it is so worn that it can’t be adjusted out.
20. Extend the tail stock spindle about 2/3rds of the way out, and check for excessive movement up and down, side to side, and in and out.
21. Check the spindle nose, and the chuck mounting method. If it’s a D- series, are the holes for the cams buggered out? If a screw on type chuck mount, are the threads dinged up? And is the shoulder at the rear of the threads straight and undamaged? It serves to square the chuck up the lathe spindle’s center axis, so it better be! If it’s an L taper type, is the taper smooth and ding free? Is the spindle being supported by its bearings or can you grab it and move it in multiple directions. Is the internal taper in the spindle (used to hold a dead center for turning between centers) undamaged and in good shape?
22. Check for magnetic drain plugs in the oil reservoirs, and if present, check them for large chunks of metal (a bad thing!), small shavings are normal wear of the gears, but teeth from gears, etc. are not!
23. Here are three good videos by TubalCain on how to buy a used lathe. Parts 1, 2 and 3
24. https://www.youtube.com/watch?v=1MqYOgtQGdA
25. https://www.youtube.com/watch?v=nYni5QP0qyw
26. https://www.youtube.com/watch?v=WU4SkuPzhNQ
27. Check that the dials and their friction locks on the carriage crank, cross feed crank, compound crank and tails stock crank all revolve smoothly and that they will stay in position when you set them.
28. If it’s got a DRO, make sure it works through the full range on all axis.

OK, on to looking at used Vertical Milling Machines
A lot of the same advice applies to vertical mills that applies to lathes.
1. Check the ways under the X and Y axis, are they dinged, chipped, worn? You can set the way lock screws firmly, so that the axis you are looking at won’t move, then loosen them just enough that it will slide, and see if it moves freely from one extreme of travel (X+ to X-) by starting with the screws tight at one of those extremes, then reverse the procedure and try it by tightening them at the other extreme, and moving it towards the other end, and finally, by tightening it in the middle and then moving both left and right. Doing it this way will let you detect where there is any wear in the ways, which will normally be in the center of their travel.
2. Check the spindle, does it move up and down in the Z axis smoothly? It should. Check it again with the mill running, at all possible speeds. Listen for odd noises, grinding, squeals, etc.
3. Check the table, does it have a bunch of divots drilled into it, or marks where an end mill has dug into it? These can be filled, but it is a lot of work to fill, scrap, and stone it back to level and perfect again.
4. Check that the table raises and lowers smoothly (if it’s a knee type mill that is, Mill/Drill tables don’t raise or lower, they are fixed.
5. Check the head, is it in tram, and if not, can it be put into tram, or has someone buggered up the worm and gear that drives it in either the Nod or Tilt directions. Nod is up and down like you NOD your head, raising and lowering your chin towards or away from your chest. Tilt is like tilting your head so that your left ear touches your left shoulder, or your right ear touches your right shoulder. If the head isn’t in tram, that is, perfectly 90° perpendicular to the top of the table in both the X and Y axis, you can’t mill a flat surface, or drill a hole 90° perpendicular to the surface of a workpiece mounted on the table.
6. Check the wiring , switch and relays, same as you would for the lathe, for bug or rodent gnawing, arcing, loose connections, etc.
7. If so equipped, check that the one shot lube system for the table ways works, and check for lube in the cups for the spindle bearings.

That’s about it for mills, they are a bit simpler than the lathe, but just like buying a car, don’t get in a hurry, take your time, the right used machine at the right price will come along.

Oh, and the amount of time to check all the above things on a lathe or a mill before being able to make your decision to buy or not, 5, maybe 10 minutes tops.
A bit more if you go so far as to turn a test bar on the lathe, that will take 10 minutes by itself.
 

Harley

Obsessed Member
Forum Supporter
#2
Oh, and the amount of time to check all the above things on a lathe or a mill before being able to make your decision to buy or not, 5, maybe 10 minutes tops.
A bit more if you go so far as to turn a test bar on the lathe, that will take 10 minutes by itself.

But it took me 40 mins to read all that! Old Man Top is gonna be stuck on #1 for at least a month!!:001_tongue:
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#6
Wait I thought we were just supposed to call you to check them out?
You can do that, but I don't work cheap! Chocolate Oreos with double stuff ain't cheap, and that's my price.

Mills, and even more so, lathes, can be very dangerous, not something you want to learn to use completely by "just doing it". There are a number of good videos out there by Mr.Pete 222, also known as TubalCain, and others by "This Old Tony" than can teach you a lot and keep you safe, and the American Gunsmithing Association has video courses you can buy, with Darrel Holland as the instructor, that will teach you how to run a lathe and a mill. Good courses, and I don't say that just because I was one of the editors and reviewers, , they are very well done.

I have personally walked into a machine shop in a large defense industry contractor just moments after a lathe operator, running a 15 horsepower 24x160 lathe was sucked into it and dismembered, and on another occasion walked in as the paramedics were getting ready to transport a lathe operator who had just lost an arm to a 13x36 2 horsepower lathe.

This kid got lucky, you will see the accident at around 3:10 into the video

https://www.bing.com/videos/search?...885C677A99ABC68A541F885C677A99ABC68&FORM=VIRE
 

Dusty

Obsessed Member
Forum Supporter
#7
I have personally walked into a machine shop in a large defense industry contractor just moments after a lathe operator, running a 15 horsepower 24x160 lathe was sucked into it and dismembered, and on another occasion walked in as the paramedics were getting ready to transport a lathe operator who had just lost an arm to a 13x36 2 horsepower lathe.

This kid got lucky, you will see the accident at around 3:10 into the video

https://www.bing.com/videos/search?...885C677A99ABC68A541F885C677A99ABC68&FORM=VIRE
Man, I would hope that I would have enough common sense to not get wrapped up in one. I see stupid things every day, people putting their own lives in danger. They don't seem to care or are not smart enough to tell what they are doing is stupid. I'm always yelling at people, hey don't do that.
 

Pcmaker

Obsessed Member
#8
What's a good mini lathe and mini mill to get? I have limited space in my garage, but I have my eyes set on getting me these
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#9
What's a good mini lathe and mini mill to get? I have limited space in my garage, but I have my eyes set on getting me these
Check out Grizzly and Little Machine Shop, both carry quality small lathes and mills.

I usually recommend buying the largest lathe and mill that your budget and workspace will allow, as most folks with an interest in guns and cars and machining will quickly discover that while the mini machines are fun, they really won't let you do a lot of the work you want too.

The real minis like the Sherline or Taig or Emco are quality machines but extremely limited in power and the size of the work pieces they will handle.

For lathes, figure you need a work space at least 4 feet longer than the lathe and with about a foot behind the lathe and two feet in front of it.

For a mill about the same, but more ceiling height as mills can run pretty tall, my big mill is almost 8 feet tall.
 

emcon5

Debris Blanc
#10

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#11
That is both terrifying and hilarious.

I picked up one of the Harbor Freight multi-purpose machine center for free a while back from an estate, simply because I was willing to haul the heavy bastard away. Haven't done anything with it yet.

I assume it is crap.
Assuming you are talking about a combination Lathe and Mill, like this one
http://cdn0.grizzly.com/pics/jpeg500/g/g4015z.jpg
then the answer to your question is:
Yes, and no.

For a beginner, those machines are a disaster, for an experienced machinist, they are merely an annoyance, but one with limitations.

They generally lack the rigidity of a single machine (lathe or mill), and the spindle is usually so high above the lathe bed , that owing to the lack of weight and reinforcement in the headstock, the spindle often suffers from excessive vibration. The tail stock suffers a similar fate.

In short, they are very top heavy, and can be a danger if not bolted down securely to a substantial table or work platform. Be careful moving it.

The mill is part of the headstock, but is above the lathe center, so it tends to add vibration to the head stock when using the lathe as a lathe, and when used as a mill, it lacks rigidity because the column is so small.

Additionally, in the Mill mode, you don't have that much free space under the spindle nose, which limits the height of work pieces it can accommodate.

The saddle/carriage becomes your table in mill mode, and it is rather small, and again, lacking in the all important rigidity. It is difficult to secure a work piece of any significant size onto it, and it won't hold a very big vise either.

There are ways to overcome most of its faults, but a novice machinist isn't likely to know them, nor have the patience to figure them out.

To the experienced machinist, they are a pain in the @$$ because you have to do so many "work arounds" the machine's weak points that it adds a lot of time to almost any project.

They can be capable of fairly decent and accurate work in the right hands, once you figure out how to get a decent surface finish out of them by eliminating their inherent vibration and chatter, which affects both finish and accuracy.
 

emcon5

Debris Blanc
#12
Assuming you are talking about a combination Lathe and Mill, like this one
http://cdn0.grizzly.com/pics/jpeg500/g/g4015z.jpg
then the answer to your question is:
Yes, and no.
Pretty much, but that one looks nicer. It is this one:
https://www.harborfreight.com/media...ab33525d08d6e5fb8d27136e95/i/m/image_1469.jpg

So smaller and even less useful :D

It is sitting on a tool cart right now, I need to mount it securely before I even consider doing anything with it. I also need to find a square key for the lathe chuck, it is missing.
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#13
Pretty much, but that one looks nicer. It is this one:
https://www.harborfreight.com/media...ab33525d08d6e5fb8d27136e95/i/m/image_1469.jpg

So smaller and even less useful :D

It is sitting on a tool cart right now, I need to mount it securely before I even consider doing anything with it. I also need to find a square key for the lathe chuck, it is missing.
Well, if HF doesn't have one, then just measure the square with a good pair of calipers (dial or electronic) and then you can order one from MSC, VME (Victor Machine and Tool) Shars, KBC Tool, World Tools, Travers, Grainger, McMaster-Carr, Rutland tool supply, etc.

If you can't find one at any of the above, send me the dimensions of the square, and how deep the square socket is, and I can make you one and send it to ya, takes about 5 minutes on the mill and lathe is all.

I have always made extras of several lengths for my lathes, makes it handy to adjust the 4 jaw chuck by having a second key, shorter, to go on the back side so you can adjust two opposing jaws at one time.

Never leave the key sitting in the chuck, not even for a second, your hands should never come off the key when it is in the chuck, get into that habit right from the start and you will never have a key get flung out of a chuck at high velocity (can be fatal) because you forgot it and then turned the lathe on.

Happens all the time to folks who get sloppy with their safety habits.

In my gun shops, I set up all the lathes so that the chuck keys had to be back in their holders before the lathe would power up. I made holders with micro switches at the bottom, wired into the safety cover switch circuit on the lathe to do that .

Put the key in the holder, it pressed down the switch(es) and the lathe would start. Leave even one key out, no spinna da spindle.
Keeps anyone from getting careless, or being tired (never machine while tired/sleepy/drunk/high/etc.!) and getting hurt or damaging the lathe.

As a result of that modification, there was never a flung chuck key in any of my shops. Well, not flung by the lathe anyway!
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#14
Just checked Harbor Freight online, doesn't look like they carry the 3 in 1 Lathe Mill Drill machines anymore, so it might be tough to get a chuck key from them but still worth a try.
 

emcon5

Debris Blanc
#15
Well, if HF doesn't have one, then just measure the square with a good pair of calipers (dial or electronic) and then you can order one from MSC, VME (Victor Machine and Tool) Shars, KBC Tool, World Tools, Travers, Grainger, McMaster-Carr, Rutland tool supply, etc.

If you can't find one at any of the above, send me the dimensions of the square, and how deep the square socket is, and I can make you one and send it to ya, takes about 5 minutes on the mill and lathe is all.
I appreciate the offer.

I measured it, came out just under .32", which would make it 5/16" I believe. Looks to be pretty readily available, I can even get it from Amazon.

In my gun shops, I set up all the lathes so that the chuck keys had to be back in their holders before the lathe would power up. I made holders with micro switches at the bottom, wired into the safety cover switch circuit on the lathe to do that .

Put the key in the holder, it pressed down the switch(es) and the lathe would start. Leave even one key out, no spinna da spindle.
Keeps anyone from getting careless, or being tired (never machine while tired/sleepy/drunk/high/etc.!) and getting hurt or damaging the lathe.

As a result of that modification, there was never a flung chuck key in any of my shops. Well, not flung by the lathe anyway!
That is clever, good idea.

Then again, nothing is foolproof to the sufficiently talented fool.

Just checked Harbor Freight online, doesn't look like they carry the 3 in 1 Lathe Mill Drill machines anymore, so it might be tough to get a chuck key from them but still worth a try.
Yeah, I think it was discontinued several years ago.

Running joke about Harbor Freight is that it is "The Hammer Store" because everything you buy there will at some point turn into a hammer. Problem is when that happens, this hammer will be about 300 lbs.
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#16
I appreciate the offer.

I measured it, came out just under .32", which would make it 5/16" I believe. Looks to be pretty readily available, I can even get it from Amazon.

That is clever, good idea.

Then again, nothing is foolproof to the sufficiently talented fool.



Yeah, I think it was discontinued several years ago.

Running joke about Harbor Freight is that it is "The Hammer Store" because everything you buy there will at some point turn into a hammer. Problem is when that happens, this hammer will be about 300 lbs.
Yup, .3125 is 5/16", the socket is usually a hair bigger.

Amazon has everything now days.

If you can find one, and the price isn't too high, go for the self ejecting, spring loaded 5/16's chuck key, it prevents you from ever leaving the key in the chuck.

Like this one on E-bay for under $10
http://www.ebay.com/itm/like/231452232274
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#17
Oh, and before firing up the Horror Fright 3 in 1 ,you might want to check the ways , make sure all the places that are supposed to have oil do, check the oil in any reservoirs not only for level, but for being clean (no sand or gravel or boulders or metal chunks off missing airplanes in it) , check the drive belt, the condition of the power cord and plug, etc.
 

NYECOGunsmith

Obsessed Member
Staff member
Moderator
#19
What would you like to do with it?

I mean, what kind of projects do you have in mind that you would use it for?

Reason I ask is, it's a good little lathe, but if you are thinking of threading barrels, crowning barrels, etc., even pistol barrels, it isn't up to a lot of those tasks due to limitations in bore size (spindle bore I mean), distance between centers, horsepower and torque.

It would be good for making replacement pins, small screws, firing pins, and such however. And of course for making small model steam engines, gas engines, etc. that can be made to run just like the original big ones do.
 

Pcmaker

Obsessed Member
#20
What would you like to do with it?

I mean, what kind of projects do you have in mind that you would use it for?

Reason I ask is, it's a good little lathe, but if you are thinking of threading barrels, crowning barrels, etc., even pistol barrels, it isn't up to a lot of those tasks due to limitations in bore size (spindle bore I mean), distance between centers, horsepower and torque.

It would be good for making replacement pins, small screws, firing pins, and such however. And of course for making small model steam engines, gas engines, etc. that can be made to run just like the original big ones do.
Mostly small tools, screwdriver bits really and random small stuff. I don't see myself making something exceeding 10 inches in length. I just don't have the room to have a larger lathe since I still have to get a mini mill