Hello again readers.
You have a gleaming green lathe, you have a solid workbench made just for it. Let’s put them together. This article will walk you through the process of leveling your lathe.
First you must buy beer. Without beer you may have a hard time getting the guys to come over to help you lift the lathe up onto the bench. The general rule is to buy two beers per helper. If you buy more than two beers per helper the helpers get all wobbly and at the end of it you still have a lathe on the floor. If you buy less than two beers the helpers will tire easily and be afraid of injuring their backs. “I have a bad back” is code for more beer is required.
With the crew sufficiently liquored up direct them to lift the lathe form the floor onto the bench. This is an activity you should direct rather than participate in since lathes tend to be heavy and you don’t want to hurt your back. Besides, you bought the beer. Once the lathe is in place excuse the helpers and get to work.
Place the lathe on the bench in such a way that the controls on the headstock (left end) hang over the front of the bench. Using a square pushed up against the lathe bed, leadscrew or ways, measure to the front of the bench and make it equal near the headstock and the foot of the lathe. Locate the attachment holes. Stick a Sharpie marker down inside each of the holes to mark the location on the bench. After the required hole locations are marked push the lathe back towards the wall so you can drill the holes.
Many people use a paddle bit (correctly called a spade bit for those who knew what a paddle bit is) in an electric drill. For those seeking a spiritual cleansing, a brace and spur bit are the weapons of choice. So go drill the holes. I can’t believe I even had to say that. Surely just mentioning the drill and bit would be enough wouldn’t it? A writers life is filled with such indignities.
This seems like a good time to scoot the lathe back over the holes. Alrighty then. The lathe is over the mounting holes in the bench. Time to go to Harbor Freight and buy a horseshoe shim assortment. Then go across the street to Home Depot and buy some nice grade 2 or grade 4 bright bolts that are just small enough to enter the holes and long enough to go through a washer, the lathe foot, the bench, another washer and a lock washer and STILL have enough length left to mount the nut on. Split lock washers with a plain nut are fine although flat washers with a Nylock nut would be better.
Back from the store? Good. Mount the bolts in place and torque the nuts to the snug setting on your ratchet. You have now completed step one Lathe Mounting.
So why even bother to level your lathe? Does the Navy level the lathes on their tenders which will be rolling through the waves and never be level again unless they are in port on a windless day and not even then? Yes they do. Why do they? Because only by leveling the machine can you remove any twist that might be in the bed. It really isn’t about level it is about twist.
If you are fortunate enough to have a lathe with prismatic (incorrectly called Vee ways) then you will also need parallels to get the level above the prismatic way. I suggest you buy a couple of lathe toolbit blanks tall enough to get the level above the vee. Toolbits are ground to very close limits but you should lightly stone them anyway just on principle. If you are a poor guy like me you might have a lathe with flat ways and leveling becomes much easier. That is the ONLY good thing about flat ways except being able to build bed attachments easier but that is another story.
About levels: Buy, rent, borrow or steal the very best machinist level you can lay your hands on as shown here.
Good Chinese machinist levels are available for less than $75 on eBay. You will also need a good 2 foot carpenters level. What is a “good” carpenters level? Well, surely there could be no better level than a good old cast iron level made by Stanley, Lufkin or Millers Falls before 1950. Before you go moaning about how they are not available go look at eBay. There are hundreds of them on there. Buy a decent one and not a bent one. Take it to your local machine shop and have them grind it flat and parallel. You should do this because you will then have a very fine BAP (Big Ass Parallel). The level will cost less than $20, the grinding will cost less than $50 and for $75 you will have a BAP that would cost hundreds and hundreds of dollars if you bought it new. In addition, because the level is 70 years old it has had lots of time to stabilize. When you have it ground it will stay straight and parallel way past your lifetime. You cannot say that about the more expensive new one you would have to buy. A BAP is a tool you will use for many things throughout your machining career. It will also draw ooh’s and Ahhh’s from the crowd when you pull it out of the roll away tool box and place it on a little silk pillow made just for it. Now you can bridge long distances with the BAP and lay the precision level on top of it. This will essentially give you a very long, very precise level.
During this phase do not tighten the nuts, just snug them. Lay the BAP along the ways left and right, to see that the headstock is higher than the foot. If it is not shim the headstock end higher with the horseshoe shims. Lay the BAP across the ways front to back near the headstock and start shimming with the horseshoe shims until you can see no error in the center vial. Again lay the BAP along the ways and shim the foot of the lathe until you have attained level that way. One more time lay the BAP across the foot of the ways and again shim to level. You might think you are done now but no, you are not. We have now completed step two Rough Leveling.
Break out the machinist level. A good one will measure as close as .0006 per foot per graduation. That is nigh onto perfection. Lay the super level across the lathe ways at the headstock as shown.
Tighten the nuts on the headstock end. I use a torque wrench set to 50 foot pounds torque. Add whatever shims are necessary to get the alignment to within a couple thousandths per foot. Yes, oh yes, this is a royal pain, but it will pay huge dividends down the line. Again, lay the level along the ways as in this photo.
Raise or lower the tail of the lathe by adding or removing shims until you are within a couple thousandths per foot. Now lay the level on the back way just to make sure it also says level within a couple of thou. If it is close do not alter the shim. Finally lay the level across the foot of the lathe like this
and shim to a couple graduations on the level. You have now completed Step Two of this process. Your lathe is already straighter than 99% of all the lathes in amateurs shops. Now we will continue on to make it a thing that songs are written about.
Again we lay the level across the bed at the headstock. Use a long ratchet, breaker bar or torque wrench to tighten one of the bolts enough to bring the machinist levels vial to zero. Do exactly the same at the foot of the lathe. Now use the BAP or just the machinist level if it is long enough to diagonally measure the bed as in the following three photos
It should be perfect, if not, back up a few steps and get everything closer. Again set up the BAP or level this time from headstock front to tail end rear. It should be perfect. You have now completed leveling your lathe.
I know this has been awful. It is a lot of work. It is absolutely worth it. If you have problems with alignment in later articles, then it is because of improper leveling. If you do not level the sucker, you will always have to fight and fart around with alignment. Do the work it is worth it. For those of you who did not hear that last sentence here it is again. Do the work, it is worth it.