Leveling the lathe

Leveling the lathe: How important it is to level my lathe?

Leveling the lathe is an absolutely necessary procedure no matter what type of lathe you own. Even with the most accurate and well-made machines you will not be able to produce accurate work if it’s not properly leveled. The weight of the lathe or the force from the bolts that we use to secure the lathe will cause the bed to be twisted, throwing the headstock and tailstock out of alignment due to the uneven surface of the floor or the bench.

How to level my lathe

A precision level is a tool that will make your life a lot easier but it’s not absolutely necessary for the job. By leveling the lathe approximately with a good quality level and by taking some cuts on a bar of steel and making some measurements with the micrometer we can determine on which side our bed is seating low or high and we can correct any leveling issues.

This is a trial and error method and probable it will take some time to build a clear sense of what is actually happening, especially if you are a newbie. So if you can afford a precision level is the best way to go and if you think that this is too much of an expense for just leveling the lathe once, think again. A lot of factors can throw the lathe out of level and this is especially true for the bench lathes. Lathe leveling must be checked periodically and readjustments must be made if necessary.

The Lathe Bench

The lathe bench must be substantially constructed as possible. If you use wood for the bench top, choose the thicker and harder wood is possible. I’m using four adjustable think metal legs on my bench. Two of those are seating exactly under the lathe legs to prevent the wood from bending under the lathe weight over the time. My bench top is mounted on the wall also. Bolt the bench legs to the floor if possible. Level your bench before place the lathe on it.

How I did it

This is the tools that I use to level my lathe. I don’t own a precision level yet but I’m keeping my eye on Ebay for a used one.

Clean the ways first and loosen the bolts that hold the lathe on the bench.

Since the vees of the lathe bed are not equal on height I’m using as a parallels two thin HSS tool bits that I have measured with my micrometer and they are equal to place the level on it. Allow some time for the bubble to come to rest.

The level must be placed as close as possible to the spindle and the bubble on the middle of the ways. Any adjustments must be made on the bench for now.

My experience with that level in the past showed me that I can increase the accuracy by placing a very thin paper under the level on each side at a time.

If I place the paper in some side and the bubble it’s still seating at the middle this is an indication that I am a little low on that side.

It looks that my lathe is leveled on this side.

I’m repeating the same process on the tailstock end of the bed. This is not a precision level so I’m always placing it on the same direction, otherwise I’ll have false reading.

After finishing the transverse leveling I’m tightening the bolt on the headstock . This will cause the tailstock side to shift a bit. The headstock now is my fixed point and I have enough room at the other side to make all the necessary adjustments .

Before I start tightening the tailstock side I’m placing my dial indicator on the bed just to get an idea of how much the lathe bed will be twisted.

Even a few turns are enough to offset the bed. My dial indicator will show more than 0,1mm of deflection after I completely tighten down the bed. This is definitely going to effect my lathe accuracy but how much we’ll find out later when I cut a test piece.End of Page 1

Test cuts and adjustments

Before I take any cuts I’m warming up my machine for at least 15 minutes. Here in this example I’m using a 20mm in diameter steel rod that is sticking out of the chuck less than 60mm. The ideal would be a 25mm in diameter rod and two collars to be machined on it, one in front of the chuck and the other at the end of the rod. This is something that I’m not doing here to avoid decreasing the diameter farther more. I’m using a very sharp tool at the finest feed to take less than 0,1mm test cuts at a low rpm.

Let’s take some measurements, .42mm plus near the chuck

and .48mm at the other end. That makes a 0.065mm of deflection in a distance of 5cm approximately. Not so good.

I know that my bed is twisted the way I show in the picture with the ruler. That cause the tool bit to getting lower from the center as it travels across the ways and my work piece is getting bigger.

I’m using two paper cards folded in half two times to rise the tailstock end of the bed, one on each side of the leg. The ideal supposedly, is to use metal shims but I don’t have in hand so thin shims to make the necessary adjustments and I’m afraid that the shims will penetrate the softer wood when the bolt will be tightened.

t the other hand I know that the paper is consistent in thickness and my experience from work holding tells me that it can take a lot of abuse. I don’t know, I will give it a try.

I’m tightening the bolt as much as possible.

For now on I will take two light test cuts to eliminate the possibility of effecting my measurements from the previous inconsistent results.

.42 plus

and .41. I’m getting closer.

I will add a half card folded in two on each side of the leg.

And I’m taking another cut.

Now things has change, my work piece is slightly smaller away from the chuck.

My lathe bed must be twisted the way I show in the picture.

This side is probable a little higher and that cause the tool bit to getting closer to the work piece as it travels across the ways.

I will remove one piece from the folded card that I added previously on this side to lower the bed.

I repeated the same process again and now my work piece it’s again a little bigger away from the chuck. The piece of the card that I removed it was too much. I need to add a thinner piece of paper in place. Now I believe it’s obvious why you need a precision level.

Let’s see what we have now, .30mm and

.30mm .Finally I made it.

Mini Lathe Optimum D180 x 300 Vario | TU2004V