Getting it level is the first, and not necessary, step.

Getting it to turn parallel as you have done with a test turning piece is the final, and necessary, step.

As long as it turns parallel, actual level does not matter. Worn old lathes can have wear on the bed that throws a level out.

Hi Chris,

If you haven't already checked Harold Hall's website, he has an explanation on how to set up the lathe here.

Thor

Edited By Thor 🇳🇴 on 06/07/2022 18:30:37

Levelling for the purpose of eliminating bed twist can't be done with an ordinary builder's level – they're not sensitive enough. Errors caused by bed-twist are too small to detect with them.

You may be fixing a problem you don't have, maybe creating trouble in the process! What's the evidence? If you turn a stiff rod at least 25mm diameter to the same slightly smaller diameter over a length of, say 150 to 200mm, what's the difference in diameter at each end? The diameter has to be measured carefully with a micrometer, which requires practice. If the lathe cuts an unacceptable taper, then it's time to look at levelling or Rollies Dad.

Beware of precision measuring as required to set lathes up accurately. Often highly confusing at first and even experienced practitioners get it wrong. For example, the taper measurement I recommended will mislead unless you can reliably get a good finish by taking light cuts with a sharp tool – itself a learning challenge. And then it's best to know tapers also occur when metal rods flex under cutting pressure, even if the lathe is perfect. It's important to practice technique before taking results too seriously.

It may not matter either! When work is done close to the chuck, as much of it is, the error caused by bed twist is hard to detect. It only causes bother when cuts are taken over long distances.

Dave

Edited By SillyOldDuffer on 06/07/2022 18:37:06

This is why you cannot use an ordinary level for aligning machine tools. They don't even register a movement that will send a sensitive level full scale.

**Link**

Quite so, Bear

Which is why I pointed Chris towards all those previous threads

Levelling, in the sense used by surveyors and ‘lathe levellers’ is simply process of using a level to find the relative height of two points [and, if appropriate, to facilitate their adjustment].

A levelled lathe need not be an ‘orizontal lathe !

MichaelG.

So, if a precision level gives an accuracy of half a thou per foot, and your old Myford has easily 4 thou wear on the front way in one place, and 2 thou wear on the rear way, which is common and within tolerance for not needing a regrind, that is a difference of 2 thou over the width of the bed, which is 4 inches. So that is equal to 6 thou per foot of difference between the ways due to uneven wear.

What is the point of putting a half-a-thou per foot accurate level on a bed with 6 thou per foot of wear? If you twist the bed to get a level reading, the rest of the relatively unworn bed will be 6 thou per foot out of level.

So with a used old Myford etc, it is best to not worry too much about super accurate levels and follow the instructions in the Myford factory User's Manual to bolt the lathe down without distortion by using a clock on a 12" piece of bar in the chuck while tightening down the mounting bolts. Any movement of the clock and that bolt needs a shim around it.

Then do the turning test as Chris has done on a test piece of 1" bar 4" to 6" long and measure it for taper and shim the tailstock end mountings accordingly, as per the Myford User's Manual. This is the ONLY test that really matters. All the rest is theory until you take a cut under real-world conditions and cutting forces and see what your worn old lathe is really doing.

Thank you Michael. A lot indeed. And that is about all that needs to be known to get your lathe set up, if you include my above proviso re the dangers of using sensitive levels on worn beds. (Although Myford above specifies levels with a sensitivity of 3 thou per foot which are not so sensitive by today's digital standards.) If you have a brand new unworn lathe bed, then page 1 will get you back to where the lathe left the factory, all nice and level and flat. Pages 2 and 3 are the relevant ones for old lathes with a bit of wear in them.

It's like they say: When all else fails, read the manual! Your post should be enshrined somewhere on this site as the standard reference to all levelling questions.

Edited By Hopper on 09/07/2022 07:03:08