Leveling a Warco 1224 Gear Head Lathe

I'm after a little help / advice.  Could someone out there help by stepping through the process of checking the machine is level.  I've read so much about this I can't quite get my head round the best approach.

 

I'll tell you what I've done, when I first go the machine I installed the two cabinets that the lathe sits on. 

I anchored these to the floor (I checked the floor to be generally level).

I then placed my machine on these and nipped up the bolts.

With my machine level checked across the bed to get the machine level in the X and Y planes.  (I'm guessing that the machine ahould be exactly the same close the he head stock as it should be down at the tail stock.

Where it read out I shimmed under the lathe casting that was bolted to the cabinet (not under the cabinet at the floor) (Right or Wrong??)

When I was turning it had never seemed to as good as it should be always creating a taper (even over a small length)

I was worried that something was wrong at the headstock so I mounted a test bar in the head stock and its fine within 0.02mm over 300mm and 0.01mm out when spunat both the headstock and 300mm away.

I now think I have some type of twist in the bed?

I there some better way of having some jacking bolt arrangement to fine adjustment of the bed then loack them in place?

 

Thanks for any help.

Cheers

Ant 

 

Hi There

I covered setting up a lathe in the practical engineer articles.

They are available on-line on this website.

regards David

 

In one of my old engineering textbooks the reference to levelling the lathe appears to have little to do with the machine being horizontal, but is described as the process of getting the machine setup accurately. That is things like the alignment of the headstock,slideways etc.

 In a book on machine tool design by Konigsberger, he states that a good machine tool should perform accurately hanging from a crane!

  I cannot see any technical reason why a lathe should be exactly horizontal as some people seem to be concerned about.

  yours

      John

The reason for setting a lathe horizontal is that the only readily available independent  reference instrument for these purposes is a (good) spirit level.  Obviously this is only useful if the machine is horizontal.  Actually a clinometer, with its angle adjustment capability, is a far better device for setting up machine tools than a precision level.  Mine has 30 second graduations on the vial and settings to better than ± 5 seconds can easily be achieved.  In comparison a master precision level is a complete PIA to use.  A clinometer can also be easily used to set a machine up a few degrees off level.

 

Precise lengthways leveling isn't that important.  It's twist across the bed you need to eliminate. For practical purposes with our size lathes 1 thou per foot longitudinal cut taper results from 1 minute of arc of twist across the bed per longitudinal foot.

 

Its important that the lathe be set-up with the bed in its natural, unstressed, condition. During the bolting down process of a machine after shimming or jacking so that it sits level you must use the spirit level to ensure that nothing has moved.  The practice of jacking a lathe against the bench or floor to remove error is, despite what Tubal Cain says, an abomination which should never be considered by a normal user.  If a lathe won't set-up true with the bed in the unstressed condition it is either severely worn, has suffered from past abuse (cast iron will flow under long term stress) or so badly made as to be useless.  A worn machine should be repaired, a badly made one scrapped as , probably, should an abused machine with a twisted bed although it is in theory possible to take out the twist by applying counter stress and waiting.  In my view life is too short to attempt un twisting.  Regrettably the Myford 7 series are extremely vulnerable to twist abuse.  Jacking against the bench or floor makes the lathe alignment dependant on the relative strengths and thermal properties of lathe, bench and floor.  Working in this manner its very easy to end up with an unholy mess of stresses fighting each other into some sort of balance "right now" to give good results on turning tests.  Couple that with the possibilities of correcting un-noticed tail-stock offset error by the same jacking process and its easy to see how ages can be spent getting nowhere.

 

Clive

Ian

 

In practice lathe beds are, somewhat surprisingly, weak in twist for small deflections.  Doesn't help that there is fair bit of leverage involved given the length of unsupported bed between head and tail supports.  Serious deflections, as in measure with a ruler or visible to the eye, are a different matter but its pretty easy to twist by a few thou or even tens of thou.  Absolute structural stability, as in no movement at all, over significant distances is very difficult to achieve even with pre-loaded and internally pre-stressed structures. 

 

Clive 

Would fastening the lathe at a single point be enough? Just so it wouldn't walk off the bench? Or, fasten one bolt snugly at the headstock end and another (looser) at the tailstock to stop any tendency to literally go in circles? The bench in this case would be large and stable that tipping would not be a problem.

 

I expect that there are valid reasons that this won't fly.

 

Please enlighten me about the whys.

This is more or less how I have fastened my minilathe. The head stock end is firmly bolted down with two bolts (it seems unlikely to distort in the narrow direction) and the tailstock end bolts are just finger tight.

Mike