Leveling a lathe

[Glenn]

If a lathe is suppose to be set up level, how can a lathe be used on a ship where level is always changing?

The same set up from the ship should be able to be used on land, or am I way off base somehow?

[rthibeau]

Not a sailor, but I believe the lathe is levelled to the floor, bench or whatever it is mounted to. The work is held level relative to itself, so it could be used upside down or at any angle...in theory. The leveling to the mount is to keep the ways from twisting thereby throwing the accuracy of the lathe off. The rocking of a ship is on a different level and doesn't apply to this leveling.

[BobStrawn]

In the case of a ship the lathe is much closer to level. Sea level.

Bob

[HWooldridge]

Yes, it is more of a twist issue than actually being level. Twist puts the tailstock off center with the headstock - causing a potential for inducing unintended taper on a machined part. Having the ends high or low can cause a "belly" in the part because the carriage either rises or falls in relation to the part.

This is more of an issue with older long bed lathes that are not fastened to a frame or cabinet. I have my 10" Sheldon on a dirt floor and it will hold .001 all the way down the bed but it's bolted to a large rigid cabinet.

[Jim Pennock]

We have guy at work who ran a turret lathe in the navy during Vietnam. He said the worst thing about it was the coolant sloshing around.

[rthibeau]

Which coolant was that Jim...the machine or operator's coolant??

[irnsrgn]

Lathe leveling was brought up at one of the conventions I used to attend and developed into a very heated discussion as usual especially with 80 to 100 shopmen assembled in one room. The part that stuck in my mind was from an 80+ year old Master Machinist who was setting next to me and kept quiet thru it all. But, he did confide in me his tried and true method for setting a lathe as he called it. His method was to shim the headstock end higher than needed and level to within .0001 per foot, then go to the tail stock end and using a little screw jack in the exact middle under the ways to jack it up till the bed was level to within .001 of its length, let it set for 2 to 3 days so the metal in the lathe bed returned to normal as it was machined, check it for level again then check the tailstock end crosswise to the same specs as the head stock. If it didn't level itself in this 3 point contact set up with no external twist to the end, it would never cut true no mater what you did to it.

Most old machinists were very particular and one of the things they always did when turning between centers was to dial in or center the tailstock in the position it was going to be used in every time for each set up.

As for leveling on a ship, its usually fastened down to the steel deck of a ship which in the way its put together gives a very stable un twisting mounting surface. Not counting chance encounters with torpedoes, bombs and internal below decks fires and explosions.

I had a friend who was a machinist on a Sub Tender and for some unknown reason they put the smithy shop directly above the machine shop, the Smithy had a 500 lb LG hammer in it, and they had to give all the compartments below and adjacent to it at least an hours notification prior to using it. LOL

[John N]

on a boat i doubt a spirit level / box square would be much use !

what most c/l turners will never admit is if the tollerance is really critical to a thou, or better than .001" then its a grinding job, and they are only roughing it out

[robk]

On lathes and ships....I've heard tale that when a ship is under way that machining was a no-go. Something about the way you could see the tailstock move when sighting along an open center...perhaps some other old hand could be more specific.

[yesteryearforge]

Please describe an OPEN center