Leveling a 20"x80"

Ive searched and read all the previous threads on this subject, but any extra DOs or DO NOTs would be appreciated, ive never done this before...this lathe appears to have 8 jacking points rather than the 6 commonly talked about in the other threads...

My basic procedure is to start with three of the levelling bolts, this way you get everything close with minimal effort, and you don't bind anything, since any three points always rest in one plane. Once you're as close as you can get to level with three bolts, tweak in the rest. If you get it perfect with three, then you're in for an easy day of it. Set a heavy steel block on the floor with a dial indicator mounted and registering on the lathe at a solid point near the next levelling jack and zero it. Tighten the lifting nut 'til you register a lift of .002" or .003" then tighten the clamping nut 'til you bring it back to zero. Repeat until you are at a level of torque that you find acceptable. Rinse and repeat at the other levelling stations. Above all, have fun!

So I take it you found a replacement for the old Harrison. What model is the new lathe?

wyzkydd2358: When you do the "lift and set" at each additional point, I presume you shim if necessary, is that correct?

If your lathe has jacking bolts designed to support the machine full time install plate pads under them. Running jacking bolts down on concrete isn't a good thing to do.

If you have to pry up and shim, make up shim packs that are neat and tidy using a minimum number of shims. Haphazard stacks of washers and flat bar scraps can and will collapse at the worst moment.

Level the first two pedistal pads unter the chuck first, then the two in front of the inboard end of the tailstock pedistal. Then the two under the index train then the two on the far right and repeat. If one pad has no weight in it drill into the concrete and install a bolt to pull it down to firn support. There's no hard and fast procedure. You have to go reound and round a few times anyway refining the leveling. And do it again a week, then a month later.

200 lb will deflect an unsupported 4" concrete slab to a small degree. If your slab is broken or has soil subsidence under it, your weight may be enough to affect the final stages of leveling. If that's the case make your observations of the level vials from the operator's usual standing spot.

I've only ever levelled lathes in an industrial context i.e. on concrete floors. Usually each jacking screw will have provision for a holding down bolt hole either near to the jacking screw or through a hollow jacking screw, if at all possible you should use all of these holding down bolt holes. Running a lathe with a four jaw chuck at any sort of speed or a three jaw at high revs without bolting it down is hazardous to say the least and will not lead to good finishes. Forrest's advice is sound enough but try to avoid the temptation to keep levelling up and up, the nearer you can keep your lathe to the floor the better. As Forrest advises if there are no jacking screws and have to shim up keep the shims neat and tidy and to a minimum. Levelling up is not the end of the story Cathead, you will need to do a basic alignment test before considering your lathe ready for action .Regards Tyrone.

Its definetly an interative process. If possible I like to use a torque wrench on the jack screws so that I have some feel of the amount of force that is occuring at each point and hoping for a "somewhat" equally distributed load (at least side to side).

SND
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Member # 1087

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posted 04-23-2006 09:47 AM
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So I take it you found a replacement for the old Harrison. What model is the new lathe?


Ya..finally..its a new Acra Turn

Using a torque wrench is a new one on me Jstolaruk, I'm not sure what it will achieve, lets say one or two of the threads are damaged or rusted up , you will not achieve anything just using a torque wrench, it's suck it and see I'm afraid. If you can get a helper to swing on the spanner whilst you watch the level it will make the job easier. Another reason for using all the holding down bolts is that you can ( within reason ) sometimes " bend" a worn bed straighter than than it really is by a judicious use of holding down bolts and jacking bolts.

Tyrone has got it nailed, along with Forrest's input for unbolted machinery. I'd never ever install a lathe without it's being anchored to the floor with hold-down bolts, which, as has already been stated, usually go through hollow jacking bolts attached to the lathe. The torque wrench is a nice thought, but assumes that the lathe is perfectly straight and parallel in its free state, which is not always the case. Sometimes you'll have to pull down on two bolts, yet jack up on the one in between them to get things straight, even with no wear. Remember, there are apprentices everywhere, even in the places that made these machine tools. I often use a mirror if no helper is available so I can be down by the levelling screw and see the bubble at the same time. As Tyrone noted, you'll also likely need to do an alignment test if your lathe doesn't cut straight after you've levelled it. This test will tell you if your headstock is out of alignment with the ways. If, after you've levelled it, it cuts a taper while free-cutting a bar of stock in the chuck, you've got an alignment problem. You can also use a "test bar" and a dial indicator.

Even if your lathe turns pretty good chuck work to start with you need to check other things ,such as head stock/tailstock alignment and parallelism, it's too late when you've turned a piece of scrap and you don't know why.

Tyrone, the torque wrench is just for reference and I didn't say or mean that it should be used instead of the traditional methods. You are correct that other factors can influence the readings.