Rollie's Dad's method

When I first set up my lathe, on a way-too-flexible floor, it took me
a long time to get it dialed in. Part of that was the floor's fault,
part was that I didn't have much clue what I was doing. I did
finally get the lathe lined up, but I have no idea how. I seem to
remember that it involved about a million cut-and-try experiments,
some intense profanity, and luck.
Time to do it again, this time on -- hallelujah! -- a concrete
floor. I recall from way back that some people were fans of Rollie's
Dad's method of lining up a lathe. I've just looked it up and it
seems sane. (See
formatting link
for an
explanation.)
What say you? Is this a viable way to set things up? Any problems
with it? 'Cause it sure looks simpler than cutting a thousand test
bars.
Pete
Reply to
artfulbodger
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For normal usage, I would not use, nor would I recommend, either method.
Much simpler would to be to use a precision level, parallel and gage block(s) to level the lathe ways.
Next I would use a cylinder, turned between centers, that has a near and far diameter of exactly the same diameter (the middle is not necessarily important for a machine in good condition). Use this to set the tailstock position.
It seems the link's attempt is to correct mis-alignment between the ways and the headstock by stuffing paper under the latter.... a poor fix, at best. It does not address levelness of the machine nor any twist in the bed....
If you find vertical misalignment or that the headstock and/or tailstock axes are no longer parallel with the ways.... rescraping is in order.
Reply to
Gene Kearns
Go get a copy of "How to Run a Lathe" from south bend, and perform their two collar test. It's all you need to do, and takes nothing besides a micrometer and a piece of stock in the chuck.
Jim
Reply to
jim rozen
Yeah, but that won't do the whole job, will it? Or, let me rephrase: leveling across the ways won't do the whole job, and I can't level along the ways because, though I have a very good level, I don't have anything I can really use as a parallel.
Yes; tailstock's not a problem. I keep just such a bar handy, and use it to reset the tailstock whenever I've set it over for some reason. (Note that Rollie's Dad's method doesn't address the tailstock at all. It's just to get the spindle & ways lined up.)
I grant you, the business about paper is ridiculous. But I have plenty of decent shim stock around.
Now you've lost me. It doesn't address level, that's true; but it seems that twist in the bed is precisely what it does address.
BTDT. Fortunately the lathe doesn't need any scraping. The shaper did, though. It took way too long, but the result was good and, God help me, I had fun doing it. A lathe bed, OTOH, I'd rather not do. I'd drink poison long before the job was done.
Thanks for your help. Curious to have your further comments on Rollie's Dad's method vis a vis twist in the bed.
Pete
Reply to
artfulbodger
Got it, but it's been a long time since I've read it. Thanks, Jim, I'll have a look.
Pete
Reply to
artfulbodger
Well and good, I'm sure, but *start* with a properly leveled machine so it isn't leaning in any direction. While lathes will run fine out of level, if you have yours established properly before you make any fine adjustments, you will be able to rely on the machine being level for certain functions. Chucking irregular objects in a 4 jaw, using a level for setup, for example. The minor amount you may be out when you do your final tweaking would be far better than to have it out a few degrees because you sought a straight cut without concern for level setup.
Harold
Reply to
Harold and Susan Vordos
The *concept* of shimming the headstock is bizarre, to me! Hell, the relationship between the two was established at the factory... what caused it to change since then?
That, I think, is the fallacy of this method. Once you get things bent around where the indicator is happy with the wobbling rod, how can you then trust the tailstock... which I'm sure you'll eventually need!
Actually, it seems to approximate some projected spindle axis based on two points on the rod... as if the headstock was no longer pointing in the right direction. Most lathe wear is near the headstock... if you create some axis based on this wear the tailstock is not going to line up.... especially if you have shimmed something....
Reply to
Gene Kearns
Hey there, Harold. The notion of using a level for setup, it's just foreign to me. Last you knew, I had my machines in the unrenovated house next door to where I was living: lathe on the sun porch, shaper in the kitchen, milldrill & bandsaw in the dining room, and all the floors were made of rubber. If I put a level on my workbench, I could walk a circle around the bench and watch that bubble go from one end of the vial to the other. I set each machine up so it was good if I stood in just the right place, and that was how I worked.
Now that I'm on a decent floor, I still don't have a way to get the lathe really level. I can get it close, yeah, but to get it right I'd need a good parallel or at least a longer level than the one I've got. (I've got a Starrett, a good one, but it's only 8" long.)
No matter: for the time being, I'm still working on a bench that's not bad, but not great, so perfect levelling is moot. I hope before long to weld up a good steel cabinet & put the lathe on that. Then, finally, I'll be able to level the machine for real. Until that time, it's all a matter of getting things close enough for jazz. It gripes me, but there it is.
Pete
Reply to
artfulbodger
Ah. Confusion. The idea isn't to shim between headstock and ways, but to shim under the lathe's feet, at the headstock end. If the method called for shimming between headstock and ways, no, I'd not do it. But shimming under the feet, well, that's just normal, innit?
Reply to
artfulbodger
Ever read that book Harold? I gave my copy away a few years ago or I would sent it to you.
They say:
1) mount the machine to a solid, unmoving floor.
2) level it with a spirit level.
3) once this is done, then do the final arbiter check for accuracy: the two collar method.
Interestingly if you read what Hardinge says about setting their machines up, there is absolutely *no* mention of any kind of spirit level.
Step one: Plunk the machine down on a solid floor. Step two: drop down the tab inside the back cabinet so the machine doesn't tip.
Done.
Because of the ingenious hardinge kinematic mount for their beds, a spirit level is not needed at all, nor is any bed tweaking or leg shimming.
Jim
Reply to
jim rozen
Hold on right there because what you just said makes more sense that you realize.
"Getting it close enough" actually means something.
It means you've decided on a tolerance for cylindicity of the parts you make - how much larger diameter can they be on one side, a certain distance from the other diameter on the other side.
And it means you have a means to measure that, and to make corrections in a systematic fashion, to improve the tolerance level.
And it means you are understanding the fundamental limitations of your equipment (bench stability, floor stability) that prevents you from achieving an arbitrarily higher level of accuracy.
If you stop and think about it, these are the exact same steps that any high accuracy endeavor has to deal with. Doesn't matter if it's +/- 0.005", or +/- 5 microinches. Its the same plan of action, and there are some folks who *never* figure this out, and use holy water and magic potions to line up their machines.
Jim
Reply to
jim rozen
I think you guys are reading it wrong. I took it to mean shimming the 2 corners of the main lathe frame (the ways) to the cabinet to take out the twist. Now, if your cabinet has 4 adjustable feet, it just makes the job simpler (and my Myford base does)
Reply to
nospam.clare.nce
Actually, I doubt that it did change from the time it was set up. But if one expects the tolerance of a $400 machine from China to be as close as those of a $15,000 machine, you are sadling mistaken.
"Gene Kearns" >
Reply to
Grady
The Colchester Chipmaster has the base mounted on 3 points onto the floor so it is automatically free of twist Geoff
Reply to
geoff m
And likely so to others as well, but don't discount if as a viable method of setting up strange objects. I've done it with success on more than one occasion. A good example is in setting up a part at an angle. I'm not suggesting it's something you'd do routinely, but it's yet another of the tools in the arsenal of skilled craftsmen. Don't close any doors where machining is concerned. Often the most absurd suggestion is the best solution to a problem.
I've never invested in a high precision level, either. I use a Starrett model 98, likely the 8" level of which you spoke. The point is, I know that my machines are not leaning by a degree or two. To ignore level before beginning to trim any machine isn't a good idea. Use what you have and hold your machines as close as possible. That's far better than ignoring the issue.
You might be surprised to find that you can't get your machine properly leveled, even with a metal bench. All depends on how rigid the bench is, and how rigid the lathe bed is. My Graziano sits on three points and refuses to go dead level, with a slight twist at the tailstock end. The only thing that will correct it is to unbolt the bed from the heavily cast base and shim, pulling the bed in alignment with the attaching bolts. That's assuming the base didn't move, and the bed did.
I'm not pleased with it, but the lathe still functions well. And it is, otherwise, *level*. That means when I lay something on a surface, it isn't inclined to grow legs and wander off. If for no other reason, machine tools should be level to avoid that very thing.
Good to see you back.
Harold
Reply to
Harold and Susan Vordos
Compensating for misalignment of headstock to bed by twisting the bed seems like a recipe for excessive wear to me. I'd recommend buying or borrowing a precision level, get the bed levelled in both directions with mounts considerably firmer than paper. Once that is done, then any misalignment of the headstock can be corrected. Once that's done, things should stay put and work well long time.
Reply to
Don Foreman
Can't say as though I spent a long interval with it, but a couple years ago Susan sold one on ebay. It came in a lot of things that was auctioned from a military installation. Pretty elementary stuff, but all important for the uninitiated in the way of using a lathe, naturally. Doubtful a seasoned machinist would learn much. I had a book much like it, sold originally by Sears (one of which I bought when I purchased my first lathe in the early '50s). The book went with the lathe when I sold it way back in the late 50's., a model 109,. 6" machine with the 1/2" -20 spindle that bent easily.
Exactly my point when I suggested the machine should start out level. Get it close, fine tune it by turning. Your comments, " It's all you need to do, and takes > >> nothing besides a micrometer and a piece of stock in the chuck." conveniently leaves out the leveling process. I don't recommend it. I get the idea you didn't intend to say it that way, though, or you wouldn't be quoting from the SouthBend manual.
Chuckle! I'm going to assume you know better than to think you can mount the typical machine that way. My Graziano, for one, can be placed on the floor and operated. The heavily cast base is more than rigid enough to support the bed as it was shipped from the factory----------but they *still* recommend you level the machine.
It's more involved than their kinematic mount---------mass and rigidity play a huge role in stability, as you well know. I'd also suggest to you that modern manufacturing facilities tend towards quite level and flat surfaces. That's a far cry from some of the older installations, where you likely couldn't get away with such an installation.
Hardinge machines are solid enough to not demand level for precision. That doesn't mean you don't benefit (albeit in other ways) by leveling. Many a machine can be operated successfully at strange angles. It's just not normally a good idea. Regardless of their ability to run out of level, leveling their machine, as well as any other, is a good idea, so things stay where you put them when you let go of them. Have you ever worked on a surface plate that wasn't level? Need I say more? Also, don't discount the fact that you may, on strange occasion, wish the machine was level, so you could use a level for setup. Maybe you haven't done that in the course of running your machines, but the day will come. It has for me.
Harold
Reply to
Harold and Susan Vordos
As far as I'm concerned, the levelling can be done with a carpenter's level - it's only done to keep tools from rolling around in the chip pan. The real accuracy comes from the second step. I've seen too many folks try to do precision setups with a spirit level, with the reasoning "well the machine was set up level, so if I level the workpiece then it will be cut accurate.
In other words, using a level when a good indicator should be used instead. IMO most folks don't level to make their machine accurate, they do so to make their setups easier.
Cast iron is not that rigid. The bed will twist - might not be much, but it will. And that impairs accuracy. But even with a Graziano, one should still check to see how the machine cuts once it is levelled.
I would say the hardinge beds are much less rigid than your graziano. Because the headstock end is supported on two, and only to point contacts, and the tailstock end is supported by a steel ball in a V-groove, no gravitational forces can ever impart twist to the bed - and because the machine was originally set up at the factory with that same mount, all the accuracy in the initial build is available with no need for an kind of spirit level.
Because my south bend 10L, which has a bed as sturdy, or even sturdier than the hardinge machines, has the older leg style bed mount, a twisting moment is invariably applied between the headstock and tailstock ends. The key to getting it set up is to get that moment to the correct level. In a new machine that means 'zero' or, rather, the amount that was there when it was set up at the factory originally.
Jim
Reply to
jim rozen
Oh, no, not at all! It has always seemed a very sensible (and fast) way to set up certain kinds of work. Just guessing, I'd think it'd be more often useful in milling work than on the lathe; but that's neither here nor there. Reliable people have said that setting up by level is a tremendous timesaver, and I believe them. But the idea of doing it on my old shop's trampoline floors? Ha! I remember teenut once, singing the praises of his level machines and how they made some setups a breeze; I read his message and laughed, and never considered it again.
Now, I guess, with decent floors, I can revisit the idea.
Yep, that's the one. Pretty li'l thing and way more precise than the carpenter's levels I was used to.
True. I really don't know how rigid the lathe is: I don't know what to compare it to. It's a benchtop unit, a SB 9" long bed. At the time it was made, it was way more rigid than other lathes in its class. I don't know how noodly it is next to a new lathe of its size. I do know it's juuuust a bit more flexy than some two ton Hardinge. Oh, well. Carefully set up, it's neither too worn nor too wobbly to cut straight.
As for the bench, we'll see. I'm about one step away from pouring a couple of concrete pillars and mounting the lathe on them. THAT would settle a thing or two.
Thanks. It's nice when, for at least a while, life settles down somewhat. Finally I get to do something about all those castings in the garage. They've been looknig so forlorn.
Pete
Reply to
artfulbodger
I don't get it. Almost any benchtop lathe will twist from its own weight, right? So what's unusual about shimming to correct it? (As for paper shims, you'll get no argument from me. I can't think of anything more Mickey Mouse, except maybe using a sponge.)
Pete
Reply to
artfulbodger

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