Me and Rollie's Dad

[SteveHGraham]

I am fiddling with the "Rollie's Dad" method of leveling my lathe. I moved it back where it should be, and I started by aligning it horizontally. No problem. But when I tried to do the vertical leveling, one of the screws came off the garage floor.

I assume I should start with the four corner screws at least 360 degrees past the point where I get resistance, because otherwise, I have no slack to work with when I go from horizontal to vertical alignment. Is that right?

Not sure what to do with the middle screws. I guess I'll lower them till they take a little weight, but I don't want them messing with the alignment, do I?

[SteveHGraham]

The manual that came with the lathe mentions "leveling blocks" attached to the spindle, which seems to make no sense whatsoever. I haven't looked at them yet. I assumed that if there are internal adjustments, they should wait until I've done all I can with the screws.

I suspect these things actually BALANCE the spindle, and that the Chinese only have one word for "balance" and "level."

[John Evans]

Remember Steve all you are really after is all readings ON the lathe equal each other. That is the machine it's self can be off either front to rear or end to end SLIGTHLY with no ill effects as long as there is no twist discernible. On something like a mill with flood coolant closer to dead level is better or any machine with a flat table so things don't roll off. And at each place you set the level rotate it 180* to confirm the reading. Again avoiding twist or a hump/sag is the point of this exercise.

[John Evans]

Steve: I would suspect any "leveling blocks " for the spindle would be for aligning the spindle/head to the ways and not to be used for machine setup. In other words don't concern yourself with that area.

[BadDog]

Don't mess with the spindle or headstock, they *should* be good as is. You can confirm later, see comments in Sealkillers thread sometime back.

Rolies dad's method is useful, but generally you just use a machinists level like the Starrett 98. What is it, something like 0.0005 in 12" or so? Note, not a carpenters level! But these lathes are so rigid (even my 60" lathe!) that it's all but impossible to twist them perceptibly while leveling. RD is for dealing with twist without a level. My advice, find a level to borrow or buy. Even the Starrett can generally be found easily on ebay for under $100. I got a like new still in a box that looked new 12" Starret for $60 off Craigs List locally. And just because I ran across it cheap, I got a 6" off ebay (no box), seems like I only paid $40 for that, including shipping.

I seem to recall someone posted a "proper" sequence for leveling a 6 or 8 point lathe. For my 6 pointer, I wanted it higher so I didn't have to stoop, and gives me storage (for shorts and tools) underneath. So I turned 6 slugs from 5" (or was it 6"?) diameter steel stock, each about 5" long, and turned a divot in the center of what would be the top to capture the dog-points of the monstrous leveling screws. With the lathe on the spacers, I leveled it with only the outer 4. I found that it was VERY easy to lift one of the tail stock end feet while adjusting, and that it introduced no measurable twist. Once I had it leveled, I pulled up the inner screws till they had firm purchase, then noticed that it had lifted all the weight off one of the corners, and I had lost my level state, so it was an iterative thing at that point.

[SteveHGraham]

My big problem right now is running out of screw thread. I'm starting from zero, backing all the screws out until they're loose and then going back in two turns. I figure that ought to give me enough thread to play with.

There are a million "machinist" levels on Ebay, but a lot of the cheap ones look highly suspicious to me.

[dly31]

Don't be afraid to use metal shims or blocks under the screws if needed. Your garage floor could be very unlevel.

If your lathe is very rigid and/or straight, which I suspect it is, the ideal situation would be to have each screw take its share of the weight. You can generally tell that by the torque needed to turn the screws. If you are trying to correct a misalignment, you may very well find one or more screws off the floor when or before you finish. If you can get a pry bar equidistant between two screws you can get a some idea of their loading by checking whether they both lift off the floor equally.

I could be wrong but I imagine that lathe and cabinet will be stiff enough that you will not measureably effect its alignment and just need to level the whole thing as a unit, keeping reasonably equal weight on each screw.

[BadDog]

If his is like mine, that means a roughly 30 mm bolt with over 1.5" of travel. I hope his floor isn't that bad out of level. Just back those screws up till they are barely through the casting, and start from there. You'll have plenty of travel for all but the very worst floors. And if you do, yeah, just use some heavy plate for spacers. Mine were all gunked up from coolant, so I removed them, cleaned them, oiled them, and replaced them. In that way I could feel the torque on each and get reasonable load balance, at least that was the goal.

[EdK]

I believe Rolllie's Dad's method is only useful after you've taken the twist out of the bed. I'm sure I'll be corrected by the experts if this is incorrect.

Ed

[BadDog]

Perhaps I'm getting it confused then. I really haven't seen much about it since I moved on from the 9x20 group which seemed rather fixated on it, and my memory was that it was due to twist. <shrug>

[JTiers]

EdK is 100% CORRECT......

"RDM" is an "internal" measurement...... No external reference. It is essentially the same thing as the "two collars" test. It is NOT USEFUL for leveling..... in general.

There are two variables..... level , i.e. "bed twist", and alignment of the spindle to the ways. RDM OR "two collars", will check EITHER of them, IF the other one is KNOWN GOOD.

But you cannot check level with RDM if the spindle alignment is in question, or vice-versa. So in general, you must use the level, which gives an "external reference", to check level, and then can use RDM or two collars to check alignment. Two collars seems much more direct to me, but YMMV.

if you need a wrench, don't try to use a screwdriver or pliers.....

[BadDog]

J's reply rang familiar, and prompted me to take a moment refreshing before trying to get some sleep. Google turns up quite a few relevant hits. One seemingly good one that seems relevant is available here and another here. Those and others are probably worth looking at if you choose to pursue for whatever intent.