Hi @Christianstark ,
Your story had made me thinking back to my own leveling....
I agree with Mark, while there could be errors, the lathe rails should have been made very well at the factory and so should be straight. To have this metal get a twisted set in it later is difficult to believe unless it has really been abused or the metal had stresses built it before it was machined and then stresses were later relaxed somehow (excessive heat. vibration, etc). Metals are excellent linear spring materials and do not take a deformation unless they are pushed beyond the deformation limits.
However, I noticed when leveling (flattening.. as my floor has a considerable pitch) my PM1440GT, which should be even heavier than your 1340, that there was a difference in the lift of the two tail stock stand leveling screws ... it is certainly not awful, but is perceptible.. So naturally I too ask why? However, I have done nothing serious about yet. (I viewed this stiffness as probably good as it means that the lathe bed is really stout and it is not easily twisted ... or, if you believe it is bad, untwisted.) However, it was viable to twist the bed with the leveling screws so the bed and stand weight must be enough to affect things somewhat.
David's comment about leveling off of his home made stand top raises a question. Are the PM stands heavy enough to actually influence the lathe bed twist? Suppose for a second that the bottom bolt hole surface of the lathe is not parallel and flat WRT to the lathe rails or that the stand surface is not square to the sides and bottom of the stand. Then bolting the lathe bottom holes tightly to the stand would put the stand at a twist angle relative to the rails causing a torque (twisting action) on the rails/bed. Given the geometry this should be mild, but so should a slightly uneven/level floor, but it still would exist. Adjusting the stand leveling feet would tend to remove this torque, but one would not adjust them the same amount to do so. Under a severe case one could have one of the two stand feet touching the floor to try to remove this stand induced torque! As David did, we should all probably be leveling at the top of the stand rather than at the floor! Or maybe even both places.
By the way, I spent a lot of time measuring the stands for the 1440GT when I was putting them on casters. Basically they are a heavy sheet metal which has been bent/folded to 90 degrees at each corner to form a rectangular cylinder and the ends are welded together. After this, holes and plates are cut and welded to and into it. They are pretty good, but nothing precision about them and they are not square so I see no reason that their surfaces would be flat/parallel/perpendicular to the lathe rails at the bolt holes for the lathe.
If this thought is correct, then the stand weight/torque twists the lathe rails and your anchors are then being used to try to create a counter torque to removed the stand induced twist!
If your initial thought that the lathe is just not heavy enough then should we not be able to just add weights to the lathe bed (sort of what you are doing by anchoring)? And would it not be possible to just remove the tail stock to test this weight concept somewhat?
Leveling should not be all this difficult nor take a lot of time. I put my lathe on casters so I could pull it out to work on it, to clean around it, or to change the oil catching matting that I put under it. Each time I have to lift (or lower) the lathe by the leveling feet to get it off/on/off the casters.
By the way, your talking about the struggles to move your lathe reminds me that a good pry bar is very handy. I purchased this one, that has steel rollers with ball bearings, at the end. Says 3 tonne on it but I don't even have anything that big to try to lift. https://www.amazon.com/gp/product/B07SHL3H7L It works great to move things or even to just lift them a bit to adjust shims, blocks or leveling feet. Most recently I use it to just move my refrigerator-freezer over a bit to better clear a cabinet.
Dave L.
Your story had made me thinking back to my own leveling....
I agree with Mark, while there could be errors, the lathe rails should have been made very well at the factory and so should be straight. To have this metal get a twisted set in it later is difficult to believe unless it has really been abused or the metal had stresses built it before it was machined and then stresses were later relaxed somehow (excessive heat. vibration, etc). Metals are excellent linear spring materials and do not take a deformation unless they are pushed beyond the deformation limits.
However, I noticed when leveling (flattening.. as my floor has a considerable pitch) my PM1440GT, which should be even heavier than your 1340, that there was a difference in the lift of the two tail stock stand leveling screws ... it is certainly not awful, but is perceptible.. So naturally I too ask why? However, I have done nothing serious about yet. (I viewed this stiffness as probably good as it means that the lathe bed is really stout and it is not easily twisted ... or, if you believe it is bad, untwisted.) However, it was viable to twist the bed with the leveling screws so the bed and stand weight must be enough to affect things somewhat.
David's comment about leveling off of his home made stand top raises a question. Are the PM stands heavy enough to actually influence the lathe bed twist? Suppose for a second that the bottom bolt hole surface of the lathe is not parallel and flat WRT to the lathe rails or that the stand surface is not square to the sides and bottom of the stand. Then bolting the lathe bottom holes tightly to the stand would put the stand at a twist angle relative to the rails causing a torque (twisting action) on the rails/bed. Given the geometry this should be mild, but so should a slightly uneven/level floor, but it still would exist. Adjusting the stand leveling feet would tend to remove this torque, but one would not adjust them the same amount to do so. Under a severe case one could have one of the two stand feet touching the floor to try to remove this stand induced torque! As David did, we should all probably be leveling at the top of the stand rather than at the floor! Or maybe even both places.
By the way, I spent a lot of time measuring the stands for the 1440GT when I was putting them on casters. Basically they are a heavy sheet metal which has been bent/folded to 90 degrees at each corner to form a rectangular cylinder and the ends are welded together. After this, holes and plates are cut and welded to and into it. They are pretty good, but nothing precision about them and they are not square so I see no reason that their surfaces would be flat/parallel/perpendicular to the lathe rails at the bolt holes for the lathe.
If this thought is correct, then the stand weight/torque twists the lathe rails and your anchors are then being used to try to create a counter torque to removed the stand induced twist!
If your initial thought that the lathe is just not heavy enough then should we not be able to just add weights to the lathe bed (sort of what you are doing by anchoring)? And would it not be possible to just remove the tail stock to test this weight concept somewhat?
Leveling should not be all this difficult nor take a lot of time. I put my lathe on casters so I could pull it out to work on it, to clean around it, or to change the oil catching matting that I put under it. Each time I have to lift (or lower) the lathe by the leveling feet to get it off/on/off the casters.
By the way, your talking about the struggles to move your lathe reminds me that a good pry bar is very handy. I purchased this one, that has steel rollers with ball bearings, at the end. Says 3 tonne on it but I don't even have anything that big to try to lift. https://www.amazon.com/gp/product/B07SHL3H7L It works great to move things or even to just lift them a bit to adjust shims, blocks or leveling feet. Most recently I use it to just move my refrigerator-freezer over a bit to better clear a cabinet.
Dave L.
