Ed in Tampa wrote:Not bad luck, in fact I don't do luck. Luck has nothing to do with it anything that is as adjustable and as configurable as the SS will have to have tolerances that will allow for some movement.
We all know there are five lock points on the SS and depending on many variables each time you loosen and tighten them things change. Let us not forget even the amount of torque we use to tighten those five locks can and does change things.
When we are talking .003" a .001" change which only requires nothing more than a bump of sawdust on lock wedge throws the alignment off by 1/3.
Repeat-ability is exactly what I'm talking about. You can align the main table to .003" parallel to the blade and loosening the blade on the arbor it could and usually does change that, now figure in the five lock points and movement that is realized in each of these and suddenly .003" is lost.
Now many times have people reported that uneven floors have caused them problems? When we are talking thousandths of an inch everything that moves or even where the machine is sitting on the floor can effect the alignment.
Dusty I trust you! Prove me wrong. Adjust your machine to whatever tolerance and then loosen the table side it back and forth on the way tubes, slide the headstock, rise the table up and down, crank the arbor in and out and move the SS couple of times while you do each of these then move the SS to a new spot in your shop and check your table alignment. Make sure you loosen and tighten each lock using varying torque and move each component while the SS is in at least five locations in your shop. Then wheel the SS back to the new spot at least 2 feet from where you set your machine up to start with and see. Tell us.
Don't do this stuff in such a way to prove me wrong do everything like you are building something. I could guess that if someone did all this with kid gloves and made sure they tightened every lock using the same torque, the same pressure, the same sequence on the component being tightened and was careful to pick spots in the shop and on the machine to stop at they could keep the tolerances fairly close. But if this is all done like we are working and must make an adjustment out of sequence to the usual sequence or maybe to pull or push things over to get with an 1/8 inch on the cut things will change.
What you describe here is much like what goes on in my shop on a daily basis with one significant exception. I do NOT routinely move my Mark V.
I also do agree that there are many factors that contribute to changes in alignment. The five locks being the major ones. If they are not secure - all bets are off.
I also concur that if you grab hold of the main table and apply pressure in all directions, the table moves. I have measured those movements and find them to be on the general order of .015". Additionally, when the pressures are removed, the table tends to return to normal.
I do everything that you describe, except roll the machine around the shop, and I find that over time my alignments have held.
Because I know that there are all these variables, when I am getting ready for a project (especially a critical project) I verify alignments.