joe_cool wrote:I wonder if John Burger after doing his double tilt upgrade if his extention table aligns on both ends?
OK, I don't remember nor can I find the thread I wanted to post this to but it is relevant here so here goes.
This was all done on my MK 7. First I checked the table tilt to the blade. It was dead on 90 degrees. Then I checked the miter slot parallel to the blade. I am off 0.005". Close enough and not worth fooling with. Then I checked the main table for flatness. It is not perfect but not bad. Left to right across the front the right corner is down about 0.008". Across the middle the right edge was down about 0.006". Across the back end it was flat. Diagonally left front to back right it was flat. Diagonally right front to left rear the front corner was down about 0.008" as expected.
Next I installed my two fixed extension tables leveled them with the main table and checked for co-planer with the main table. They were both off slightly left to right. So I thought I would use Dusty's method using the connector tubes. I have four short tubes and none of them are perfectly straight. I rolled them across the Powermatic cast iron table top and they are all out 10+ thou. Anyhow, I loosened the bolts on the right extension table, slid the main table to the right, installed the connector tubes and tightened the locks. The back of the table came up fine but the front was low about 0.030". Huh

OK the fence is misaligned. I got out the fence gauge and sure enough it was too low. Huh, that is the wrong direction.

So I abandoned the tube idea and went with the straight edge. I still have no idea why the tube did not work on the front. I got everything level and co-planer on both extension tables with the straight edge as I have always done.
Once everything was level and co-planer I checked diagonally across the entire surface using Dusty's method with a string. I don't have a straight edge long enough either Dust. You said something to the effect that the results are far from perfect. Well, my results are as close to perfect as I think you can get. It is pretty hard to tell from the pictures but those strings are dead straight when you sight along them and if there any gaps to the table I couldn't see any.
Now for the question of swapping fixed end tables on the MK 7 with no alignment problems. No quite. Next I swapped the tables. The right table on the left side was fine. The left table on the right side was not. It was not co-planer left to right. It was not much, 0.030" or so, but not perfect.
BUT there was another interesting issue. When I swapped the tables the left table was 1/8" lower than the main table and the right table was 1/8" higher than the main table. Remember I use adjustable stop collars on all my tables so when I drop them in there is no change. Again Huh

how can that be? The only way is if the main table is not parallel to the way tubes. Remember the main table is dead square to the blade. I measured from the top of the way tube to the top of the table on both sides. The left side is 1/16" higher than the right side. That corresponds perfectly to the difference I saw when swapping tables. You can see the difference in the pictures of the level. Oh, notice how level my floor is.

This may or may not be a MK 7 issue. It seems to me that there are two things that can cause this. The way tube holes and the table tube holes in the carriage are not 90 degrees (not a MK 7 issue per se) or the way tube holes in the double tilt end castings are not in the same vertical plane.