What would cause this

[dusty]

If I recall correctly, those who have upgraded to the double tilt bases (i.e. Mark 7 style) report that, after the upgrade, the extension table can be switched end-for-end without losing alignment.

I believe that is correct but I would sure like to hear from a dozen or so that all say the same.

[jsburger]

If I recall correctly, those who have upgraded to the double tilt bases (i.e. Mark 7 style) report that, after the upgrade, the extension table can be switched end-for-end without losing alignment.

Hmmm... I wonder why that would be. I never checked when I upgraded since I have two extension tables. I need to play with this and see what happens.

[Bruce]

It looks like the right side needs to be raised with your adjusting bolts (you can see them in your photo). I am assuming your main table is already adjusted level.

If he does that and then moves the extension table back to the other end the alignment issue then will be there. Remember, he reports that he just finished doing the alignment on the right end and then moved the table.

I missed that little detail, Dusty. Thanks.

[dusty]

If I recall correctly, those who have upgraded to the double tilt bases (i.e. Mark 7 style) report that, after the upgrade, the extension table can be switched end-for-end without losing alignment.

Hmmm... I wonder why that would be. I never checked when I upgraded since I have two extension tables. I need to play with this and see what happens.

Hmmm...I'd put book on it be the direct result of the two Base Arm Assemblies being identical and the absence of a Headrest Locking Mechanism. Those changes, when combined, almost guarantee that the Way Tubes and Bench Tubes are properly and consistently oriented with respect to one another.

I came to realize a significant alignment issue when I was assembling my Shorty (less legs) up on my work bench. With the Base Arm Assembly and the Head Rest Assembly sitting on the bench top with Bench Tubes inserted and secured, I found that the Base Arm and Headrest did not rest firmly on the bench top. Loosening the set screws that secure the tubes and twisting the Headrest and Base Arm, I was able to get then to sit squarely on the bench.

Now, securing the set screws was an issue because I had no access. Once that was solved, I had no alignment issues.

With legs attached and the entire Mark XX resting on the floor produce this alignment issue unless you have a perfectly smooth, flat and level floor in your shop. If we were to take a poll, there might be two shop floors within this group that meet that criteria. Mine is NOT one of them. Mine was an open car port when the slab was poured. Because it was an attached car port, code prevented me from having it poured/finished level. Some BS about a slope being required so that when the snow and ice from under my car melted, the water would not collect in the car area.

[jsburger]

If I recall correctly, those who have upgraded to the double tilt bases (i.e. Mark 7 style) report that, after the upgrade, the extension table can be switched end-for-end without losing alignment.

Hmmm... I wonder why that would be. I never checked when I upgraded since I have two extension tables. I need to play with this and see what happens.

Hmmm...I'd put book on it be the direct result of the two Base Arm Assemblies being identical and the absence of a Headrest Locking Mechanism. Those changes, when combined, almost guarantee that the Way Tubes and Bench Tubes are properly and consistently oriented with respect to one another.

I will have to think on this and do some checking. The base arm assemblies are now two pieces on each end. As for a headrest locking system, there are now two, one on each end. If they are both loose you can lift the way tubes and everything attached completely off the base. That is why when you tilt vertical you need to be sure the pivot end lock is engaged or your way tubes and everything attached could end up on the floor.

[dusty]

If you have both, just compare the amount of movement on the headrest end of the 510/520 with the small amount of movement on either end of the Mark 7.

[jsburger]

If you have both, just compare the amount of movement on the headrest end of the 510/520 with the small amount of movement on either end of the Mark 7.

I will but do you understand that the way tubes and all other things attached to the way tube on the double tilt MK 7 are not solidly attached to the base? BTW, when I said earlier that there was slop in the extension tables it was with my MK 7. I will try with my MK V shorty.

[charlese]

Aligning extension tables is a tricky job. I remember several years ago when Nick called our attention to set screw #9.(see parts diagram) This little screw is used to raise or lower the tail end rear way tube. Purley a mechanical bending action on the "way tube tie bar" when locked down.

[algale]

I would think that the fact that both base assemblies on the double tilt now how cast stops for the bench tubes is helpful for alignment purposes. On the Mark 5, the there are no stops on the headrest end.

[JPG]

I will again state the logical purpose of that set screw is to insure the tubes(all 4) are parallel to each other. Most importantly the way tubes are not twisted relative to the bench tubes.

However other things need be correct also.

The bench tubes must not be in a twist either. This is where the flat floor and the legs come into play. Put another way, the end castings must be parallel(front to rear perpendicular to the tubes) to each other and vertically. A leg not resting on a flat floor can cause that to be compromised.

I think the legs can accommodate slight variation in floor flatness, but can raise off a low area and create potential rocking. In that case we are subject to deflection of tubes etc.

I contend that if the Mark 5/V has that set screw adjusted for tubes to be parallel and not twisted, the left/right mounting of a single extension table is possible with it aligning on either end. What is required is to create the same condition that the Mark 7 has(The tubes are in the same relative positioning to the bench tubes/end castings at both ends).

However the end castings can be mounted skewed on the bench tubes, so that must be eliminated.

Problem is, getting all this stuff aligned with differing end castings and way tube mounts. The Mark 7 eliminates that(both end castings etc. are identical). Add the positioning of the way tube set screws on top(accessible when laying horizontal) and the elimination of way tube twist becomes trivial if not automatic.

I will attempt to demonstrate in the next few days. Probably start a new thread and link to it from here.