Mark 5/V Extension Table Alignment

[benush26]

I have no dog in this hunt. I bought a second aux table without the magnetic strip (so it easily identified) and it always goes on right, original on the left.
However after reading all this I have come to wonder that if all four holes in the casings are not co-planar on the X and Y axis and all not PERFECTLY parallel to each other, is it even possible to get both tables swappable?
Any deviation corrected for one side would not be there when the table was swapped, therefore the "corrected" deviation would reappear on the other side.
In this case the main table would be only a reference for either side separately but not both sides as an assembly.
Unless the holes used for connecting the ends of the tubes and the carriage and the posts into the trunnions and holes where the table legs were inserted are perfectly machined and kept in that alignment, I see no way to make aux tables interchangeable.

Just my 2 cents.

Be well,
Ben

[dusty]

Your 2 cents are worth a couple dollars in this discussion.

So far I have to admit that the tables may not be swapable (without additional adjustment). The four holes in the castings of the Extension Table may not be properly oriented and they are not coplanar. I believe that that is why those are all adjustable (the purpose for all the nuts and washers).

My expectations of the Double Tilt may have been too high. I thought that with both end castings being identical that the old alignment issues would become mute. They certainly have not yet and I am beginning to believe they won't.

Funny thing is that my jointer "permanently"resides on the left end of the Mark V and I never use an extension table there. Exchange-ability is really not an operational issue; this is just one of those things that bug me.

[dusty]

I have not yet given up on making extension tables swapable but I have abandoned the bench top test bead. It did not alter the problem at all. I thought that even if it did not lead to a solution it would reduce the level of incompatibility just because the two end castings are so close together. Being shorter than a Shorty changed nothing. Being on a "flat and level" work bench changed nothing. Eliminating the legs as contributors (by resting the bench tubes on cans rather than the legs) changed nothing.

I am almost out of wild ideas but I am not yet ready to throw in the towel.

[algale]

Take the extension tables off the legs. Insert the extension table legs in both castings and secure. Are the legs all at the same angle per a Wixey measurement? Is not, can one casting or the other be loosened and twisted until they read the same?

[JPG]

The 'facts' as I understand them(no reference is made here to adjustments etc.).

The spt bores must be perpendicular to the bench/way tubes at both ends and front to rear.

It is this relationship that must be realized or success will be elusive.

Also the bench and way tubes must be straight. If not, same as above.

Let me elaborate since this is not intuitively clear and is actually three separate requirements.

The bench/way tubes being horizontal requires the spt bores to be vertical. That is the first perpendicular requirement. This can only be observed from the normal operator [position.

The spt bore centers(front to rear) must be perpendicular to the bench/way tubes as well. Both these reference lines(bench/way tubes and spt bore center front to rear) are horizontal. Thus the perpendicularity is only observable from above.

Lastly the spt bores must be perpendicular to the horizontal plane defined by the bench/way tubes pairs. Again the spt bores are vertical. This can only be observed from the ends of the bench/way tubes.

The aux tables are adjustable to compensate for any deviation from these requirements.

If however the 'other' end does not deviate identically*, the aux table will not align at both ends.

* since the castings are rotated, some deviations would result is opposite direction 'deviations'. i.e. an spt bore tilting to the right would tilt to the left on the other end. Ditto a front/rear tilt.

Thus I conclude that getting the three degrees of 'normalcy' (perpendicularity) is the path to success and fiddling with the table adjustments is futile. Only way I see to accomplish that is by shimming the bench tubes in all three axis.

Measuring the 'normalcy' is an elusive task as well.

We are totally at the mercy of manufacuturing tolerances.

The double tilt has a greater chance of success than the historical tie bar.

Either could gain success IMHO. Could being the operative word. Not the same as easy. Getting there by 'adjusting' only I now realize is not likely.

[dusty]

The Bench Tubes do establish the base reference for all that follows. With that I agree. Therefore, if the Bench Tubes are "in the same plane and equal distant apart, the reference has been established. All future measurements must be made relative to that base.

End of discussion. Anyone who might want to discuss this further can PM me. I'll be out in the shop checking perpendicularity.

[dusty]

The Bench Tubes do establish the base reference for all that follows. With that I agree. Therefore, if the Bench Tubes are "in the same plane and equal distant apart, the reference has been established. All future measurements must be made relative to that base.

End of discussion. Anyone who might want to discuss this further can PM me. I'll be out in the shop checking perpendicularity.

This is close to correct but close counts only in horse shoes and hand grenades!

In my quest for extension table interchangeability I have become more and more frustrated while at the same time becoming more enlightened.

It has been said by some and accepted by others that interchangeability is not possible. With that statement I do disagree. However, it may be true to say that "universal interchangeability is not possible".

Several comments to this thread and others have stated that the relationship of the bench tubes and way tubes to one another is very important. What I have been missing is that the angular relationship to one another is also important. Reference the following:

Shaft and Tube Angle Verification.png (96.33 KiB) Viewed 2237 times

Dimension have not been included because I suspect that no two machines will measure exactly alike. This is one of the barriers to this quest.


Again, dimensions will likely vary from machine to machine. I have annotated this drawing with the angle measured at only one corner of my machine. Measurements must be taken at all four corners. More importantly, if interchangeability is to be achieved, all four corners must be the same.

I have three setups on which I can check this relationship. Three setups means twelve corners to measure. After making and recording the twelve corner measurements I was astonished to find that I had absolutely no correlation at all. I made twelve measurements and got twelve different results. Some are close to expectation while others are not.

Here is the tool that I cobbled together to make the measurements.

Tool to Check The Tubes.png (71.43 KiB) Viewed 2199 times

Angular Verification 001.JPG (125.46 KiB) Viewed 2237 times

The solution is still most elusive but I am getting closer each day. I have a real nice sliding bevel square but it is not long enough for this task so I "made one". The iGaging Angle Cube is really not needed to ascertain whether the four corners are the same or not. If they were the same that would have been obvious.

[algale]

I'm embarrassed to say that I'm not sure what these diagrams purport to show. Are these the base castings? Viewed from above? From the face where the way and bench tubes enter?

[JPG]

From the bottom up, a pair of bench tubes, a pair of way tubes, an idler shaft and at top the quill shaft.

I am not sure why the way/bench tube angle is being measured. Perhaps to establish the bench tube/way tube/quill shaft relationships. The spt bores are what is relevant from this perspective.

In the second pix, the way tubes appear to be 'twisted'.(IIUC)

Keep in mind, the way tubes will only affect the main table.

[dusty]

I'm embarrassed to say that I'm not sure what these diagrams purport to show. Are these the base castings? Viewed from above? From the face where the way and bench tubes enter?

They show nothing except as a collection of facts for me to use as I stumble my way through all of this. If my machines were assembled correctly as should find those relationships in reality.

As for the ways with respect to the bench tubes, if they are not in the proper perspective, alignment of the extension tables could be effected. Someone keeps mentioning twist. Here is where I can measure the existence of twist if it exists.

You might say they are the bench castings but they really are just the end view of all the tubes and rails with the drive shafts thrown in.