Mark 5/V Extension Table Alignment

[dusty]

After receiving and installing my Double Tilt Upgrade Kit I began two or three different projects, one of them the Extension Table Alignment.

Why can an Extension Table that has been aligned at one end of the Mark V not be used at the other end without doing at least some tweaking and in some cases needing to make major adjustments?

All that I personally can confirm at this point is that this condition does exist (at least on my two Mark Vs). It is my further understanding that other users have the same experience. I'll try not to insert conjecture about what others experience.

This morning I very meticulously aligned two extension tables at opposite ends of the Mark V and then swapped them one for the other. The results were very disappointing. After the swap, one of the tables was high on the input side while the other was high on the output side. Which is which might be important. I will document that with an edit here.

I took the Extension Tables off and turned them upside down on my workbench and using extension tubes tied them together. The purpose was to make a comparison of the support legs on the two tables. I expected them to align to one another almost perfectly. I was so wrong in my expectations.

A visit to my cardiologist forces me to close this discussion for now but 'I, like MacArthur, shall return' only I won't be in Manila.

[algale]

This would seem to indicate that twist is being introduced in the legs or whatever the new name is for the headrest and base assemblies such that the bores that accept the extension table legs are pointing in different directions. Either during set up or when placed on the ground.

I would consider taking a long leg off a SPT and put it in each bore one at a time and put a Wixey on it to see what angle readings you get.

[dusty]

This would seem to indicate that twist is being introduced in the legs or whatever the new name is for the headrest and base assemblies such that the bores that accept the extension table legs are pointing in different directions. Either during set up or when placed on the ground.

I would consider taking a long leg off a SPT and put it in each bore one at a time and put a Wixey on it to see what angle readings you get.

There may be a twist. If there is, I'll be frustrated because in one way or another I have been told that more than once.

In response to your post, however, I have done something else. I have the Bench Tubes being supported by two barrels so that the Shopsmith legs are off the ground. I did this as sort of a pseudo return to the rebuild process. In addition, I have loosened all four of the Way Tube set screws so that they can take their own positions in the Pivot Arm bores.

Up on Different Legs 004.JPG (136.07 KiB) Viewed 3739 times

This is a look at the Extension Tables after the swap but I think I have to disregard this and start over now that the Mark V is resting on other than its own four feet.

[JPG]

I do not know what is supporting the two aux tables in the second pix. However it indicates the tables are not in a common plane left/right.

The initial description relates an error in the front/rear plane.

Needless to say this confuses me.

I am not sure what was accomplished by placing on an unknown surface(barrel tops) and loosening the way tubes other than to cause the way tubes to assume an alignment to the unknown(due to the barrels) alignment of the bench tubes.

IIWM, I would for now back track to not referring any alignment to the main table, but rather simultaneously align the two aux tables to each other at opposite ends, then swap and 'observe'. Dig out that laser level.

[thunderbirdbat]

The main table is adjusted perpendicular to the saw blade/sanding disk. The aux tables are adjusted to the main table. Does this mean the the saw blade/sanding disk is not perpendicular to the way tubes/floor? If this is the case then the slight angle would not allow the aux table to be swapped as the angle would be opposite at the other end.

[JPG]

The main table is adjusted perpendicular to the saw blade/sanding disk. The aux tables are adjusted to the main table. Does this mean the the saw blade/sanding disk is not perpendicular to the way tubes/floor? If this is the case then the slight angle would not allow the aux table to be swapped as the angle would be opposite at the other end.

The floor is irrelevant. The blade/disk face in a parallel plane to the spt mount bores(center axis) is what matters. Parallel means both left right and vertical. If so. the main table adjusted to the blade/disk should also align with the both aux tables. All that is left to adjust on both aux tables is the front/rear tilt to match the main table(horizontal plane of all three table top surfaces).

I suggested the exclusion of the main table(at this point in the process) so as to eliminate it as an intermediate reference.

The current goal is to determine why swapping is not successful, so concentrating only on the tables/posts/mounts should help reveal the reason why.

[thunderbirdbat]

The main table is adjusted perpendicular to the saw blade/sanding disk. The aux tables are adjusted to the main table. Does this mean the the saw blade/sanding disk is not perpendicular to the way tubes/floor? If this is the case then the slight angle would not allow the aux table to be swapped as the angle would be opposite at the other end.

The floor is irrelevant. The blade/disk face in a parallel plane to the spt mount bores(center axis) is what matters. Parallel means both left right and vertical. If so. the main table adjusted to the blade/disk should also align with the both aux tables. All that is left to adjust on both aux tables is the front/rear tilt to match the main table(horizontal plane of all three table top surfaces).

I suggested the exclusion of the main table(at this point in the process) so as to eliminate it as an intermediate reference.

The current goal is to determine why swapping is not successful, so concentrating only on the tables/posts/mounts should help reveal the reason why.

How do you know that the mount bores are parallel with the blade/disk? A few thousands out of parallel will be noticeable over the length of the SS. When aligning the aux table you also adjust the side to side height with a straight edge to be level with the main table. In my adjustment procedure step 81 and 82 adjusts the side to side level. "Hold a straightedge on the infeed (81)/outfeed (82) top surface of both the worktable and extension table, as shown in Fig. B-102 (81)/B-103 (82). AS needed, adjust the top nuts located on the infeed (81)/outfeed (82) side of the extension table, in order for the straightedge to be level across both the worktable and the extension table infeed (81)/outfeed (82) sides." If the bores were parallel to the blade/disk this would not be required. Also what is the manufacturing tolerance for these parts? The tolerances could also account for the requirement especially when multiple parts are combined.

[JPG]

We do not 'know' that they are.

However for end to end compatibility, they need to be very close.

Yes the 'book' describes aux table alignment procedure.

Only for a single table to one end(typically the right end).

It is the desire for that aux table to also magically be aligned when moved to the left end that we seek a solution for(or at least understanding why it is elusive).

Getting there requires out of box(book) thinking re how it can be accomplished. It requires breaking it all down to geometry and the effects adjustments has on that geometry. Hence the use of parallel, planes bores etc. wording.

Dusty is possibly chasing his tail, but I have been in the chase with my Mark 5 Goldie myself. I understand his rationale re the headrest of the Mark 5/v contributing to the incompatibility and share his belief that the double tilt can at least minimize the problem.

We are however at the mercy of manufacturing tolerances as well as assembly/alignment details.

If the aux tables were not adjustable about all three axis they could not be aligned on either end. That adjustment takes place at the top of the mounting tubes platform. The lower end of those tubes are referenced to the spt bores. As you noted a small deviation projected across the width(end to end of the ss) could result in significant 'error'.

No we do not know the magnitude of those manufacturing tolerances, but only become aware of them by their effect.

We are hopeful that we can gain sufficient understanding so as to make that magic happen. We may be doomed to failure, but we have it in us to have to try.

[dusty]

The main table is adjusted perpendicular to the saw blade/sanding disk. The aux tables are adjusted to the main table. Does this mean the the saw blade/sanding disk is not perpendicular to the way tubes/floor? If this is the case then the slight angle would not allow the aux table to be swapped as the angle would be opposite at the other end.

Yes, the main tale is set perpendicular to the blade. This establishes the reference surface for most every other measurement.

The Extension Tables are then adjusted to the Main Table.

The blade, if all is kosher, will be perpendicular to the plane established by the Way Tubes.

This all checks out fine until one moves an Extension Table that was aligned on the right end to the left end. This is when the confusion begins.

SIMPLE SOLUTION: Dedicated right side and left side extension tables.

Simple, yes and if I never get to the bottom of this that is just the way I will work. It is the fact that I don't understand why this occurs that frustrates me. It seems there should be a simple resolution but I have not found it.

[jsburger]

The main table is adjusted perpendicular to the saw blade/sanding disk. The aux tables are adjusted to the main table. Does this mean the the saw blade/sanding disk is not perpendicular to the way tubes/floor? If this is the case then the slight angle would not allow the aux table to be swapped as the angle would be opposite at the other end.

Yes, the main tale is set perpendicular to the blade. This establishes the reference surface for most every other measurement.

The Extension Tables are then adjusted to the Main Table.

The blade, if all is kosher, will be perpendicular to the plane established by the Way Tubes.

This all checks out fine until one moves an Extension Table that was aligned on the right end to the left end. This is when the confusion begins.

SIMPLE SOLUTION: Dedicated right side and left side extension tables.

Simple, yes and if I never get to the bottom of this that is just the way I will work. It is the fact that I don't understand why this occurs that frustrates me. It seems there should be a simple resolution but I have not found it.

I don't understand it either. I would certainly like to understand why. I just think there are too many variables.

Go back and read our thread in September on the same subject when I did all this stuff over and over on my double tilt with pretty much the same results. It might give you an idea of what to try next.

http://www.shopsmith.com/ss_forum/maint ... 16898.html