Main Table and Trunnion Alignment Before Mounting

[DLB]

...I don't know if all of the main tables are built with the same rib structure as mine. I have four tables representing at least two different vintages (505/510/520 only).

I noticed very recently that there at least two variants of the black tables, so at least three total. One (the older?) has four holes on the bottom in addition to the four for the trunnions. The purpose or intent of those extra holes is not known to me.

There was a time when the 'miter slot true to main spindle' alignment was done using the edge of the table and sanding disc. That's the procedure in a manual I bought in the early 80's because I had no manual for my Greenie. In it: "The sides of the table are machined perfectly parallel with the miter gauge slots." In that manual there is no mention of a factory alignment and the wording implies that the machine is not aligned at the factory, in contrast with later manuals. This procedure is much easier to perform than later procedures, but I presume there is a reason why it was discontinued in favor of using a saw blade and miter slot as references.

- David

[dusty]

I have a disappointing (to me) update. What I have been attempting can be done probably on only a given table. In other words -- NO universal procedure. While I have tables that look alike (ribbing format) they do not measure the same. The deviations are significant enough to make it impossible to achieve repeatability from one table to the next. What I had in mind MIGHT work on a specific table but could very well not work on the next "look alike table.

Another complication: I know some have said I was wrong from the beginning but now I know they are correct. The Main Table Legs are not perfectly parallel and are not suitable as a reference surface. This was a rude awakening for me.

[DLB]

It would be very interesting to know exactly how the SS jig works. I don't expect we will find out. And whether the .010/10" is the error budget for just the assembly aligned in that manner of if that somehow represents accuracy of the slot-to-blade number we are accustomed to using. But my interest in alignment is mostly about better results. (Better, compared to the procedure in the manual and presumably better than .010/10".) From my perspective there are multiple important things all being adjusted or effected by how the trunnions are bolted to the table:
1) Trunnions must be true to the tie bar and parallel to one another.
2) Trunnions must be the correct distance apart for proper operation of the tilt and tilt locks.
3) Table must be true to the axis of rotation.

We know (?) that 1 and 2 don't work reliably on systems that have been in the field for a while if we use the procedure in the manual. We don't know why. Therefore we may use the $20 bill trick that conflicts with the manual. We, the users, did not create that trick. It comes from the mothership. It conflicts because it sets the trunnion spacing, #2 above, differently than in the manual. But we don't all use it. I personally only use it on a system that exhibits a problem, usually either the tilt does not work smoothly or the table is not flat when the locks are tight. My reasoning is that I believe I will get better results on #3 if the tilt lock is tight, as in the manual and as I'm going to use it when I'm operating the saw.

- David

[dusty]

I don't disagree but your statements but

1) Trunnions must be true to the tie bar and parallel to one another!

This is strictly a function of the tie bar and can not be altered. If these conditions are not present...order a new tie bar.

2. Trunnions must be the correct distance apart for proper operation of the tilt and tilt locks.

By design to the tie bar the trunnions are separated by a distance of 14 1/2" and will be parallel to one another unless...again you need to invest in a new tie bar.

3. Table must be true to the axis of rotation.

This is achieved by adjustment. The only one of your stated requirements that can be altered and that can be done (given the current design) only by carefully positioning the table on the trunnions. There are many different ways to do this and I have three or four (or more) of my own techniques and when employed provide the intended results.

The dollar bill trick works but it has little or nothing to do with alignment.

[Ed in Tampa]

It would be very interesting to know exactly how the SS jig works. I don't expect we will find out. And whether the .010/10" is the error budget for just the assembly aligned in that manner of if that somehow represents accuracy of the slot-to-blade number we are accustomed to using. But my interest in alignment is mostly about better results. (Better, compared to the procedure in the manual and presumably better than .010/10".) From my perspective there are multiple important things all being adjusted or effected by how the trunnions are bolted to the table:
1) Trunnions must be true to the tie bar and parallel to one another.
2) Trunnions must be the correct distance apart for proper operation of the tilt and tilt locks.
3) Table must be true to the axis of rotation.

We know (?) that 1 and 2 don't work reliably on systems that have been in the field for a while if we use the procedure in the manual. We don't know why. Therefore we may use the $20 bill trick that conflicts with the manual. We, the users, did not create that trick. It comes from the mothership. It conflicts because it sets the trunnion spacing, #2 above, differently than in the manual. But we don't all use it. I personally only use it on a system that exhibits a problem, usually either the tilt does not work smoothly or the table is not flat when the locks are tight. My reasoning is that I believe I will get better results on #3 if the tilt lock is tight, as in the manual and as I'm going to use it when I'm operating the saw.

- David

There is fourth you did not mention the trunnions must hold the table at the same height compared to the quill. SS sells table shims to level the table to the quill. I also believe unless the trunnions mounting face and the table mounting face are ground flat to each other or they will throw off alignment.

That said I think the original table alignment method is more than suitable ( close enough) for wood working. I will say I am a fan of the $20 dollar bill to keep from putting potential warping pressure on the table. The real problem in the alignment procedure is the inability to tighten all trunnion bolts while the table is locked in it alignment position. The requirement to tighten two trunnion bolts and then loosening the tilt on the table to pivot it to a poistion to enable you tho tighten the other two bolts can and often does change the just set alignment.

[edma194]

There is fourth you did not mention the grunions must hold the table at the same height compared to the quill.

You need some strong and well trained grunions for that. I think most of them will flop around uselessly on the carriage.

[DLB]

I carefully re-watched SS101 with the $20 bill trick, this time with the manual open in front of me to compare. There are more differences between the two procedures than I realized. Does anyone know if the procedure Nick was following is written down somewhere?

One example: As Ed in Tampa points out, tilting the table before locking down all four trunnion bolts creates some risk to the alignment. The manual has you tighten the left bolts and rotate the table 45 degrees CW, away from the headstock, then retighten the tilt lock before tightening the right bolts. SS101 has you "snug" the two left bolts, raise the table, and rotate it both directions a bit, then CCW 45 degrees. I'm guessing the direction of rotation is deemed important, because raising the table with two bolts snug further increases the risk to the alignment. No commentary on this part, but it looked like he "snugged" the tilt lock, I think with the bill still in place. (That's one thing I've missed in prior viewings, but the emphasis on the comparable step in the manual brought it home.) Then "snugged" the two right bolts, then tightened all the bolts in a different sequence. Like a torqueing sequence but with no torque spec. Not surprisingly, he had no issues with the trunnions dragging on the tie bar bosses during tilt. However, he had a huge alignment error and did not measure for table flatness. Results were not better than he started with.

Ideally you want a small clearance between trunnions and bosses so the table tilts easily, but excessive clearance will bow the table. Thus, a $20 bill or 0.0043" shim.(?) And that is right for all tables/trunnions? And can be done while still aligning the miter slots to a tight tolerance, or is some error accepted here due to the shim? (Would I expect the alignment error value to be the same when I'm done and with the tilt lock tightened as normal?)

- David

[dusty]

As you know, the trunnions are automatically spaced approximately 14 1/4" apart by design. This dimension can be changed slightly because the trunnion bolt holes are larger that the bolts used to secure them. To avoid pushing them too close together the infamous $20 bill is used. With this "spacer" in place after the trunnion bolts are tightened the tie bar will not drag against the trunnions. Without that space, the trunnions may drag against the tie bar. The $20 bill must be installed when the table tilt is unlocked and the trunnion bolts are loose. Then the table tilt is locked and the trunnion bolts are secured. Unlock the table tilt and remove the "spacer". The table should now tilt without dragging. Lock the table tilt and ensure that it immobile (does not tilt. Actually it is not necessary to remove the $20 bill. Actually, I have never used a dollar bill. I use a posted note folded in half.

I see no where in this procedure that should cause stress on the table. The table does not drag because it has been warped. If it drags it is because the trunnions are squeezing the tie bar. It is NOT a fault of the table tilt lock. Locking mechanism is on the outer sides of the trunnions which must be 14 1/2" + the dollar bill apart (not stated in specifications or official procedures).

I believe this issue could be permanently resolved by placing a very this spacer along with either one of the trunnions when the trunnions are mounted.

[DLB]

As you know, the trunnions are automatically spaced approximately 14 1/4" apart by design. This dimension can be changed slightly because the trunnion bolt holes are larger that the bolts used to secure them. To avoid pushing them too close together the infamous $20 bill is used. With this "spacer" in place after the trunnion bolts are tightened the tie bar will not drag against the trunnions. Without that space, the trunnions may drag against the tie bar. The $20 bill must be installed when the table tilt is unlocked and the trunnion bolts are loose. Then the table tilt is locked and the trunnion bolts are secured. Unlock the table tilt and remove the "spacer". The table should now tilt without dragging. Lock the table tilt and ensure that it immobile (does not tilt. Actually it is not necessary to remove the $20 bill. Actually, I have never used a dollar bill. I use a posted note folded in half.

I see no where in this procedure that should cause stress on the table. The table does not drag because it has been warped. If it drags it is because the trunnions are squeezing the tie bar. It is NOT a fault of the table tilt lock. Locking mechanism is on the outer sides of the trunnions which must be 14 1/2" + the dollar bill apart (not stated in specifications or official procedures).

I believe this issue could be permanently resolved by placing a very this spacer along with either one of the trunnions when the trunnions are mounted.

Thank you. My question was not about the $20 bill trick but the entire table alignment procedure in SS101. Which seems different in most ways from the manual. Unless there are multiple versions of manual, of course.

The highlighted part of your statement is where we disagree. The locking mechanism is both sides of both trunnions, similar to disc brakes. So creating a gap between trunnions and tie bar bosses, IMO, has to stress the table. The lock system applies pressure to the trunnions that will close that gap. The gap has to close for the tilt lock to work correctly. The tie bar has the bar, so I don't see the bosses moving. I don't see any way of closing that gap except by stressing the table, it is the most elastic part involved and something has to change for the gap to close. Too large a gap would have serious consequences. In my mind the table and trunnions form an upside down "U." The tilt lock squeezes the tips of the legs of the "U" together stressing all parts. The tie bar stops the movement once the gap is closed, additional force then squeezes the trunnion between boss and clamp shoe, the actual locking force.

- David

[dusty]

As you know, the trunnions are automatically spaced approximately 14 1/4" apart by design. This dimension can be changed slightly because the trunnion bolt holes are larger that the bolts used to secure them. To avoid pushing them too close together the infamous $20 bill is used. With this "spacer" in place after the trunnion bolts are tightened the tie bar will not drag against the trunnions. Without that space, the trunnions may drag against the tie bar. The $20 bill must be installed when the table tilt is unlocked and the trunnion bolts are loose. Then the table tilt is locked and the trunnion bolts are secured. Unlock the table tilt and remove the "spacer". The table should now tilt without dragging. Lock the table tilt and ensure that it immobile (does not tilt. Actually it is not necessary to remove the $20 bill. Actually, I have never used a dollar bill. I use a posted note folded in half.

I see no where in this procedure that should cause stress on the table. The table does not drag because it has been warped. If it drags it is because the trunnions are squeezing the tie bar. It is NOT a fault of the table tilt lock. Locking mechanism is on the outer sides of the trunnions which must be 14 1/2" + the dollar bill apart (not stated in specifications or official procedures).

I believe this issue could be permanently resolved by placing a very this spacer along with either one of the trunnions when the trunnions are mounted.

Thank you. My question was not about the $20 bill trick but the entire table alignment procedure in SS101. Which seems different in most ways from the manual. Unless there are multiple versions of manual, of course.

The highlighted part of your statement is where we disagree. The locking mechanism is both sides of both trunnions, similar to disc brakes. So creating a gap between trunnions and tie bar bosses, IMO, has to stress the table. The lock system applies pressure to the trunnions that will close that gap. The gap has to close for the tilt lock to work correctly. The tie bar has the bar, so I don't see the bosses moving. I don't see any way of closing that gap except by stressing the table, it is the most elastic part involved and something has to change for the gap to close. Too large a gap would have serious consequences. In my mind the table and trunnions form an upside down "U." The tilt lock squeezes the tips of the legs of the "U" together stressing all parts. The tie bar stops the movement once the gap is closed, additional force then squeezes the trunnion between boss and clamp shoe, the actual locking force.

- David

OKAY, I concede. No further debate from me even though I can complete the task without using a dollar bill. But I do accomplish this in a manner totally inconsistent with any written procedure I have read. I admit that I perform many SS tasks differently than documented.