Main Table Alignment Fun

[dusty]

Agreed. As Nick explained in the Sawdust Session on main table alignment, once you have the blade aligned to miter slot to the point where the front to back error on the blade is less than half the width of the blade's tooth's overhang (set?) beyond the blade's plate, there is no added kickback risk as compared to a blade that is more perfectly aligned to the miter slot. After that point, all you are really doing by trying to get closer alignment to the miter slot is chasing a smaller kerf width, since even a severely heeled blade will cut a perfectly straight line (at least until you heel it so much that the back of the wood hits the blade's plate, rather than a tooth).

Yet even though I know it is not really necessary, I still pull out the dial indicator and try to get as close that that elusive zero error as possible. Thank goodness that my dial indicator is only graduated in thousandths of an inch (0.001) rather than in ten-thousands of an inch (0.001). I'd probably still be at it (or, more likely, hanging from a rafter in my basement).

You too WILL recover from that affliction. I know because I suffered with it for quit a long timebut have now seen the light. I have now adopted a personal alignment goal of .005" for almost everything.

Be aware. This is just like any other addiction. It is easy to fall off the wagon and once that happens recovery is again a long hard process.

[Culprit]

The bolts that secure the trunnions to the table are embedded into the cast aluminum table. I do not believe that putting loc-tite on those screws would be advisable. I am not certain how well that cast aluminum threads would survive.

Dusty,

I wasn't saying to put the lock-tite on the steel and aluminum threads. I said to keep it off the threads, and only use it on the mating surfaces between the table and the trunnions in order to hold the table still so that it wouldn't move when you came back later to tighten the bolts to the final torque value.

[dusty]

Dusty,

I wasn't saying to put the lock-tite on the steel and aluminum threads. I said to keep it off the threads, and only use it on the mating surfaces between the table and the trunnions in order to hold the table still so that it wouldn't move when you came back later to tighten the bolts to the final torque value.

I apologize. After rereading what you wrote I can now see that is exactly what you said. I obviously saw the word lock-tite and quite reading and/or thinking.

[pennview]

One way to sneak up on making the table trunion adjustments is to snug up just one bolt (say the front right) and then use a mallet to tap the rear of the table into proper alignment, getting the table to pivot in an arc around that first tight bolt. Then tighten the one bolt that is on the diagonal from the first (the left rear bolt). Once you have those two bolts tightened, the table shouldn't shift while you tighten the last two bolts.

If the table shifts out of line when you tighten the second bolt, you should be able to gauge the distance it travels using a dial indicator or feeler gauges, and simply compensate for that travel before starting to tighten the second bolt.

One other thing you should do when aligning a table on the Shopsmith that rarely gets mentioned is to ensure that the table is perpendicular to the to the spindle in the front-back direction when in drill press mode, in order to ensure that any holes you drill will be perpendicular to the surface of your stock in those directions. Use washer-like shims to ensure they don't shift or fall out while making the other adjustments to the table. You can make the shims out of soda pop cans or whatever. Make this adjustment before doing the other table alignment procedures.

[robinson46176]

Precision table adjuster on the right.

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[algale]

One way to sneak up on making the table trunion adjustments is to snug up just one bolt (say the front right) and then use a mallet to tap the rear of the table into proper alignment, getting the table to pivot in an arc around that first tight bolt. Then tighten the one bolt that is on the diagonal from the first (the left rear bolt).

Nick's sawdust session suggests, after loosening all 4 trunnion bolts, snugging up the right rear trunnion bolt and using it as a pivot point as you suggest.

You pretty much have to snug up both the left front and rear trunnion bolts before moving to the right front and rear trunnion bolts because the right side trunnion bolts can't be accessed with the table horizontal.

If you try to snug up just one left side trunnion bolt and then tilt the table to get access to the diagonal bolt on the right side, alignment is likely to be lost in the tilting and retilting of the table.

Once the left front and rear trunnion bolts are snug (the right rear bolt is already snug), you can tilt the table and snug up the last bolt and then tighten them in a diagonal pattern going back and forth from the horizontal to vertical position as you tighten diagonally opposed bolts.

My problem was that the snugging up of either of the two front bolts was taking the table out of alignment even if I took turns and snugged them very gradually.

Eventually I did as you say and started to watch the dial indicator to see how much the snugging moved the table and in what direction. In order to get the table to tighten itself into alignment, I then deliberately misaligned the table by that much.

[pennview]

Algale, sorry about that. Was thinking about my model 500 with its four bolts, not the 510/520 that uses cap screws and has two of those inaccessible until you tilt the table. Nick has the procedure right, or you could sung up the right front and use that cap screw as the pivot. The important thing is you got it square. I've got a 510 as well, but frankly didn't remember the bit about tilting the table while making the adjustment.

What I do after adjusting is make a couple of test cuts to ensure the saw produces square cuts. If you simply crosscut a piece of squared wood, then turn one of the two pieces upside down and slide the cut faces together, you can see if the two pieces align perfectly or not across the cut as well as vertically. Use a straight edge like the rip fence to verify that the cut across the wood is square and the saw table surface to verify the vertical cut is also square.

[algale]

Algale, sorry about that. Was thinking about my model 500 with its four bolts, not the 510/520 that uses cap screws and has two of those inaccessible until you tilt the table. Nick has the procedure right, or you could sung up the right front and use that cap screw as the pivot. The important thing is you got it square. I've got a 510 as well, but frankly didn't remember the bit about tilting the table while making the adjustment.

What I do after adjusting is make a couple of test cuts to ensure the saw produces square cuts. If you simply crosscut a piece of squared wood, then turn one of the two pieces upside down and slide the cut faces together, you can see if the two pieces align perfectly or not across the cut as well as vertically. Use a straight edge like the rip fence to verify that the cut across the wood is square and the saw table surface to verify the vertical cut is also square.

Not a problem, Art, in fact I didn't realize this was a difference between the 510/520 and the earlier models.

As for making cross cuts to test for square, I'm afraid that won't tell you whether the blade is aligned parallel to the miter slot or not! As long as the miter gauge is set at 90 degrees to the miter slot you will still get a square cut -- even if the blade is significantly out of parallel to the miter slot. All that happens is you get a wider kerf because the back of the blade is cutting its own kerf, slightly to the left or right of the front of kerf being cut by the front of the blade, but the cut will be just as square as if the blade were perfectly aligned to the miter slot. You will, however, hear it and feel it. In fact, that's how I knew the table on mine was out of alignment even though I was still getting square cuts.

The real reason for aligning the blade to the miter slot and the fence to the slot is not to get square cuts (or smaller kerfs) but to avoid kickback, particularly during rip cuts when the wood is constrained between the fence and the blade and can be picked up by the rear teeth if the blade is out of parallel to the slots/fence. According to Nick, this doesn't become an issue until the amount by which the blade is out of parallel gets up to around twenty thousands (0.020) of an inch.

All the best,

Al

[jm51]

Just a thought but does the table HAVE to be connected to the Shopsmith for alignment?

Loosen the bolts then have the main table upside down in a jig that will firmly hold the table and the tubes. Once they're going nowhere, tighten the bolts.

If it's still out of alignment, the jig needs work.

[dusty]

Just a thought but does the table HAVE to be connected to the Shopsmith for alignment?

Loosen the bolts then have the main table upside down in a jig that will firmly hold the table and the tubes. Once they're going nowhere, tighten the bolts.

If it's still out of alignment, the jig needs work.

That is a very interesting approach and it just might work. All you need to figure out is when to tighten the bolts. What is the point of reference?

The miter tracks will position the table. Now the trunnions are movable and must be properly positioned. If everything was perfectly milled, I would say position the face of the trunnions so as to be perpendicular to the miter tracks.

What say you?