table saw alignment conundrum

[Brian Runau]

This is an old Craftsman cabinet base trunion mounted to the base unit. Using the digalign unit the blade is parallel to the slot within .0005 Squaring the fence to the slot and making a cut the cut is deeper on the back end of the blade. Drove me crazy until I put a square in the slot and pushed it onto the side of the blade. 1st picture is on the back of the blade 2nd picture is on the front of the blade.

The blade is off by a 1/16" or more.

I can't reconcile this with the digialign reading of .0005.

Appreciate any help. Brian

TS alignment.jpgTS alignment 1.jpg

[Lee Schierer]

The big question is: Do your cuts reflect that much misalignment and show significant teeth marks or burning marks on the cuts? It sounds to me like one of the following occurred:

1. your digital device did not have sufficient travel distance when you performed the alignment. The digital indicator should be set so the plunger is about mid point in its length of travel and then zeroed.

2. Your blade was not mounted properly and/or the blade was warped. I always mark a spot on the blade tooth root and rotate the blade to always read that spot so that I get a consistent reading.

3. You moved or bumped your table top when moving the saw or doing some other operation.

I recommend doing the check a second time using both methods.

On my saw, the toothed lock washers were moving the trunnion out of position when I did the final tightening. I had to rotate the washer teeth out of the indentations they had made in the softer trunnion metal to keep the setting where I wanted it.

[Brian Runau]

The big question is: Do your cuts reflect that much misalignment and show significant teeth marks or burning marks on the cuts? It sounds to me like one of the following occurred:

1. your digital device did not have sufficient travel distance when you performed the alignment. The digital indicator should be set so the plunger is about mid point in its length of travel and then zeroed.

2. Your blade was not mounted properly and/or the blade was warped. I always mark a spot on the blade tooth root and rotate the blade to always read that spot so that I get a consistent reading.

3. You moved or bumped your table top when moving the saw or doing some other operation.

I recommend doing the check a second time using both methods.

On my saw, the toothed lock washers were moving the trunnion out of position when I did the final tightening. I had to rotate the washer teeth out of the indentations they had made in the softer trunnion metal to keep the setting where I wanted it.

Lee, the cuts do reflect the misalignment. I tried the digialign in a couple different locations, in terms of the plunge depth and same result. My trunions are mounted on the base cabinet. Blade is mounted fine and I am checking rotating so I check front to back on the blade. Not from bumping or moving the saw.

Thanks

Brian

[mike stenson]

You're not using the same reference point on the blade in those pictures.

[Brian Runau]

You're not using the same reference point on the blade in those pictures.

The body of my square is being held in the miter slot. Blade is extended to contact the side of the blade in the rear. Then I slide the square forward in the miter slot still being held against the same reference side and the gap shows on the front of the blade. This is how the Sears manual says to check alignment. Brian

[mike stenson]

The body of my square is being held in the miter slot. Blade is extended to contact the side of the blade in the rear. Then I slide the square forward in the miter slot still being held against the same reference side and the gap shows on the front of the blade. This is how the Sears manual says to check alignment. Brian

Turn the blade, so that you're referencing the same spot on the blade. Otherwise, you're not accurately measuring the alignment.

[John Kananis]

What Mike just said above. Eliminate the possibility that there's warp in the blade. If it's the same using the same part of the blade, then loosen the bolts connections the table to the cabinet and align correctly.

[Michael Burnside]

Turn the blade, so that you're referencing the same spot on the blade. Otherwise, you're not accurately measuring the alignment.

Exactly this. Eliminate one potential problem. At the end of the day you should be measuring with respect to the miter slots not the throatplate gap, but it's ok to start somewhere.

[Bill Dufour]

The harbor fright dial indicator is $17.99. Make a simple holder from a hunk of 2x2 and a wood screw. Well worth it to settle the issue. Also used to adjust planers, jointers, drill press etc. You do not need accuracy just repeatability. Any old one that is not sticky would be fine.
BilL D

[mike stenson]

The harbor fright dial indicator is $17.99. Make a simple holder from a hunk of 2x2 and a wood screw. Well worth it to settle the issue. Also used to adjust planers, jointers, drill press etc. You do not need accuracy just repeatability. Any old one that is not sticky would be fine.
BilL D

Yea, this makes it easy to pick a tooth (colour it with a sharpie) and use the same tooth for repeatability.

[Ronald Blue]

One thing is clear. Your digalign is not accurate. Whether it's defective or an operator error you will need to determine. However if the fence is that far out as well that makes for some ugly cut's if not dangerous as well. Keep us posted.

[Brian Runau]

Turn the blade, so that you're referencing the same spot on the blade. Otherwise, you're not accurately measuring the alignment.

Mike: I did this also. It's not warp in the blade. I use this instead of a older style dial indicator. Thanks. Brian

http://www.igaging.com/page27.html

[mike stenson]

Let me take a step back and make sure I understand.

Using a dial indicator and an alignment jig, everything is OK.
Using a combination square it's off.

Is that correct?

[Doug Garson]

What is a digalign? Your square is indicating that the blade is not parallel to the miter slot (or that your blade is warped if you are not measuring to the same spot on the blade as others have pointed out). Is the digalign measuring the same distances as the square? (ie from the miter slot to the blade at the front and back) If it is also not measuring to the same spot on the blade, then the .0005" is a false reading. Maybe you have a warped blade and it is not set parallel to within .0005" as you think.

[Michael Burnside]

I'm confused. Are you measuring with respect to the miter slot to blade or the throat plate gap? If the latter, who cares about the throat plate gap?

Maybe try this

Check runout of arbor + blade:

- set your "digalign" at the front of the blade
- mark the blade with a sharpie
- while NOT moving the gauge, slowly rotate the blade one full rotation, until you see the sharpie mark again, and record the total runout

This value should be relatively small, say 2-4 thou max (mine is right around 0.001")

If the above is reasonable you can proceed, if not, you've got a problem with the blade or arbor. Replace blade and try again. If you have a granite reference surface, place the blade on that and see if it wobbles. Measure miter slot alignment using Mike's recommendation. Using that same sharpie mark, measure the front. Slide the "digalign" gauge up and rotate sharpie mark back and measure again. This should be also relatively small.

You will need to do this on BOTH sides of the blade. In particular, start with the side that your fence is on since the cut you're seeing is relative to the fence and blade, nothing more Ultimately you want miter slots aligned with blade aligned with fence, but you have to start somewhere first.

Or you can forgo the "digalign" and use a combinational square.