Measuring cut height of table saw blade

[Zac wingert]

Why would it matter to the degree you are looking for? I though you just set it so at least one tooth more or less will protrude above the workpiece. I assume it’s for some sort of joinery? Unless you are making a whole production l I’d just cut a little less and clean up with a chisel. Not trying to be critical, just wondering.

[Jacob Reverb]

...
Then I go just a hair beyond the line and lock it down.
No matter how hard I try or how tight my feather boards are (or how much force I put on the Gripper) - - for some reason the blade always seems to lift the work off the table just enough to spoil the fit.

Sounds like you're trying to get a size-to-size fit or interference fit, which will never work. You have to leave room for air (and often glue)...

[Dick Mahany]

For exact fractional inch increments, I have also used this set up gauge from Veritas/Lee Valley. Although it works well, I seldom make cuts exactly in those dimensions, and that is probably why it is no longer available.

Set Up Gauge.jpg

[Yonak Hawkins]

Get it close with a rule, then test.

This is my method as well.

[Rich Engelhardt]

Sounds like you're trying to get a size-to-size fit or interference fit, which will never work. You have to leave room for air (and often glue)...

I'm lost here. Every single video I see and every TV show I watch has the pieces fit so nice and tight they have to whack them with a mallet to get them apart when they dry fit them.
Are you saying that's not the object?
Should the pieces be loose?

You have me 100% confused at this point..

[Jacob Reverb]

I'm lost here. Every single video I see and every TV show I watch has the pieces fit so nice and tight they have to whack them with a mallet to get them apart when they dry fit them.
Are you saying that's not the object?
Should the pieces be loose?

You have me 100% confused at this point..

I see you talking about digital calipers and other people here talking about DROs, as if they were dealing with machine tools.

Well, if you use a DRO to cut a tenon that's 1.000" wide, and a mortise that's 1.000" wide, they won't fit together. This is what is meant by "size to size." You need slop to fit them together, even with a hammer.

Clearer?

[Dan Baginski]

I use my combination square. Then creep up on it if I have to.

[Brad Barnhart]

Am I old school, or just not up to speed with the wood workin' world?

Or, maybe I am lookin' at the Op's question bassackwards, but, why in the world do ya need all them fancy digital toys to adjust your blade height? This might be out of line, but, surely might near all you fellers can read a tape measure. Set the flat end of your tape on your saw deck and raise your blade to the height you're after by the top tooth of the saw blade. Then cut a test run in piece of scrap and measure that with a combination square for accuracy.

[Dan Friedrichs]

Well, say you've got a piece of wood 0.75" thick and you want to cut a rabbet joint where the remaining tongue is 0.25". It would be very convenient to have a digital indicator of exact blade height, so you could just set it to 0.50" cut depth and go.

With a tape, you need to make sure you're measuring at the top center of the blade (difficult), and your precision is limited.

Some high-end sliding table saws (Martin T60...) have electronic blade height (and angle, and cross-cut fence position...) measurement AND motorized positioning...

[Jacob Reverb]

Well, say you've got a piece of wood 0.75" thick and you want to cut a rabbet joint where the remaining tongue is 0.25". It would be very convenient to have a digital indicator of exact blade height, so you could just set it to 0.50" cut depth and go.

With a tape, you need to make sure you're measuring at the top center of the blade (difficult), and your precision is limited.

I use key stock for checking the width and depth of grooves. Simple, cheap, easy and foolproof.

Again, you need to have clearance for a proper fit. Using keystock accounts for this. Using digital measuring instruments, no matter how sophisticated, doesn't (unless you know how much slop you need to about three significant digits ... since arithmetic mystifies me, I go by "feel".)

So many guys seem to want to turn woodworking into metalworking...which is kinda difficult since every time you so much as breathe on a piece of wood, its dimensions change. When you cut it you release stresses, causing it to bulge and bend, etc etc etc etc...and you can measure it to the nearest trillionth of an Angstrom until you're blue in the face and still not be able to get it to fit together.

[Kevin Womer]

You could use a drill bit up to the max size you have. It’s pretty accurate. Then perhaps a small square beyond that, most people have both readily on hand.

[Floyd Mah]

Here's my simple technique. I use a dial indicator with a magnetic holder. It's not too expensive and I have it around for other purposes.

Make an approximate saw setting and measure the depth of the cut (with a test cut on some scrap). Note the amount of correction needed. Place a piece of scrap wood so that one end is over the blade and the other end rests on the table surface. If needed, add a piece of scrap under the latter end so that the piece resting on the blade is approximately parallel to the table. The horizontal piece is used for the following measurement. It rests on any of the teeth at the top of the blade, but mainly establishes a reference point on the blade irregardless of which teeth it rests on.

Rest the dial indicator's tip on the wood over the approximate location of where you estimate the high point of the blade is, centered on the blade's disc. The dial indicator is in the magnetic holder. Zero the dial for the current position of the needle. Now raise or lower the blade so that you have corrected for the previously measured error.

You should have the correct blade height now. The only, very slight error might happen if the blade rotates while being raised, but it's unlikely to be significant if the needed correction is small.

The advantages of this technique are:
1. Ease of adjustment.
2. Logical steps.
3. Low cost of needed tools, especially if you already have the dial indicator.

[Jacob Reverb]

[Nick Shattuck]

To clear up my original question...

In real-life, I'm an electrical engineer specializing in metrology, so I think about these things. I'd like a way to cut six 0.50" deep dados, realize after I've changed the blade height that I need two more, quickly set it back to 0.50" and make the cut again without the trial and error technique that seems to be the most popular idea here. it just helps with efficiency and reduces the frustration caused by an off-cut.

It's really not about the absolute accuracy of the height, but the repeatability, where I could write down a dimension and make cuts and come back a week later and repeat the same cuts and have identical pieces.

Hope this clears up the point of the post.

[Gary Ragatz]

I think you could do that with the Kreg setup blocks I use - as long as you're willing to work with a limited set of cut depths. The set I have runs from 1/8" up to 1/2" in 1/16" increments.