Measuring cut height of table saw blade

[Nick Shattuck]

Anyone have any good tips on measuring the height of a table saw blade before making a cut? I have a wixey digital height/depth gauge that I use now, but it's a little awkward to use on a circular blade due to me not knowing if I'm measuring the peak tooth at its peak height. I can get really close, but I still have to make a test cut and usually have to adjust a hair and test again to get the cut to the depth I want.

Is there a better way to do this? Is there a specialized tool I could buy for this?

[Dick Mahany]

I use the rear depth spine on an inexpensive digital caliper. Works perfectly for me.

[Nick Shattuck]

I use the rear depth spine on an inexpensive digital caliper. Works perfectly for me.

How do you know that you are measuring the peak of the blade? I'm assuming you do it like me and set your gauge near the center of the blade and roll the blade back and forth while slightly moving the gauge back and forth until the gauge covers all teeth that pass below it. While this works, I'm curious if there is a clever trick or perhaps a tool that makes this quick and idiot-proof.

[Bryan Lisowski]

I am going to assume you mean on a non through cut. I set a small combination square to the desired height then raise the blade until it just contacts the square.

[glenn bradley]

Dick's method has the same concerns as your commercial gauge and the same as mu shop made one.

399943

Until I got the hang of identifying Top Dead Center on the blade, I used a helper. I drew, with felt pen, a line from (on a 40 tooth blade for example) tooth 1 to tooth 21 and tooth 11 to tooth 31. This gave me a line that I could eyeball as perpendicular assuring that I had the tooth at TDC. Let me see if I have a picture of this . . .

Hmm, I don't but, here's a quick SketchUp. You get the idea.

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I will also add that I find setup blocks particularly valuable for this and a lot of other "measure by feel" situations. I keep a 1-2-3 block (https://www.amazon.com/BL-123-Precision-Steel-1-2-3-Blocks/dp/B00092CJC6/ref=sr_1_sc_1?s=hi&ie=UTF8&qid=1546293703&sr=1-1-spell&keywords=1-2-3+blockk) and a set of 4" Whiteside brass setup blocks (https://www.amazon.com/Whiteside-9810-Brass-Gauges-Piece/dp/B0012JGAC0/ref=asc_df_B0012JGAC0/?tag=hyprod-20&linkCode=df0&hvadid=309813767497&hvpos=1o2&hvnetw=g&hvrand=13646684334270590736&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9031505&hvtargid=pla-522509857574&psc=1) at the bench, and the tablesaw/router table areas.

[Matt Day]

KISS. Make a cut on a scrap piece and measure it.

[Ron Citerone]

KISS. Make a cut on a scrap piece and measure it.

That's what I do too, especially on cuts that you really wnt to be exact!

[Gary Ragatz]

I use a set of Kreg router setup bars. They work fine for me, but it will depend on what level of precision you need - the Kreg bars are in 1/16" increments.

[Rich Engelhardt]

KISS. Make a cut on a scrap piece and measure it.I do similar.
I use a digital caliper on a piece of scrap to measure the height I need.
Then I clamp the scrap to the fence and, with the saw running, I slowly snug the fence/scrap up to the blade & raise the blade up till it hits the mark.
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.

After that, I run a test cut - then remove the marked scrap from the fence and stick it on the test cut to see how the fit is.

[Nick Shattuck]

Well it looks as though I'm not missing anything here and it's just one of those things we just deal with even if it takes multiple steps. I mean, I can use the DRO on my planer to set a repeatable, accurate height in one step, use one on my table saw fence to set a repeatable, accurate width in one step, I can adjust blade tilt with a angle DRO, but I can't set blade height with one.

I wonder if anyone has fit a Wixey planer height gauge with the remote display to a table saw lift. It would be easy enough to calibrate. It seems like it would be possible to do.

[Dick Mahany]

How do you know that you are measuring the peak of the blade? I'm assuming you do it like me and set your gauge near the center of the blade and roll the blade back and forth while slightly moving the gauge back and forth until the gauge covers all teeth that pass below it. While this works, I'm curious if there is a clever trick or perhaps a tool that makes this quick and idiot-proof.

I simply very gently place the caliper body on a tooth near top dead center and with a slight roll forward and backward, find the max height. I also have my zero clearance throat plate set exactly level with the table top. Always seems to work just fine.

[Jacob Reverb]

KISS. Make a cut on a scrap piece and measure it.

That's what I do. Get it close with a rule, then test.

[johnny means]

It's easy enough to find TDC, it's simply going to be the middle tooth.

[Nick Shattuck]

This guy made his own using an accelerometer (http://www.gardnerswebsite.com/sawheight/index.html), which I think is ingenious (in that a tilted blade doesn't affect the results). It seems relatively simple so I'm surprised someone like iGaging or Wixey hasn't manufactured one.

[Dan Friedrichs]

This guy made his own using an accelerometer (http://www.gardnerswebsite.com/sawheight/index.html), which I think is ingenious (in that a tilted blade doesn't affect the results). It seems relatively simple so I'm surprised someone like iGaging or Wixey hasn't manufactured one.

Nick, that's really cool! I agree - the accelerometer is genius. I've always wanted a DRO for height, but assumed that the raising mechanism wouldn't have a good mounting point (for a traditional caliper beam-style sensor) that moved 1:1 with blade height.

[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.

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[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]

https://advrider.com/f/styles/advrider_smilies/lol8.gif

[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.

[Roger Feeley]

Heres an idea ive never tried because I just thought of it.
what if you scribe a circle onto the body of the blade below the gullets. Make it .500” below the tooth. Now you can use a height gauge set to desired height - .500”. The virtue of this idea is that you don’t have to find top dead center of a tooth.

you could try it with layout blue to start but that will wear off. A more permanent line in the metal would be nice but would change slightly when the blade is sharpened. You could keep the offset for Esch blade...



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.

[Mike Henderson]

That's what I do too, especially on cuts that you really want to be exact!

Me too. That's the way I do it.

Mike

[Nick Shattuck]

That's a good idea. At least for cuts deeper than the scribe line. The setup blocks due to their lengths would be good too for fixed heights. I think I may try to build the device with the accelerometer from the guy's plans posted earlier if someone still sells those components.

[Roger Feeley]

Well it looks as though I'm not missing anything here and it's just one of those things we just deal with even if it takes multiple steps. I mean, I can use the DRO on my planer to set a repeatable, accurate height in one step, use one on my table saw fence to set a repeatable, accurate width in one step, I can adjust blade tilt with a angle DRO, but I can't set blade height with one.

I wonder if anyone has fit a Wixey planer height gauge with the remote display to a table saw lift. It would be easy enough to calibrate. It seems like it would be possible to do.

The issue with a DRO on blade height is that most table saw trunions pivot so the Z axis distance per revolution of the crank varies depending on the angle of the trunion. Sawstop is fairly unique in that the blade is mounted so that it goes straight up and down. Sawstop owners CAN have a DRO and this is something I've been meaning to do with my SS for some time.

I have no intention of using the DRO for absolute measurement. What would be handy is relative measurement. Make a dado cut, measure the depth. You have to go .200" higher. Easy with a DRO and no problems overshooting. No problems with gear lash.

So far, I know of no one that has done this to their SawStop so I'm a bit reticent. My saw is long off warranty. I would communicate with the tech guys at SS and get their advice as to where to mount the sending unit.

Edit: if you look around, someone made a DRO for the pivoting trunion using an accelerometer and some math. I think it worked ok.

[Roger Feeley]

That's a good idea. At least for cuts deeper than the scribe line. The setup blocks due to their lengths would be good too for fixed heights. I think I may try to build the device with the accelerometer from the guy's plans posted earlier if someone still sells those components.

You should be able to find what you want at SparkFun. Do the whole thing with an Arduino. Some might call you crazy for trying this but not me. I like crazy.
My daughter clerked for a Circuit Court judge who demanded 16 hour days/7 days a week for a year. She knew what she was getting into so I couldn't criticize. But I could mock. The 9th circuit covers a wide geographic area from Guam to Arizona. So I made a row of clocks (sort of like a newsroom) showing the various time zones. Then I added a special clock for the judge that compressed her 16 hour day into 8 hours by ticking once every other second. She arrived at '9am' and left at '5pm'. The judge thought it was a hoot and kept the clocks in chambers until he retired.

I did it with an Arduino. Never worked with one before or since and I have no electronics experience. It wasn't bad.

[Mike Cutler]

I applaud the initiative to develop a height gauge, and would really like to see one made, but I gotta ask. Is this really a big problem to set the height of table saw blade? What exactly is being cut that needs to be so exact? Maybe I'm just sloppy????
Using the gage blocks in Glen's post, you should be about to get within .010" easily of any fractional measurement. .005" would not be unreasonable to achieve. Your fingers can easily detect differences <.002".
I use the same blocks Glen has, and a dial indicator. I just got an iGagging digital height gauge for the shaper, but it would easily find the height of the highest tooth in the arc of a blade if needed, which I will.
I would also caution about the test cut method, unless you know you have zero deflection in your throat plate, if the measurement is this critical.

All that said though, I think a height gauge for the table saw is a good idea.

I am not trying to be a jerk here.

[Edwin Santos]

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.

If you don't want the trial and error method, then yes set-up blocks are a good way to go. Lee Valley sells a posh set. I have some brass ones made by Whiteside. You can stack them to get to your height so long as you're not into 32nds. Used like a feeler gauge it's pretty quick to find TDC. I use them at the router table for height setting a lot.

[Ken Boyd]

Ummm. Just put a mark on the insert that marks the center of the arbor. Place whatever height measuring gauge on this mark and just rotate the blade until a tooth is underneath the gauge.

[Peter Christensen]

With a SawStop you can set a height gauge to the height you are looking for. Put it over the blade tooth and raise the blade until the brake test light flashed. Simple and easy. Would I fuss around doing that? Probably not.

http://www.leevalley.com/en/wood/page.aspx?p=61612&cat=1,43513

[Roger Feeley]

I applaud the initiative to develop a height gauge, and would really like to see one made, but I gotta ask. Is this really a big problem to set the height of table saw blade? What exactly is being cut that needs to be so exact? Maybe I'm just sloppy????
Using the gage blocks in Glen's post, you should be about to get within .010" easily of any fractional measurement. .005" would not be unreasonable to achieve. Your fingers can easily detect differences <.002".
I use the same blocks Glen has, and a dial indicator. I just got an iGagging digital height gauge for the shaper, but it would easily find the height of the highest tooth in the arc of a blade if needed, which I will.
I would also caution about the test cut method, unless you know you have zero deflection in your throat plate, if the measurement is this critical.

All that said though, I think a height gauge for the table saw is a good idea.

I am not trying to be a jerk here.

Mike, I can think of some scenarios where a height gauge would be handy.

you are making a screen using half laps. You dial in the height at xxx. Now you realize that you are short a piece. You rip the piece which involves changing the blade height. going back to the half lap height is a snap

you are sneaking up on a tenon and you overshoot. Backing off can be tricky if you have gear lash issues. You need to always approach your setting while raising the blade. Backing off a half turn and then raising to a few thousandths less is easy with a dro.

I have a dro on my router table and don’t even try absolute measurements. I use it to make accurate relative measurements.

[Roger Feeley]

Ken, you absolutely right but only for some saws where the blade raises straight up and down. Most saws use a pivoting trunion and the index mark wouldn’t work because the center of the arbor moves in an arc.

that would work with my SawStop.

[Mike Cutler]

Mike, I can think of some scenarios where a height gauge would be handy.

you are making a screen using half laps. You dial in the height at xxx. Now you realize that you are short a piece. You rip the piece which involves changing the blade height. going back to the half lap height is a snap

you are sneaking up on a tenon and you overshoot. Backing off can be tricky if you have gear lash issues. You need to always approach your setting while raising the blade. Backing off a half turn and then raising to a few thousandths less is easy with a dro.

I have a dro on my router table and don’t even try absolute measurements. I use it to make accurate relative measurements.

Roger
I have definitely found myself in those scenarios. I think everyone has. I can see the need to return to a setting, and it is difficult at times.
Don't get me wrong, I do test cuts, and will keep the "gauge blocks" for an entire project just so I can return to a setting.

I think are doing yourself a disservice with your router table though, and should consider using absolute cutter heights.
I make a lot of absolute measurements, relative to the table, with my shaper during a project and keep the values written down. I can return to within 1000th's easily. I also keep a written log, or notes, of each cutter, so that I just have to do simple math to set a cutter height. I can set the height of a lock miter, matched T&G's, or a reversible glue joint, to within a few 1000ths of being correct without a test cut. All I need to know is the average statistical thickness of the material.

[Yonak Hawkins]

... I need two more, quickly set it back ....

If you already have dados the right depth already cut, that's the perfect set-up tool isn't it ? Set a dado cut over the blade and raise the blade until it just touches.

[Al Launier]

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.

Nick, if you've already cut some dados & then realize the you need to cut a couple more to the same height, you could rub a pencil mark on the already cut dado, set it over the blade, then raise it until the blade just touches the pencil mark. Lock the blade at this height. Then cut the new dados to this height & if you really want the previously cut dados the same exact height as the new dados, then recut the previous dados. You might end up cutting 0.005" off the previous dado, but what difference would that make; they would all now be the same height.

Oops! Didn't see Yonak's post. We obviously think alike.