Table Saw Blade Height . - Woodworking Talk - Woodworkers Forum
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post #1 of 41 Old 03-31-2013, 04:06 PM Thread Starter
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Table Saw Blade Height .

The push-stick thread sort of inspired this question. I realize it has likely been discussed at length in other threads but thought it needed rehashed. My apologies if a thread exists , I didn't see one on the front page of safety.

Seems many table saw safety habits are adopted from one's own experience. As it pertains to blade height above the work, seems to
be several schools of thought .

Some say the blade should be just high enough above the work to clear it. Others say the gullets on the blade should be just clear of the work.

Correct me if I'm wrong. I'm sure you will anyway but this is my understanding of gullets and blade height and how it relates to safety.

Typically a table saw insert will have a through slot at the front and back of the blade. This allows chips and sawdust to escape from the work piece. The blade chippers will cut through the material and the gullets provide a void for chips and sawdust on a ripping blade that are ejected through the insert slots and above the workpiece.

Raising the gullets above the work allow more of the blade to cut on the downward arc and thus puts less strain on the motor. But it also exposes the user to more larger chips and debris being ejected from the top and back toward the woodworker.

When the gullets are below the work less of the larger chips and sawdust is ejected back toward the operator. Thus safer . But the saw has to work harder .

Obviously,when using a cross-cut blade, there are less larger chips be taken and the work is fed slower through the blade . This allows the sawdust to clear out and compensates for the slower cut rate that is
characteristic of a cross-cut blade.

So anyway, most have probably settled into a routine which has worked for them over the years. The best method for a particular user is the one that has worked for them. The goal being a clean cut, little to no chip out or tear out, and reduced occurance of kick-back.


Would be curious to hear everyones method. Why they choose gullets above or below the workpiece and the advantages as you see them.

On a side note and excuse the mini-rant, a big pet peeve of mine is seeing some of these so-called table saw safety videos that people just love to post to YouTube.

While the intent may be good, they should take the time to actually do it in a safe manner.

I saw one a few days ago and the guy goes through a safety lecture about wearing eye and ear protection,blah,blah, and then he proceeds to do the demo wearing long sleeves and a friggin lanyard hanging off his neck .
Really ? Talk about sending the wrong message to beginners.</rant>

Anyways, thanks for reading. and would be interested in your thoughts on tablesaw blade height.

Last edited by against_the_grain; 03-31-2013 at 04:21 PM.
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post #2 of 41 Old 03-31-2013, 04:42 PM
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I see it this way

I'll keep it at full height or 3/4" above the work when ripping. It will cut more efficiently, run cooler and pull the work into the table as the blade enters the work..
When crosscutting I use a 40T or more blade, and then have the gullets exposed.

As far as blade exposure for safety reasons, yeah the higher the blade the more potential for a severe injury, HOWEVER, your hand and fingers should not be inline with the blade,the work should have been previously surfaced flat and only a straight edge against the fence. Anything else is asking for trouble.

So, it's efficiency vs safety and if safety can be managed by push sticks hold downs, splitters, then I go with efficiency.
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Last edited by woodnthings; 04-02-2013 at 02:52 PM. Reason: added when ripping and when crossscuting
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post #3 of 41 Old 03-31-2013, 06:20 PM
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Just the gullet above the wood. If the blade is too high it is not as safe and creates a rougher cut. I think 3/4 is too high.

The lower the blade the cleaner the cut and safer it is but the blade does need to be high enough for the gullets to clear the sawdust out of the kurf.

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post #4 of 41 Old 03-31-2013, 08:45 PM
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Just sitting here thinking, I would guess that I usually have the blade about 3/8" above the workpiece. I do not think about gullets or any of the other items mentioned.

George
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post #5 of 41 Old 04-01-2013, 08:50 AM
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Quote:
Originally Posted by GeorgeC View Post
Just sitting here thinking, I would guess that I usually have the blade about 3/8" above the workpiece. I do not think about gullets or any of the other items mentioned.

George
I'm with George. 1/4 - 3/8 and let'er rip. I suppose little tinker toy table saws might require more....... ummmmmm tinkering.
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post #6 of 41 Old 04-01-2013, 11:38 AM
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I used to be the only one here that preferred to run a blade high. It seems some have changed their mind. With the blade high, the first force to the stock is down and against the table. With the blade high the cutting angle is more vertical, which means less blade to wood contact. With the blade run low (teeth/gullets near the top of the stock), the angle of cut is much longer, the blade runs hotter, and there is more tooth contact with the wood. There is more of a tendency for frontal lift of the stock as the blade enters.





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post #7 of 41 Old 04-01-2013, 12:16 PM
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1/4-3/8" higher than the work piece is my norm. When you're cutting thinner/narrower stock, uplift can be a problem and a slightly higher blade can be beneficial. It's not a problem that I normally have with thicker/wider stock.

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post #8 of 41 Old 04-01-2013, 01:02 PM
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I don't believe there is a right answer and also not a one size fits for all.

If much better results are achieved with the blade set very high, I think one needs to look at either quality of the blade, or poor saw set-up, or using the wrong blade (hook and rake angle) for the wrong purpose.

The general rule of thumb taught is 1/8" above the work piece for wood on a table saw.

Freud suggests that optimally 3 to 7 teeth should be buried in the work piece, so obviously a rip cut 24t blade will be set at a different height than a 80T cross-cut blade if we were to take their direction.

The tips of the teeth affect entrance and exit of the cut, while the sides affect the edge of the cut. Varying the blade height affects each aspect differently. The "best" height depends on what one wishes to achieve, as raising the blade higher is more efficient, using less power, because there are less teeth in contact with the work-piece, less heat and less resistance. As the teeth rake angle is a constant, raising the blade also has the effect of changing the attack angle, as the higher the blade the more aggressive the hook angle behaves and is roughly comparable to using a rip cut lower tooth count blade. Raising the teeth however means less contact between the sides of the teeth and the edge of the cut, making a planing or smooth polished cut more difficult, meaning more saw marks or a rougher cut.

Linky: http://www.woodtechtooling.com/Freud...wBladep11.html

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Last edited by WillemJM; 04-01-2013 at 01:46 PM. Reason: Linky
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post #9 of 41 Old 04-01-2013, 03:02 PM
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"With the blade high, the first force to the stock is down and against the table. With the blade high the cutting angle is more vertical, which means less blade to wood contact. With the blade run low (teeth/gullets near the top of the stock), the angle of cut is much longer, the blade runs hotter, and there is more tooth contact with the wood. There is more of a tendency for frontal lift of the stock as the blade enters."

What Mike says is very important and needs to be considered very carefully.

In community college classes, the mentality is safety at all costs. A few other considerations in the community college environment is that blades are cheaper than fingers. The community college where I've taken a few classes uses combination blade almost exclusively. (50 teeth in ten groups of 1 raker and 4 ATB teeth.) The community college rule is that the wood reaches the bottom of the common gullet. (That is the smaller gullets on a combination blade.)

I think that those two are the two extremes. I think that Mike's analysis is more for a commercial shop where a table saw may be cutting for hours on end. The community college rule is more for on-off, on-off operations.

In my shop, I can not recall a time where the saw was running for 15 minutes straight. I tend to follow the community college rule. I also favor the combination style of blade.

There are exceptions. When I need a straight as possible incomplete cut, I will raise the blade to maximum height. Also when I'm cutting a flexible high pressure laminate (Formica) I'll raise the blade to about 2". (The wind from the blade tends to lift the HPL over the blade.)

With all of this discussion, the real answer to your question is, There is no single correct answer. You have to do what makes you feel safe. The procedures that others use may not feel safe in your shop. The important rule in the shop is to not leave any body parts behind.

Use the right tool for the job.

Rich (Tilting right)
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Remember that when we have the "BIG ONE" everything east of the Rockies falls into the ocean.
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post #10 of 41 Old 04-01-2013, 07:10 PM Thread Starter
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Quote:
Originally Posted by WillemJM View Post
I don't believe there is a right answer and also not a one size fits for all.

If much better results are achieved with the blade set very high, I think one needs to look at either quality of the blade, or poor saw set-up, or using the wrong blade (hook and rake angle) for the wrong purpose.

The general rule of thumb taught is 1/8" above the work piece for wood on a table saw.

Freud suggests that optimally 3 to 7 teeth should be buried in the work piece, so obviously a rip cut 24t blade will be set at a different height than a 80T cross-cut blade if we were to take their direction.

The tips of the teeth affect entrance and exit of the cut, while the sides affect the edge of the cut. Varying the blade height affects each aspect differently. The "best" height depends on what one wishes to achieve, as raising the blade higher is more efficient, using less power, because there are less teeth in contact with the work-piece, less heat and less resistance. As the teeth rake angle is a constant, raising the blade also has the effect of changing the attack angle, as the higher the blade the more aggressive the hook angle behaves and is roughly comparable to using a rip cut lower tooth count blade. Raising the teeth however means less contact between the sides of the teeth and the edge of the cut, making a planing or smooth polished cut more difficult, meaning more saw marks or a rougher cut.

Linky: http://www.woodtechtooling.com/Freud...wBladep11.html
I read where if the gullets (the bottom of the valleys in between the teeth) aren't clear of or about flush with the top of the work piece, the chips and dust have to be plowed through the cut and expelled mainly throught bottom at the slot in the throat plate. That could cause lift also.The plowing motion through material and build-up of cut material that must be plowed through puts more stress on the motor and creates rough edges on the material.

With the gullets just clear of the top of material, there is less plowing (less trapped sawdust and chips ) and smoother cut, but still an optimum number of teeth in contact with the material ,as opposed to a blade raised too high at which point the angle of attack increases and rough cuts are the result.

I think that is basically what you said. Just wording it a little different to see if I understood that.

So roughly that works out to about ~ 3/8 - 1/2 " for a combo blade and 3/8 " or less with a crosscut blade. Sound about right ?

Last edited by against_the_grain; 04-01-2013 at 08:05 PM.
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post #11 of 41 Old 04-02-2013, 09:32 AM
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Quote:
Originally Posted by against_the_grain View Post
I read where if the gullets (the bottom of the valleys in between the teeth) aren't clear of or about flush with the top of the work piece, the chips and dust have to be plowed through the cut and expelled mainly throught bottom at the slot in the throat plate. That could cause lift also.The plowing motion through material and build-up of cut material that must be plowed through puts more stress on the motor and creates rough edges on the material.

With the gullets just clear of the top of material, there is less plowing (less trapped sawdust and chips ) and smoother cut, but still an optimum number of teeth in contact with the material ,as opposed to a blade raised too high at which point the angle of attack increases and rough cuts are the result.

I think that is basically what you said. Just wording it a little different to see if I understood that.

So roughly that works out to about ~ 3/8 - 1/2 " for a combo blade and 3/8 " or less with a crosscut blade. Sound about right ?
I have always followed the approximate 1/8th" rule and use a 40T combo blade for 95% of my work. In 12 years on my current 3hp saw, I have never experienced a kick-back, never had any issues to cause a reason for changing my methods. My rip cuts are glue up quality most of the time.

From the linky I posted, this is what Freud says, I believe they analysed this much better than I did, but it seems to agree with your post.

Quote Freud:

The sawblade's projection (t) with respect to the work piece must be greater than the height of the blade's tooth (fig. 18). Increase or decrease the projection of the saw blade to improve finish quality.

ē The number of teeth cutting the wood simultaneously must be between 3 or 4 for ripping and ideally 5 to 7 for crosscutting. With less than 3 teeth cutting the sawblade begins to vibrate leading to an uneven cut. If you want to cut work pieces with increased thicknesses (T-fig.21), but wish to maintain the same diameter saw blade, then use a blade with less teeth. If instead you want to cut work pieces with a reduced thickness, but also maintain the same diameter saw blade, then use a blade with more teeth.


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post #12 of 41 Old 04-02-2013, 12:51 PM
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Just high enough so I don't cut my stock feeder.
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post #13 of 41 Old 04-02-2013, 01:07 PM
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I'm not sure why this is an issue IF you are using the appropriate gaurd on your TS.... That guard will be protecting you from the blade, no matter what height you have the blade set at.

With that being said, and taken into consideration, I have found that it really matters on what I am cutting, and the finish that I would like to obtain, that affects the blade height.

I did not know that Freud actually had those recommendations, so thanks of sharing that, Willemjm.
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I used to be fairly indecisive, but now....... I'm not so sure.
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post #14 of 41 Old 04-02-2013, 11:55 PM
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Think about the blade as a wood carving tool. Pounding straight down into the wood is max pressure and stress. Lower the blade to get more of a skew/shaping slice into the wood. Makes more sense.
Lowering the effective attack angle of a skew chisel, with a more glancing cut, simply relieves the stress.
Push skews around in carving for a few years, you'll figure that out. I see the observations directly transferable to table saw cuts. Mind you. I have only 2 pairs of skews and 3 others, my big fun skew is a 1S/25e Pfeil.
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post #15 of 41 Old 04-04-2013, 11:13 AM
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OK so how do we handle a hand circular saw ? Skil worm gear, of course, nothing else is worth owning.
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post #16 of 41 Old 04-04-2013, 12:20 PM
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I have always had the blade just about a 1/4" exposed except that one time when after reading that the blade should be higher. I unconsciously raised the blade higher about 3/4" -1" and that was the one accident that took my finger.

Even with my SawStop that blade is never that high again.

As for the guard comment. While it's true most of the time, Anyone here that has made small cuts has probably had to do so without the guard on. Some never use it because of poor design but either way things happen. Push sticks, feather boards no matter if it's meant it will.

I think it's whats comfortable to the person. I've never had a kickback with the blade low but that don't mean anything but that I've just been lucky.

I found that the proper blade and quality of blade means more then the height. By the way I learned about the better blades from allot of you guys. I would never had bought a Premier Fusion or WW2 blade before I joined the forum but after that I ditched all the old blades and bought nice quality blades.

For what it's worth that Premier Fusion blade cut right through my finger, bone and all I like a razor.
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post #17 of 41 Old 04-04-2013, 03:53 PM Thread Starter
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Quote:
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OK so how do we handle a hand circular saw ? Skil worm gear, of course, nothing else is worth owning.
Worm geared circular saws from what I understand, are great for carpenters who do a lot of construction. I think most hobbists probably own regular circular saws but thats just a guess. Its what you are used to and what gets the job done.

I need to upgrade my cheapie Master Mechanic probably. But its made in the USA and has done everything I've thrown at it. Would like to get one with some dust collection and perhaps a little lighter with a nice platform and easy to adjust.

As for blade height or projection through the material , with a circular
saw, I typically adjust it so I'm only exposing a little part of the blade on a through cut.

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post #18 of 41 Old 04-04-2013, 07:28 PM
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Originally Posted by rrich View Post
"With the blade high, the first force to the stock is down and against the table. With the blade high the cutting angle is more vertical, which means less blade to wood contact. With the blade run low (teeth/gullets near the top of the stock), the angle of cut is much longer, the blade runs hotter, and there is more tooth contact with the wood. There is more of a tendency for frontal lift of the stock as the blade enters."

What Mike says is very important and needs to be considered very carefully.

In community college classes, the mentality is safety at all costs. A few other considerations in the community college environment is that blades are cheaper than fingers. The community college where I've taken a few classes uses combination blade almost exclusively. (50 teeth in ten groups of 1 raker and 4 ATB teeth.) The community college rule is that the wood reaches the bottom of the common gullet. (That is the smaller gullets on a combination blade.)

I think that those two are the two extremes. I think that Mike's analysis is more for a commercial shop where a table saw may be cutting for hours on end. The community college rule is more for on-off, on-off operations.

In my shop, I can not recall a time where the saw was running for 15 minutes straight. I tend to follow the community college rule. I also favor the combination style of blade.

There are exceptions. When I need a straight as possible incomplete cut, I will raise the blade to maximum height. Also when I'm cutting a flexible high pressure laminate (Formica) I'll raise the blade to about 2". (The wind from the blade tends to lift the HPL over the blade.)

With all of this discussion, the real answer to your question is, There is no single correct answer. You have to do what makes you feel safe. The procedures that others use may not feel safe in your shop. The important rule in the shop is to not leave any body parts behind.
Good writeup.

George
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post #19 of 41 Old 01-09-2016, 08:47 AM
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Guys, I'm wondering since we are talking about "ripping". Did anyone see the attention note in the picture from Frued.
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post #20 of 41 Old 01-09-2016, 10:08 AM
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In addition to a faster cut, a high blade gives a less violent kickback due to a smaller torque on the workpiece in case the blade is pinched. In contrast, a blade almost buried in wood produces the beast of a kickback!

Thus a high blade is better for safety, provided of course we keep our fingers away from it at all times. For slender workpieces, always use a push-stick to clear the blade.
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