Basic table saw question

[Stephen Cherry]

This may seem a little too simple, but when using a table saw, for best QUALITY OF CUT, is it better to have the blade up high so that the teeth are striking at almost a 90 degree angle, or is it better to have the blade height slightly thicker than the wood thickness. With the blade low, it's more of an angled cut.

Any thoughts?
Thanks
Steve

[Roger Feeley]

Hi Steve,

That is absolutely NOT a stupid question. There are a number of competing dynamics:

Safety: When asked how far above the wood the blade should protrude, he replied "How deep do you want the cut in your hand?". Put simply, more exposed blade is just that much more risk.

Quality of cut. This differs from blade to blade but there is an ideal angle of attack. Hold your wood next to the blade and rotate it so the tip of a tooth is right where it would just touch the wood. As I recall, the ideal angle of attack is around 7 degrees but there are certainly others who can advise you better.

In practice, I don't like the blade just barely poking up over the the wood. If the blade is a bit dull, the wood sometimes wants to ride up and over the blade and that's a bad thing. I like the blade 1/2" to 3/4" above the top of the wood. It seems to help hold the wood down.



confused yet?

But I also don't want to just leave the blade way up either. The safety issue aside, that amplifies any inaccuracy you might have in the alignment of the fence to blade. Keeping the blade lower reduces the distance between the front and back of the spinning blade.

Still another reason to keep the blade low is what will happen if you have a catch. A low blade would not tend to launch the wood up but just fling it out the front and hit you in the jewels. If you have a catch on a blade at it's highest, the back side of the blade can send that wood right for your head.

[Prashun Patel]

I have heard but cannot verify that higher blade means fewer teeth in wood at one time, and also changes angle of incidence into the wood to nearer to perpendicular. This in theory pushes the piece down instead of forward, reducing risk of kickback.

Personally I keep my blade so the gullets just clear the wood. That is supposed to help chip ejection, reduce heat and make for a cleaner cut.

[Joseph Tarantino]

according to freud blades, the blade should be elevated so the blade gullets just clear the surface of the workpiece. that way the teeth shear through their cuts for a smoother result than the more direct angle of attack if the blade were elevated to it's full height would produce.

[Howard Acheson]

Here is something from Freud. It applies to their blades but is probably good for other good blades too.

QUOTE

When using the correct Freud blade for the application we recommend 1/2 of the carbide tip (1/8" to 1/4") above the material. They are designed for proper angle of attack and number of teeth working at that height. You should have 3 to 5 teeth working in the wood for ripping and 5 to 7 for crosscuts. For tricky materials like veneered plywood or laminate you may need to vary a little to get the best performance (raise the blade slightly if you get chipping on top and lower if there is chipping on bottom). Different manufacturers may have other recommendations for their blades.
__________________
Charles M
Freud America, Inc.

CLOSE QUOTE

[Bob Wingard]

FORREST recommends running their blades very high ... I don't think there really is a BEST answer to this.

My experience has been that a high blade gives me a better cut, and it is easier on the blade due to lack of heat-producing friction that is hard on the teeth ... plus, the downward cutting action seems to be less likely to cause a kickback. Can't prove any of it, and I won't even try ... just an opinion based on personal experience.

What I DON'T agree with is the concept that a lower blade will hurt you less ... assume you're cutting 1" material and you have the blade 1/4" or so above the stock ... lower blade is more likely to allow/cause a kickback, possibly pulling your paw into 1-1/4" of exposed blade ... if you think that would be a fun thing to do, I guess you would favor the low blade concept.

I really would like to see someone with no partiality do a comprehensive study of the physic vs. safety vs. cut quality vs. blade longevity.

[Jeff Duncan]

Some good responses here already! Here's the thing, it really does depend on what your cutting, and as mentioned there is really no one right answer. If you want to see for yourself get some scrap of either melamine or hardwood plywood. Make some cuts, (crossgrain if using ply), and see what your cut looks like top and bottom! If you start with the blade really high you'll probably find your getting a perfect cut on the top, but the bottom will be splintery. By lowering the blade gradually you'll see the quality of cut on the bottom of the workpiece improve as the quality at the top degrades. So in reality you need to set your blade to achieve the results your after. If I'm cutting material where the bottom is not seen, I raise the blade for the best cut on one face. If I need both sides I play with the height until it's pretty good on both....usually 1/8" - 1/4" of exposed tooth.

Now for ripping solid wood I like the blade higher. I adjust it according to the type of stock....if it's clean stock I'll go about 3/8" +/- exposed blade. If it's rough stock than 1/2" or more exposed. Crosscutting I keep it pretty tight....maybe an eighth.

One thing to remember is the more exposed blade, the more dangerous a saw is. So you have to determine your own level of comfort balancing safety with quality of cut;)

good luck,
jeffD

[scott spencer]

As others have stated, there's really no single "best" answer. "Best" cut can be interpreted a couple of different ways, and the position of the blade to achieve best cut depends on the cutting objective, and on the blade parameters itself...so best position varies. The edge of the cut is one aspect to consider, and the exit of the cut is another.

The edge of the cut is heavily influenced by the side grind geometry of the blade, but number of teeth and feedrate are also factors. The longer the sides of the work piece are in contact with carbide, the more highly polished the edge of the cut becomes. There's a fine line between a polished edge and a burned edge, and the user needs to control those variables to get the ideal cut. There's more edge contact when the blade is set lower, but there's also more edge contact when there's more teeth, and tighter side clearance tolerances of the blade, so the ideal height setting varies.

The exit of the cut is more influenced by the top grind of the blade, but number of teeth, feed rate, and blade height are also variables to some degree. A higher blade setting tends to move any tearout from the back vertical edge of the cut to the bottom horizontal edge of the cut....which scenario is "best" for tearout depends on where you'd prefer to have any tearout located on a particular work piece....fortunately there are other techniques to minimize tearout, so I'd focus on edge quality regarding blade height. Using the correct blade for the job, my general rule of thumb is to bring the blade up to the bottom of the gullets. If your material is burning, try raising the blade slightly or using fewer teeth.

Good TS setup, a good ZCI, and a sharp clean blade are also factors in cut quality. The lumber is also a factor....flat square lumber tends to yield better cut results that an uneven board.

[Andrew Pitonyak]

I saw a video and I think that ultimately it was tied back to Forrest.... Sadly I cannot remember where and I was unable to find it.... But....

The person demonstrating had a reason and a height for different cuts. For example, a higher blade meant a cooler cut (if I remember correctly).

The guy used a different height for rip cut versus cross cut. I think that he also had a preferred heigh for plywood. I should really find that video.

[Andrew Pitonyak]

Try this video: http://www.youtube.com/watch?v=-SgdTXphEJ4

High blade, less heat expansion is his first point while rip cutting. Perfect glue-line rip.

About 1" above the stock for a cross-cut.

Watch the video to see what else he says. 22 minutes.

[George Gyulatyan]

A while ago I had a thread on whether I should upgrade my saw's motor or not for ripping thick stock. I then purchased a WWII 20T blade and that worked better. With the WWII blade there was an instruction sheet stating that if you experience burning, raise the blade 1" - 2" above the stock as this will help the blade run cooler.

I have comparison cuts with Freud GLR, WWII 20T and Freud GLR raised over 1" above stock cutting 8/4 maple here:
http://www.sawmillcreek.org/showthread.php?174350-Upgrading-table-saw-motor-Goofy-idea&highlight=Freud

[glenn bradley]

As you've already noticed from the responses, it depends and personal approaches differ. For the best quality of cut, use the right blade for the job. "Do-it-all" blades compromise every cut in order to do all cuts pretty well. As to height and geometry of tooth to material engagement, there are volumes on this. I enjoy the old adage; "never raise the blade higher than you want it to go into you hand". Just kidding on that last part. Lots of good responses here.

[Lee Schierer]

As you have noted there are a lot of opinions out there. If you are using Freud Blades follow their recommendations. I use Freud blades exclusively and I use their height adjustment recommendations and get excellent results. If it is a Forrest blade follow theirs, etc. If your saw is properly aligned and you are using a crosscut guide or sled when cross cutting and a rip fence when ripping then the chances of a kick back become quite small. You can make them even smaller when ripping by proper placemewnnt of effective feather boards. If you are nervous about making a particular cut it is probably because it is dangerous and you should find another way to do it.

[David Kumm]

I would have to think the blade diameter makes a difference as well. A 16" blade attacks the wood at a different angle than a 10" and the speed of the tip into the cut would affect the quality also. Dave

[scott spencer]

I would have to think the blade diameter makes a difference as well. A 16" blade attacks the wood at a different angle than a 10" and the speed of the tip into the cut would affect the quality also. Dave

I would have to agree.