Table saw blade height.

[Spectric]

Looking at table saw blade setting, been discussed on here but nothing conclusive. Books tell us to have the blade just protruding through the workpiece whilst others say have it right through, so who has what thoughts on this subject and why please. Drawing attached showing 315mm blade with 40 teeth and cutting 22mm sheet.

 

[Hornbeam]

Just protruding will give you a finer cut as there are more teeth actually in the wood. Not so important for ripping but definitely for cross cutting

 

[doctor Bob]

I like it high.

 

[JobandKnock]

I was taught that just.protruding is safer - less chance of a serious injury if there is any hand/blade contact. Not that I ever need to use a saw without a crown guard, oh no

 

[sirocosm]

I have found that higher can give a cleaner cut on the top side. It can also slightly extend the capacity of a sliding miter table. And of course if you are notching something or making a partial cut, you can't have it too high. Also for thinner materials higher seems to work better, especially if they are not completely flat, like 1/4 ply often can be.

It can also depend on what you are cutting, if you are the type to use your saw with a multicut blade on things other than wood.

There are a couple other situations that it is probably best not to mention.

I am not so sure about safety, looking at your graphic it suggests lower would mean more chance of kickback.

I tend to set mine to be a bit higher than required most of the time, unless there is a reason to go higher.

 

[sometimewoodworker]

I have always found that a low blade makes a smoother sided cut, while with the same blade in the same material a high bladed cut can have chatter marks.

 

[Sideways]

A high blade is exiting the stock closer to 90 degrees, so more likelihood of tearout on the lower surface.
That's most of the arguments covered now.
If you remember them, you can choose what matters to you on a case by case basis. There is no one size fits all answer.
My default is the 10mm protrusion because of the safety argument. I have a slider and can stand to the side out of the line of fire on a lot of cuts. The risk of kickback is pretty low on thin stock and man made sheet so no need to go high.
If I was ripping something thick that was hard to push or that might pinch and kick back, I'd raise the blade full height to minimise those risks.
If I needed the very best clean top edge, again the blade would be full height but probably with the scriber on to keep the back side edge clean.

 

[Doug71]

My blade generally stays set at full height.

A clean, sharp blade is important whichever method you use.

 

[Spectric]

If you take the safety aspect out of the equation then we have

Just protruding will give you a finer cut as there are more teeth actually in the wood.

I have found that higher can give a cleaner cut on the top side.

"A high blade is exiting the stock closer to 90 degrees, so more likelihood of tearout on the lower surface. " So cleaner on the top side ?

And @doctor Bob , in a commercial shop where safety is very important you like it high, because ?

 

[Doug71]

If you have the guard set correctly it makes no difference safety wise if the blade is high or low, in fact it is more likely people will remove the guard if the the blade only protrudes a few millimetres as it doesn't look very dangerous.

Theory is also a high blade stays sharper longer and generates less heat.

 

[Spectric]

Theory is also a high blade stays sharper longer and generates less heat.

That is a good reason to leave high, will have to go and do some trials in the shed and see what results I get, upto now only had it just coming through but have remembered that my timber merchant has his sliding table saw blade set full height.

 

[TRITON]

You also should be aware of angle of attack so to speak. The angle of the front leading edge of each tooth in relation to the height above the workpiece and how that first contacts the timber.

So if the blade is high, at full cut for 100mm, and the timber being cut is 25mm, then the angle the tooth first impacts the timber is more downward.
Think bang bang bang bang bang bang hitting the timber downward slicing action would produce vibration, which would lead to a less than smooth cut. Set lower the tooth angle approach' the timber as less of an angle and is effectively coming from the front, say angled at 45 degrees, the action is more pushing fromt he front in, at said angle.

 

[doctor Bob]

each blade tip cuts a fraction of a mm, and follows the arc of the previous tip.
I like a clean cut the higher the blade the cleaner the top cut.
I have an electric rise and fall but it woulkd do my nut in to move it up and down all day long

 

[powertools]

I think that this guy explains everything.

 

[sirocosm]

Nice video, I think I am going to make one of those inserts, the slot in my stock insert is way to wide, and my saw doesn't have a riving knife. A bit surprised his just sits there, mine is screwed down.

 

[guineafowl21]

Another vote for blade full height:

- Easier on the saw (and less pushing as a consequence), less burning
- Less tendency for the piece to be shoved towards you, and for kickback in general (cf cutting with a chainsaw - ‘just protruding’ is a bit like cutting with the nose of the bar)
- Cleaner top cut

If you touch the blade, you’ll get a nasty injury whether the blade is just protruding or fully up. Maybe nastier with the latter, but your fingers should be nowhere near the blade in the first place. Chip limiting blades are also much safer than the old plain blades - maybe the ‘just protruding’ argument came from those days?

I also agree with @Doug71 ‘s point about awareness - if the blade is prominent, you’ll be more aware. Also, if you have to keep adjusting the blade height for different thicknesses, you’ll get slack and just leave it in place eventually.