Shape of Festool's blades and depth-of-cut question

[Alaska Ranger]

A current thread once again discusses users' choices of backing board for their plunge-saw cuts - styrofoam, mdf, the MFT/3 table top, cast-off smooth plywood and so on.

Virtually all report they drop the blade something along the lines of "a few mm's into the sacrificial board".

Now, I learned that the most efficient blade depth, and one which causes the least amount of tear-out because of each tooth's angle of attack, occurs when the blade is more-or-less 1/4" proud of the cut surface.

So..... how to reconcile these disparate situations? Are the Festool blades' rake and gullet depth that different from traditional blades?

 

[chrisrosenb]

I do not go by the recommendations of some factory engineer, I go by what works for me out in the field.

 

[jonny round boy]

I do not go by the recommendations of some factory engineer, I go by what works for me out in the field.

That reminds me of a greetings card I saw recently, that said something along the lines of:

"Men don't read instruction manuals. They are merely the manufacturer's suggestions on how something might work..."

[big grin]

 

[ccarrolladams]

A current thread once again discusses users' choices of backing board for their plunge-saw cuts - styrofoam, mdf, the MFT/3 table top, cast-off smooth plywood and so on.

Virtually all report they drop the blade something along the lines of "a few mm's into the sacrificial board".

Now, I learned that the most efficient blade depth, and one which causes the least amount of tear-out because of each tooth's angle of attack, occurs when the blade is more-or-less 1/4" proud of the cut surface.

So..... how to reconcile these disparate situations? Are the Festool blades' rake and gullet depth that different from traditional blades?

As the saying goes, "Mileage will vary"

With my TS55s while cutting cabinet grade plywood using the 48 tooth fine blade that is standard on the TS55, I limit the depth of the cut into the sacrificial surface to 1-2mm on cross-grain and 2-3mm on long rip cuts. That was the consensus of experienced TS55 users in January 2006 when I bought my first one. By then I had nearly 60 years experience building cabinets from plywood. I did my own experiments with my new TS55 on guide rails. It appears to me that the Festool fine blade is designed for a minimal exposure.

The depth stop is calibrated in mm. The guide rail is 5mm thick. So for cross-cuts I set my TS55 at 25mm to cleanly cut 19mm plywood. I set for 26mm on rip cuts.

Of course different style blades need more depth. My rule of thumb is to expose the blade so that the bottom tooth is clear of the gullet, then adjust more or less until I am happy with the quality of cut and efficiency of the sawing. I follow the same principle when using a beam, slider or conventional table saw. The amount of exposed blade is a function of the blade design as well as the material being cut