Wooden File and sample cuts.

Done with my homework, boss.

Here is the wooden file:

You only need half of it. And we are interested on the profiles. So let's cut it.

On the right, a cut 90 degrees to the file's axis, on the left, 60 or so degrees, keeping the saw vertical. Respectively, they correspond to file with no slope, and 30 degrees slope, no fleam since the saw is vertical.  (For my definitions of rake, fleam and slope, go here)

Now, I keep the same angle with respect to the file axis, but I make a cut that is not vertical, that is, I add a bit of fleam:

Capicci? Now not only the angle is different, but the shape is also asymmetric. That's precisely what you are looking for when filling japanese teeth. That way, you don't touch the neighbour tooth when filing.

And now, an experiment not to be realised by kids in their homes. You need the supervision of an adult.

This is how it looks when you file with a japanese file and neither fleam nor slope.

The file loved it so much, that it decided to leave a few pieces on the steel.  The nicks on the middle of the are from this "experiment".  I have another one, don't worry, I'm still able to file.

Now, this is the money shot.

On the right, I filled only with fleam, but on the left... yes indeed, you guessed it, take a candy. On the left cut, I used a slope of around 30 degrees and 30 degrees fleam. Now the thing is working. The file eats the steel without any problem, it just flows and cuts. Beautiful. And you even can start to see a bevel on the scraper. (I just realised the fleam is on the other direction, sorry about that...)

I filed roughly the same number of times in the 3 cases. The last one (slope and fleam) went deeper because the file cuts way more on every stroke.

If you want more experiments filing metal with no fleam and no slope, you have to send me the file. I'm not wasting mines any more for the sake of research on that stupid configuration.

Unless you have any objections, I declare the case of the japanese slope to be closed. Now somebody should cook dinner — I'm getting hungry.