A recent customer asked if I would document the process of taking his old Disston D-8 (at left) and share pics with him. I agreed and thought it would also make a great post. I’ll try to let the pics do the talking.
Before I can file and sharpen I needed to smith the saw to remove a bit of a kink and bow. To do this I keep pressure on the plate by bending it down on the anvil and use a speically modified hammer.
With the plate true once more, I had to address the sway to the toothline. You can see the dip from the heel towards the toe. This is very common and not helpful in sawing. You want a straight toothline or a slight crown. This saw needs a good jointing before filing.
Jointing a saw is just like jointing a board. I use an 8 or 10 inch mill file.
Now you can see the toothline is nice and straight with an ever so slight corwn, or convexity.
The result of jointing the saw down so much is these little stumps…they are all that remain of the teeth. But this is good…it allows me to even the gullets and create new, evenly spaced and properly sized teeth.
Here’s what they look like after shaping.
I create these by filing straight across the plate. I am not filing any fleam yet. I begin to file the gullets and even the spacing of the teeth by accentuating my file stroke to either side as needed. The goal is to make the gulelts of even depth and the flats of the teeth the same size.
I start by roughing in the gullet.
Then define and even the depth.
Now refine the depth of the teeth.
And bring them to full size and shape.
I do this in two inch patches all the way down the saw until all of the teeth are even in size, depth and shape.
The saw is now jointed, the teeth are properly defined. This is what saw teeth should look like before sharpening.
I now set the saw teeth.
I set each tooth firmly and alternate one side then the other to set the teeth left and right.
I once again joint the saw to create a flat on each tooth…
Now the saw is ready for sharpening. Because this is a crosscut saw I file 25 degrees of fleam into the teeth. I do this by filing at an angle from perpendicular and use a simple visual aid that I call a fleam guide.
Here’s the first group of teeth ready for sharpening. You can see the flats created by second jointing.
To create fleam I file every other tooth removing half of the flat. This makes the once previously rectangular flats now trianglular.
Then I go back and file each tooth that I skipped to create the other side of the tooth geometry. The result is a knife edge, or what we call fleam.
I continue this process all the way down the saw until all of the teeth are sharp with proper geometry.
The final step in sharpening a saw is stoning. I lay the saw flat on my bench and apply a strip of blue tape to the plate. This protects the saw plate and creates a depth stop for evening the set and removing the burr.
The result is a row of razor sharp teeth in prefect alignment.