I managed to grab a few hours when it wasn’t raining and decided to sharpen Big Joe, the first of my crosscut backsaws. I got ¾ of the way through filing in new teeth and my file gave out. I’ve ordered some more files which should be here early next week, so I’ll return to Big Joe in a future post. I didn’t want to waste the day however, so I decided to sharpen a handsaw instead – a first for me.
Some months ago, I restored a couple of 26” Disston D8s. This one is 8PPI (points per inch) with a nice apple handle.
The D8 was a revolutionary saw when it was first released. Here are some of its features.
- Skewed back (concave) – reduces the weight of the blade and improves the balance of the saw.
- Taper ground plate (thinner at the back than at the toothline) – reduces the weight of the plate and the amount of set required. The plate is the same thickness along the toothline and at the handle end, but the thickness of the plate is gradually reduced from the teeth towards the back edge and from the handle towards the toe as shown below.
- Breasted toothline (convex ‘crown’ along its length) – arguably mirrors the natural swing of the arm, keeping more teeth in contact with the wood.
- Revolutionary ‘in the plate’ tote – instead of sitting behind the plate, the grip was brought forward. It was also the first saw handle to have the kerf cut with a circular saw blade. The top of the handle is solid wood and covers the top of the saw plate which adds strength.
So I clamped the saw in my saw vise and jointed the teeth taking care to follow the convexity of the toothline.
I decided to keep the saw at 8 PPI (7 TPI), but alter the tooth geometry from 15 degrees of rake to a more aggressive 12 degrees of rake with 20 degrees of fleam. Here goes my first attempt at filing a crosscut saw.
After jointing the saw to get my ‘shiners’, I re-shaped the teeth.
The following photo shows the teeth after shaping. Need2boat (Joe) has mentioned a couple of times on my previous posts in this series that I chose to learn to file the hard way by starting with backsaws instead of handsaws. He was SOOOOOOO right. I found shaping these teeth really easy, even without one of my templates stuck to the side of the plate.
Now it was time to add some set to the teeth prior to sharpening. I measured the thickness of the plate at the heel just under the teeth to be .041”.
I adjusted my saw set to give me .003” of set either side, which after sharpening and dressing the teeth will probably end up more like .0025”
Next I stuck a 20 degree fleam template to the top of my saw vise and went down the teeth from heel to toe sharpening every alternate tooth. I then sharpened the teeth in between from the other side of the bench. I was having so much fun that I totally forgot to take any photos of the sharpening process (sorry about that). I tried to take a close-up of the finished teeth, but the wife’s little camera distorts the image if you get too close. This is the best I could get I’m afraid. In my rush to beat the rain, I also neglected to brush off the wood fibers.
Anyhow, here’s the finished saw.
I only just got it sharpened before it started raining again, so no video of it in action for the moment. It cuts well though.
Sorry this episode was so brief. I was just glad to get a couple of hours in which to do something productive. Normal service will be resumed shortly.
-- Andy -- Old Chinese proverb say: "If you think something can't be done, don't interrrupt man who is doing it."