Frame Saw: Important tweaks

After a bunch of sessions with the new frame saw, I determined that it wasn’t working the way it was supposed to. It didn’t cut quickly, the kerf was too wide, and the blade wandered all over the place. I suspected that more than one thing was wrong, and I had a few ideas.

First, I caught on to the fact that the blade wasn’t really sharp, although it had the appearance of being sharp. I really need to learn that if the guy who made your saw doesn’t have a name like Wenzloff, it probably isn’t sharp, so you should save yourself a lot of trouble and sharpen it before using it. Groan.

I reshaped the teeth to have a fairly aggressive zero-degree rake angle, and took a considerable amount of care when sharpening to make sure that the tips were all very close to the same height. The result looks like this:

frame_saw_new_teeth

When doing this, I realized two additional things about this blade. First, it had way too much set, and second, the saw plate is a little thicker than I thought it was. This latter point was a big deal, because it seemed like the tips of the points originally were chamfered or slightly rounded. I couldn’t see this originally, even with reading glasses. And obviously, it makes a big difference in use, because, as I find over and over again, sofa-shaped blades don’t cut wood very well. (I wonder why.)

The difference in sharpening alone was really remarkable. Because the process removed most of the set, it made for a wonderfully thin kerf, and therefore, it tracked a line much better, even though the blade wasn’t terribly taut. And the more aggressive and sharp teeth cut much faster and smoother.

Now, the second problem I was having was that I couldn’t increase the blade tension too much, because the little screws that I was using to hold the blade in place were snapping due to the tension:

frame_saw_failed_pins

Yikes. So I cut and filed a few brads for this purpose:

frame_saw_new_pins

Now that there’s enough tension, I don’t have a problem with the blade twisting around (thanks for the pointer, Dan). The only issue I have now is that it’s difficult to keep the blade straight when tightening it up. Christopher Swingley uses a wrench on the flats, which seems like an idea that might work.

After making these two changes, this saw really seems to be on the right track, and I think I’ll be able to do decent work with it. I already sawed out some 3/16″ slices from a couple of smaller boards (without even marking!), and they came out great.

There always seems to be a lot of discussion about frame saws, and what kind of blade is appropriate. Tom Holloway’s saws use thin blades, and I can attest to how effective they are, having played with them. Bob Easton uses thicker blades from old Disston saws and that seems to work too. It seems to me that there’s more than one way to skin a cat.

A case in point here is what I edited in as a note in my last post, that there’s a version of a Japanese saw, the “oga kobiki” or something, that has a gigantic blade, but seems remarkably easy to use. Check out the pictures in this link if you haven’t yet. You see how that tiny woman is using that huge saw? Look at how beautifully the cut turns out. Oh, how I would love to examine that saw that they’re using.

So it seems that if the kerf is even enough–not too wide, not too narrow, of constant width, and straight–it doesn’t matter how big your blade is, as long as it’s slippery and sharp.

I don’t think this is going to be the last blade for this frame saw. I’ve got some ideas that might make it faster. Let’s just say that the gigantic teeth on the Japanese saw got me thinking.

I also got to thinking that I might need to do something about my saw vise. It works pretty well for small saws, but when you start to file the big teeth, it shakes too much. What to do here? Finally make my own? Cave in and get one of those new Gramercy saw vises? Find someone who has a good one and mug them?

Frame Saw: Push or Pull?

One of the interesting features of a frame saw is that one can use it as a push saw (with enough tension on the blade) or as a pull saw. Which is more appropriate, if there is such a thing?

I thought about this while in the process of resawing some beech, a bear of a process when the board is a 13.5″ wide slab. I had the saw in at roughly 45-80 degrees and it seemed to me that it was much faster pulling than pushing. What could have caused this, other than not enough blade tension?

As pretty much anyone will tell you, during ripping, your saw teeth are acting as little chisels and are hopefully shaped as such. But then wouldn’t the factor of grain orientation come into play?

  • When pushing into a board with the tooth side of the blade at an acute angle to the board, you are generally sawing with the grain, as you would with a plane.
  • When pulling out of the board, you are sawing into the grain, invoking tearout.

If you tear out, is that a bad thing? It seems to me that it would be faster because your saw would be continuously digging itself into the fibers. Of course, it would be tougher work. Would it also help avoid tracking the grain?

Think of the Japanese timber saws (stuff like the Kobiki Nokogiri or whatever its name is) — these are notoriously quick pull saws.

Well, I think I’ll do some more sawing to see what I like in practice. Probably with something other than a 13.5″ wide chunk of beech, though.

[Edit: Check out this blog post that a friend dug up for me. They’re ripping chestnut logs in a demonstration of traditional techniques, letting lots of people try. The big saw is called “Oga Kobiki” (大鋸) or “Daigiri” or something like that. Check out the angle they’re using in the wood versus the rake angle of the teeth.]

Frame Saw: Almost Finished

To make the handles into one end of the frame saw, I first marked out the length-wise dimensions with a pencil and the cross section limits with a marking gauge (hard to see in this photo, but they’re there):

frame_saw_handle_markout

Then I set to work shaping the handles. I used my Shinto saw rasp first. I really like that tool: cheap, innovative, and highly effective.

frame_saw_handle_rasping

To finish shaping, especially at the edges, I used my Gramercy saw maker’s rasp. Then I smoothed it out with progressive grits of sandpaper on a dowel, starting at 120 grit. Finally, I hand-sanded to 320 grit, and called it ready:

frame_saw_handle_shaped

Then I assembled the saw with the newly-waxed blade:

frame_saw_assembled

So far, so good. I tried it out and quickly found that I will need to do some version of the trick that others have done to keep the blade square. It does tend to slip around. It also seems like it’s necessary to practice technique, because this thing does have a tendency to slip out of the kerf because the blade is so thin.

And then there’s the issue of workholding. Hmm. Clearly there is more work to be done here.