When I learned to sharpen a saw the first time the result was acceptable but mostly this was because my saw was new and it was a first time sharpening for me and it. The process seemed simple enough because it was a ripcut saw and the teeth are sharpened square across with the file passing at 90-degrees to the saw plate in both plains. The gullet itself fixed the angle so it was mostly governed by this. Unfortunately, not much emphasis was given with regards to length of stroke and downward pressure, both of which must have measured control. Over the months my saw teeth began to develop large and small teeth alongside one another. Too much offset pressure resulted in gain to one tooth and loss next door to the adjacent one or ones. But it was by this that I learned.

I recall buying a Japanese saw file for the first time. I thought it’s slender profile in the shape of a diamond pattern made it an unusually lovely tool. Passing it into each gullet, the teeth offered little resistance because of the relative angle to the plate on pull-stroke saws. This was 30 years ago. I found the task simple enough and soon the saw was sharp again. This was my first encounter with a Japanese saw. It was at that time that the hard-point saws began to gain increased credibility because they eliminated any need for sharpening. . . forever. In those days disposing of things seemed always destined for the so-called landfill. It should have been called land pollution but that is just my view. Back then no one had recycle bins that I ever recall seeing. Of course recycle does minimise waste and the same steel can be reconstituted. I still will always question the making of saws with built in disposability. It’s such a sad day, yet for most, it’s seen as something, well, just easy and clever. I learned to sharpen a saw by just repeating the practice and not giving up until I got it right. I think that if I can learn to sharpen a saw, most people can too!

A few years ago I introduced a new concept for my ripcut saws and that was to add a third bevel in the form of a strengthening bevel to the rear of the saw teeth. I had started to do this some years previously because I wondered if the teeth would stay sharper with the added back support to the fore-edge. It works well and takes but a few minutes. Now then, you don’t need to do this just after you have sharpened the saw because you do have a good cutting. I did do it the first time to test out my theory. I had just sharpened my saw and then added the back-bevel. It worked!

Adding a back bevel to teeth strengthens the tooth so that it has support at the rear which reduces edge fracture. Some Japanese pull-stroke ripsaws can be resharpened and you can add this to the saw teeth.

Having never seen or heard of this being done before I felt something of an adventurer — a sort of defying tradition on the one hand and then on the other, totally accepting of them and my standing on the shoulders of giants who went before me. What happens is simple enough. I sharpened the gullets of the rip with a single pass through the gullet at a measured length and hand weight. This regulated the depth of cut to the steel and ensured the teeth stay the same height. Once done, I passed the file onto the tip of each of the teeth at an angle as shown in the drawing to create the back bevel I wanted. You must take care not to take it down too much as you rely on the edge to guide your filing. This too was a mere single pass stroke of very light hand weight. As if you are somehow just stroking the tooth. There is no force used and if anything I am suspending the file across the tip to take off the barest amount. Even so, this results in a flat plain about .75mm wide. This is enough not to do again for about five standard sharpenings. On very fine-toothed saws, this is a little less easy because of the size and the width of the saw file. I’d say it’s not worth eye-strain or the effort doing it to teeth 18 PPI or more. On 16 PPI and less, it is definitely worth the extra pass as it is literally two minutes’ work.

Another consideration is one I use from time to time and that is to simply repeat the third bevel rather than both gullet sides to the front and back of the teeth. This effectively sharpens the key edge and corners to the teeth and of course the ‘chisel edge’. You can do this three or four times with light-handed passes. Ultimately you will take the gullet down again with conventional filing to reestablish the full-depth gullet again.

I say all of this because saw sharpening is worthy of consideration and who knows what innovative concepts might emerge. Another point to ponder (pun intended) is the file teeth themselves. Most people refer to a saw file as a three-sided file when in reality they are six-sided–three main wide ones and three narrow. Funnily enough, it’s not the wide ones that generally limit the life span of a saw file but the three less-noticed narrow facets. These are the ones that stop the file from cutting because the narrow ‘corners‘ fracture much more quickly than the wider faces and once they are damaged they prevent the file from reaching the side faces with the larger cutting surfaces and thus deepening the cut is in fact impossible. That said, if you take a fine hacksaw blade, like the ones used in junior hacksaws, you can run a single pass into the ‘V’ of the gullet, and then the file will cut just fine. This is not a bad thing to do as it lengthens the life of the file altogether. It’s not quite so pretty but it works well and saw sharpening goes quickly for several sharpening after that initial gullet treatment.

22 Comments

  1. Patrick Stephens on 22 July 2020 at 2:33 pm

    Paul, when I was a young lad, I can remember my Grandfather sending his hand saws to a sharpening service. Now 70 years later, you have taught me how to sharpen and set a saw for free and without having to wait 3 day. Old dogs can learn new tricks. Well done, sir.

  2. Sylvain on 22 July 2020 at 4:46 pm

    Question
    Paul, would using slope while sharpening a saw make the file last longer?

    The idea: If when filing horizontally, one hear an horrible noise, inclining the file might suppress the noise. It would have to do with the saw thickness and the spacing of the file tooth. If it is 1:1, it would rattle; while inclining the file would change this ratio. It would be better to have more than one file tooth engaged any time.
    Sylvain

    • John on 23 July 2020 at 6:01 am

      Sylvain’s question:
      Sharpening a saw with the file not perpendicular to the plate is usually described as furnishing the saw with “sloping gullets” and has been a common enough practice for a long time. The result is that the the angle between the teeth is less than the usual 60 degrees (how much less depends on how much the file departs from a perpendicular attitude to the plate) and the shape of the teeth becomes somewhat attenuated compared with teeth sharpened with the file perpendicular to the plate. The advantage of sharpening a saw to this configuration is that the saw cuts more deeply than a conventionally sharpened saw on each stroke. The disadvantage, which is no real disadvantage to a reasonably fit man, is that it requires more power from the arm of the sawyer to make the stroke. Hence, before the advent of portable power saws, the sloping gullet configuration was favoured by brawny carpenters for their crosscut hand-saws so as to get their work done more speedily. Such a configuration effects a similar change to the use of a crosscut cabinet back saw but whether to do it in a cabinet shop would depend on the type of work undertaken there.

      Old cast-iron saw vices catered for sharpening saws with sloping gullets by permitting the plate to be set at an angle less than the perpendicular, so that the otherwise challenging business of filing at a constant angle of slope to the plate could be maintained by simply keeping the file at the horizontal whilst concentrating on filing at the correct fleam attitude..

      Filing sloping gullets is a relatively smooth process but the answer to the question of whether it serves to preserve the lives of files awaits some appropriate form of experimentation. Sylvain’s observation to the effect that more file teeth than for conventional filing are engaged on two sides and one edge of the file at any instant whilst filing for a sloping gullet seems correct.

    • JohnM on 27 July 2020 at 1:45 pm

      If you have the saw in a proper rigidly mounted saw vice with only the teeth protruding you should not get vibrations in my limited experience. For long saws it sometimes helps to hang some heavy rags such as an old towel over the parts of the saw outside the vice – that dampens the blade and stops it vibrating or ‘singing’ if you excite the resonant mode, this works when working any long length of metal only supported in the middle.

      The other thing to try is a finer saw tooth file, the more teeth cutting the metal at the same time the less the risk of setting up vibration.

  3. Christopher Johnston on 22 July 2020 at 6:39 pm

    What is wrong with grinding off the hardpoints when dull and resharpening then .? Is that not possible?

  4. Ian Blackman on 22 July 2020 at 9:20 pm

    Paul. I often have trouble starting my push saw. Obviously I can draw the saw back, but I can’t push it forward even with the lightest touch. It seems to me that adding the back bevel would solve this problem as it would cut the wood fibres on a light pull and avoid the problem. Is this one reason for this modification?
    Love your stuff. Thanks.

    • Sylvain on 22 July 2020 at 10:13 pm

      I can’t find it, but there is a P.S. video about this.
      Basically making the first few teeth not dull but much less agressive (at the end of the saw opposite to the handle.)

      • Bill on 23 July 2020 at 1:16 am

        I believe it was in one of his recent Q&As. Also probably in several other videos. 🙂

    • Paul Sellers on 23 July 2020 at 10:53 am

      Ian, I have recommended people take a flat file and file the starter teeth, about ten to fifteen of them, at an incline with just one or two strokes. The saw will then glide into the cut. When you resharpen the saw just file these gullets with the same number of strokes as the main length of teeth. https://youtu.be/mP0DgxIb-xs?t=414

    • gerald anania on 23 July 2020 at 12:45 pm

      I believe most woodworkers follow the practice of not pulling the saw backwards to start the cut. Going backwards almost always results in the saw skittering side to side. The kerf is erratic and that means when you start to push the saw it does not track well.
      As Paul says in his videos on sharpening and sawing. creating a less agressive rake for the first couple of inches reduces the difficulty of starting a saw. Also putting too much pressure on the start of the cut is always a problem you need to let the weight of the saw do the work. A well sharpened saw will do the work for you.
      As an aside I purchased a 3 pt rip saw that was well sharpened when I got it. I wanted to use it for resawing. It was extremely difficult for me to start the saw with that very aggresive tooth pattern. I did not want and did not think I should adjust the first couple of inches of rake on that hand saw. Felt it would ruin the saw . Instead i used a less aggressive rip saws to create a kef then went back to the 3 pt saw. I guess it is a less sophisticated version of the kerf saw . I have gotten better starting the3 pt saw but it si difficult to learn.
      Another thing to avoid is nibbling on the start cut,

    • Malcolm Smith on 24 July 2020 at 9:20 am

      I always meant to pick up on this back bevelling bit forgot – time to try.

      Easing the rake or size of teeth at the toe can help starting cuts. Taking a nick from the wood with a chisel at the start can help too.
      More importantly for me with my larger rip saws is taking the weight of the saw in my hand via the lower horn. However, practice is a must for me when pulling out one of the big beautiful beasts – just half a dozen strokes to reintroduce me to the balance and weight. I’m not a fan of nibbling nor of having a large no go area between me and my line.
      P.S. Takes me longer to climb up on and down from the bench these days – Paul’s fault for introducing me to a more comfortable and effective personal bench height. But it is my favoured rip position – kneeling helps me get the angle of presentation of the saw right for me. Time to make a saw bench – old Workmate suffers from shake rattle n roll.

  5. Joe Christensen on 27 July 2020 at 4:02 pm

    Interesting that you mentioned getting increasingly large and small teeth – I’m doing that (somehow!) to one of my rip saws. I read and re-read what you wrote… I’m still unsure what I’m doing wrong.

    • TimD on 29 July 2020 at 12:05 pm

      I have the same problem when sharpening my rip saw. I have improved somewhat by striving to keep each stroke identical in terms of length and downward pressure. It am getting better with practice, bright light, and some magnification!

      • Mike Brandstatt on 27 August 2020 at 12:52 am

        What turned the light on for me was to “forget” trying to keep the strokes of the file all the same and even, for me that was very difficult if not impossible. Joint the tooth line, making sure that every tooth gets a shiny flat on it, the width of the flat on the point of the tooth will guide the action that you take with the file. With this method the “flat is everything”. Don’t count file strokes or concentrate on one tooth at a time, work multiple teeth at a time , file to bring all flats to a point by biasing the file toward the front or back of each tooth, In other words file to bring the flats to an equal width until they disappear, at which point your saw’s tooth line is sharp, straight and even. I have found that this gets all the teeth to the same size and height. I hope this is helpful.

  6. Greg Saue on 27 July 2020 at 9:03 pm

    What is the most efficient way to convert a crosscut saw to rip tooth?

  7. joe o sullivan on 28 July 2020 at 1:15 am

    The idea of another bevel on top of the tooth is great.
    I’m pretty sure if I had thought of this myself I wouldn’t have done it, because my brain would have just thought: “This can’t work, if it did then somebody would have thought of it years ago”, and I would have just sharpened the saw in the traditional way.
    I think I’m going to remember this lesson: “Just because it hasn’t been done, doesn’t mean it won’t work!”

  8. Timothy Sweeney on 28 July 2020 at 4:49 am

    Good evening, Mr. Sellers. I’ve a question, if I might.

    I watched your video on cutting new teeth into a saw (Oxford says “retoothing” is a not proper word) and my questions is: Is there a formulae, or rule of thumb for how deep to make the initial gullet cuts on other TPI than presented in the video? It seems like one of those things that has a surprising simple answer.

    But perhaps not! Thanks you for all of the knowledge you so freely share. You bring a great deal of happiness to a lot of people.

    Best wishes, Mr. Sellers!

  9. Adriano J. M. Rosa on 2 August 2020 at 3:53 am

    That’s why I follow you.
    New points of view and a good explanation.
    Thank you.

  10. John E on 6 August 2020 at 10:33 pm

    Sounds like the same concept as putting a micro back bevel on a plane blade.

    • Paul Sellers on 7 August 2020 at 8:55 am

      I understand the comparison but, no, it’s actually nothing like it. The back bevel on the cutting iron would actually be a front bevel when in the plane and this alters the presentation of the cutting and bevel above, steepening the cutting strategy. We do this to approach more awkward grain. It works. But on the saw it does nothing to alter the presentation of cut so it cuts identically with or without the true back bevel we create. This more shallow angle strengthens the actual cutting edge and that is its purpose. The steeper incline on the plane iron is not for strength but for a changed cutting dynamic.

  11. Simon Fitrzyk on 14 September 2020 at 8:03 pm

    How about creating the microbevel with a very light hammer stroke from behind and above the tooth? The resulting microbevel would be very similar, (maybe the very point will hang over forward a little,) but the metal at the point would be compressed, tougher, instead of removed.

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