Questions answered – Recutting saw teeth

Q:

Paul,

I just bought a Disston 14″tenon saw on ebay the teeth are in bad shape i will have to cut new teeth. I was wondering if 12 ppi would work as well as the original 14 ppi. Thanks Paul, I always enjoy your blog, great information.   Also building a new bench per your book. Thanks again,

Dennis

 

A:

There are some issues here, Dennis. We should be entering the realms of fleam cut and ripcut here.  When teeth get larger we obviously have less teeth per inch run of saw. The larger the teeth the nearer we come to shaping the teeth to a fleam cut. 12 ppi can go either way and a ripcut pattern will work fine for tenon cheeks and other with-the-grain cutting, but not always so for many if not most crosscutting aspects of the same joints and so this will automatically necessitate a second, smaller-toothed saw for crosscutting shoulders. Not really a big deal as generally we tend to keep a small saw to hand too. The problem lies more with large tenon cutting in coarse-grained woods such as oak, where the large teeth tend to tug and rip at fibres when used on any crosscutting work; rather than severing. As most tenon saws are sharpened to a ripcut pattern, you will definitely need a second saw and especially is this so for large work. On the other hand, restoring a 14-16ppi pattern size will enable you to do what most people do and that is sharpen with a progressive ripcut pattern that cuts both with and across the grain using only a single saw. Alternatively you can put a passive rake on the teeth, but then that compromises the power of the ripcut, which is not what you want for tenon cutting at all.

8 comments on “Questions answered – Recutting saw teeth

  1. This is gobbledegook… perhaps you could stop and think before you write once in a while.
    And then write something that makes sense or point us to a useful link.

    • I have to say that I disagree with what you have written, and quite frankly if you do not appreciate the style in which Paul writes his posts, simply do not read them. There are plenty of us who enjoy what he has to say and how he says it.

  2. Paul,
    The only part I do not understand is the progressive ripcut pattern (although I haven’t taken the time to see if you explain it in your fine book.) Could you please review its characteristics? Thank you.
    John

    • There are two types of progressive teeth and both ways work the same and produce similar results that are in fact almost indistinguishable.
      Two modern day people are having one type made on their saws. Their type starts with smaller teeth and progress to larger teeth after a short distance. this isn’t new and neither are they recent inventions. They are a little more difficult to establish by hand methods although I have done it on saws myself.For those of us sharpening by hand we simply level the file on the first 1-2″ of teeth depending on the size of the teeth and the type or shape we want to ‘ease’us into the cut. This is very simple to do and even when people come to the classes with other makes of saw . they often adopt this method to their saws before they leave.

  3. I’ve literally sharpened thousands of backsaws, and the assertion that most are supplied with rip teeth is indeed poppycock. The vast majority sold came with either 13 or 14 point crosscut teeth. Large saws meant to use with a miter box had 12 point crosscut teeth. It is very rare to find a saw that has rip teeth unless a previous owner filed them in.

    Further, while progressive teeth are nice, suggesting this to a novice is equally as foolhardy. It’s like someone asking how can they learn to read and in response handing them a copy of Moby Dick. All the main makers on this side of the Atlantic never supplied their saws with progressive teeth, and somehow people managed for all these years. There are many places to learn to file saws online. Take a quick google, get a 6″ Double Extra Slim Taper and try it out.

    • No matter. The question is about tenon saws not the generic “backsaw” Americanism here so not really apples for apples. In 95% of cases craftsmen-sharpened saws, that is the man at the bench sharpening his own saws who never sent their saws away because they couldn’t be without them, sharpened their saws for ripcutting because of the speed and effectiveness of cut. Mostly shoulders were cut with smaller tenon or dovetail saws which were also sharpened for ripcut because yet again we see that the majority of cuts were indeed ripcut. It’s simple if you think about the physics of it really. A crosscut saw would be pretty useless for the majority of the work in tenon and dovetail joints, the two primary needs for tenon-type saws.

  4. Paul,

    Perhaps that’s how craftsman roll on your side of the Atlantic, but here in America, people use backsaws filed crosscut for crosscutting tasks (tenon shoulders, slots across grain, etc) and backsaws filed with rip teeth for ripping tasks (Tenon cheeks, dovetails, etc). I’m guessing people who made them and sold them as such intended them to be used in this manner, otherwise they would have just sold one saw with one tooth profile. Further, if what you said was indeed true, then you would see only vintage backsaws with rip teeth, not crosscut teeth which is the case. Your reputation and prolific writing is great, but you are WAY off base in this instance.

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