Thread: Tenon saw - reverse cant to blade

Hi Sam, & welcome to the Forum.

It's unlikely there is a real 'reverse' cant on your saw - you might find it is simply that the spine is sitting high at the toe end. Spines often get knocked out of kilter.

If it is genuinely 'reverse-canted', I very much doubt it is intentional (it would give the saw a most unaesthetic look, to my eyes), but I can't think how that could have happened other than by someone using an odd sharpening technique. Normally, a slight cant develops in any well-used saw over time, because the teeth at the toe end tend to need more attention from the file than those at the heel, which do little work.

Anyways, I'd suggest you take a mallet and give a few gentle taps on that spine and see what happens....

Cheers,

Banged the spine back on with a mallet, all good now

What a newbie! Thanks Ian

Originally Posted by Sammyb81

Banged the spine back on with a mallet, all good now

What a newbie! Thanks Ian

Don't be the slightest bit embarrassed, Sam. You had the good sense to ask a question about something that seemed odd to you, and luckily enough, my answer helped solve your problem. We all start out knowing nothing, those who ask questions inevitably end up knowing more.....

Cheers,

Ian

On the subject of cant (that's without the apostrophe) and seeing as how we have your attention, what is the intended purpose? To my eyes it always looks odd, out of balance and certainly out of symmetry. Was there a practical function? Was it deliberate? I know that it is easy enough to tap the plate into the spine too far, but I gather some saws were produced deliberately this way.

Lastly is there any way of telling that the cant was intentional as opposed to being a badly fitted saw plate?

So many questions .

Regards
Paul

Hi Paul. Although your question on the merits of cant was directed towards Ian, you may also find some value in this article written by Isaac Smith.

Stewie;

I just cant stop myself: yet more discussion of hang | Blackburn Tools

Anyone feel free to comment, please - I ain't no guru!

Paul, this topic has come up a few times and there was quite a discussion on it in a thread, somewhere, but it was a bit of a side-issue and not reflected in the thread title, so I couldn't find it in a quick search.

I agree with a lot of what Isaac says in the article Stewie pointed to, however, I cannot see how cant has anything to do with hang angles! By my definition, HA is measured relative to the tooth line, so it's irrelevant whether the back is parallel to, or at any angle to, the tooth line.

Personally, I think much of what's written about cant is cant! I've suggested it may have been a way to squeeze more blades out of small pieces of precious saw plate(?), but no-one seemed to like that idea much. There have been various attempts to ascribe a function to it, but they are very weak arguments, imo. Let's face it, the vast majority of backsaws are parallel, or at least start out that way, and work perfectly well! However, I've seen quite a few that started life with parallel blades and acquired a very appreciable cant over time. This is largely because the teeth towards the toe do much more work and often get more attention from the file during sharpening. They are also the teeth most likely to encounter stray metal, and need a bit of re-forming more often. Over the years, it shows. A little saw I bought new in about 1980, with a perfectly parallel blade, has now got a noticeable cant, precisely for those reasons.

I rather like the look - it says "this saw has been used, & has served someone well for a long time!" My theory is that someone else, way back, also liked the look of a well-loved blade & decided to hurry the process up a bit by sending them out of the factory that way.

I simply cannot see how a canted blade makes a saw any better or more precise for sawing. I make D/T saws with and without cant, and to me there is not a jot of difference in functionality. I reckon it's purely aesthetic; I like the look of a sloped back, but I can use either just as well (or badly, depending on the day!) and just as accurately. But I remain open to persuasion. If anyone can come up with a truly convincing argument for a functional advantage of canted blades, I will happily recant.....

Cheers,

There are plenty of examples of older saws made with cant.
Check out this tenon saw from the Seaton's Tool Chest: The Magic of Seaton's Chest by Jim Hendricks
The key reason (other than just plain fashion) is the idea that you are less likely to cut below the line on the far side with a tapered saw.

Originally Posted by hiroller

There are plenty of examples of older saws made with cant.....

Indeed there are, Matt, but in comparison with the number of saws made with parallel blades, a pretty small %! Not very many appear in old catalogues, and a goodly number of saws wearing canted blades today almost certainly started out parallel. The earliest saw that seems to have been deliberately made canted is that famous 'Kenyon', from the mid 1800s I think, but not sure of the date, but it certainly was a long while ago.

Originally Posted by hiroller

....The key reason (other than just plain fashion) is the idea that you are less likely to cut below the line on the far side with a tapered saw....

Perhaps you are, but how canting brings it about, I cannot fathom. How the saw finishes a cut is determined by the angle between handle grip & tooth line, the height at which the work is held, and your 'natural' sawing stance. If you position the work at the right height, you shouldn't need much conscious input, the cut will end with the saw parallel with the bench top. The spine could cant up or down or anywhere in between, as far as I'm concerned, it won't affect the other, far more important geometries!

Cheers,

I totally agree that the most important thing is the angle between the sawyer's hand and the tooth line.

It seems to me, however, that there would be two ways to adjust this angle.

The first way would be to change the handle. For an oldschool sawmaker, this involves a bit of math, creating a new pattern, rasping and sanding out a new handle, then testing it and, if it doesn't work as desired, doing it again. For the mass production crowd, this means paying someone to sit on CAD, design the handle, transcribe it into whatever language CNC machines speak, and then pumping out X of them.

The other way, however, would be to just use the same handle template and add cant to the saw plate. I know jack about metalwork, but this has got to be a fairly easy job. Also, couldn't you just loosely fit a plate to an existing spine and just swap it out with plates with varying degrees of taper until you found the one you liked and then fully "seat" that plate into the spine and call that done? Likewise couldn't a mass production company just offer the same handle and spine with varying degrees of tapered plate to adjust the effective angle?

All I'm getting at with that poorly educated attempt at explaining myself is that maybe adding cant to a saw plate is just an easier way to adjust the effective hang angle on a saw without having to adjust the shape of the handle. Perhaps this could explain why some of the major manufacturers offer both a canted and straight version of certain saws instead of multiple handle/hang angle options?

Or maybe I'm way off base. Wouldn't be the first time...

Cheers,
Luke

Originally Posted by IanW

I simply cannot see how a canted blade makes a saw any better or more precise for sawing. I make D/T saws with and without cant, and to me there is not a jot of difference in functionality. I reckon it's purely aesthetic; I like the look of a sloped back, but I can use either just as well (or badly, depending on the day!) and just as accurately. But I remain open to persuasion. If anyone can come up with a truly convincing argument for a functional advantage of canted blades, I will happily recant.....

Dear Ian,


i am afraid there is absolutely no way of persuading or convincing you. every reason given to you , well you don't accept or preempt with an answer. at this point i think its a bit like perhaps you need to accept that its like some people use a coping saw to work on a DT and some people chisel all of it out. its almost impossible to convince one to change to the other


i would like to point out that working on small joints and by extension using a small DT saw the Cant is less important or useful, so it is quite possible depending on your method, work flow and or speed you would not notice a jot of difference. not to say Cant isn't useful on a smaller DT saw just that the lager the back saw and joint the more handy it is to have a saw with Cant.

Originally Posted by IanW

I rather like the look - it says "this saw has been used, & has served someone well for a long time!" My theory is that someone else, way back, also liked the look of a well-loved blade & decided to hurry the process up a bit by sending them out of the factory that way.

i agree it might have a certain romanticising to it for some people but i really struggle to see the logic in the overall theory? are you saying saw makers of old, at the height of using hand tools before any machines , that relied on making and selling tools to the trade to make a living, not hobbyist would sully their reputation by selling back saws that looked pre-worn. by that logic why not send out hand saws and all other tools showing signs of wear for the same reason?

Originally Posted by IanW

Let's face it, the vast majority of backsaws are parallel, or at least start out that way, and work perfectly well! However, I've seen quite a few that started life with parallel blades and acquired a very appreciable cant over time. This is largely because the teeth towards the toe do much more work and often get more attention from the file during sharpening.

I dont think anyone is saying a back saw ‘must’ have a Cant or isn't a genuine back saw if it’s parallel , there is a place for both. when it comes to back saw work of old and especially since machines there is probably more places where a parallel saw would be used, on site, a large amount of work using a mitre box or not only requires a parallel back.


What metal do the front teeth come across?


i don't entirely go for the front teeth wearing so just the front get filed either? if you joint the saw you do it from one end to the other, if a tooth or more is damaged or missing you just leave it missing, as time goes on and further sharpening the tooth grows back. if you just file the front teeth you will end up with a blade that has a hill in the middle. one never sharpens just the teeth that are dull, and besides the whole saw plate is generally in need of touching up. i

Originally Posted by IanW

Not very many appear in old catalogues, and a goodly number of saws wearing canted blades today almost certainly started out parallel. The earliest saw that seems to have been deliberately made canted is that famous 'Kenyon', from the mid 1800s I think, but not sure of the date, but it certainly was a long while ago.

americans traditionally by the time they were making great saws typically made steel backed and parallel saws. before that the english ruled the roost, and at a time when workshops joinery shops were purely producing work by hand. there are a sufficient examples if you look hard enough, not entirely easy to find any old english catalogue showing saws in general. occasionally find them if you subscribe to the english historical society or look in many old books. Thats not to say there are not plenty of parallel back saws examples either. also the early saw makers didn't put out catalogues very often, even the big names which one would think should be easy to find are difficult, like R.Sorby for example only put a catalogue out every ten or fifteen years, so finding examples takes some effort. its a long time ago eh

Originally Posted by IanW

Originally Posted by hiroller
....The key reason (other than just plain fashion) is the idea that you are less likely to cut below the line on the far side with a tapered saw….


IanW
Perhaps you are, but how canting brings it about, I cannot fathom. How the saw finishes a cut is determined by the angle between handle grip & tooth line, the height at which the work is held, and your 'natural' sawing stance. If you position the work at the right height, you shouldn't need much conscious input, the cut will end with the saw parallel with the bench top. The spine could cant up or down or anywhere in between, as far as I'm concerned, it won't affect the other, far more important geometries!

have to agree with hiroller ; doing little DT’s and time not being a factor, the short length, stroke of cut and depth of cut it is easy to cut and can almost (can be, not ness good practice to do so but can be done, even with confidence) be done without even looking at the other side at all.


however larger joints and larger saws it becomes more apparent, so its probably a case of diminishing need the smaller the saw or cut is. it is all very well to say just keep the tooth line parallel with the bench but the reality is not the same, (too much overthinking math and geometry here i think, if thats all it takes then a blind person could do it as well as anyone else). the finishing of cutting joints and not being even a mm or a part of a mm over on the other side is not acceptable. my old joinery teacher would go nuts.


no human can be expected to cut joints with precision and not look over the back, though i am sure there are some Utube experts that might show off to do it, but in the real world making money (or forget making money just call it being efficient) and not making errors one looks over the back. this is were a Cant’ed saw can be helpful, it saves time, you can cut quickly and confidently and only need to look over the back just to finish perfectly on the line. can you do it with a parallel saw, sure, with a slightly modified technique but a saw with Cant is just better, you can look at the top of the saw and keep it level with little effort, you can not watch the teeth to keep level with the bench anywhere near as easy as the timber is in the way, you are required to look over the back more often if doing it that way.


The other day Derek pointed to a page of his where he showed some (4) DT saws, talking about comparisons and such. but one thing i noticed that wasn't his main intention and i found interesting was he showed his interpretation of how different people begin a cut, he gave names to them, some people he knows i assume. thats not important but interesting that he had the three examples.


one example shown starts the cut with the saw handle up high and teeth on the front/further most corner of the timber, the second with the saw teeth near flat along the line and just touching the front corner (not using the front teeth by the way, you start a little way along the blade length), then the last example he showed was one that starts the cut from the back corner of timber with handle held down low. the first i never use (well never say never), the last i use on very large deep cuts, 4-6 inches in depth or more and rotate the work, so similar but not with handle down low. but many or most i use the second example, it gives the best assurance of adhering to the lines and producing a straight cut with minimal time. one needs a light touch to start the cut.


i have heard you mention a number of times that you often relax the rake to make a saw easier to start, not an uncommon method and not a criticism. However a saw with Cant basically does the same thing (so i kinda struggle to see why you don't get where people are coming from). because the saw is with Cant (and remember a larger saw usually has more Cant), you begin the cut with a slightly relaxed rake and smoother entry and you end the cut the same way, no tear out at the corner. whilst in the middle or majority of the cut you have a nice aggressive rake that you have already built a good steady sawing action with.


so do you use a coping saw or a chisel


cheers
chippy

Originally Posted by ch!ppy

....so do you use a coping saw or a chisel ...

Both. I usually use a small turning saw to cut out the bulk of the waste, followed by a chisel.....

Originally Posted by ch!ppy

.....i have heard you mention a number of times that you often relax the rake to make a saw easier to start, not an uncommon method and not a criticism. However a saw with Cant basically does the same thing (so i kinda struggle to see why you don't get where people are coming from).....

Now you have me utterly confused, Chippy. Are we talking about the same thing. i.e., "cant" being making a blade that is less tall at the toe than at the handle end? Ok, presuming we are talking about the same thing, these are the aspects I need explained, i.e., how it works, not simply a statement that it does. Think of me as a slow learner, not a recalcitrant...

First, how does sloping a spine alter the rake angle of teeth? Certainly, you can alter the effective rake angle by the way you present the teeth to the work - this is what we all do when starting a cut, is it not (I generally start on the far side, btw, but sometimes I start on the facing side, I'm certainly not hung up on that aspect!)? To my simple mind, how you present the teeth at any given height of the work piece has everything to do with the angle between grip and tooth line, your height, arm length & stance, & absolutely nothing to do with whether the back of the saw slopes down, or in any other direction!?

I also fail completely to understand how a sloped back helps you to finish a cut level? It seems more logical to me that if anything, it would be easier to estimate with a parallel blade. If the spine is parallel with the bench when the saw hits the bottom of the cut on the side facing you, then it should be in the right place on the far side. Figuring out where the teeth are from the back of a sloped spine would be more of a challenge for me.

By 'metal' I mean nails & grit. Nails aren't a big concern if you work with new wood (unless it comes from fence-line & backyard trees, damhik!), but grit is, and it gets onto stored wood or is part of its structure. I'm sure you are a good sawyer who uses as much of the blade as you can, but I'd be surprised if even your saws don't wear a bit more at the front. When jointing, I file til I've got a flat on all teeth, and my Scottish heritage means I try to minimise metal removal. Generally, you'll see little, even, flats towards the heel end after a couple of light strokes, but the front end usually needs a few more, so I concentrate the effort there for a few strokes, then finish with one or two full strokes along the whole toothline to keep it straight. Perhaps I should make sure I file the exact same amount from all teeth, but it's very hard to judge that, so over time, the front sneaks down. It takes a lot of jointings over a lot of time, but it clearly happens to many of us.

And Luke, take it easy - it's actually quite easy to use the same handle for either a canted or a parallel blade on a similar-sized saw. You'll see some carelessly-fitted handles that are 'off' but usually, they are made so that the flats where the spine cutout is made are parallel with the top of the spine. To maintain that relationship, you would have to rotate a handle meant for a parallel blade, thus altering the grip angle. I just did some calculations and the slope of the 'cant' is somewhere around 2 degrees. So the answer is simple, you either forget about the small difference & hope no-one notices, or maintain the desired hang angle, & re-shape the flats so that they remain parallel with the spine. The amount of wood that needs to be removed is very minor, and the slight difference it makes to where the holes will be in the plate is functionally insignificant. At least that's how I go about it ....

Cheers,

Originally Posted by IanW

And Luke, take it easy -

Sorry, I didn't mean to sound argumentative. In hindsight I guess maybe my post sounds like I'm trying to forcefully oversimplify the idea, but it's just because I don't really know much (anything) about the topic.

I'm paying attention though...

Originally Posted by Luke Maddux

Sorry, I didn't mean to sound argumentative. In hindsight I guess maybe my post sounds like I'm trying to forcefully oversimplify the idea, but it's just because I don't really know much (anything) about the topic.

I'm paying attention though...

? You know me well enough not to take me too seriously, Luke! It seemed to me that you were complicating it a bit, actually, so I was just trying to calm your enthusiasm a little.

I don't think it was necessary to make an endless range of handles. What I've 'discovered' is that it takes only minor modifications to a basic pattern to fit a range of applications. That could either be done by producing certain types in batches, or by leaving it to the the bloke fitting the handle on the blade to adjust the fit, depending on what sort of saw it's supposed to be. The former would likely be more efficient....

Cheers,

Originally Posted by IanW

Both. I usually use a small turning saw to cut out the bulk of the waste, followed by a chisel.....

Ok, i kinda took that for granted that if you use a coping or fret saw to remove the bulk then you finish off with a chisel.


there are two schools or methods of removing the DT waste. i like you use the same method but the other school removes waste using only a chisel, more a german thing i think (I can not remember the origin) or just another way. but people that use that method can get pretty adamant that that is the best way, just as quick and so on. its not worth the debate. if someone uses that method and it suits them then by all means don't get into the argument. its amounts to a waste of energy and besides it is a reasonable way of doing it.

Originally Posted by IanW

Now you have me utterly confused, Chippy. Are we talking about the same thing. i.e., "cant" being making a blade that is narrower than the toe than at the handle end? Ok, presuming we are talking about the same thing, these are the things I need explained, i.e., how it works, not simply a statement that it does. Think of me as a slow learner, not a recalcitrant...

yep, talking same thing.


thought i explained, not just a statement. but i’ll have another try

Originally Posted by IanW

First, how does sloping a spine alter the rake angle of teeth?

Static, the two saws, one with Cant one without, sitting on the bench it doesn't alter. its just a bit of steel and wood sitting there. but for an example to try and explain , imagine you have two saws one with Cant and one without. now file your desired rake along both saws saw. at this point its still just a lump of steel and wood, identical teeth but one has a Cant or a sloped back. please note that i pointed out that the smaller and shorter the saw has a diminishing effect. i.e. an 8” DT will not be as effective as a 12”, 14”, 16” or if you have that size 18” back saw. still has an effect (very small) on a small DT saw, but not as much and not as ness. as i said before. on a small 8” your probably going to do just as well with either on small stock. not entirely because of geometry but because of method.


this is where i think , not being disrespectful , but lack for better vocabulary, are coming unstuck. too much geometry, math and theory and forgetting the human element, your not a statue per sa with a few moving hinges in your elbow and shoulder thats keeps to the perfect same position thought the cut. a picture, say on that technical link talking about perfect degrees and stance etc is just a still frame picture, not a person moving, through the stages of cutting a joint. also keep in mind that this method involves the notion that you keep the top or back of the saw level throughout the majority of the cut, which is the widely accepted method. you set your height of work and such to accommodate this as a matter of natural course.


so imagine you have two saws and people making the same tenon. one with a sloped back and one without. say you both start the cut identical, same result. then you move to the main stage of the cut and level out the saw back (not the teeth as you said in previous post, because you can not actually see them well enough anyway, you can as a spectator looking from the side or looking at a picture but not as the sawer). once you level out the back of the saw the rake becomes more aggressive and obviously cuts quicker with less labor, which is desirable. changing the height or angle of attack or stance isn't the point. keeping the saw back level is.


i think you can see in your minds eye or draw an exaggerated picture of the teeth on paper of two saws, one with Cant and one without, both with the same rake, now tip the sloped back saw until the back is level. you can now see you have made the tooth point more forward, which gives you the more aggressive cut.

Originally Posted by IanW

I also fail completely to understand how a sloped back helps you to finish a cut level?

because you are human, not a machine or move like a foley saw sharpener. you are not perfect, no one is

Originally Posted by IanW

It seems more logical to me that if anything, it would be easier to estimate with a _parallel _blade. If the spine is parallel with the bench when the saw hits the bottom of the cut on the side facing you, then it should be in the right place on the far side. Figuring out where the teeth are from the back of a sloped spine would be more of a challenge for me.

The theory is there, but in practice it doesn't work that way, one can not ‘estimate’, its not accurate, you need to bend the back and look. now with a small saw, say for example a short 8” DT saw, your stroke is very short, it is very easy with a shallow cut to cut level and not even look at the rear of the cut. although i bet most do, human nature and the temptation is there to check. but for the sake of the argument lets say you don’t. no problem.


however with a longer saw, deeper cut your stroke is longer and opens up to not being perfectly flat//level, at least you can not presume that you are so perfect that you only need to look at the front when you have reached the exact depth, you can easily be out a mm or so on the other side in regards to depth.


in theory as you say if you kept the back level on a parallel saw it would be identical on the other side. you rely on your perfection of sawing (and the longer the saw and deeper the cut introduces more movement away from perfection. its not as though your a machine) but take the real risk of cutting past the mark which simply isn't acceptable. using a saw with Cant gives you that safety margin and you can cut down to the line, peek over the back just at the end and finish the tiny bit.
Using a parallel saw you need to alter your angle near the end, or take the risk, or ,which is the more common way, you tend to have to peek over the back more often near the end. so just nicer with a Cant’ed saw because it saves that extra moving about. once you dip the front of the Cant saw near the end (as your peeking over) to finish the cut the rake relaxes at the same time as matter of course. only a small amount ,granted, but it does so just the same, as a side benefit .

Originally Posted by IanW

By 'metal' I mean nails & grit. Nails aren't a big concern if you work with new wood (unless it comes from fence-line & backyard trees, damhik!), but grit is, and it gets onto stored wood or is part of its structure.

hmm, dont think i can agree with you on that one. one doesn't use a backsaw to rough cut stock and by the time you are using a back saw (used for its thiner blade and accuracy for joints) the timber has been milled, cut to length and planed. i cant say i notice grit in the pores of the timber

Originally Posted by IanW

I'm sure you are a good sawyer who uses as much of the blade as you can, but I'd be surprised if even your saws don't wear a bit more at the front. When jointing, I file til I've got a flat on all teeth, and my Scottish heritage means I try to minimise metal removal. Generally, you'll see little, even, flats towards the heel end after a couple of light strokes, but the front end usually needs a few more, so I concentrate the effort there for a few strokes, then finish with one or two full strokes along the whole toothline to keep it straight. Perhaps I should make sure I file the exact same amount from all teeth, but it's very hard to judge that, so over time, the front sneaks down. It takes a lot of jointings over a lot of time, but it clearly happens to many of us

i think i can partly agree with you here. but in general its the edge , keeness, that goes off the teeth, if they have worn down much at the front its probably been too long between sharpening and have been using a somewhat dull blade for while. but i take your point.


cheer
chippy