Thread: Disston 14" Backsaw Questions

Originally Posted by schuld66

I picked up a Disston 14" backsaw today -- 'H Disston & Sons Philada' medallion, etch is very faint, but visible -- the coat of paste wax I applied seems to make it more difficult to read. The stamp on the spine is very clear and easy to read.

My first question is this -- is it normal for the distance from the bottom of the spine to the teeth at the toe (3") to be different than the distance at the heel (3 1/4")? I hope I wasn't too confusing, but the blade seems to be inserted in the spine crooked. If this isn't normal, can this be fixed? With the handle off, I can see that if I tried to move the blade further into the spine at the heel, the spine would cover the top sawnut hole.

My second question is this -- in the second to last photo, you can see the teeth at the heel. Are there some broken teeth there, or are they just shaped differently than on the rest of the saw teeth?

Dave the saw plate for this saw (compared to early English saws that do "cant" from heel to toe) should be the same depth at toe and heel. The back at the toe has been knocked down. There are lots of Internet tutorials on fixing this - HOWEVER - if the toothline is straight, don't worry about it.

Second question - the saw has been sharpened without jointing. As the teeth right at the heel typically do not go into the wood, they do not wear down, so do not get filed. The distance between the last tooth and the general toothline is probably an indication of how much the saw has been used (and filed). Make sure you joint the toothline nice and straight before you sharpen it.

Cheers
Peter

What Peter said.
Those last few teeth are decidedly wonky! I see this quite a lot, and my theory is that it's because the last bit of plate at the heel can rarely be clamped properly in most saw vises, due to the handle cheeks getting in the way. As a consequence, that last inch or so is floating free, which makes it very hard to file properly. The best way to do a decent job (I think) is to take the handle off, so that you can clamp the whole blade securely. If I'm in a hurry, & just touching-up a saw, I sometimes put a small clamp on the free bit of blade, which steadies it enough to do a half-decent job on the heel teeth. But I think a lot of folk decided that since that part of the saw never comes in contact with wood, they just ignored the last 6 or so teeth, or sort of scratched at them as best they could (which is not very well!) and didn't care what they ended up looking like.....

Cheers,

Originally Posted by IanW

What Peter said.
Those last few teeth are decidedly wonky! I see this quite a lot, and my theory is that it's because the last bit of plate at the heel can rarely be clamped properly in most saw vises, due to the handle cheeks getting in the way. As a consequence, that last inch or so is floating free, which makes it very hard to file properly. The best way to do a decent job (I think) is to take the handle off, so that you can clamp the whole blade securely. If I'm in a hurry, & just touching-up a saw, I sometimes put a small clamp on the free bit of blade, which steadies it enough to do a half-decent job on the heel teeth. But I think a lot of folk decided that since that part of the saw never comes in contact with wood, they just ignored the last 6 or so teeth, or sort of scratched at them as best they could (which is not very well!) and didn't care what they ended up looking like.....

Cheers,

There is validity to the approach that says if it ain't dull don't sharpen it. For touchup sharpenings I might give teeth like that a light stroke, or not. The eventual consequence of course being what you see here, a concave toothline. The thing that the previous user neglected of course was as stated, jointing. But if you joint every touchup sharpening you will soon end up with a narrow sawplate. So how often do you joint the teeth? Every third or fifth filing? When you notice an uneven toothline? Maybe only when it's necessary to set the teeth? I don't have a formula for that.

Originally Posted by bridger

...... So how often do you joint the teeth? Every third or fifth filing? When you notice an uneven toothline? Maybe only when it's necessary to set the teeth? I don't have a formula for that.

I don't have a formula, Bridger, but there are several situations where I find it necessary to file the tooth line.

The first is on a piece of brand-new saw plate. For whatever reason, there are often segments of a new edge that are extra hard and these will make your file skate when marking out for the teeth. You can feel these hard spots on the first stroke or two with the jointing file, but after 3 or 4 strokes, they have gone, & there is nice, even resistance to the file all the way along your new edge.

Once a saw is toothed, set, & sharp, I usually get 2 or 3 'light' sharpenings (i.e., a single light stroke of the file per tooth) before the saw has lost too much set and needs a 'serious' sharpening, which includes re-setting. As long as the teeth look even, a reset followed by a slightly heavier sharpening is usually sufficient. That's say, two firm strokes plus a light 'finish' stroke.

If I have to sharpen a saw on which the teeth have become very uneven (my dad called them "cows 'n' calves"), a light jointing to produce at least a small flat on the top of every tooth helps to decide which side of the file to lean on to bring the cows back to heifers, & keep the tops level. Some people advocate a light jointing every time you do a serious sharpen, to ensure you keep teeth level. This only removes a fraction of a mm of metal, and I think you would have to do an awful lot of that sort of jointing to reduce your saw's width noticeably.

Then there are the real basket-cases where you have to file until there are just a few stumps of teeth (or perhaps none at all if you are changing the tpi of the saw), and that's going to cost an appreciable amount of metal.

I have a hand saw of my father's that was used daily for about 7 or 8 years, then very sporadically after that because he went farming. So it would have had many sharpenings for its first few years but only rarely for the next 50, until it came to live with me, about 6 years ago. I estimate it's lost less than 1/2" in width since new, so it will see me out, and several more weekend wood-warriors (worriers??) before it reaches the 'use by' date.

Cheers,

Originally Posted by IanW

I have a hand saw of my father's that was used daily for about 7 or 8 years, then very sporadically after that because he went farming. So it would have had many sharpenings for its first few years but only rarely for the next 50, until it came to live with me, about 6 years ago. I estimate it's lost less than 1/2" in width since new, so it will see me out, and several more weekend wood-warriors (worriers??) before it reaches the 'use by' date.

Ian, I agree it depends on circumstances, I have used more than 4 jointings on old saws in very ordinary condition, especially if restoring some breasting (so many old saws are concave), and as you say it takes a long time to wear a saw down if looked after. I have a very old Groves 28" rip with massive concavity - but good tooth shape, and sharp. I guess the previous owner had learnt to saw with it like that.

I may have this wrong... when you file a saw you are taking metal off, and without jointing, the saw gets progressively narrower. Therefore a light jointing before a touch-up (which is my practice) is going to take off infinitesimally more metal than not jointing; after all I am just evening out the wear. And the benefit is that I have the small flats guidance for my kack handed filing. I note that MarvW(erner) on WoodNet follows this jointing practice, and it only takes a few seconds.
Cheers
Peter

Originally Posted by Heavansabove

......I may have this wrong... when you file a saw you are taking metal off, and without jointing, the saw gets progressively narrower. Therefore a light jointing before a touch-up (which is my practice) is going to take off infinitesimally more metal than not jointing; after all I am just evening out the wear. And the benefit is that I have the small flats guidance for my kack handed filing. I note that MarvW(erner) on WoodNet follows this jointing practice, and it only takes a few seconds....

Peter, I agree, light jointing isn't going to sacrifice much metal, and if that's the best way for you, then that's the best way to do it.. I excuse myself from the extra step in 'touch-up' sharpenings by the following reasoning: With a light stroke of the file, I am probably altering the height of the teeth by a good deal less than a light jointing would, so as long as the teeth were level to begin with, & my file strokes are even, the amount of potential variation should be something less than infinitesmal. However, if you wait til the saw is quite dull before you resharpen, there will be appreciably more wear on the teeth in the centre, and you will need an extra stroke or two to bring those teeth back to sharp. The front & heel teeth will come sharp with very little metal removal, so just a very light stroke will restore these. In a few dozen sharpenings done that way, you could get quite a dip in the middle of the saw, which I imagine is how your saw came to be the way you described.

In a perfect world, you should be able to keep the points of the teeth perfectly level by filing each one the same amount, which means filing the front & rear teeth more than needed to simply bring them back to sharp. However, I'm certainly not able to keep a tooth-line perfect over multiple sharpenings, so light jointing on some sort of regular basis is an essential step for me, both to keep the the points in line, & to keep the teeth even!

Cheers,

For a light sharpening of the saw teeth I would still include a light jointing across the top of the tooth line. You may not hit every tooth in doing so but they will generally represent at least 90 % of the overall number. Would I then sharpen the low teeth not picked up during the light jointing. No. Leave them until they are picked up next time I joint and sharpen the saw. That way the teeth that were sharpened will reduce slightly in height to be much closer to the 10 % of low teeth that were not filed. The hand saw should still perform reasonably well.

Stewie;