New Life for an Old Saw – Advanced Filing and Restoration

[Bob Smalser]

A 6-dollar flea market beater? Yes, but this one is a Disston Acme 120, originally a cabinetmaker’s finish saw tapered and hardened to run without set, and one of Disston’s finest. You can’t buy a new Western hand saw of this quality today at any price. So let’s see if it can be given another lifetime of use in a slightly different form.

Old saws filed so many times their tips resemble pencil-points usually aren’t worth the trouble, as when they get that thin and narrow they are too easily kinked, and this one’s no exception. Restoring this in its original 26-inch length isn’t a good option for it to survive another generation of use. So I’ll shorten it to panel saw length to make it useful again, but that’s not as straightforward as it seems either if the saw is to please the eye and hand. Panel saws had smaller handles than their full-sized counterparts, and their blades were contoured to match their smaller proportions; they weren’t just stubby versions of full-sized saws.



I don’t have a small #120 handle, but I do have an extra Keenkutter panel saw handle and another complete matching saw to use as a pattern. These Keenkutter #88 skewback saws were made by Disston between 1890 and 1926 using #16 handles and probably P26 blades from the Harvey Peace factory they bought out, for which Disston offered custom etching in hardware store logos like EC Simmons’. Mr. Simmons knew his saws. These are not only excellent, taper ground saws, their profile pleases my eye. I scribe the new profile onto the #120 blade, and use the bevel gage to duplicate the tip angle. I’ll make the #120 a 22-inch saw based on the amount of blade remaining.



Saw steel grinds quickly and relatively cool using a coarse, 8” wheel, with the occasional water dip as the wheel gets close enough to burn what will be the final profile. Here I don’t just grind up to the scribed line, I take the line. You can also use various shears and metal cutting saws, but grinding doesn’t distort or bend the blade.



I fair the curves by drawfiling using 2d-cut and smoother 1st-cut single-cut files. This is done largely by feel. When I feel a bump I alter the file angle for a more aggressive cut, and finish using my finest single-cut file straight across. The files are chalked and frequently brushed both to keep them from clogging and to prevent stray filings from causing scratches during finishing. I rarely use chalk when jointing and sharpening however, as it often masks what I’m trying to see.



After fairing I ease the sharp edges slightly using the fine file in the drawfile mode.



I fit the new handle and drill the bolt holes using a cobalt bit. The easiest method is to mount the handle and carefully drill through it, indexing each fresh hole with a bolt to insure alignment is maintained. Clamp the saw down during drill extraction to prevent it riding up on the drill.



On the anvil using light and heavy hammers, I remove the saw’s tension, hammer out the kink and retension the entire blade as I’ve detailed in previous articles on permanently removing bends and lumps in saw blades. Saws straightened in a vise, by bending over the knee or even by hammering flat won’t remain straight for long without stretching the edge and back to restore the tension put into the blade when it was manufactured. This is especially critical in narrow saws filed past the areas originally tensioned.



This blade isn’t heavily rusted and isn’t pitted, so I forego phosphoric acid to seal the pits and merely clean the steel using 4 grades of Scotchbrite in sequence lubed with mineral spirits.

Continued….

[Bob Smalser]

Sanding is followed by a green rouge buff against the direction of sanding to restore some shine. If you don’t wear gloves when buffing, you won’t overheat the steel. The hot spots caused by the friction will distort the blade badly, but if the blade is tensioned properly it will return to straight when it cools.



Because I’ve shortened the saw the etch will be off center and unsightly to my eye, so I’ll blue the blade to hide it. But this is a good opportunity to demonstrate how to raise an etch like the faint one you see here.



To raise an etch, first avoid sanding it without using a sanding block when you clean the saw. Then degrease after buffing using mineral spirits followed by stronger trichloroethylene, and apply cold gun blue from a sporting goods store to the area of the etch. Follow the instructions on the bottle for curing and oiling.



After the blue cures, simple rubbing with a sanding block and 600-grit wet-or-dry paper lubed with WD-40 or honing oil will reveal any etch remaining. All these bluing solutions will rust if not oiled, some badly, so don’t omit it.



I then phosphate blue the entire blade, using the procedures I detail in a previous article on rust proofing tools. This type of blue applies a layer of rust-inhibiting phosphate to the steel, which also slightly fills the scratches and grinding marks present, making the blade a bit slipperier. You can read more about this at Brownells.com.



I secure the saw in the vise and lightly joint it to see what I have. While the joint and teeth look well-maintained to the naked eye, this saw has faults typical of hasty commercial filing, and filing for sharp points at the expense of the joint. One row of teeth is shorter than the other along most of its length where one side was filed past the flats on the teeth made by the joint, and the saw was filed by machine using a file larger than optimum for these 11 tpi crosscut teeth. The gullets are perfectly uniform, but are too large, making the teeth extremely short. Tooth height and the resulting gullet depth are important because the gullets hold and carry the sawdust out of the kerf. The weight of the blade can no longer push the teeth into the wood if the gullets pack tight with sawdust half way through the stroke.



Jointing insures all the teeth perform the same amount of work during cutting and involves more than just regulating tooth height. When the tooth line is wavy as shown above, the saw stalls as teeth on the forward slope of a bump bite wood, and those teeth wear more quickly.



This tooth line isn’t perfect either close to the tip, but it’s more than adequate for efficient sawing. Keep in mind as we go that my goal isn’t perfect saws, it’s perfect sawing, and there are differences between them.

Continued…

[Bob Smalser]

Jointing is also where you add or subtract “breast”, the amount of crown in the tooth line. Crown breasted saws are more difficult to joint, but rake sawdust more efficiently and crowns are always most pronounced on saws for green wood with gummy sawdust like the old one and two-man felling and bucking saws once used to harvest trees. Here I show a saw with a light breast on the left, a full breast in the center, and a straight or unbreasted saw on the right.



Before we look at filing, let’s look at files. Saw files are tapered triangular files with 60-degree corners, come in several confusing sizes, and always have “1st-cut, single cut” teeth as these cut slowly but produce a finer finish than coarser “2nd-cut” and multi-tooth files. Vintage Saws and file manufacturer websites like Simonds International have helpful guides for what size file is best for each pitch of saw, usually expressed in tpi or teeth per inch. But what if you don’t have the recommended file? Can you substitute?



Yes, you can substitute. There are two factors guiding recommended file size. The first is you want the narrowest file possible so you can see the saw teeth better, yet you don’t want the file to use more than half its width when filing a tooth. That way you have three completely-sharp cutting surfaces on each file to use as each wears out.



The second factor is gullet width. The wider the file, the wider the flat at each corner, the wider the gullet it will produce…and the wider the gullet, the shorter the tooth. Of course there are limits. A knife edge file would minimize the gullet, producing a taller tooth, but the blade would also be prone to cracking at the gullet, and there are a couple hundred years of trial and error behind those file size recommendations that shouldn’t be ignored.

But you can certainly substitute files. New files of acceptable quality are expensive, and excellent values can often be had buying boxes of NOS taper files in off sizes and 2nd-cut files. You can use the coarser 2nd-cuts to shape the teeth and finish with your 1st-cut files. 3-inch Regular Taper, 1st-cut files aren’t considered saw files, but can be currently had for pennies each, and substitute nicely for 3 and 4-dollar 5-inch Slim Tapers and 6-inch Double Slim Taper files. Just be aware that switching file sizes on the same saw can change the shape of the teeth due to even minor differences in gullet width, and the same can be true when switching manufacturers of the same size file.

Saws are filed in the stages detailed in several on-line articles on basic saw filing, like Pete Taran’s at the Vintage Saws website:

1) Jointing to even tooth height and straighten or fair the tooth line or breast.
2) Shaping the teeth to even the size of the flats made by the joint and set the rake angle.
3) Filing the “fleam” or cutting edge bevel angle until the flats disappear, creating sharp teeth of uniform height.



The major benefit of sharpening your own saws is you can tune them for how you use them. I usually work outdoors in damp, air dried wood and use hand saws where the mass of the work piece and the required angles and finish often preclude the use of power tools. Often 30 linear feet at a time too, driving study and experimentation in what makes the most efficient saw for my tasks. Accordingly, my saws are generally filed with the full crowned breasts and sloped gullets my boatbuilding family has used for generations.



What are sloped gullets? Here are two identical 4 ½ tpi rip saws. Identical except the saw in the foreground clearly has taller teeth, and also a slight back bevel on the rear edge of each tooth. The gullets appear to be alternating between two different heights too, yet the cutting edges above even the high gullets are over a third longer than the saw with level gullets behind it. Seen at a different angle those teeth look almost Japanese, and that’s probably not a coincidence. It was filed holding the file at a 45-degree angle to the blade, instead of straight across or 90 degrees to the blade like the saw in the background was filed. The geometry of a tri-cornered, 60-degree file is such that the greater the angle it is held at, the taller the tooth it produces. Brent Beach has a web page that examines sloped gullets in more detail, including their history and accurate engineering drawings that better demonstrate their geometry. If you ever wondered why many antique saw vises articulate to 45 degrees away from the filer, you’ve now found the reason.

I find the taller teeth work more efficiently in the wood I use. They bite a bit deeper because they rake damp sawdust a bit better, and the back bevel that sloped gullets produce on rip teeth score the wood on the back stroke for easier removal on the front stroke. You’ll have to try them and see if there’s any benefit with the woods you use. Whatever your preference, how to file sloped gullets isn’t described anywhere else and they are another tool to place in your kit if you ever feel you need them.



When changing a saw to sloped gullets, I combine the steps of shaping the teeth and filing the fleam angle into one step, and concentrate on “filing to the joint” instead of equalizing the size of the flats made by the joint during tooth shaping followed by counting file strokes to produce teeth if equal height during filing. Accordingly, I don’t use carbon black or other aids to insure I don’t skip a tooth, as skipping a tooth doesn’t matter when concentrating on the joint. I also tend to file one side less than I would when filing conventional teeth, switching sides more often, and sometimes even rejointing if I make a mistake and file a tooth past its jointing flat. Notice I have my usual fleam angle scribed into the jaws of my saw vise. I prefer a shop-made wooden vise with long jaws because I like to file while standing and I can file an entire side without having to move the saw in the vise.



On the first passes I’m hogging off a relatively large amount of steel, and am concentrating more on getting out my gullets, establishing a uniform rake angle and not filing past the jointing flats than I am about the fleam angle. I’ll emphasize the fleam later on my final passes when filing is easier, and I may even change the rake angle later after testing the saw on wood.

Continued…

[Bob Smalser]

Keeping your angles constant when changing sides takes practice, and it’s also useful to move your work lights so you can clearly see the jointing flats.



Don’t continue filing if you can no longer clearly see those jointing flats. Take a break, move your lights or add magnification. Also don’t hesitate to rejoint if you make a mistake and file past one. Moreover on saws like this one with uniformly short teeth and one entire row of even shorter teeth, or on saws where you are adding crown to the breast, you often have to compromise your initial jointing or not leave enough gullet on the short teeth to rest the file in, which is necessary for basic tooth spacing. You can see here that even after a full pass on each side, one row of teeth remains significantly taller than the other, so rather than attempt too many tasks at once with the file, I rejoint and begin again.



I generally set the teeth before my final pass on each side of the saw so any damage caused to the cutting edges by the saw set is removed. Here you can see several small jointing flats remaining on the top of the teeth. When setting, I’m careful to place the plunger of the sawset at the same spot on each tooth, and when possible slightly back from the cutting edge bevel to minimize damage. And yes, although these Acme saws were designed to run without set, if a tad of set makes your saw more efficient on the wood you cut, then you can add a minimal amount without damage by using the lowest settings on your sawset.



Rip saws filed with sloped gullets are set differently than rip saws with normal teeth where teeth can be set in either direction. Sloping the gullet puts a small bevel on the back of each tooth, creating a point, and the point must be bent outward to create the desired flat chisel point of a ripping tooth.



On my final pass to eliminate the remaining vestiges of jointing flats, I do so by leaning the file into the backs of the teeth rather than continue to file rakes and fleams. Uniform rake and fleam angles and their cutting edges are important, but the backs of the teeth aren’t when your only objective is sharpening the points on the teeth. Finally, given a choice between leaving some small jointing flats and over striving to make sharp points, leave the flats. It’s the fleam edge that does most of the cutting, not the points, but the edges of short teeth don’t get to cut much at all.



I make some test cuts in relatively hard, air dried Douglas Fir at 12% moisture content to insure the saw cuts smoothly and accurately to a line before stoning off any wire and flash caused by filing. When filing sloped gullets for the first time, you may tend to file in more rake than the blade will take, so be prepared to put the saw back in the vise and make another pass on each side to reduce it.



The finished hybrid panel saw. Cost? Six dollars, one file, and a couple of evening hours.



My short saws don’t get used much, but can be handy. They also can be practically free, and it’s kinda fun when among the #120’s, #12, #16 and #88 shown it’s hard to tell which if any began life as a short panel saw.

[Peter Malcolm Jardine]

As usual, brilliant. Thanks Bob.

[Bruce Taylor]

Fascinating, and useful.

[Ross M]

That's a keeper.

A Page\Save As\ (I am no longer at the mercy of the forum gremlins) keeper.

Thanks!

Ross

[Dave Fleming]

Yet another well written, informative essay on tools and the re-hab thereof.

I for one, appreciate and look forward to your posts.

[Bark]

Does anybody else here wish Bob Smalser was your next-door neighbor?

[Eric D]

Dave, I could not have said it better, so I won't try, thank you Bob!!!!

When is the next one?

[J. Dillon]

Very thorough Bob. You make me want to break out some old saws and take a 2nd look at them. Thanks.... I think

JD

[Kim Whitmyre]

Quality is the substance of life; few attain it this day and age.

[Woxbox]

Superb. Now I'm feeling guilty about the condition of a saw or two of mine.

[Vince Brennan]

Speaking of lists, Bob is now on the 'official' list of "People I Want To Be When I Grow Up."

Amazing how many of 'em are on the Forum.....

[Bob Smalser]

....on tools and the re-hab thereof.

Shucks, I thought you'd get a kick out of the pink chalk.

Sidewalk and graffiti chalk from a toy store. Schools don't use blackboards any more, and finding plain old white in large sticks is almost impossible.

Just like you can't buy a western hand saw today for any amount of money that comes remotely close to the quality of the best of these antiques, you know the world has changed when I have to stand in line with kiddies at Toys 'R Us to buy chalk for my files, pipe cleaners for my Petersons, and modeling clay for glassing gunstocks.

[PeterSibley]

Thanks Bob ,another good one ....much appreciated !

You say you can't get a good Western handsaw anymore but I have to admit to liking Sandviks (even with their horrible red plastic handles ) Have you any experience of them , how would you compare them ?

[George Ray]

Making the world a better place by keeping traditional hand crafts alive and by sharing.
Thanks!

[erster]

you know the world has changed when I have to stand in line with kiddies at Toys 'R Us to buy chalk for my files, pipe cleaners for my Petersons, and modeling clay for glassing gunstocks.

Lets face it. We are all kids, playing with age appropiate toys. I think it also could be said that we are actually reverting back to our childhoods when toys were made of real wood and kids actually used their minds to create human powered gocarts and bathtub and pond boats too with scrap lumbers.

[Bob Smalser]

When Disston quality began to go down the tubes in the 1960's, the shop I was familiar with who used hand saws a dozen at a time changed to Sandvik, who are still in business today making good hand saws. I believe they even bought Disston and own the name today.

But while Sandvik made a competent saw longer than Disston did after WWII, the all the saws you see in my pictures were made before 1928, and some as early as 1890. For a host of reasons, more hand saws were made between 1890 and the mid-1930's than in any other period, making them available and cheap today. And 1928 is the year Disston began taking shortcuts in manufacturing with all their competitors following suit.

There is no comparison in polish, hand tensioning, and sometimes even temper between a Disston made in 1927 and a Disston made in 1957, and the same is true for Sandvik.





Today for an Acme in original condition you pay a hundred to 150 bucks, and the best handsaw made today is the Roberts and Lee, also around 150 bucks. I'm not out to poormouth R&L; I'm delighted someone still makes hand saws that can be resharpened....buying 20 and 30-dollar replacement blades every time you dull a saw must get old.

But hold this 1890 vintage Acme in one hand and a new R&L comparable in thickness and taper in the other and there's no comparison in the polish that makes steel slick. And nobody at all today makes a thin, cabinetmaker's saw like the the 1896-1917 vintage #12 I show below the Acme. These had blades several thousandths thinner yet as well tapered as the Acme, rivaling the best hand-made Japanese saws in taper and thinness. Use a well-tuned old #12 against a new R&L or PAX for a day and you'll find there is no comparison.

But like the Acme's, nice old #12's can also be expensive today. The trick is to study the saws and look for sleepers. For example, Disston's #16 cabinetmaker's saw was a cheaper saw in its day than the #12 because Disston said is was made of a lesser steel. Today the steel's have been analyzed and we know the steel for all Disston's saws came out of the same pot, the only differences being what gage and how much tensioning was applied. Gage and tensioning are related, tensioning being the only way to make a super-thin saw that won't easily kink. I can't find one tiny bit of difference today between my #12's and #16's...they are identical in thickness, taper, tension and polish, so I look for #16's to buy. Further, I look for hardware-store logo #16's to buy, as this was the best saw Disston offered with the option of a custom etch. Today a nice #12 runs 80 bucks and up....a nice #16 35 bucks and up....but few know what a Keenkutter #816 really is, and nice ones can be had for lunch money.

Filing sloped gullets died out in the 1890's with the advent of Foley filing machines when even Disston began filing their best saws my machine. Today so few people know how to do it, and modern sawmakers are so eager to beat it down (because machines and minimum wage workers still can't do it) you can consider the skill lost. Moreover, I'll never be a filer of the skill Disston used to employ. Add the right teeth to these old, hand-tensioned saws and they'll compete with anything ever made, at any price.

[Lew Barrett]

Uncle Bob does the best tutorials in the business.

[erster]

Uncle Bob does the best tutorials in the business.

And it takes a bit if time added to the process and about five shots to get one shot thats just right, or has been my experience. Great work indeed. There are certainly times that I will bring out the select one but few jobs for me warrant them now. They are nice to keep around though.

On a side note, a finely honed handsaw used to play the sweetest tunes, sorta like orchestra music to my ears.

[adampet]

Thanks Bob,
Another article for the ages. I sure hope someone is making a book out of these.

Adam

[Jay Greer]

Bob,
I'd like to add my own appreciation for your taking the time to preserve knowledge that is in danger of being lost!
Fair Winds,
Jay

[Andrew]

Bob, can you explain blade tension? Googling the term winds up pointing to bandsaw blades.

Thanks.

[Bob Smalser]

Bob, can you explain blade tension? Googling the term winds up pointing to bandsaw blades.

Exactly. Because all of what was ever published on tensioning blades has always been written by sawmakers oriented toward their sawmill customers using large, expensive blades. Hand saw makers OTOH, expected you to buy one of their new, $2.00 saws instead of repairing the one you just kinked. Truing saw blades to get more use out of them isn't easily mastered. The mills and saw mechanics themselves treated this information as trade secrets and although it's still done today (often by a computer-controlled machine), much has been lost.

Large circular blades warp when the log moves in the dogs and torques the blade, after which the blade wants to climb out of the kerf, making it dangerous in addition losing its accuracy. In order to run true on an arbor, the steel of a circle needs to be "faster" (tighter) on the edge than in the center. In addition to warping like a circular saw blade, large band mill blades are made with a cup to fit the wheels, and that cup is put into the flat blades by making both edges of the blade "faster" than the "loose" center area.



The better hand saws were tensioned the same way their larger cousins were tensioned. At first by hand and later using trip hammers shown in the Disston factory pic above. You can feel the difference in two saws by picking both up and shaking them to feel how stiff or floppy their blades are. Stiffer is better. Then mike the blades to measure taper and thinness. Thinner and stiffer is better still because the thinner the kerf, the less sawing effort. A high taper combined with thin and stiff is best of all, because the more taper in the blade from top to bottom and front to back, the less set the teeth require, resulting in smoother cuts as well as narrower kerfs. Compare your flop test and micrometer measurements with old catalogs listing prices, and you'll find a clear correlation. Thinner and more tapered blades required more "smithing", and if you remove a handle on and old hand saw and see a stamped "X" on the blade hidden beneath it, that was Disston's mark for "extra" smithing work.

Today a new R&L tapers from around .034 to .028 at the back and .040 to .037 at the cutting edge before any set. This is about the same as a Disston D-8, an inexpensive but high-quality saw designed primarily for framing carpenters and general use. The very-common D-23 is a saw of similar quality. A Disston cabinetmaker's saw like the #12 or #16 OTOH, can run as thin as .028-.017 at the back and .033-.027 at the edge, are a different saw entirely in use, and don't have modern counterparts today outside of Japan. My family referred to them as "gents saws" compared to our D-7's in a derogatory manner only because we couldn't afford them.

There are two basic methods to make a blade as thin as .017 not be so fragile as to easily kink. Today's method is to temper the blade so hard and stiff it can't be filed and has to be replaced. The more difficult method is to temper the steel to it can be filed and tension the edge using a hammer and anvil. You can't buy a resharpenable sawblade today as thin as the best old cabinetmaker saws except one hand-made in Japan at an appropriate price.

Post #24 of the FAQ has two posts I did on tensioning sawblades. Basically, when you hit thin steel with a round-faced hammer, you make a dimple that pulls the surrounding steel toward the center of that dimple, stretching it and making it stiffer. Hundreds of such hammer blows can make the cutting edge and back fast (stiff) or loose, and can remove bends and other damage. The only hard parts in reaching those objectives are how hard to hit and where to hit.

http://www.disstonianinstitute.com/factorytour.html