The Backsaw Project

Prototyping

I've always wanted an open-handled back saw, but have been too cheap to buy one for what they are worth, and didn't want one that was all beat to death, either.  I made up my mind to give making one a try - but didn't want to commit myself until I knew for sure that I could do it.  I started researching it on the web, but found woefully little in the way of helpful information.  I did find some early email conversations between modern saw makers on the oldtools discussion forum archive from early in their saw-making efforts -  but all of them inserted their blades into a solid chunk of brass that they had milled a slot into using a milling machine (something I will never likely have).  

I wanted to make a saw like the old-timers did (before such milling machines).  Old saw makers formed their back saws by bending brass or steel over a blade rather than by milling a slot and inserting the blade into that.  I did find a few who had made their own backsaws by bending brass, including one who used all found materials - i.e. used a grain shovel for the blade steel (simply too cool) and it inspired me to give it a shot. 

A prototype was in order - so I made myself a makeshift small metal bending brake out of some angle iron, found myself a suitable piece of brass (a door kick plate), and successfully bent it over a piece of saw steel that I'd cut from a larger saw:

 

The brass was much too thin to really be of any use, but as a proof of concept, it worked beautifully and convinced me to go ahead and try to make some.  As it turns out, after catching a lucky break on a piece of brass on eBay, I had enough to do a governor's dozen (that's 11 - one short of a real dozen), so went ahead and made them.  This series of articles will document what I did in the process of making those saws.

First up - what to use for materials.

Saw Steel

All of the steel I used in these saws came from old saws that I purchased off of eBay.  Don't worry, no valuable saws were in the lot, they were mostly 1960's and newer vintage, and from a variety of brands including Disston, Stanley, Bishop, Craftsman, and no-name Warranted Superior saws.  All had good steel in them, from what I can tell... Here's the first lot of saws that I bought that I used:

And the second lot:

The second lot had a few winners in it that I hung on to rather than cut up, including a WWII era D-8 and D-7 that are in excellent shape, and the top lot included a 100 year old D-7 that I also kept.  The rest were cut up for use in these back saws, at a final cost of about $1.00 a blade.  I still have steel left for other saw projects I want to try.

I should talk about the thickness of the blades...  Back saws made today are generally made from spring steel that is about .020" thick.  Older standards varied, but were also down to that thickness.  The steel in these saws vary in thickness, but are all thicker than .020" - some of the steel is up to almost .040" thick in places.  Yes - I said "in places".  Older, high quality saws were "taper ground" - this means that after the steel was forged, they were ground down to be thinner at the top of the blade than at the bottom.  This is not the case for all saws, and is rarer today than ever (I believe Pax saws are still taper ground).  The tapering is not uniform across the width of the blade, though - I saw a catalog that showed how Disston saws were tapered and it resembled this:

The blade, as shown in the diagram above, would be thickest at the right and the bottom, and vary in thickness between .010" and .015" or so.  The tapering is done to help keep the saw from binding in its own cut.  Many newer saws that you buy today will not have this feature.

I tried to cut what I wanted from the top of the blade, to get the thinnest section possible.  I do not believe, however, that the tapering has the slightest effect when you use these saws as material for the backsaws.  My main goal was to spend as little as I could.

---

One other consideration you might have when choosing the steel you want to make yours from is how you are going to cut the slot in the handle for your new blade.  If you don't have a saw thin enough, you will end up with a sloppy fit.  Too thin (i.e. using a dozuki) and you will have trouble fitting the blade into the handle.   I have 5 old backsaws - 2 Disston, 1 Jackson, and 2 "warranted superior" saws, and of them, only one had the right combination of thin enough blade and proper set to use successfully to cut the slot in the handle for the new blade, one of the "warranted superior" saws.  The others were all too thick, believe it or not.  I don't have a way of measuring anything that fine, so you'll just have to take my word for it, though...

If you are interested in purchasing new steel for the blades rather than mining old saws, McMaster.com offers this:

Spring Steel:
Item #9014K65
Flat Shim Stock Strip Blue Tempered Spring Steel, .020" Thick, 6" X 25"
$ 13.70 Each (at the time this was written).

That steel is tempered blue, but that could be sanded off if you prefer (I've not tried it myself, but I do have it on good authority that it is easily done). RC hardness is listed at 44-51. I wouldn't use anything thinner than that, myself.  If you can find polished swedish spring steel (i.e. made by Sandvik) that is essentially what the modern makers use.  Any steel you use should be hardened to at least a minimum of 44 (48 and above is preferred) on the Rockwell hardness scale and a maximum of around 54 or so - the harder the steel is, the longer is will keep its edge, but the tougher it will be to sharpen.  Too hard, and you won't be able to set the teeth without breaking them.

Once the steel is acquired, it needs to be cut to size.  The brake I made for bending the back will only handle up to about 10" in length, so that in itself determined the length of blades I needed.  For height, I would recommend somewhere in the range of 2-1/2" to 3-1/2", with 3" being about optimum, as this will leave about 2" of exposed blade after the back is installed.  More than 3-1/2" and you begin to lose the stiffening quality the back provides, and less than 2-1/2" and there isn't much useable blade left (the backs -at least the ones I made here - are close to 1" in depth).  Also remember, that the finished size of the steel blade needs to be about 5/8" longer than the brass back you use for it - for the portion you don't see in the handle.

I'd love to have a metal cutting band saw - but not having one, I put together a makeshift "table saw" using my circular saw with a metal cut-off blade installed:

 

The saw's base is simply screwed to a piece of particle board.  A piece of plywood screwed to the "table" serves as a fence, and I just clamp the whole affair to my bench, as you can see.  If you do this, you'll probably need to wear a pair of gloves while cutting the steel, both because of the sharp edges and possibly because of the heat (bigger issue when cutting the brass than the steel).  Keep an open pail of water handy to dunk the steel into to keep it from getting too hot.  Make sure your fence is aligned properly, and your cuts are true - if not, the blade will want to bind against the steel which could throw it out of your control (do not stand in line of the blade!) or heat the blade up.  You must avoid heating the blade up to avoid "tempering" (softening the steel) the blade.  A very little bit of bluing along the very edge can be tolerated, so long as  you take the time to file it off if it is on the cutting edge, but do try not to.

Another useful tool is a pneumatic cut-off tool, shown here next to one of my circular saws with a cut-off blade:

It's great for short cuts where the circular saw would be at a big disadvantage, though my air compressor can't keep up with it for longer cuts.

In any case - if you use existing saw blades, they will probably need a bit of clean-up, and this would be the time to do the majority of that work as it is more difficult to do once you have the backs in place.  I used a belt sander with 120 grit paper for the bad ones, then used progressively finer grit sandpaper by hand until I had a decent enough polish on them - probably stopping at around 400 grit or so at this stage.  I'll put a final polish on them after they are assembled but for now, getting any rust off is the most important.  Do not use any blades that have been pitted with rust - a bit of surface rust is ok, but the pits will be a detriment to your new saw both functionally and aesthetically (a few won't hurt).

To make the metal bending brake - you'll need: 

three 10" long and two 18" long pieces of 1-1/2" x 1-1/2" x 1/8"  angle iron;

two 1/8" x 1-1/2" x 18" pieces of flat steel;

a slug of #8 to #10 sized, 1" long flat head machine screws with appropriate nuts and washers;

four fairly thick washers (the thickness of the brass - or you can stack thinner ones)

a pair of door hinges.

Because I don't have much in the way of metal-smithing tools, I did most of the work for these saws making due with what tools I had on hand.  There were a couple tools I needed to purchase, though - without which, I doubt I could have successfully made these saws.

The first two tools, and the most important in my mind, are a hammer and anvil.  For the anvil, I happened to be in the local Harbor Freight when they had a sale going on, and picked up a "Made in China" 55 lb. anvil for $30.  Not a fancy one, mostly because I'm not kidding myself into being any kind of a blacksmith - just need the mass that an anvil like this provides for bashing the backs over the blades.  

 

You don't even have to spend that much.  Dad has an anvil he's made from a short chunk of railroad track, mounted to an old I-beam, and it works just dandy.

I  also used a 4 lb. hammer.   That's right - a 4 pounder.  Mine is wood handled, but here is an HF fiberglass handled one that retails for about $9.00 that would also work:

You *need* a 4 lb. hammer to make these back saws, in my opinion.  A smaller one simply won't do - or will yield unsatisfactory results.  The larger hammer made bending the brass a veritable breeze in comparison with anything else that I tried.  It wasn't that I was swinging that hammer in a wide arc, quite the opposite.  The weight of the hammer let me get by with much smaller swings, affording me more control over them - which subsequently meant doing less damage to the brass.  Of course, your experiences may differ, especially if you are practiced in blacksmithing.

Finally, if you want to stamp your name into the brass you'll need some lettering stamps.  The ones I used are 1/8" tall, and cost about $5.  The rest of the tools I used are all standard issue woodworking tools you should be able to find in any good woodshop.