Saw build along – Blade, Part I

This is the eleventh entry in a nineteen part series that covers the construction of one of my saws from start to finish. For links to the other entries, please see the full chronological index.  -Ed.

Cutting the blank

***When working with spring steel, it pays to be careful. The edges can be very sharp, and wearing eye protection and gloves when handling it is highly recommended.***

My blades are made from polished and blue tempered 1095 spring steel, hardened to Rc 48-51. It is available from any number of suppliers, and is sold in various thicknesses and sheet sizes. I buy it in rolls that range from 10 to 25 feet in length.

Roll of 1095 spring steel, as received.

Roll of 1095 spring steel, as received.

 

After uncoiling the steel, I place tape where I will cut, then mark the lines on that with a pen. All of the cuts are made with a Beverly shear, first cutting to length and then to width.

blade-shape-02

Cutting the blanks to length on the Beverly shear.

Cutting the blanks to length on the Beverly shear.

Cutting the blanks to width.

Cutting the blanks to width.

 

The shears leave a decent edge, but they do need to be cleaned up with a file. The ends are checked for perpendicularity to the edge that will be the toothline; the backside is checked for straightness. This second step is extremely critical – the edge of the blade that will be installed into the back must be either dead straight or slightly convex. When the back is driven onto the blade, any concavity will result in a bow along the toothline. The edge should also be chamfered or rounded over to make installation in the back easier. Do not, however, form a knife edge, as this can damage the back as it is driven on.

Whenever I hold the blade in a vise, I protect it from scratches with a layer of tape or paper.

Cleaning up the end of the blade.

Cleaning up the end of the blade.

Checking the end for perpendicularity to the (future) toothline of the blade.

Checking the end for perpendicularity to what will become the toothline of the blade.

Deburring the edges.

Deburring the edges.

Cleaning up the back edge of the blade. The toothed side will be addressed when I sharpen the blade.

Cleaning up the back edge of the blade. The toothed side will be addressed when I sharpen the blade.

Checking the back of the blade for straightness. Err on the side of convexity, and any concavity will bow the blade when it is installed.

Checking the back of the blade for straightness. Err on the side of convexity, as any concavity will bow the blade when it is installed.

Chamfer or round over the edges. The edge should be blunt, not sharp, so that it slips into the slot without catching and marring the brass.

Chamfer or round over the edges. The edge should be blunt, not sharp, so that it slips into the slot without catching and marring the brass back.

 

Finally, the back end of the blade must be clipped to fit in the handle. I seat the blade fully into the back, then slide it into the handle as far as it will go, making sure to keep the back parallel to the top of the mortise. After taking the measurements, they are transferred to the saw blade itself, which is then cut and deburred with a file.

Clean any chips or debris out of the slot so that the blade will fully seat in it.

Clean any chips or debris out of the slot so that the blade will fully seat in it.

Slip the blade fully into the slot, then place both of them into the handle. Push the blade as far back as it will go into the handle. Check that the back is parallel to the top/open edge of the mortise.

Slip the blade fully into the slot, then slide the assembly into the handle. Push the blade as far back as it will go into the handle, then check that the back is parallel to the top/open edge of the mortise.

Measure the distance from the bottom of the blade to the end of the slot in the handle.

Measure the distance from the bottom of the blade to the end of the slot in the handle.

Measure the distance from the back edge of the blade to the end of the slot in the handle.

Measure the distance from the back edge of the blade to the end of the slot in the handle.

Transfer the first measurement to the blade.

Transfer the first measurement to the blade.

Transfer the second measurement to the blade.

Transfer the second measurement to the blade.

Connect the two measurements.

Connect the two measurements.

If the measurements were accurate, this should be the proper angle so that the handle seats properly in the handle.

If the measurements were accurate, trimming to this angle will seat the blade properly in the handle, providing a little extra protection against slipping.

Trim the back edge with the shears.

Trim the back edge with the shears.

 

Next up:  shaping the back, a most exciting endeavor.

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8 Responses to Saw build along – Blade, Part I

  1. Greg says:

    Thanks for all of the great info you’ve put together on your site. I’m planning on building my own backsaw and I was wondering if you have any suggestions for cutting the saw plate if one doesn’t own a shear (that would include me). Or are you planning on selling saw plates now that you have a fancy toothing machine?

    • admin says:

      Greg, Your timing is impeccable. I just added toothed blades to my website, along with kits. I will officially announce it later today on my blog.

      There are several ways to cut your own plate, however. Aviation snips work well on thicknesses up to about 0.032″. You can use an angle grinder, or even a hacksaw (it helps to sandwich the steel between two pieces of wood first). I have also “cut” it by scoring it with a carbide point, then bending along the line until it snapped.

      Best of luck with the build!

      Isaac

  2. art peterson says:

    Just bought a saw kit. The teeth are cut, are they set? I’m new at this and should probably know, but I don’t. If I have to set the teeth do I do it before or after sharpening? Any blog information about setting 15TPI teeth? I have saw tooth setting tool and a saw vice. I just re-toothed an old backsaw – what a job, had to re-do it three times.

    • Isaac says:

      Art, you will need to set the teeth. My order of work is to joint the teeth, do a quick sharpening to get rid of the flats on the tips of the teeth (at this time, I don’t take great pains to get the teeth perfectly sharp), then set the teeth. After setting them, I joint the teeth lightly, then do the final sharpening. This time, I make every effort to ensure that the teeth are as perfect as possible.

      I am working on a saw sharpening series, but it will be some time before that is finished.

      For 15 ppi teeth, I use either an Eclipse style set or a Stanley 42X with a plunger that I ground down. The biggest thing is to make sure you are bending the tooth close enough to the tip so that you don’t distort teh saw blade.

      Keep at it,if you can figure this out on a 15 ppi blade, then bigger saws will be a breeze.

      Isaac

  3. mikeal love says:

    What is the best way to clip the back of the saw blade to fit into the handle if I do not have a shear?

    Thanks

    • Isaac says:

      I’ve used aviation snips to cut spring steel up to about 0.032″ thick. The thicker material takes some effort to cut, but it’s about the cheapest way to get it done. It doesn’t leave the cleanest sedge, but a minute of work with a file takes care of it.

      The other method I have used is to score the cut line with a carbide point. Score it as deeply as you can, then clamp the blade in a vise, with just the waste sticking up, then bend the waste back and forth. It will quickly start to crack and then will break off completely. If the blade was clamped tightly right at the cut, it should not be distorted very much, and can be cleaned up with just a bit of file work.

      I’ve also heard of people clamping the blade in a vise, with just the waste protruding, then cutting it with a cold chisel (start at one end of the cut, and work on down the line).

      The last method I can think of is an abrasive blade in an angle grinder.

      Thanks for reading, and hope this helps.

      Isaac

  4. Devon Wright says:

    Hey Isaac,

    I have a question about the steel coil of 1095, is there any issues with straightening the stock, does it have issues wanting to stay curled up? What about a longer saw like a tenon saw vs a dovetail saw?

    • Isaac says:

      Devon,

      Yes, you will almost certainly need to straighten the stock. You can do that before (as I do for my kits) or after (as I used to do with my finished saws) assembling the blade and the spine. In general, the smaller and thinner the blade, the easier it will be to straighten it. There are pictures and a description of the method that I use to flatten the blade/spine assembly in a later blog post.

      Isaac

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