Making a saw blade knife

Saw blade knife with padauk handle.

I made this knife from a circular saw blade. There is an internet myth that claims circular saw blades are made from low carbon or mild steel, or just junk steel, nothing could be further from the truth. Saw blades spin at over 3,500 rotations per minute and endure significant stress while cutting wood, the steel must be high quality and very tough. Unfortunately blade makers are not very forth coming with what steel they use and the resulting speculation breeds all sorts of rumor. Many people believe these blades are made of L6, a common tool steel known for it's toughness and impact resistance. A few have sent blades for metallurgical analysis and the results confirm an alloy that is very similar to L6. Still there are a number of people who for whatever reason insist these blades are garbage steel. I'm not a metallurgist and can't say what steel is in any particular saw blade but neither can anyone else who isn't the manufacturer of that blade. What I can say is that many people have made knives from circular saw blades and in testing those knives are very tough and hold an edge well. If you need a disclaimer, here it is: cheap things are cheaply made. I believe that if you use a good quality blade from a respected manufacturer then you're likely to get good steel but this is recycling, there are no guarantees.

Step one was cutting the rough shape from an old Delta saw blade using a 10" cut off wheel in a chop saw. This steel is hardened and cuts very slowly. It is so hard near the tips where the carbide is brazed that I had to break it, even the cut off wheel wouldn't cut it. Usually you will see knives made from annealed (softened) steel which is later hardened then tempered. Since this steel is already hardened and I do not have proper heat treat equipment, I chose to keep the factory heat treat and just be careful to keep the blade cool while cutting and grinding; that meant lots of stopping and waiting.

 

 

The handle material is padauk, a South American hardwood often used for xylophone keys. It is hard and somewhat oily. The red will "bleed" out when the wood is wetted, especially with any kind of solvent. Normally the handle would be attached with pins but this steel is too hard to drill with normal drill bits so I have to rely on epoxy.

The handle scales clamped while the epoxy hardens.

The handle was shaped with disc and spindle sanders, then hand sanded with 120, 150, 220, 320, & 400 grit sandpaper. Sorry, no pics of the sanding.

The finish is shellac and wax. Not an especially good choice for a knife but the padauk is tough wood and would be fine without a finish but the shellac stops the red from bleeding.

Top down shot of the handle.

No trouble with a Roma, fresh from the garden.

See through radishes!

Making a Wood Carving or Marking Knife with Disposable Blade

Swann Morton scalpel blades have become popular for marking knives. They are a high quality, carbon steel, disposable blade available from the U.K. David Barron, among many others, uses them in his marking knives, epoxied solidly into the handle. The carbon steel blades are easy to sharpen and take a keen edge. I ordered some last fall and have considered several ways of making the blades replaceable.

Swann Morton 01 Scalpel

I started with a scrap of Spanish cedar. Cut a slot through the end deep enough for the blade. Drilled and countersunk a screw hole to retain the blade. Then sketched and cut out the handle shape. Full details are in the build video. My apologies for the lack of pictures but this was spontaneous and slotting, drilling, and sketching the handle blank was a less than a five minute minute job.

The blade is secured with pieces of walnut veneer that fit like splines in the kerf above and below the blade. As seen in the video, I did not adequately glue the veneer or didn't allow enough drying time (probably both), and the spline failed. On the second try I used cyanoacrylate glue which is holding up fine so far. There are stronger ways to secure the blade but I wanted to try this first as it's the easiest. If it fails again I will insert a brass pin above the blade. An alternative is an inner frame of metal with a cut out for the blade, then attached wood scales. I might do that in a future video.

I am not a carver and did not make this knife with carving in mind but wanted to see how well it might work for chip carving. The blade is very thin and sharp, and had no issues slicing through poplar. My skills are obviously non-existent and it would be interesting to have an experienced carver's opinion.

Most prefer single bevel blades for marking knives as you can hold the flat of the blade against a straight edge. These are double bevel blades but by holding them at a slight angle you can achieve the same accuracy.

Video

Blades are available from:

scalpelsandblades.co.uk

or

Echo Iron Mongery on ebay

I have no affiliation with either seller.

Shop made chip carving knife with mahogany handle

Using a french curve I drew this pattern on 1/4" hardboard. 

Cut out and sanded the edges smooth.

The blade is a Dewalt reciprocating saw blade. I removed the yellow paint and cut the shape with a Dremel and cut-off wheel. The funky shape is partly because I had cut a piece off for a marking knife and partly so it would be secure inside the mahogany handle.

 

I carved a mortise out for the blade and secured with epoxy. 

You can see the handle shape traced on the mahogany blanks.

Excess wood was removed with a combination of saws, chisels, and sanding machines.

Handle finish is blonde shellac then buffed with 0000 steel wool and wax.

Blade was polished to 2000 grit using automotive sandpaper. Edge was ground by hand then sharpened with a diamond file and sandpaper.