Saw Keychain - From Sawzall Blade

Build a very strong keychain tool from a Sawzall Blade .

Motivation:
It is often a desperate move scratch at something with your keys.  At best you will tear up whatever you are trying to cut or pry, at worst you will break your key and be stranded.  I've tried to make a keychain tool that could replace a small pocket knife or utility knife  -- so I would think 'where are my keys?' instead of 'where are the scissors?'

Overview:
The first half shows how to make a simple saw keychain.  In the second half I do some more detailed grinding to make a knife-like tool that fits well in my finger tips.

Some key points:

1. Sawzall blades are very tough metal
2. Drilled hole with dremel grinder
3. Shaped and cut with bench grinder

Here is a video of the final tool:

Stuff:

1. Sawzall Blade
2. Center punch
3. Grinder Dremel bit
4. Drill
5. Bench grinder

I wanted this to be about the size of a key - so I used my keys to determine the length.

I used an old screwdriver to make scratches to mark the length and hole.

Use a center punch to start the hole.  This will keep the bit from drifting around as you try to start the hole.

It took a long time to make a hole in the blade.

I tried a regular drill bit with poor results.

A blue grinder from a dremel kit worked well, the bit was nearly destroyed.

I made a jig by putting nails into a board very close the blade.

Test the hole. 

The hole here is a little too small to fit over both rings of the keychain.  Measuring the keychain, the hole needs to be almost 0.2"

I used a bench grinder to shape the saw.

Removing several teeth makes the saw easier to hold.

To clean up the sides of the blade, use a fine grit wheel and a light touch.

Cut the blade to length on the square corner of the coarse wheel.

The sawzall blade cuts on the pull, so the key chain and keys can be used as the handle.

The fat end of the blade can be made into a second tool.  This part already has a good size hole.

Shape on the coarse wheel and polish on fine.

I tried to give the back of the blade a curve.  Also ground off several teeth to make a little handle.

Here are the final pieces.

This one is pretty beefy.

I've changed the shape to make this a more practical hand tool.  As a saw it just ripps stuff, this is more like a small knife or x-acto blade.

It is now pretty kick-ass.

I will(might) post details when(if) I get a chance. 

Here are some more images of the saw in action.  It is tough enought to screw in a screw, cut a tire, mangle rusty car metal.

The saw is good, but it does more ripping than cutting.  There is also a spot that digs into my finger.

Here are some dremel tools that are able to grind the tough metal.

A bunch of the teeth have to go, in order to form a blade.  The rough cutting is done on the grinding wheel.

The inner curve was hard to get right.  I put the dremel grinder in a drill press and held the knife in my fingers.

The blade is only angled on one side (like a chisel).  The back is flat.  This allows you to sharpen the knife be pressing the flat side against a flat sharpening stone.

I have some fine stones with curved edges.  I have these for sharpening curved wood lathe chisels (gouges).  They need honing oil and can produce a very sharp edge -- probably sharper than is really needed.

I sharpened these by going back and forth between the curved side and the flat side.  You sort of get a little sharp edge that bends back and forth, when it is gone the blade should be very sharp.  I test the sharpness by dragging the blade gently across my fingernail  -- it should immediately catch the nail.  In some of the pictures you can see little chunks of my finger nails missing from this.  A dull blade will just slide across the surface.

I got a decent polish by rubbing the knife on a piece of wood covered in a fine rubbing compound (for a car).  At this point the tool is tiny and sharp, so it was pretty hard to handle.

There are dremel tools that are grit and rubber  -- but I didn't have any on hand.

Be sure to keep your keys and touch screen phone in different pockets!