After trying to cut out intricate shapes using a jigsaw (to no avail), and seeing guyzo35's Instructable on the subject, I knew I had to make one of these for my own. In this instructable, we'll convert a handheld jigsaw into a bench-top scroll saw, allowing us to cut small and complex shapes from light materials with ease. We'll also see if we can improve guyzo35's method, to make the scroll saw more functional.

What you'll need:

-The Sacrificial Jigsaw: Don't worry, we wont break it.

-Scrap wood: You'll need some ply wood and something a bit thicker for the supports.

-Wood Screws

-Nuts/Bolts

Tools: Drill, Sandpaper, Clamps, Measuring implements

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Step 1: Cut Out the Top and the Base

Mark out a two 250mm X 300mm rectangles from a sheet of plywood, and cut them out using the jigsaw. These will serve as the top surface, and the base of our scroll saw. Give the edges and surfaces a good sand, particularly the piece you choose to use for the top surface.

Step 2: Make the Front Supports

Measure the length from the base plate of the jigsaw to the top of the handle. The supports we make must be longer than this to accommodate the jigsaw. Mine just just over 180mm, so, using some thicker wood, I cut out 2 lengths of 200m each. I then clamped the two pieces together, and cut another 5 mm or so off of each side, to ensure both were exactly the same length.

These can now be screwed onto the base as shown. Be sure to pre-drill and countersink your screw holes, or you'll risk cracking the wood.

Step 3: Mount the Jigsaw to the Top Surface

-Remove the metal base from the jigsaw using its included hex key. There is a single hole already in the base, but you'll need to drill three more, so there is one in each corner.

-In the center of the plywood surface we cut out earlier, mark the position for the jigsaw base to be bolted, as well as the position that the blade will protrude.

-We can now drill out the 4 matching holes in the plywood, countersinking them with a spade bit, so the bolts lie flush to the wood surface when we're done. We also need to drill a large hole for the jigsaw's blade.

-We can now reattach the jigsaws base onto the jigsaw, and place the plywood surface over the top, so that the jigsaw blade sticks through.

-Place a washer into each hole in the wood, and run the bolts through, fastening them with a nut each on the other side. The bolts are a bit tricky to tighten, I held them in place with a flat screwdriver and tightened them with a spanner from the opposite side.

Step 4: Mount the Jigsaw to the Base

Place the assembly from the previous step onto the base we made earlier, and screw them together from above, remembering to pre-drill and countersink all screw holes. The jigsaw shouldn't touch the base, but should be suspended from the top. It's important that the screws are flush with the top surface, or they'll get in the way when trying to use the scroll saw.

At this point I also cut some remaining wood used to make the supports to shape, and added two more supports to the back of the machine, this made it much more rigid.

Step 5: Stop Now, or Go Further!

At this point our scroll saw is functional, by clamping it to our bench-top, its is quite rigid, and works for many applications. This is also where guyzo35's Instructable ends.

While our scroll saw is much better at cutting intricate shapes than the original jigsaw was, I found two main issues with its operation:

- The Blade was not held in place well enough, and drifted from side to side (especially at higher speeds)

- The Blade has a much higher width than a typical scroll saw blade, leaving much to be desired when cutting tight curves.

Step 6: Decrease Blade Width

Decreasing the blades width will allow you to cut tight curves and around corners much more easily.

Move the blade so that it is at the highest point in its movement, then be sure to unplug the jigsaw.

Mark the lowest part of the blade that sticks out, we don't want to grind any of the blade below this point.

Remove the blade from the jigsaw, and using a bench grinder, grind the back side of the blade down to the desired width. Dip the blade in water to cool it off as you're grinding, if you let it get too hot it may lose its temper, and will cut very poorly. Discoloration of the metal is a sign of this.

When you're happy with the width of the blade, you can install it back into the jigsaw.

Step 7: Make a Blade Guide

A blade guide will keep the blade from drifting side to side while cutting, particularly after lowering the blade's width, and at higher speeds.

I used a small piece of PVC for this, though I suspect a hardwood might work better if you have some laying around.

I cut a small, angled notch into the PVC using the scroll saw, then suspended it behind the blade using a piece of wood held up by some thicker pieces, that are screwed into the top of the scroll saw's frame.

The drop of oil on the end of the guide helps it run better.

Remember:

-The blade guide should never sit higher than the blade, at the blades lowest point in its movement.

-The guide limits the size of material you can cut, both by height and by the position of the guides anchor point. So mount the guide as high as you can (but recall the previous dot point) and place the guides anchor point as far back, and as far to one side as you can.

Step 8: Conclusion

With a little extra effort, it feels and works a lot more like a scroll saw and a lot less like an upside down jigsaw. It's not as good as a commercial scroll saw, but for a grand total of $0, I think it works pretty damn well.

Thanks to guyzo35 for his instructable, which gave birth to this one, and have fun!