What Is a Spiral Saw?
It wasn't until the early 1970s, when Bob Kopras built the RotoZip, that this become possible. Imagine a power tool that you can drill straight into wood or drywall (the plunge part), then move sideways to cut holes (the cut part). It's simply not possible with a drill or router.
For example, a jigsaw will cut, but it won't plunge. That's a separate step you need to undertake with...a drill. You begin to see the difficulties.
A RotoZip spiral saw looks like a handle-less drill. Its RotoBits move at extremely high RPMs. Start it up, plunge it into the material, then carefully cut out your piece.
RotoZip's most famous use: as a drywall tool for cutting electrical box openings--while the boxes are in place. If you think this is a small matter, you've never tried to do this.
Many buy a RotoZip saw just for this one purpose. But it's a useful tool for cutting rounded or amorphous shapes in many other thin materials like laminate. Changeable bits even allow you to cut masonry and to blast out grout.
How Did It Perform?
The RotoSaw does cut thin, soft materials well. As long as you pay attention to instructions about moving clockwise or counter-clockwise around the bends, you'll have near-perfect control over the tool.
The included Multipurpose bit plunged into and cut those thin materials (5/8" drywall or 1/4" wood) with ease. Take the RotoZip beyond its intended limits and the bit will start smoking as it tries to penetrate the material.
The key is to purchase the right bit for the job. They have bits for fiber-cement board, windows/doors, tile, grout, laminate, metal, and underlayment, as well as a range of other general-use bits.
RotoZip RotoSaw is lacking some basic smart features. It does not have a soft friction grip handle (though the shape of the handle will assist your grip). There is no secure place to store the wrench (I store it on a loop attached to the power cord, but the wrench eventually loosens and falls out).
But those are minor annoyances compared to the collet system of holding in the bits. Collets are removable metal sleeves that hug the bits and help them fit into the collar of the tool. So, when you change a bit, you need to change the collet, too.
You need to locate a like-sized collet to fit each bit. Because no sizes are indicated on the collets, it's a matter of trying them on one by one until you happen upon the right size.