Replies

1. 
   AlanWS | Oct 08, 2006 04:09am | #1

   A riving knife can look like a lot of different things. What makes it a riving knife rather than a splitter is that it moves up and down as the blade does, which allows the gap between the blade and the knife to remain pretty much constant. You can have a riving knife that follows the back of the blade by only about 1/8", and that rises to just a hair under the height of the blade. This type of riving knife can be left in place for non-through cuts. Having something solid above the blade is helpful, and like many splitters, riving knives sometimes do. If you search on this website, you will find as much discussion of riving knives as you could want.

2. 
   hammer1 | Oct 08, 2006 06:00am | #2

   I don't like posting this webpage without a few comments. It does show a picture of a typical riving knife but there are some dangerous things going on in the article. In a way they help to show some of the disadvantages and possible dangers with a riving knife.

   A riving knife is designed to prevent the kerf from closing up and pinching on the blade. This can be a cause of kickback but it is just one of the causes and the knife won't prevent some others. In order for the knife to keep the kerf open, it has to be very close in size to the kerf. A thin kerf blade will require a different size riving knife than a full bodied blade. The knife must be aligned with the blade, both straight ahead and up and down. If the alignment is off, it can force the work sideways into the blade. This may actually cause a kickback.

   The knife pictured in this article is sometimes known as the "widow maker". It has a single attachment bolt and an open slot for adjustment. If the bolt gets loose, or the operator doesn't tighten it. or misalignment causes undue pressure, the knife may get launched by the blade.

   The article also shows a picture with the author's hands behind the blade pulling the last of a cut. Riving knife or not, your hands don't belong there, period. His push stick is in sight but the knife would be in the way unless a deeper slot was cut into the push stick.

   Some riving knives are shaped differently. Some have guards attached. They may have a mounting bracket that adjusts or you may have to use shims. Getting a tight knife aligned properly can be frustrating with some saws. Most have to be removed for non through cuts and dado work.

   http://www.garymkatz.com/Tool%20Reviews/RivingKnife.htm

   Beat it to fit / Paint it to match

3. 
   eddiefromAustralia | Oct 08, 2006 06:26am | #3

   Hi Bruce,

   Take a look at these pages - should let you see the differences.

   http://www.safetyline.wa.gov.au/pagebin/guidothr0007.htm (currently the site is off line -> Sunday maintenance of the server at a guess - was an excellent source of information.)

   http://www.osh.govt.nz/order/catalogue/archive/rivingknives.pdf#search=%22%22riving%20knife%22%20Workcover%20OR%20Department%22

   http://www.hse.gov.uk/pubns/woodindx.htm (halfway down the page is a link to Circular Saw Bench Safety.)

   Cheers,

   eddie