Replies

1. 
   Pete99353 | Jan 30, 2011 12:06pm | #1

   As a person who has deep respect for kickback here are my thoughts on the subject:

   Equal widths could work but would require precise set-up which can be difficult with some saws. Even if perfectly set up initially you have the problem of deflection of the blade and/or the Riving Knife (RK) while in use. Thinner blades deflect more than thicker blades.

   One or two thousandths doesn't seem like much of a difference. The only way to know for sure is to test it. If you have some run out in the blade or arbor it may not be an issue. The run out would create a kerf slightly wider than the thickness of the blade. Make a test cut, preferably a rip, about a foot long and measure the width of the kerf to see if run out helps you situation.

   Sharpening the front edge of the RK is an interesting idea and one that in my humble opinion has merit. It's something I'd try after determining the kerf width is the same as the blade and therefore narrower than the RK. The RK is there to keep tensioned wood from closing up on or making contact with the back side of the blade, thereby preventing kickback. On highly tensioned wood the kerf closes quickly. As long as the RK is close to the back of the blade and the kerf does not close tight before making contact with the RK you should be good to go.

   My last choice would be to sand or file the RK to be thinner than the blade. Good luck

   Pete

1. 
   willjeep4food | Feb 02, 2011 09:34pm | #7

   Thin Kerf Saw Blades & Thick Riving Knife

   Pete, 

   cautious testing (keeping count of my fingers) to see how the parts - Freud Thin Kerf and Bosch portable table saw splitter/riving knife assembly actually perform.   It seems too close and likely to result in just what is trying to be avoided.  Thank you for your comment - every idea and perspective makes it clearer.

2. 
   JerryPacMan | Jan 30, 2011 12:11pm | #2

   A riving knife should be thicker than the plate thickness and less than the kerf thickness.

1. 
   BruceS | Jan 30, 2011 12:59pm | #3

   Knife thickness

   You are totally correct on this answer.    Problems will arise with blades like the Freud glue line ripper that have a very close difference in grind between the blade plate and the kerf of the cutters.  

   Personally,  I would not use a riving knife that was thicker than the plate at all.    And adjusting a riving knife that only  has .001 clearance on either side of the blade plate is asking for the next to impossible.     I use many types of blades, crosscuts and rippers dedicated to their designed jobs and they all have different kerfs.   I'm not a combination blade person.   I would need a half dozen riving knives.   What a set up nightmare set up that would be.

1. 
   willjeep4food | Feb 02, 2011 09:29pm | #6

   Thin Kerf Saw Blades & Thick Riving Knife

   Bruce S.

   Excellent advice - Count to 10!  full inventory is good!

   Exactly the blade involved and the riving knife/guard assembly is on a Bosch portable - just seems a little too tight to hope for clearance - may need a different riving knife solution for the thin kerf blades.

   thank you for your comment and knowledge

3. 
   JerryPacMan | Jan 30, 2011 02:13pm | #4

   This was recently posted on the FOG by John Renzetti.

   "Hi, Felder in their catalogs used to give a formula for the recommended

   splitter thickness. It was the blade body thickness plus .2mm and this of

   course was less than the kerf. The most common thickness for blades 250 to

   315 is a 2.2mm body with 3.2mm kerf cut. The 2.4mm thickness splitter works

   here. The larger 350mm blades mostly have a 3.5mm kerf and a 2.5mm blade

   body. The next size riving knife is 2.8mm so this would work on the 350mm

   blade."

   The plus .2mm is .008" decimal.  One mm is .03937".

   Jerry P

    

1. 
   willjeep4food | Feb 02, 2011 09:23pm | #5

   Thin Kerf Saw Blades and thick Riving Knives

   Jerry

   Thank you for your insight on both comments, putting it into measurements as Felder's did helps to "see it".

4. 
   willjeep4food | Feb 02, 2011 09:41pm | #8

   Thin Kerf Saw Blade & Thick Riving Knife

   Howie, 

   Thanks for your comment.  I have checked out the price for a 2nd splitter/riving knife to have modified.  Might be a little bit of a challenge in that it is also the mount for the guard and the pawls (clever folks these Bosch people) but between the paint and a few thousandths of metal - all the parts might work.    the other challenge is that the splitter/RK has a vertical slot - like having two splitters/riving knives - tow potential faces to catch the end of the stock being cut.....

   I sent a note asking Bosch about the problem (I saw that someone else had received an acknowledgement from Bosch that it was/is a problem) to see if maybe they would be offering a thinner RK....hope springs eternal!