Replies

1. 
   3fingers | Dec 30, 2004 05:49am | #1

   This is common with most wood.  That is why newer saws have a riving knife just beyond the blade to help with this problem. 

    

   What I do is just wedge a shim in the board so it wont kick back.  Also when the stock is warping that bad make sure you joint the piece or you'll have problems later.

2. 
   JeffHeath | Dec 30, 2004 06:48am | #2

   Steve

   What you are doing is an accident waiting to happen, and can be extremely dangerous.  I'm not trying to scare you, but I am trying to warn you.  Several issues could be causing the problem, both with the wood, and with your saw.  Apparently, you do not have a splitter on your saw, which is the piece of metal or wood the same thickness as your blade, sticking up just behind your blade.  A splitter will not allow the board to squeeze your blade.  You could be working with wood which has not been jointed flat and planed parallel, or you could be working with reaction wood, wood that grew on the tree in a non-vertical location (i.e. a branch), and has internal stresses which are releasing when being cut.  All of these are a recipe for disaster.  Why do you think he calls himself 3 fingers?  A splitter properly installed after the blade will help, or a wedge put in the kerf just after it safely passes the blade will keep the wood from squeezing the blade.

   I must tell you that when building furniture, when I encounter reaction wood like this, it immediately finds its way to the firewood pile, because it will continue to move, resulting in problems with your furniture.  Not all oak has this problem.  In fact, proper stock preparation with the jointer and planer will usually eliminate this problem before you get to the table saw.  Review your procedures, and I'm sure you will get better results.

   JC

1. 
   Rich14 | Dec 30, 2004 07:31am | #3

   Steve,JC is absolutely right.If you go to the Woodworking Archives and do a search under "kick back" you will find several very informative articles about your problem. You are very lucky that you have not had a serious accident. The causes and prevention of kick back are something every one who uses a table saw for ripping should know.Rich

3. 
   olopua | Dec 30, 2004 12:44pm | #4

   This can also happen when the wood has been improperly dried in a kiln
   resulting in what is called "case hardening". There is a way to test a scrap of your wood for case hardening. Check "UNDERSTANDING WOOD" BY Bruce Hoadley.

1. 
   bigguy05641 | Dec 30, 2004 04:17pm | #5

   Thanks for the responses.

   I have noticed that I have more problems with wood I purchase at one lumber yard versus others.

   I think I will try the wedge, I had considered this, but wasn't sure of it's appropriateness. General Motors Master Technician

   ASE master technician

   woodworker wannabe

1. 
   JeffHeath | Dec 30, 2004 07:42pm | #6

   Steve

   I forgot to mention the 1 1/2 inch scar on the right side of my chest from a kickback (the only one I ever had) that also broke 2 ribs.  It hit me so hard it knocked me 6 feet backwards, and I bent the garage door of my first shop so bad (I'm 6'1", 240 lbs.) that I had to replace the door.  It wouldn't go up any more.  I'd felt like I'd been shot with a gun.  (Unfortunately, I know what that feels like as well.)

   My advice to you is to not purchase lumber from that source anymore.  I've learned over the years that certain retailers of lumber either don't know how to store it, or don't care.  Either way, there are plenty of sources for good wood out there.

   JC

    

2. 
   mike4244 | Dec 30, 2004 07:57pm | #7

   Take this piece back to dealer, if they are reliable they will take back all you purchased that was not used.Install a splitter , but DO NOT rip this lumber. Take heed from the other posts, using reaction wood is not only a waste of time , but dangerous.

   mike

4. 
   walnutjerry | Dec 31, 2004 04:25am | #8

   Steve-----It sounds as though you may be using air dried material vs kiln dried. Kiln drying does more than just dry the wood if done properly---it also stabilizes the wood.  I am no technician on kiln drying but after spending 5 years working with a millwork company you learn a few things. One of which is "there are exceptions to most rules".  Lumber purchased from a reliable dealer that sells material that meets NHLA rules and AWI standards should give a minimum of problems.

                   Cheers, Jerry

    

    

1. 
   BarryR | Dec 31, 2004 07:41am | #9

   Wood can be properly or improperly dried in a kiln or out.  You're much more likely to get case hardening from kiln dried wood than from air dried wood, however.

1. 
   walnutjerry | Dec 31, 2004 08:16pm | #10

   I agree with you for the most part Mangler-----air drying will not stress relieve the wood as kiln drying will do if done properly. There is a test you can do to check the board to see if it is stress relieved.  It involves making a "tuning fork" from one of the boards in the stack. Usually a board from the center of the stack.  Crosscut a piece 1" wide from the center(lengthways) from the board. Turn it up so the end grain is facing upward and cut out a "U" shape leaving equal amounts on the outside edges. If those edges remain parallel after removing the cut out then, supposedly the material is stress relieved. If the "legs" of the tuning fork move in or out then it is not stress relieved.

   I am always open to further knowledge concerning wood-----the more I work with it the more I realize I do not know.

                                Walnutjerry