Replies

1. 
   woodman2263 | Mar 26, 2007 09:24pm | #1

   Velo,

   Turn the board onto the other edge.  You are doing nothing but putting a nice smooth edge on a curve.   Hold the board up and see which way the board bends.  You want to run it through the jointer with the bend down.  Each pass will start to cut away the high spot on each end of the board.  As soon as the high spots are gone, you will hear the jointer cutting all the way down the board.

   Jeff

    

1. 
   velomark | Mar 26, 2007 09:47pm | #2

   Woodman2263:

   I am gluing up boards for a table top and am therefore jointing the outside edges of the board.  I can already hear the jointer cutting all the way down the board.  I cannot see a noticeable bow on any of the edges but when I put the boards together the middle 60% of the board meets but the two ends don't.

   Thanks Cheers,

   Velo

2. 
   JohnWW | Mar 26, 2007 09:58pm | #3

   As already suggested, your problem could be with your technique.  As the other poster explained, a convex edge is hard to straighten out, do the concave edge of the board first and then trim off the the convex edge of the board with a saw before finally jointing the second edge.  The shop should have an instructor who can take through the basic technique of using a jointer.

   A second possibility is that the problem is being caused by the outfeed table being set wrong.

   It is a myth that the outfeed table on a jointer is set at the height of the blades.  It will be close, but the best setting for the outfeed table height is achieved through the procedure outlined below: 

   Assuming there are no mechanical problems, the blades are sharp, and the tables are flat and coplanar, setting the outfeed height is a simple procedure, so I'd start out trying to adjust it before trying anything else.  Being you are in a school shop, you should definitely check with the instructor before attempting this.

   To set up the outfeed table height, you'll need two test boards, each about 1/2 to 2/3's as long as the overall length of the jointer, these boards should be close to perfectly flat on their wide faces with no large knots.  If you primarily work with hardwoods, this adjustment will be more accurate if the test boards are also a hardwood.  Never plane MDF or plywood on a jointer unless it has carbide blades, the glues in them will dull steel blades very quickly. 

   Start by dropping the outfeed table so that it is approximately 1/16 inch lower than the top dead center height of the knives in the cutting head.  In this position, the outfeed table will definitely be too low.  Also set the infeed table for a 1/16" cut.

   Take a pass with each of the test boards and place them together, planed edge to planed edge.  With the table too low, you should find that the planed edges are concave when placed together and each board's trailing edge will have a small snipe over the last inch or so. 

   Next start to raise the outfeed table by small increments, taking test cuts on both boards after each adjustment.  As you bring the test boards together after each height adjustment, you should see the midpoint gap diminish and the trailing snipe disappear.  Keep adjusting the outfeed table upward by small amounts until the edges mate perfectly and you'll be all set. 

   If you overshoot the setting, the boards will be touching in the middle and gapping at the ends of the joint.  If this happens, drop the outfeed table to below the correct height and try again to get the correct setting by raising the table.  Don't try to make the adjustment by lowering the table, since the setting will likely slip after the machine is used for awhile. 

   If this procedure doesn't solve your problem, I'd replace the knives with a freshly sharpened set, and repeat the above adjustments on the outfeed table.  If you are still having problems after that, then it is likely you have some problems with the alignment of the tables with each other, which will be harder to diagnose and fix.  However, it is unlikely that anything else is wrong provided the machine has been well maintained.

   John White, Shop Manager, Fine Woodworking Magazine

1. 
   user-211435 | Mar 27, 2007 06:19am | #5

   Hi John,

   I just wanted to let you know that I watched your video about your workbench last night and enjoyed it.

   I spent many years working on very expensive homes, where everyone had little tricks and home-made tools to do the job with, and this would fit right in.

   Thanks for sharing.

   Hal

   http://www.rivercitywoodworks.com

    

1. 
   JohnWW | Mar 27, 2007 04:00pm | #6

   Hal,

   Thanks for the kind words, you have gotten my day off to a very good start.

   John W.

1. 
   woodman2263 | Mar 27, 2007 04:08pm | #7

   John,

   Could you take a look at my question on the biesemeyer splitter and let me know your thoughts?

   Thanks

3. 
   Napie | Mar 26, 2007 10:02pm | #4

   The tables of the jointer might be out of adjustment. You can get a curved edge if the outfeed table is to low. Also, are you keeping pressure on the outfeed end of the board?  That is where the newly trued surface should register the cut.