Replies

1. 
   Rich14 | Mar 03, 2007 06:23am | #1

   Jim,

   I can't tell you why you're getting tearout, but you could try other bits, slowing the router speed, using a "backer" strip against the mitered piece so that the bit enters that first, then passes into the mitered piece.

   I use a Freud FTG ripping blade to cut spline slots. No tear out. See the attachments.

   Rich

   
1. 
   jimbell | Mar 03, 2007 09:41am | #4

   Thanks. I'm cutting long splines or through splines (3 1/2" this time). I changed to a Freud 1/4" bit (fairly new) and still got some tear out.

   Do you also cut the through spline grooves on the tablesaw?

   Jim

1. 
   Rich14 | Mar 03, 2007 04:12pm | #5

   jim,I'm not sure what you mean by through splines.That's interesting that using a router is causing a tearout problem. I was going to do it on the router also, but once the rip blade method worked so well I never tried anything else. I wouldn't have anticipated the problem you're having. How about applying masking tape firmly to the entrance point of the cut?Rich

2. 
   Napie | Mar 03, 2007 07:27am | #2

   I use the table saw instead of the router.  I find it works much better.

1. 
   wchips | Mar 03, 2007 07:52am | #3

   You can use a biscut cutter too

3. 
   4DThinker | Mar 04, 2007 01:45am | #6

   I'd vote for cutting the spline groove on the table saw.  With a left tilt powermatic saw it is easier than cutting the original miter.

   The saw blade may not be 1/4" though, and not leave a truely flat bottomed groove.  The one I'm using is a bit bigger than 1/8". I don't recommend trying to make two passes with a single blade to get a 1/4" groove, but you could certainly put a dado set in there with 1/4" worth of blades to do the same job your router is making hard for you. 

   I teach furniture design to college kids, and in the first class they take thay all have to make a "joinery box"  that has one splined miter corner.  We used to use the router, but dropped it for the table saw after getting too many complaints about tear-out like yours.

1. 
   Rich14 | Mar 04, 2007 02:03am | #7

   4D,The Freud FTG ripping blade results in a perfectly flat-bottomed cut.BTW, putting splines in the miter joint is just about the most bullet-proff way to make these joints (see the pics above). I made dozens of frames in Maui before I moved to Arizona. (A change from consistent medium to high humidity to an environment that changes from bone dry to ghastly humid, weeks at a time, several times a year.) The corners have remained absolutely tight. Not a sign of opening at either the inside or outside corners.With frames finished in the standard frame shop way, V-nails, brads and glue, opening and shifting of miters due to humidity changes is a fact of life.Rich

2. 
   jimbell | Mar 06, 2007 06:55am | #8

   Thanks. I find it reassuing to know that entire classes of wordworkers have had trouble with router tear out on spline grooves in mitre joints. I'll try a 1/4" dado set on the table saw and see how it works. I'm thinking a stop block and a backing board, plus sharp dado blades (as my old Freud set is loosing its edge).

   Regards,

   Jim Bell