Replies

1. 
   YesIWood | Mar 22, 2007 01:53pm | #1

   Autodave,

     If I understand you you are using a 1/4" up cut spiral bit (good choice) then you would use a 1/4" round over bit.  I caution you to mill a long strip of 1/4" tenion material then cut it into small pieces.  Just cut the loose tenion pieces a little short so you don't bottom out in your mortises.  Plus it will give you a little room for excess glue.

   Joe

   Even a broken clock is correct twice a day...

    

2. 
   AlanWS | Mar 22, 2007 06:40pm | #2

   For your tenon stock, yes you want a 1/8" radius roundover, which will cut an arc with 1/4" diameter, to fit the mortise cut with a single width of a 1/4" straight bit.

   The fit at the rounded edges of the tenon stock is less important than the faces anyway. Endgrain is a good place to leave a little space for glue and air escape.

3. 
   brad805 | Mar 22, 2007 11:19pm | #3

   I take it your mortise sizes are different sizes than the tenon stock you can purchase?  Lee Valley sells them and they are similar to biscuits in that they expand with the application of the glue to give a tight fit. 

4. 
   MikeHennessy | Mar 23, 2007 02:34pm | #4

   I'm a bit puzzled by your post. Why are you using a router to mill slip tennons -- which are normally simply cut with a saw out of stock of the proper thickness? As to rounding over the corners, it's no big deal and can be done with a block plane, rasp, or other tool. Making the corners *exact* will not increase the joint strenght and, once the joint is glued up, you'll never see 'em again!

   Mike Hennessy
   Pittsburgh, PA

1. 
   Jfrostjr | Mar 23, 2007 03:30pm | #6

   I give them a 'lick and a promise' with a strip of old 80 grit belt sander cloth.Frosty

5. 
   Napie | Mar 23, 2007 03:19pm | #5

   I do a lot of loose tenon joints and don’t bother to round over the edge.  The left over space gives a little room for the glue to flow into.

6. 
   tms | Mar 23, 2007 05:32pm | #7

   Hey Dave,

   I presume that you mean you mill your mortises with the spiral bit. I suggest that you use your table saw to make your tennons out of a long piece of stock. I also don't bother with a round over bit on the tennons. I simply champher the arris with a block plane. The champher acts as a glue relief to prevent a hydraulic block.

   Good luck,
   Tom

1. 
   woodman2263 | Mar 23, 2007 05:52pm | #8

   I couldn't agree more with tms, napie and mike.  They are right on the money.  By the time you set up the 1/8" roundover bit and run the tenons through you could have used a rasp, block plane or sandpaper and been done drinking a cup of coffee.

   Jeff

1. 
   Rich14 | Mar 23, 2007 06:14pm | #9

   I'm not a fan of using the router to do this either, but one could set it up to produce perfectly-fitting loose tenon material (with round ends) for pre-determined mortise lengths, or mortise lengths determined by the loose tenon material, used in a stop-block template.

   This would produce tenon material for perfectly -matched M&T joints just as available from several commercial sources of equipment makers and tenon material.

   For a large run of loose M&T joinery this would work very well and would help with joint alignment which could be very accurate if the tenon set up and mortise cutting is done well.

   Rich

1. 
   woodman2263 | Mar 23, 2007 06:24pm | #10

   Rich,

   I agree with you 100% about making a bunch to have on hand.  I don't know about anyone else here, but I don't want perfectly fitting tenons going into my mortises.  I take my block plane a chamfer the entire tenon all the way around on the edges so there is "extra space" all around the inside of the joint.  This not only provides a small tolerance for adjustments if necessary but also I don't have a much squeeze out. 

   I don't much care for clean up so this is the way I put them together.

   Best,

   Jeff

1. 
   Rich14 | Mar 23, 2007 06:46pm | #11

   Hmm. . . There are lots of times when I rely on "perfectly fitting" joints to position the pieces exactly as I want them for glue up. But I admit, this is done with squared-up joinery, not round-ended mortises or tenons.