Replies

1. 
   Alex_Higgins | Feb 17, 2002 08:41pm | #1

   *
   Scott:
   I suppose part of the question is, how do you cut mortises? I have a Jet mortiser capable of accepting up to a 1/2" mortise chisel, which tends to motivate me to cut 1/2" mortises, which is perfect for up to 1" parts. I have cut 5/8" mortises by cutting two rows of 5/16" holes, cutting halfway through the stock from each side. The end result was pretty good, and it has to be if you have through mortises where all the joinery shows. As to your question, I think a 5/8" tenon sounds right. I think 3/4" sounds too bulky. I am planning on making this piece myself someday. By the way, did you do quadrilinear posts w/ q-sawn figure on all sides, veneer them, or what?

1. 
   Bob_Lang | Feb 17, 2002 11:02pm | #2

   *All of these seem to be in the right neighborhood, my best guess was for the legs to be 2 15/16" square, with both the front & back rails @ 13/16", and the panels 1/2" thick. My choice would be a 1/2" thick tenon for the rail to leg joint. One could argue either way for the thicker front rail, my thinking is that 3/4" is thick enough, that some strength will be gained when support for the seat cushion is added out of sight, behind the rails.Bob Langwww.craftsmanplans.com

1. 
   Scott_Cudrnak | Feb 18, 2002 12:16am | #3

   *Alex,I cut mortises with a plunge router, so buying a different bit is far less painfull than buying a hollow chisel bit. This piece will not have through mortises, but will meet in the leg. I intend to use a box joint at the end of the tenons, where they intersect within the leg. This gives more glue area than mitering the tenon ends. I did quadralinear posts. I think my way works pretty well (so who doesn't), and it's different from what I've read. I don't cut square-edged strips first, but rather rip beveled strips straight off the parent board to save wood. I tilt the blade towards the fence, clamp a feather board to the fence to force the piece flat on the table. A spacer offsets the feather board to push on the top of the trapezoid. The wide face of the strip runs on the saw table, providing the best support. I used a jointer to clean up the saw marks. I tip the fence to an acute 45-degree angle. The strip's face runs on the fence, one bevel runs on the jointer table, and the other bevel points plumb, away from the fence. Use a feather board & spacer off the rabbeting table to push that bevel, which translates to force the piece against the fence and the table. Always straighten your stock. I tried to cheap out and skip that step, but it did not work as well.

2. 
   Alan | Apr 05, 2002 07:20am | #4

   Scott,

   The formula furniture makers, and others, have used for centuries to determine the thickness of a tenon is the tenon should be more than 1/3 and less than 1/2 the thickness of the thinnest stuff:  e.g. on 4 quarters stuff the tenon should be around 3/8".

   Alan

1. 
   BernieMaas | Apr 05, 2002 08:29am | #5

   That may be a rule of thumb - but, it's not the only rule that works.  We've used 1/2" inch tenons on 4/4 (3/4 finished) stock for years - leaving an 1/8 inch shoulder all around.  Usually that tenon is mortised into 6/4 (1 1/2")  finished stock.  Works fine.

   Edited 4/5/2002 1:32:34 AM ET by Bernie

   Edited 4/5/2002 1:34:10 AM ET by Bernie

2. 
   DKowlasky | May 03, 2002 01:04pm | #6

   Sorry this may be a little late.. however.. the information is still good.. and besides.. I just learned how to get around this forum.. sooo.... thought I'd give it a try..

   Design of your mortise and tenon:

   #1 The tenon thickness (which corresponds to the width of the mortise) should be about 1/3 the thickness of the stock that will be "mortised" (the mortised stock may be a different thickness than the tenon stock.. thicker in some applications)..

   #2 The tenon width (which corresponds to the length of the mortise) should be no more than 5 times its thickness.. with a maximum width of about 4".. if a wider tenon is planned.. it should be divided into 2 tenons (well.. 2 mortises also.. of course.. also rule #4 about the size of horn should apply here to the space between the 2 tenons/mortises)..

   #3 When a blind mortise is used.. the depth of the mortise (which corresponds to the length of the tenon) should be 2/3 of the width of the board into which it is cut..

   #4 Leave a horn that is about equal to the thickness of the board (the horn is the material left from the mortise to the end of the board into the which the mortise is cut)..

   These are traditional rules that work for most cases.. however.. they can be adjusted for other special specific applications..

   Dave²