Replies

1. 
   user-1119429039 | Mar 24, 2008 08:20pm | #1

   Dear mahogany,

   Check this article from our archives:

   http://www.taunton.com/finewoodworking/Workshop/WorkshopPDF.aspx?id=24110

   David Heim
   Managing Editor
   FineWoodworking.Com

1. 
   mahogany | Mar 24, 2008 10:59pm | #2

   Thanks David!!! Very interesting article, but I´m looking for a jig to be used in my dedicated slot mortiser...may be a good article for the magazine.

1. 
   JohnWW | Mar 25, 2008 01:35am | #4

   If you can mount a router dovetail bit in your mortiser, then you just need to make a simple cradle to solidly hold the post on the machine's sliding table so you can feed the end of the table leg sideways into the bit. You aren't confusing a slot mortiser with a chisel mortiser by any chance?John White

1. 
   mahogany | Mar 25, 2008 04:41pm | #5

   Thanks John!!

   Is a dedicated slot mortiser, italian made by SCMI, very beefy, very precise and a pleasure to use, mortising and doweling.

   The speed is not important for a router bit type? The slot mortiser runs about 4000 rpm.

   I will try using a dovetail router bit and share with you the results.

   Best regards,

1. 
   JohnWW | Mar 25, 2008 06:32pm | #8

   It seems that the follow up post from Chris B. gives you the needed details. The router bit would cut better at a higher speed but will perform adequately for this application if you first clear the slot with a straight bit as Chris described and feed at a moderate pace.John W.

2. 
   mahogany | Mar 25, 2008 08:40pm | #10

   Thanks John, you were rigth form the beginning!!

   Regards,

2. 
   user-1119429039 | Mar 24, 2008 11:11pm | #3

   I'll check with Chris Becksvoort.

1. 
   mahogany | Mar 25, 2008 04:47pm | #6

   Thanks David!! I will try to use a dovetail bit as John sugested...but i guess that can´t be so simple, because Mr. Becksvoort mention a "complex jig ans a long history".

   As soon as I try it will share the results with the forum.

   Regards,

1. 
   user-1119429039 | Mar 25, 2008 04:51pm | #7

   Dear Mahogany,

   I have some details from Chris Becksvoort. Here's how he describes his jig:

   The jig for cutting sliding dovetails on the slot mortiser:  I use a 3/4 x 5 x 24 piece of baltic birch plywood with two uprights, both about 3/4 x 5 x  x5.  The first is at the very end and has a 1" hole drilled to accomodate the tenon at the top of the post, the second is located farther along the jig, at the post's maximum diameter, just above the legs.  This second piece has a 3" hole drilled or band sawn, and is cut in half horizontally. Both pieces should have the holes drilled at the exact centers of the 5 x 5 uprights, to  insure that the post will be perfectly parallel to the jig,  the mortise table, and the cutter. Like the first piece, the lower half of the 3" hole piece is screwed to the jig, perpendicular to it's length.   Both halves are lined with leather, cardboard or felt, so the post doesn't get dented.  

   The post itself should have pencil lines perpendicular to its length, to locate the 3 dovetails, 120° apart.  Work the 1" tenon at the top of the post into the 1" hole.  It should be a very snug fit, with no play.  The lower end of the post should fit snugly into the bottom half of the cut-out.  Place the other half on top, directly over the bottom half, and clamp the top half down with the machines hold down.  Double check to be sure that the center of the post is the same height  at either end, and the same distance from the cutter.   If not add shims to correct the problem.  Insert a 1/4" straight bit into the chuck, and line it up with the pencil mark.  Set the depth of cut.  Cut the full lenght of the slot, loosen the hold-down, twist 120°, tighten and repeat, twice more.  This cuts a waste slot, to put less pressure on the dovetail bit to follow.  Then change to a 1/2" dovetail bit , set the correct depth, and repeat the cuts.

   Hope this helps. Let me know if you need clarification on anything here.

   Best,

   David Heim

1. 
   mahogany | Mar 25, 2008 08:39pm | #9

   Thanks David! I will try it. My only concern is the distance between the slot mortiser chuck and the sliding table. Slot mortiser bits are much longer than router bits. I have seen a longer router dovetail bits for special machines or jigs.

   Regards, this forum is the best.

   P.D. Please say thanks to Mr. Becksvoort. I his work is amazing.