Replies

1. 
   rslatm | Apr 15, 2003 02:06am | #1

   Make the mortise parallel in the apron and angle the mortise in the leg where you have more stock
2. 
   Lilshaver | Apr 15, 2003 09:16am | #2

   I don't have any problems with loose tennons in most applications. I actually prefer them because they are usually less fiddley. I can make loose tennons fit better quicker than those cut out of the stock. However in this case, it seems that the tennon is too short in the apron. I would advise you go with Rick's approach, or better yet, cut the tennon integral with the apron.

3. 
   k9s | Apr 15, 2003 04:49pm | #3

   Don--Offsetting the loose tenon to the inside of the apron may help the additional length you need--Bruce

4. 
   MHargrove | Apr 16, 2003 10:04am | #4

   I've got this exact problem on my current project -- a small triangular table.  Two of the aprons are meeting legs at 45 degrees.  I'm going to use loose tenons, and route mortises into both apron and leg.  The apron will have the 45 degree bevel cut on it, but if you make an extra deep mortise while the apron stock is still square, and *then* use your favore mitering technique to cut the 45, what looks to be a tricky mortise is actually easy.  I'm building a jig to hold the leg, which does have to have a 45 deg mortise cut into it.  I just dreamt up the jig tonight, and it looks good on paper :-)   I glued up a couple of extra legs to practice on tomorrow night.

   -M.
1. 
   TomMGTC | Apr 16, 2003 02:16pm | #5

   One of your mortices will have to be angled for this to work won't it?Tom

2. 
   SgianDubh | Apr 18, 2003 08:48am | #9

   If I read you right, Mark, you're trying to solve the classic problem of assembling a triangular frame of three legs and three rails. Mortice and tenons are a difficult option, particularly in a small frame. The difficulty is that, as viewed from above, a triangular frame of this type only fits together easily in a drawing. If you picture assembling the job from above, any two legs, and all three rails can be got together easily-- the only problem is that the tenons sticking out at the end of the rails that are yet to receive the last leg are already in their final position, and somehow that last leg has to be got in place.

   The usual solution is to make the mortices and tenons a bit sloppy so it'll all wiggle together, and the bigger the frame, the more flex is available in the rail, so reducing the sloppiness necessary in the mortises and tenons. There are other solutions, such as angling a couple of tenons into one specially made leg, but that tends to make the tenons weak through them being mostly short grain.

   I've always found it much easier to work a face on each leg that is perpendicular to the length of the rail and to make every joint a sliding dovetail-- similar to a typical single column, tripod table construction from the English Georgian and onwards through the Victorian era, etc. In your case, Mark, simply lay the rails on a flat surface in their final position, or something close to it, top side down, and slide the dovetail slotted legs in place with a bit of glue, and maybe lash it up with a webbing clamp or two.

   As to Donalds original problem, you might do as others have suggested--- change the angle of the mortice in the leg to be parallel to rails length, offset the mortise for the loose tenon to the inside face of the rail, change the angle of the rail to leg joint a bit-- you could use a curved rail for instance, or use a traditional tenon worked out of the rail, and the last option would be to redesign the project and the joinery to eliminate any perceived weakness.  Slainte. Website                                   The poster formerly known as Sgian Dubh.

5. 
   rslatm | Apr 16, 2003 11:05pm | #6

   Angle the mortise in the leg is the way to go for sure.  Just curious as to what machine, method, you are using to make the mortises.  A slot mortiser?  Jigged up router?
1. 
   DonaldCBrown | Apr 17, 2003 12:29am | #7

   ...what machine, method, you are using ...

   Its a sort-of slot mortiser--an x-y table to move the workpiece and a router and spiral bit to do the mortising. Angles require building a ramp of the appropriate slope and clamping that to the x (or is it the y?) table.

   Thanks to you and others for the suggestions.

2. 
   MHargrove | Apr 18, 2003 07:54am | #8

   One of your mortices will have to be angled for this to work won't it?

   Yes, exactly -- 45 degrees for my project.  I built a jig to let me route the mortises.  A couple of pix of the jig are attached.  The two visible stops are sitting on small pieces of T-track.  I put the router down on the jig, then adjust one of the stops to center the mortise, then adjust the other to the width of the router base.  Not visible are two other small pieces I clamp on as length stops for the router to set the mortise length.

   "Centering" a 45-degree mortise required several experiments, but once you get the sight-picture it's easy to reproduce.

   -M