When it comes to M&T joints, I suck. They look like crap and fit like, well they fit poorly. I just don't do them for that reason.
My life has changed. Under the tree was a Delta mortising machine and Delta tennoning jig. Finally put them together today and made a near perfect joint the first time out. It brings new life into woodworking as now I can finally make projects with M&T joints with no fear. I hope to start on one this weekend. The design is in my head already, just have to put it on paper and then start cutting. It is just going to be a simple magazine rack with a poor rip off of mission style.
Sure wish I had this combo when I built the Tudor bench and the 50 m & t joints..
For even better fit and consistency, try cutting your tenons with a double blade setup, cutting both cheeks at once. You aren't dependent on all of your wood being perfectly consistent in thickness.
Being a fairly new woodworker (or sawdust maker as my wife calls it), would you explain the mechanics of a "double blade setup"? Do you mean that you install 2 blades on your TS? What do you use for a spacer? How about the insert? If you could ease the confusion that's rampant in my old brain, I'd greatly appreciate it. Thanks in advance, Tom
On 28 Dec 2003 19:17:08 -0800, snipped-for-privacy@cox.net (Tom) scribbled:
Yes, 2 *identical* blades with spacers.
For spacers, I use 1/2" polycarbonate (lexan), 1/8" acrylic (plexiglas), other thin plastic scraps, cardboard from cereal boxes, paper, shims that came with my dado set. Anything else that's flat and that can be cut with a hole saw would work. I cut the spacers with a
2-1/2" hole saw, and then drill a 5/8" hole for the arbour.
You will need to make zero-clearance inserts, but then you have a few, doncha? You should be using them in any case if you're cutting tenons.
The procedure is to first cut the mortises. They don't have to be perfectly centred, but they do have to be a consistent distance from one side of the piece of wood you are mortising. Then you set up the blades and spacers so that the thickness of the tenon is exactly the same as the width of the mortise. A few test cuts and adding and removing shims are probably needed here, although I did get lucky once.
Then you adjust your tenoning jig, again with a few test cuts, until, when the tenon is inserted, the face of the tenoned board is exactly flush with the mortised board. Bingo! Just be careful to always put the same face against the tenoning jig.
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Or just use the same reference face on the tenon jig at all times.
Have tenon stock milled. Yes, it is preferred to mill it all at the same time to get it to the same size, but things happens in life.
This process described below is for centered tenons. If an off centred (centered for some viewers) tenon is required, then make the shoulder cuts on one face first, then adjust saw height to make the other face shoulder cut before starting the face cutting operation. Additionally, this is but one way of achieving tenons with the same thickness.
Cut the two shoulder cuts on the face sides of the tenon stock. If the stock has some variance in its thickness of 1/16" or less, one shoulder cut will be a little shallower, and once the face cuts have been made, a little clean up with a sharp chisel is in order if one does not raise the saw height to the full tenon length. If cutting shoulders on the edge sides, adjust saw height, and cut edge shoulders.
Cut the first face of tenon.
Adjust tenon jig to cut other face of tenon with the same face against the jig that was used for the initial face cut. In other words, offset the jig by the thickness of the saw kerf and the desired tenon thickness. The caveat here is if the jig will allow for it due to the thickness of the tenon stock, or the design or capacity of the tenon jig. The delta jig mention in the OP does work in this manner for 3/4" stock, or at least the delta tenon jig in my shop does.
Cut other face of the tenon.
Result -- same thickness of tenon, even though there might be a slight difference in the thickness of the tenon stock. This method is a bit slower than the two blade method. Not all saws can handle two blades and a spacer, and some woodworkers either dont have two blades or the inclination to use their saws in this manner.
For the delta jig, a spacer the thickness of the base plate is used during the above process.
*Cut tenon face furthest away from the reference face (usually marked somehow to signify that it is the good face) on all the tenon stock.
*Offset the jig. This usually means the tenon stock is now resting on the table saw top instead of the jig base plate. Put the spacer on the table saw top beside the jig, secure the tenon stock into the jig, remove spacer to a safe place to the side. Instead of using this spacer, one could adjust the saw height. To speed things up even more, often the jig and table saw are only set for the initial far face cut. For the second face cut, two spacers are used: the temporary one used to set the height of the tenon stock, and a second spacer (as thick as the saw kerf and tenon thickness) is sandwiched between the stock and the jig face.
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