This is a long table for hobby work, surface is a 6' piece of countertop. I"m using a 5" wide apron all around, 66" long, which I hope is wide enough to prevent sagging, cornered with 2-1/4" legs. So how to join the apron pieces to the legs? I started to think M&T, but the way I cut tenon cheeks is to hold the piece vertically in a jig and run it through the TS, and this won't work for a 66" long piece of wood. Then I thought of using a hangar bolt through a diagonal brace at each corner (what's that joint called?). Finally I thought to use biscuits. But I still don't know which is best. Advice, please?
On 08 Aug 2003, Dick Smith spake unto rec.woodworking:
If you can support the apron pieces horizontally, perhaps with a helping hand, you can cut the tenons with repeated passes over your tablesaw blade. Set the fence to the depth of the tenon, the saw blade to the thickness of the amount you want removed, and go to it. A bit slow, but effective.
Biscuits are dandy if you need help edge gluing boards, but as a mechanical joint on a 6' table that's going to see heavy use, they won't last a week.
Saw them by hand, Dick. - it's not that hard to do. Mark out your joint using a mortice gauge or marking gauge, knife in the shoulders deeply with a craft knife. Run a blunt pencil over the gauge and knife marks. Because the pencil is blunt, it won't go right into the cut, so it will leave two parallel pencil marks like little rail tracks, one on either side of the cut. You're aiming to remove the little line on the waste side of the cut, and leave the little line on the good side. (This is called splitting the line and is easier than it sounds with a good saw)
Put the apron in the vice at 45 degrees-ish and saw the diagonal of the both cheek pieces. Flip the wood vertically and saw the other two diagonals of the same tenon. Stand the apron in the vice vertically and saw vertically downwards to the shoulder line - the two diagonal cuts you've made already on each cheek will act as guides and give you a good accurate cut.
Clamp the apron flat on the bench and make the shoulder cuts.
You can't beat M&T for a good strong leg joint. Forget biscuits and eschew hardware.
You can do the cheeks as an 'overlapping' set of dado's.
clamp a short piece (i.e. stops well _before_ getting to the blade) of stock to the fence, such that the edge of the blade *AWAY* from the fence is the required depth of the cheek. but the board up against that guide, and make a pass over the blade. rotate board 180 degrees, and do other side. then rotate 90 degrees to do one short edge, and another 180 to get the other short edge.
Now, pull the board back "most" of the width of the dado, and make another
4 passes.
repeat until you reach the end of the board.
Voila! *grin*
Note: the way this works is _exactly_ "backwards" to what you're used to. You used the fence to determine the thickness of the cheek that was being removed, and the height of the blade to determine how 'long' the tennon was. With _this_ method, the fence determines how 'long' the cheek is, and the height of the blade determines the thickness of the cheek that is removed.
NOTE: if the cut-off is different on wide and narrow sides of the board, do all the wide side 'overlapping' cuts first (both sides), *then* re- adjust the blade height for the narrow-side shoulders, and proceed with all the narrow side 'overlapping' cuts.
This is somewhat slower than doing the 'vertical' board, but lets you manage with nearly _any_ size of rail.
How about a router and jig. Do a google search for mortising jigs, or router mortising jigs. The Dewalt website had a nice one that I use alot. It works great. I would give you the URL, but my computer crashed 2 days ago, and Im just getting back up. The nice thing with the router jig is it doesnt matter how long your apron pieces are, as long as you can lay them flat, you can affix the jig to them, and cut away. Good luck.
The board (e.g. stop block) clamped to the fence is not really necessary in this situation, is it? Since there is no 'cutoff', there is no loose piece to get kicked-back, right?
If I understand kick-back correctly, you can run your board right up against the fence when you are _not_ making a through-cut. Anyone?
************************************ Chris Merrill snipped-for-privacy@christophermerrillZZZ.net (remove the ZZZ to contact me)
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There goes that little voice in my head again, saying "be careful!!!". I'm thinking that this is a 5 foot plus hunk of wood that may not move exactly as you like. I'd use a wide sled here if the fence played such a role. Tom
"Better safe than sorry" applies, when dealing with 'big' pieces.
With a *5-1/2*foot*long* board, there is a non-trivial risk of it 'twisting' a bit, while riding against the miter guage.
If the board is butted up against the fence when this happens, it will result in the board 'binding' between the fence and the blade.
With *UNPREDICTABLE* results. I'm sure you're familiar with Murphy's Law. This is the kind of situation where _O'Brien's_Law_ comes into full play. It states, simply, "Murphy was an *optimist*".
If the board is _not_ constrained against the fence, then it 'twists' freely, and the -only- side-effect is a slightly widened kerf, and/or maybe a little 'burning'. Essentially the board is free to move side- to-side, that "very tiny amount" needed to minimize the blade contact with the side of the cut.
Do you feel *LUCKY* today??
Note: if the piece was only a couple of feet long, it'd be *much*easier* to keep it 'tight' to the miter guage, and thus a 'greatly reduced' risk of twist/bind.
30+ years ago, the shop teacher at my high school had a saying, that he used with regularity: "you've got to out-think the materials you work with".
*NOT* terribly flattering, when the 'materials' are a block of wood, and he _intended_ it (mostly, anyway) along the lines of 'measure twice, cut once', *but* it is a *very*valuable* precept with regards to shop _safety_.
Anyway, there _were_ a fair number of kids in the class who -did- have trouble 'out-thinking the materials'.
The facts remain, (a) that the "inate animosity of inanimate objects" *is* a real force, (b) if you don't give it a _chance_ to act, you're unlikely to be surprised, and (c) O'Brien is *always* looking over your shoulder, awaiting any opportunity.
That's ok - if you're cutting a rabbet - which is essentially what your are doing when cutting a tenon in this manner. No matter which way you tilt the piece (forward or back) the corner that stays in contact with the fence defines a pivot point. There is no part of the board that can get _closer_ to the fence/blade than it was when it is against the fence.
In other words, whichever way the board moves, the board is moving AWAY from the blade and fence. There is nothing remotely dangerous about that.
Of course, this assumes that you start at the _end_ of the board and work your way into the tenon.
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