Through Mortise Jigs, Round Tenons - With Router?

[Patrick Irish]

I'm closing in on finishing my first real woodworking project using joinery and no nails or screws. My dad, contractor of 30+ years, gets so frustrated its taking me this long and that I'm not using pocket screws :D

I've certainly took my time but have been learning as I go. Figured out how to taper the front legs and route some detail. They were 1 1/4 x 2 1/2, too square looking. Making deep mortises accurately is tough. Using a plunge router and DIY jigs I've got it to work but did encounter times where the bit wouldnt go deep enough and had to chisel the rest. This resulted in things not 100% square. I need to get longer bits for mortising.

Do you round the tenon or square the mortise on a through mortise? I wasnt confident in my squaring the tenon PLUS I didnt have a chisel that was 3/8 wide so I rounded the tenon with a file and sand paper. Looks good in the picture but there is a slight gap on top and bottom. Fits tight though.

Are there tricks for through mortises and tenons so lines and fit are perfect? I used guide bushings and slot in a piece of wood so the bit couldnt move left and right. Just required clamping and paying attention to a line I made.

Pic of table so far. I plan on running a stretcher shelf thing connecting the legs and mortising into both ends. The board will also taper from 5 1/2" on the thick end to 3" on the other end.

335100

[pat warner]

"Are there tricks for through mortises and tenons so lines and fit are perfect?"
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No, but if you call homework and practice (days & days) tricks, then yes.

In my view, square through tenons look better than rounded.
Requires the mortice to be corner chiseled, more difficult than rounding a tenon.
But that's what this art/hobby is all about, namely patience and practice.
Notwithstanding, you're to be commended on such a rigorous early project.

[Robert Hazelwood]

End mills are an option for a long router bit, and they cut well. The shanks will be the cutting diameter of the bit, so unless it is 1/4" or 1/2" bit you'll need an adapter bushing. I actually found a 3/8" collet for my Bosch 1617, so I can use my 3/8" end mill without needing a bushing. Keep in mind longer bits, especially if they are solid carbide, are riskier and you need to be careful in your fixturing, and limit how much material you remove in one pass.

I square all of my mortises regardless of whether they are blind or through. Before I rout the mortise, I make a square knife line at each end of the mortise and rout up to about 1/32" away from the mark. The knife line gives a reference for the chisel and limits any tearout from the router. On a through mortise, I will transfer the knife marks around the reference edges of the board so that I can make corresponding knifemarks on the other side that line up exactly. You will need to chisel from each side. You don't need a chisel exactly as wide as the mortise- although that is nice to have, it can be done with a narrower chisel. The knife line makes it fairly easy. And, as in any situation where you are chopping to a line, you want to sneak up on the line in small increments, rather than going right for the line on the first chop- too big a bite will tend to push the chisel past the line and you'll end up with a gap.

I've always used a homemade edge guide to do mortises, so I'm not sure how your template setup registers to the piece. With an edge guide you want to reference it off of the same edge on both faces when doing a through mortise. The stock preperation also needs to be done well - the piece should be square and all sides parallel to get consistent results.

[David Gutierrez]

kudos on the project. nice...

[John TenEyck]

Through mortises make sense when you want to use some form of wedged tenon, either permanent or knockdown. But if it's just for decorative purposes there is a far easier way to get that look w/o making a through mortise. Make a regular mortise for the stretcher tenons, and then route a shallow mortise on the outside of the leg for a decorative stub tenon. That way you can use a rounded tenon and avoid having to square the corners of the mortise for the larger, deeper mortises. On the outside you can square up the shallow mortises w/o much work and then fit the stub tenons to them. If you goof, no big deal, just make another stub tenon. And any little misalignment you have between the inside and outside mortises will be invisible.

It's even easier if you use loose tenons. Then you just route matching mortises in both the legs and ends of the stretchers and join them with a loose tenon. This approach allows you to cut the stretcher to final length before cutting the mortises, and avoids having to fit an integral tenon.

Strength wise there's no difference, although one could argue that a well fitted loose tenon is stronger than a poorly fit integral one, so why make it difficult? There's no need.

John

[lowell holmes]

I have the Mortise Pal tenoning jig. It is no longer available. I don't know if anyone is selling theirs or not.
Anyone that gets mine will have to buy it from my wife after I'm gone and God Willing that will not be anytime soon.:) It does an absolutely great job on through tenons.

There is a tool, General Tool model 870 mortise and tenon jig, you might want to look at. Home Depot adds show one. I doubt it will do as well as the Mortise Pal, but it looks like it might be one to look at.

The price is a fraction of the cost of the Mortise Pal.

[Bruce Wrenn]

HF sells a set of mortising bits for your router for about $10. You could always cheat. Don't do through mortise, but add a "button" to other side to give the illusion of a thru mortise. One of the WoodSmith shows on building the library table featured this method.

[lowell holmes]

I use mortise and tenon joinery more for strength rather than appearance. However, I do favor the appearance. In chair building, mortice and tenon joinery is required for strength. Manufacturers use dowel joints for attaching rails to posts. I've had to repair too many chairs where the joinery failed. As far as I know, one of my M&T joints has never failed. Just for the record, I hand cut M&T joints as well as using the Mortise Pal. There are times when one method or the other is appropriate.

[Mike Cutler]

I'm closing in on finishing my first real woodworking project using joinery and no nails or screws. My dad, contractor of 30+ years, gets so frustrated its taking me this long and that I'm not using pocket screws :D

That's because to your father, time equals money. I bet he's a pretty good guy though because he let you find your own method. Good on you for holding out against the pocket screws. ;)

I've certainly took my time but have been learning as I go. Figured out how to taper the front legs and route some detail. They were 1 1/4 x 2 1/2, too square looking. Making deep mortises accurately is tough. Using a plunge router and DIY jigs I've got it to work but did encounter times where the bit wouldnt go deep enough and had to chisel the rest. This resulted in things not 100% square. I need to get longer bits for mortising.

The router is a powerful, and extremely versatile tool, but as Pat stated it takes time, patience and practice to master all of the things it can do. There are also things is can't do.

Do you round the tenon or square the mortise on a through mortise? I wasnt confident in my squaring the tenon PLUS I didnt have a chisel that was 3/8 wide so I rounded the tenon with a file and sand paper. Looks good in the picture but there is a slight gap on top and bottom. Fits tight though.

I personally would have gone with a square, through, wedged tenon, if I was going to that much work. I would have pinned it through the side also. It's a lot easier, in my opinion, to round a tenon, than square a mortise by hand. That's nice work you've done there, and if that is the style you like than you will need to invest in a mortise chisel set. That way you're not limited again.

Are there tricks for through mortises and tenons so lines and fit are perfect? I used guide bushings and slot in a piece of wood so the bit couldnt move left and right. Just required clamping and paying attention to a line I made.

Time, practice, and patience, or do a "faux" through tenon as John suggested. It will still require good work to execute it, but it's easier to fit. If you start out your mortise with the chisel, to define the edges, and then switch to the router, you'll end up with a cleaner exit edge.

Pic of table so far. I plan on running a stretcher shelf thing connecting the legs and mortising into both ends. The board will also taper from 5 1/2" on the thick end to 3" on the other end.

335100

The table should look really nice when you're finished. be sure to post a pic when it's done.