Router Mortising Jig/Fixture

The block the clamp is attached to should not go up all the way or
should be removable to allow mortising in the center of a stile or
rail. This design would only be useful for mortising stock a fixed
distance from the stock face. Fine for cabinet doors, but not as
useful for making offset mortises in table legs and things like that.

I've found, with jigs like this, that the one clamp is inadequate and
the work will move when being cut. An additional clamp helps,
but but slow down setups for each cut.

You really need to plan to get a clamp head pretty close to right on
top of where the mortise is being cut. That's why many of these
sorts of jigs have holes in them for clamps.

The frame member will wiggle under cut load from the end mill, so
the solid clamping is pretty important to getting consistent mortise
width.

Thanks Leven. I seriously looked at building a Horizontal Mortiser, being the HorizontalMike that I am ;-) but really like the simplicity of a vertical mortiser for the moment (need to get some projects under the belt).

Loren,
Thanks for pointing out some things I have NOT thought about:

"The block the clamp is attached to should not go up all the way or
should be removable to allow mortising in the center of a stile or
rail."
BINGO! Maybe I could just shorten the vertical fence to start just AT the beginning of the mortising opening and use one of my Veritas dog-hole surface clamps to hold the removable vertical clamp/board. That would make this setup more flexible.

"This design would only be useful for mortising stock a fixed distance from the stock face"
This is why I am making the opening 2in wide. I have depth adjustment abilities with the router fence, but just HOW MUCH MAX DEPTH ADJUSTMENT DO I NEED from the edge? 3-inches? 4-inches? Right now I am looking at building rather simple Mission style tables and such… but I am sure I will progress from that sometime in the future.

"...one clamp is inadequate…"
I'll add a second and use additional furniture clamps if needed.

"You really need to plan to get a clamp head pretty close to right on
top of where the mortise is being cut. "
I am thinking that making the vertical block clamp/board independently anchored to the front of the workbench MAY help me take care of this?

Mike, here's a photo of a horizontal mortiser that I made several years ago. I use it mostly for cutting tenons on the ends of long stock, but it works well for mortises too. Very simple and stable. The one that Steve posted looks a little unstable, with too much hardware. It's based on the one in the book "Making classic Joints with power tools" by Yeung Chan

Here are some pictures of mine. I built it as a prototype a few years ago and just kept using it. The main difference is that mine uses a fence as the guide on the back and the fence can only move along one axis. With this I can mortise any thickness of stock with any thickness of mortise. It is nice to set up for repeatable mortises. I can clamp stop blocks in the fence track to have identical length mortises. I have even taped 4 degree shims to the face to mortise at different angles. When I make a better one I will improve the clamping. Maybe some t tracks with some type of clamps to go in them. The support wing screws off and it is not needed, but I like that I have it there to clamp things to.
I really debated between this type of jig and one with bushings. If I were to use bushings I would need more jigs for different thickness of stock. I can adjust my fence depth to stock over 3" thick (like bed posts).
I never considered using my bench vice. I may have to try that.
Yours looks good. The one thing I would consider improving is your clamping system. It is the one thing that I don't like about mine. At some point your vertical block that your clamp is on will get in the way. Mine does all the time and it is much smaller. Yours would be nice to have when cuting a mortise in the end of stock but I just use a line to line it up on and that seems to work.

Tim

Jim,
It was one of those balls to the wall kind of things in that my FM radio (walkie talkie) died shortly after launch and my flying partner and our HS student chase driver lost contact with me within the first 5 minutes of the flight. I had borrowed my buddy's radio and he had forgotten to charge it. So before I got to a thousand feet (above the ground) the radio started giving out. I flew the first 10-15 miles by watching my flying buddy's location while working the thermals. Then at roughly the 15 mile mark I had to make a decision to either follow my buddy to the west and follow what he thought was good lift or continue heading north north west in what I thought would pan out (while still being reachable by road via chase driver). I chose to stay my course to the NNW and found a good thermal to work that got me back to 5k or so in altitude. My friend got shot down and landed within 2-3 mile after that and our chase driver picked him up. From that point I was on my own and that second portion of the flight was probably some of the best flying I ever had the opportunity to do.

Normally I would (should I say wood?) work the lift above 5 thousand feet before heading downwind looking for my next thermal (heading NNW), but with no one following me I needed to be more aggressive and would head out earlier at 4,500 feet or less sometimes. I would glide NNW feeling/listening (to my variometer/vertical airspeed indicator) and sometimes got lower than 1,000 feet which was normally a death nil indicator because thermals usually don't kick off below that altitude and you are left scratching out your last glide to landing (in other words looking for a place to land that doesn't have trees, etc.). I remember 3-4 of them before I came up on San Saba. Just south of San Saba I got down to just 900 feet and looking at my watch saw that it was after 5 or 6pm and knew it was late for thermals to still be active. Luckily, I caught what was probably the last thermal of the day just on the south end of town. It was weak, but as I worked it, it took me directly over town and I topped out at nearly 5,500feet above the town with the sun hanging low on the horizon.

My goal had been to try and get to Goldthwaite, TX but that was at least another 20 miles NNE and I couldn't even see it on the horizon. So I started looking around and saw the San Saba Airport. The lift was light but steady at 5,500ft but I started thinking as I looked at the airport,... NO radio, NO water, NO clear goal on the horizon,... so I started circling ever so gently over the airport. I figured the San Saba Airport was as far as I could fly that day and with gentle circles I managed to stay in the air for nearly an hour more, directly over town and the airport before finally landing, not on the airstrip but nearer the airport manager's trailer to the south of the runway (and in the grass). After landing, I unhooked from my glider and walked a couple hundred feet to the trailer and knocked. The gentlemen, a retired sheriff, answered and was amazed that he could not see any motor on my glider. After explaining where I was coming from, he let me call my girlfriend in San Antonio. My flying buddy and I had already arranged to use her as a contact point if and/or when we might lose contact with each other during our flight.

After making contact with the girlfriend, I went back to my glider and started breaking it down and packing it up for transport. Before I could finish with that task my flying buddy and chase driver rolled up at the airport honking and all smiles. They had continued north and had stopped in San Saba to check with my girlfriend in San Antonio, got the message and was nearly at the airport before I got there! It was a great flight that day! And one to remember! I flew nearly 50 miles that day.