# Table Routed Mortises



## PorterCable690 (Apr 24, 2012)

There are many technical approaches to create mortises and one of them is to use a tabled mounted router. It is fairly easy to use a variety of methods to measure out and mark the dimensions of the mortise on the piece. But what happens when you try and translate those measurements then position your piece on the router table in relation to the cutter bit? Tricky, tricky....

Here is an easy recipe to help that situation:

1) Mark your piece with the boundaries of your mortise;
2) Tape a blank piece of paper on the face of your closed router fence;
3) Raise the top of your mortise bit about an inch or so above the table surface and position your fence to the desired distance away from the cutting edge of your mortise bit;
4) Position your piece approximately at the starting or finishing boundary point of the mortise path and so it rests on the mortise bit;
5) Use a dental mirror ($7.95 USD at CVS) to position your piece exactly at the starting or finishing boundary point on your piece;
6) Mark a vertical line on the paper following the vertical profile of your piece;
7) Label that vertical line either "S" or "F" to represent either the starting or finish boundary point of your intended mortise;
8) Mark another vertical line on the paper just prior to your starting and finishing vertical lines. You should now have four vertical lines. The two inside vertical lines will be your safety lines that will alarm you when you are approaching the final boundaries during your routing path travel;
9) Lower your mortise bit to the desired starting height;
10) Turn on your router and lower your piece on the rotating mortise bit midway between the boundaries of your desired mortise path, making sure you keep your piece securely against your router fence;
11) Advance your mortise cutting while using the vertical lines as your start and finish guides to complete the mortise.

Easy parcheesy...


----------



## mjdorsam (Nov 27, 2011)

Keith:

Great Instructions - the Forum benefits from members trying and documenting approaches like this. 

As a suggestion, you may want to consider using a feather board to ensure a continuously tight fence-to-workpiece fit while lowering the work piece onto the bit - the bit will try to throw the piece.

Recently, in another Thread, the Forum discussed using Guide Bushings for a handheld approach to the Mortise, and the RT for the Tenons - which is the way I'm doing 40 of them, now. Either way, the Router Table approach provides stationary tool stability, and the precision available from the RT/RT Fence setup.

As an aside, can you share how you will do the Tenons? 

Thanks, 
MikeD


----------



## Mike (Nov 22, 2004)

Mike, this is a situation where feather boards are of little use. It would be more trouble to position them for a short piece than it is worth. Featherboards are best used on long pieces where you must change your hand position while feeding the material.

The dental mirror is an interesting idea, one I have never seen before. Let me share the Router Workshop method for cutting mortises. In this case the mortise is a through cut making a slot but it works the same way. Make a mark and position your fence so your material is centered on the bit. Put some tape on the top of your fence. Slide the material up to one side of the bit and transfer this location to the tape. Repeat on the other side of the bit. Mark lines on each side of the tape the distance you want the offset to be... how far from the edge of your piece you want to start and stop the cut. For narrow pieces like this rail you can clamp blocks in the start/stop positions for easy alignment. Plug in and start your router then lower your material onto the bit. Make your cut. While holding the material in place power down your router. Once it has stopped remove the piece. Repeat this for all your mortise cuts. I have seen several sources suggest to be sure your mortise is perfectly centered you should reverse the piece and repeat the operation. When you think about it this is seldom critical, it just has to fit. You can eliminate problems by making a small mark on the face side of your piece and always placing that side down to the table or against the fence depending on the operation.

Every instructional video I have seen says you must play with sneaking up to the size cutting a tenon to fit. I think it is much easier to cut a mortise in the mating piece and use a floating tenon. Consider this: you make a cut with a router bit. The router bit is a known size, for example 3/8". Cut a long strip to 3/8" thickness and then saw it into the lengths you need for the tenons. Much easier to my way of thinking and the joint will be just as strong as if you had spent the time sneaking up on the tenon size. Another advantage to using this method is you can select a hardwood like birch for a strong joint, even when using soft wood like pine for the project. You can also make a bunch of tenons and have them ready for use on your next project saving on set up time. Or you could spend hundreds of dollars to buy a Festool Domino machine for the same effect. :jester:

The photos below show the set up process for the mortise cuts on a flat piece of Masonite but it is the same for all mortise cuts. You can also complete the steps shown and have a mortising attachment for your plunge router.


----------



## mjdorsam (Nov 27, 2011)

Mike:

Thanks for the follow-up - I see your point. I guess I'm hesitant to lower a piece of wood onto a rotating bit; though, I'm having difficulty with my current - guide-bushing - approach (the bushings (the PC-type within the Bosch retainer) are not remaining centered, and the router bit is chewing them). I'm in a slow competition of gaining experience while attempting precision work.

I will try the approach you've mentioned - again, thanks.
MikeD


----------



## PorterCable690 (Apr 24, 2012)

MikeD -

In most cases, I use floating tenons for a variety of reasons. Not the least of which, I seem better able to get the final fit and finish that I want and need with the least amount of finish sanding.

So here is what I do. I always mortise first on the router table as previously described then fit the floating tenons to the mortise. Take into consideration the final width of your floating tenons then make your mortises to that length. 

I begin with a piece of dimensional, in this case, poplar - 1/2" by 5.5". Rip it on a TS. Cross cut to the desired length. Use a sharp hand straight edge chiesel to round the edges, all the while, aiming to mimic the same profile of the mortise made on the router table. Start with one end of the floating tenon removing material off the edges then the other end. It usually only takes a few chiesel strokes to get the rounded profile where it needs to be for a tight fit. Once in a while, I may have to block sand the newly rounded edges of the floating tenons to get that snug fit. I tend to label each end of the floating tenons and the corresponding/mating mortise with a unique number so that the wood shop gremlins don't interfere when many floating tenons are required for a project. 

My experience has been that this techinque is truly part art, however, being the utilitarian that I am, speed is paramount to me since my time is limited. I've tried round over bits and measuring, but I can whip these kinds of floating tenons out much faster using this approach with better accuracy, and less finish sanding.


----------



## PorterCable690 (Apr 24, 2012)

MikeD-

BTW... I also have a habit of pinning my tenons from the backside of the workpiece. I tend to gravitate to 1/4"-dia. dowels slightly sanded along their lengths to accommodate for glue and glue swelling, then tapped into place. A little orbital sanding to flush and you are there. 

Here in sunny SoCali we don't have to worry about humidity and the respective joint expansion issues. 

Currently, I'm working on a headboard and the dowel pins will add an extra level of strength for those unexpected, yet significant, forces that a headboards have to endure when you have honeymooners as overnight guests. With a CalKing mattress, the span is over 70-inches necessitating extra umph in the tenon department.


----------



## mjdorsam (Nov 27, 2011)

I'll post pictures today - yesterday was a 1hr+ glue-up; and I'm now removing excess glue (the epoxy swells during drying, and all of my joints look horrible); then pinning the tenons. I pre-drilled (cross-drilled) the mortise cavity on the drill-press, after a dry assembly; the glue-up was successful, though more messy than expected; and the project (an Outdoor Bench) is now a rock-solid one piece. I have about one day clean-up and final sand; then, attaching the seat slats.
MikeD


----------



## PorterCable690 (Apr 24, 2012)

Yup... the mortise and tenon techinque takes a bit of practice as it is as much an art as it is engineering. The word "frustration" comes to mind when talking about M&T's.

You might consider drilling your tenon pins after your glue up...it tends to be less messy due to less glue push out through the pre-drilled holes and there is usually less finishing sanding involved. Hear, hear to less finish sanding.


----------



## PorterCable690 (Apr 24, 2012)

In the event, that a deadline is fast approaching, time is of the essence, and pinning the tenons is necessary but becomes a time vampire....here is a quick and easy way to shorten the task.

An off-the-shelf irrigation pipe cutter makes sizing wood pins from long dowels as easy as slicin' salami.


----------



## jeremy.honner (Feb 10, 2014)

I find it helps to drill an undersize pilot hole first. Its then easy to drop the piece on to the bit and avoid hitting the start or stop markers, and the piece drops in more easily.

I also try to use a stop block where the piece length permits to get more accuracy and repeatability.


----------

