Mortise/tenon w. plunge-router

[Niels J. Larsen]

Having just browsed Pat Warner's website, I stumbled across his mortise/tenon jigs.

Since I'll have to equip my not-ready-yet shop, I was thinking about buying a Festool MFT and use my Festool OF1400 router for this (instead of the jigs Pat Warner uses).

However - no matter how I were to do it - there's something I can't figure out:

How do you make sure that the mortise and tenon have the same width/thickness - i.e a tight fit ?

Looking at Pat Warner's website - you control the width of the mortise either by the width of the cutter doing only 1 pass - or by doing more than 1 pass.
The width of the tenon is controlled by the cutter itself.
So - how do you make these two fit precisely ?

I could imagine that if the stock used for the tenon was just 0.5mm thinner than what you had planned - then you'd end up with a loose joint.
Also if doing more than 1 pass for the mortise - I could imagine that everything would have to be VERY precise (guides, etc.) in order to get a tight fit.

All of this is based on me not having much experience with a router (yet), so forgive me if this is basic knowledge

What am I missing here ??

Thanks,
Niels

[Mark Singer]

With loose tenons , just make the mortises first. The size is then determined and make the tenon stock to fit by cutting on the bandsaw to the correct width and thickness. The same is true for true tenons....its just more difficult to get a precise fit with all the surfaces...

[John Stevens]

Hi, Niels. I've got the OF1000 and use it for routing M&T joints. Like Mark Singer, I prefer floating tenon joints to traditional M&T joints, but I've done some traditional M&T joints with the Festool router and MFT.

For traditional M&T joints, I use scraps that are the same thickness as the the work piece and I make test cuts, adjusting the router setting until the tenon fits properly. Once you get a good fit on a scrap piece, you'll get a good fit on your work pieces.

I use a "right angle jig" that's based on ideas by Pat Warner and Tage Frid. There's a pdf article with pics that shows the jig I made, but I don't think I'm allowed to post a link to it here. If you go to groups.yahoo.com, and search for the word "festool" you should be able to find the Festool Owners' Group. The pdf file is there under the "files" section. (By the way, the Festool Owners' Group is a very nice resource for info on these unique tools.)

[Rick de Roque]

I agree with Mark, loose tendons are the way to go when using the router (unless you have the FMT which is expensive). I built this slot mortiser from FWW (I can't remember the # off hand) and it has worked well and was cheap to build. I make the tendons by cutting the width on the TS and then use my planer to thickness the tendon. Tight fit and quick to use.

Rick

[Dave Richards]

Niels, you might take a look at the instructions for doing mortises and tenons with the WoodRat. You can download the instructions at the WoodRat site.

I'm not specifically telling you to buy a WoodRat although it does a great job of making mortises and tenons with a router. You might get some ideas however about how to do the referencing to get mortises and tenons aligned. The method they use is very low tech but it works. I have applied the ideas to other things with success as well.

[George Matthews]

I built this slot mortiser from FWW (I can't remember the # off hand) and it has worked well and was cheap to build.

Interesting... move the piece rather than the router.
I'd like to investigate further. What does FWW stand for?


-

[Jamie Buxton]

I cut most mortises with a plunge router. For simple 90 degree joints I cut the tenons on the table saw. I adjust the rip fence to get whatever width the mortise wants. A few years ago I finally bought a fence with a microadjuster, so that makes the tweaking a little easier. I generally use floating tenons for angled joints. The floating tenon makes it easier to get the shoulders all in the same plane.

[Paul Dwight]

Niels,

You're correct that with the FMT the width of the mortise/tenon is fixed by the diameter of the cutter. If you need more strength than is provided by a 1/2" tenon, you can do side-by-side mortise/tenons to your heart's content.

The FMT is expensive but I love mine. Beautifully made and works exactly as advertised.

Hope this helps. -- Paul

[Andrew Ault]

What does FWW stand for?

FWW=Fine Woodworking magazine

[Dan Forman]

You could always cut the tenon just slightly oversize, then use a shoulder or rabbet plane to achieve a perfect fit.

Dan

[Don Baer]

You could always cut the tenon just slightly oversize, then use a shoulder or rabbet plane to achieve a perfect fit.

Dan

Thats what I do but since I have neither of those two planes (yet) I just size them with a rasp.

[skip gleichman]

for loose tenons, i use long stock and plane to thickness after all of the mortises are cut. I seem to do very well when carefully planing away material until it all fits and have not had to use hand tools to achieve this.