JDługosz

I've been musing on how to cut some mortise and tenon joints. There are certainly many ways to do it, but I'm concerned with the accuracy. I've got an idea on how to make a non-adjustable template/jig using the router table with the precision fence, and then use the hand-held router with that jig.

But I suppose that most people use hand-eye-motor skill instead of metrology. How do you get a mortise in just the right spot? Or, just how perfectly does it need to fit? Do you expect there to be no gap that needs to be filled with glue, and expect the two pieces to have their faces flush with no scraping or sanding needed over the seam?

I saw a fixture in a book that held the router sideways and provided a sliding tray. It said to adjust the z-direction, raise or lower the fixture in the bench clamp! How can you get that at just the right height and be level?

—John

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bobj3

Hi John

You are right, many,many ways to get the job done..

Here's just one more and this one will put the slot dead on,,, the stock can be 3/8" to 1 1/4" wide and slot will be dead on ever time...with a floating tenon the joint will line up ever time...and it's quick and easy...


see the links in the post

http://www.routerforums.com/53377-post40.html


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harrysin

If you want a simple non critical method of jointing which is plenty strong enough for most projects and doesn't require any measuring, give a thought to biscuit jointing.

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berry

Those were great drawings and pics but I'm unclear on one point or maybe two things. Is there some sort of stop block you use, at the beginning/end of the cut, to control the length? This seems really difficult because when the router is 'twisted' to bring the bearings into contact with the side of the work piece, the base will be at a sharp angle relative to the work.

Thanks in advance.

bobj3

Hi Berry

You can put on a stop block in place but the norm you don't need one because you can see the bit at the start and the end of the slot...

To add a stop block, just take some scrap stock and go across the two upright parts of the jig, small dry wall screws will do the job..then all you need is drop and slot from one stop block to the other...I would also add a stop block for the stock you want the slot in, so you can just slide it in place and lock it in place for all the parts you need to do.. slide in and lock in place with the wedges.

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rmaxa

Welcome to the forum John. There was an article in Fine Woodworking about one or two issues back that showed how to build a mortising jig. It made setup exact every time. I've attached a link to the video that shows how to use the jig. Hope this helps.
http://www.taunton.com/finewoodworki....aspx?id=28696

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Rolf

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bobj3

Hi Rolf

I must be a bit slow ,,,what I see is a jig that will work with one size of stock, that's to say if you are using 3/4" thick stock for the rails you will need to rework the jig big time to put the slots in a leg lets say...a 2" wide one..not to say anything about most 3/4" stock is not always the same...all the time..

.But it's neat jig to put the slots in the ends...
But if you use a only one clamp to hold the stock good chance it will slip when you put the down presser down to put the slot in...but I must be a bit slow on the up take of the jig..




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rmaxa

I don't remember all the details, but it was my understanding that the jig works for more then just the ends. I was also under the impression that it was adjustable to different stock wides. I always try to ensure that all my lumber is planed to the same thickness, so I would assume if it's 3/4 it will all be 3/4. I do need to go back and re-read the article.

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Mike

John, when we are setting up for a mortise cut we generally mark the wood and this can be easily seen with most methods of mortising. The Oak Park design uses a 7" square mounting plate with roller bearings on the corners for stability. Rockler recently introduced a sub base plate with screw in pins to accomplish the same job. It's far cheaper but lacks the stability of the 7" plate. There is no reason why you could not install pins in your routers sub base plate to do the same job. As far as fit is concerned, the pieces should fit together well but not need to be forced. Yes, you need to allow room for glue squeeze out. If the parts are too tight and different woods were used you might face wood splitting with temperature and humidity changes.
The "sideways" pivoting mount works well. As you pivot the mounting plate up the bit raises. Once you are at the desired height you lock it in place. I think this is what has you confused: the starting and ending points will vary depending on how thick the wood is and how high the mortise is from the table sliding tray. The higher you set your bit, the closer to the pivot pin you are.

A router bit will leave a half oval end in your mortise which usually is ample room for the glue squeeze out.

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JDługosz

I've seen the two-peg idea before, but using bearings is a nice improvement I've not seen. I guess to make it off-center you just position it in your holder with some shim stock. It also requires that you have a bit the correct diameter, but those details are usually arbitrary so that's not a big deal.

How do you get stops to work with the base diagonal like that?