# woodrat rounded tenons



## bridger (Nov 26, 2010)

I'm a bit late to the game with the woodrat, but have plenty of experience with routers and jigs, mostly purpose built in the shop. I bought the rat second hand and am in process of setting it up. I have some parts on order, including a manual. as a first process I'd like to get it making mortise and tenon joints efficiently. what I am not seeing is how woodrat handles the rounded end mortise/ square sided tenon problem. I have looked at the woodrat site, where they show lots of round sided tenons but no instructions I have found about how to do it, and watched videos of making tenons, but they are all square sided.

somebody help me out here?


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## Mike (Nov 22, 2004)

Call the 800 number and ask Martin.

You can download the manual. I highly recommend the push bar.


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## Cherryville Chuck (Sep 28, 2010)

There is no way to cut a square hole with a round bit. You'll always have a radius in the corners equal to the radius of the bit. One solution is to mortice both sides of the joint and use floating tenons which can easily be rounded with a round over or bullnose bit. The other solution is to round the tenons off by hand. Almost all of the holding power of a tenon is the flats so the ends don't have to be perfect.


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## bridger (Nov 26, 2010)

Cherryville Chuck said:


> Almost all of the holding power of a tenon is the flats so the ends don't have to be perfect.



most of the glue area of the tenon is the cheek, yes. the edge, as per this: 









doesn't have a lot of glue area but is what registers the joint laterally. I want it to fit.

tenon router jigs that produce a rounded tenon exist, plenty of them. I just want to know how with the rat.


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## bridger (Nov 26, 2010)

from the woodrat website it appears that the rat way to rounded tenons involves a template add on called the pathfinder. simple enough, I can probably fab my own. what I don't see answered there is with the pathfinder accessory how the feed is done. I guess left/right is with the crank, in/out is freehand to the template. anyone here using the pathfinder?


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## Cherryville Chuck (Sep 28, 2010)

bridger said:


> most of the glue area of the tenon is the cheek, yes. the edge, as per this:
> 
> 
> 
> ...


Most experts agree that you shouldn't apply glue to the cheeks, there is very little holding power added and the squeeze out causes finishing problems. As I said, the faces provide almost all of the holding power because for the glue to fail it has to shear. If you round the ends of the tenon properly there will still be wood against the ends of the mortice, eliminating the problem you are suggesting. You can also pin the joint together with dowels after assembly which can be a nice looking feature.

One of the advantages of using floating tenons is that they can be machined to fit the router bit you use to mortice with. They are easy to cut on a table saw and the ends can easily be rounded with a router and table. Tenons cut on a saw or with a router often have to be fitted because of small variations in board width.


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## bridger (Nov 26, 2010)

Sorry, I meant that the face of the tenon has the large glue area.

I'm thinking in terms of a duplicator kind of device with a follower bearing matching the cutter diameter.


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## CharleyL (Feb 28, 2009)

What's wrong with a rounded end mortise and a rounded ended tenon that fits into it? Just because we made them square ended in the past, doesn't mean they have to be now. I use a Leigh FMT Pro jig to make rounded end mortises and rounded end tenons, they fit together perfectly, and the joints are as strong or stronger than square cut mortises and tenons because the fit is so much closer and more precise. I've had my FMT for about 10 years now, and would never go back to the old ways of making square ended M&T joints. I've never used a Woodrat, so I can't comment on it, but I see nothing at all wrong with curved end mortises and tenons. In fact, a square ended tenon can be used very successfully in a round ended mortise, if the tenon perfectly fits the flat sides of the mortise and the curved ends of the mortise are left empty. The spaces hold excess glue very well.

Charley


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## bridger (Nov 26, 2010)

CharleyL said:


> What's wrong with a rounded end mortise and a rounded ended tenon that fits into it? Just because we made them square ended in the past, doesn't mean they have to be now. I use a Leigh FMT Pro jig to make rounded end mortises and rounded end tenons, they fit together perfectly, and the joints are as strong or stronger than square cut mortises and tenons because the fit is so much closer and more precise. I've had my FMT for about 10 years now, and would never go back to the old ways of making square ended M&T joints. I've never used a Woodrat, so I can't comment on it, but I see nothing at all wrong with curved end mortises and tenons. In fact, a square ended tenon can be used very successfully in a round ended mortise, if the tenon perfectly fits the flat sides of the mortise and the curved ends of the mortise are left empty. The spaces hold excess glue very well.
> 
> Charley



Two problems with a swuare tenon in a rounded mortise: one, it requires an oversize shoulder to cover the gap and two it doesn't provide positive lateral registration.

I'm fine with rounded tenons in a rounded mortise, and I think I see how to accomplish it with the rat. I'll have to wait for my parts from Martin before I can implement it though.


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## Cherryville Chuck (Sep 28, 2010)

bridger said:


> Two problems with a swuare tenon in a rounded mortise: one, it requires an oversize shoulder to cover the gap and two it doesn't provide positive lateral registration.
> 
> I'm fine with rounded tenons in a rounded mortise, and I think I see how to accomplish it with the rat. I'll have to wait for my parts from Martin before I can implement it though.


They are the same exact shoulders you would have with a square tenon. The difference is that the rounding increases the width of the shoulder on the face side, the shoulder width at the perigee of the rounded end will be the same in either case, square or rounded, so in the end the shoulders are essentially the same. And the registration will be exactly the same as if you made square tenons for square mortices. You aren't supposed to remove any material at the center of the tenon so nothing changes there either. It seems to me you are assuming things which aren't true.


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