# Thru Tennons



## kimosawboy (Jan 26, 2010)

Doing a project that requires rounded thru tennons that will be shown, Mortise is no problem as just a simple 3/8 bit, but the tennons are becoming a pain.. yes I know I can hand round them by hand but I would much rather use a jig so I can get the same results every time. Any one done something similar??
G Vavra


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## Herb Stoops (Aug 28, 2012)

kimosawboy said:


> Doing a project that requires rounded thru tennons that will be shown, Mortise is no problem as just a simple 3/8 bit, but the tennons are becoming a pain.. yes I know I can hand round them by hand but I would much rather use a jig so I can get the same results every time. Any one done something similar??
> G Vavra


A 3/8" wide tenon is pretty small to use a bearing guided bit to round over. I would use my Dremel set up as a router. W/a 1/16" round over bit that has a brass pilot bearing. 
Or you could cut the rail tenons short and make some plugs to fill the hole and let extend proud of the legs. I have done this by taking a short 1X6 and cutting a tenon across the end and rounding over the edges and cutting the tenon into plugs to cap the rails, this makes them all end grain and the same look to the grain.
Just a suggestion,
Herb


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## kimosawboy (Jan 26, 2010)

I should have been more clear.. rounding the tennon shoulder..


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## mimac (Dec 13, 2009)

Use loose tenons cut all the way through.


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## kimosawboy (Jan 26, 2010)

Do not want loose tennons.. Its a chair that is held together with the thru tennons and I want the grains to match..


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## Stick486 (Jan 4, 2013)

kimosawboy said:


> Doing a project that requires rounded thru tennons that will be shown, Mortise is no problem as just a simple 3/8 bit, but the tenons are becoming a pain.. yes I know I can hand round them by hand but I would much rather use a jig so I can get the same results every time. Any one done something similar??
> G Vavra


are you doing a tusk tenon...

I use a Leigh jig for rounded tenon edges... there are others...
plan ''B'' would be to make the tenons floating since the mortises are no issue...
round over, half round or bull nose a length of flat stock and use the length you need...

.


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## Cherryville Chuck (Sep 28, 2010)

Round over the part that will show with a router and round over bit. Finish the base of the tenons with a chisel good enough so they fit the mortise.


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## kimosawboy (Jan 26, 2010)

Stick486..Not a tusk tennon and a Leigh is exactly what I would like to mimick without the 700-800 Cost.
Cherryville Chuck, Just the shoulders need to be rounded..
Here is the joinery that I'm working on...


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## Stick486 (Jan 4, 2013)

Cherryville has the plan...


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## kimosawboy (Jan 26, 2010)

I'm not worried about the part that will show . What I'm looking for is repeat ability of rounding the shoulder, using a chisel for a good enough fit will not do.


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## CharleyL (Feb 28, 2009)

I do my mortises and tenons with my Leigh FMT Pro, but you could make rounded edge tenon stock using your table saw, a planer to get exactly the right thickness, and a bull nose router bit in a router table to make a perfectly rounded edge of your tenon stock. Then just cut pieces of it to length as you need it for floating tenons to fit your mortises. If made for a snug fit a floating tenon and matching mortises will be just as strong as those made with the FMT, although it will likely take a bit longer to do.

If you study how an FMT Pro is made by downloading the manual from the Leighjig.com website and then watching the Youtube videos on it's use, you likely can duplicate most of the function of an FMT using good quality plywood, like Baltic Birch. It might be prudent to buy their templates to get the needed jig accuracy though.

Charley


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## Cherryville Chuck (Sep 28, 2010)

I was talking about using the chisel where you won't see and can't get the router bit into which is close to the shoulders.


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## DaninVan (Jan 1, 2012)

"...and I want the grains to match.."
N/A

Why would the grains match? One's face grain and the only visible part of the tenon is the end grain. I think I lost something in translation.
How does having the tenon carved out of the rail piece differ from a loose tenon inserted into it?


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## Stick486 (Jan 4, 2013)

cut the tenon...
3/16''R half round the edges on the RT...
use a 3/8'' dia forstner bit to cut the edges of the mortise to match the tenon edges..
hand shape what needs to be which will necer be seen,,,


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## MEBCWD (Jan 14, 2012)

You could do a standard MT joint or loose MT joint for construction, then do a raised inlay piece to get the look you want.


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## DesertRatTom (Jul 3, 2012)

Cut the mortise with a Forstner bit so it is as long (or even slightly shorter) than the tennon. Make a pattern that mathes the mortise, lay it on the square tennon. Mark the curve on the tennon, and pare fairly close to that line with a sharp chisel. Sand to an exact fit.

Or, make the tennon slightly short so it's maybe 1/8th short of protruding. Then cut out a shape you want to showWITH the grain from a piece of your stock and shape the edge of this piece with your roundover or other bit. Shave away a small bit of the edge to fit in the leftover mortise depth. This will give what looks like a through mortise, but it will be with the grain on the end of this cap. Glue this small cap in place, it will probably last 200 years and look better than the end of your tennon will ever look. 

The width of this cap will determine what it looks like on the finished piece. The slight tennon on the back of this cap can be cut to exact width on your router. Remove the shoulder on a long piece so it's uniform. Chop the tennon to length with a Japanese saw and a chisel. It's all hand work, but I don't see any way to avoid the hand work. This cap will also hide any wedges you might wish to put in to make a perfect tight fit.

However, NO ONE will ever check the length of these caps for uniformity and fit. The glue is the hero in this tale.


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