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I'm a real noob just starting out in woodworking. So I'm working on practicing different joints. I'm starting a very small project. I will be using a T&G joint to join several 3" boards together and I wanted to know what is the standard calculation for T&G sizing. I will be using 4/4 x 3" stock. I purchased the freud adjustable bit set and I have a Bosch router table. So what size a?

Thanks for your helpful comments
 

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The usual text book criterion = 1/3, 1/3, 1/3.
That is shoulders = 2/3 thickness, tongue & slot = 1/3.
Projection and slot depth, maybe 3/16. Just enough to hold everything together during assembly.
Picture shows 3/16 thick tongue but exaggerated length.
The longer the tongue, the more stock used up.
2 3/16 tongues uses up 3/8 of stock.
 

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Welcome Zebra. I agree with Pat, try and make it a third but your bit sizes don't always allow for perfection so somewhere between 30 and 40 % of thickness. Same goes for tenons in mortise and tenon joints. Instead of making a tongue and groove joint I usually make a spline joint instead. A spline joint is basically a double groove/floating tongue joint. In other words, it's basically the same joint except that the tongue is a separate piece. Spline joints are easier to make and you don't lose any wood in making them. As Pat pointed out you lose on the tongue side of the joint in T & G.
 

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I also suggest splines versus tongue and groove...

If you decide on splines, remember that the grain needs to run perpendicular to the boards or the spline will break easily.

When @Stick486 shows up he'll post some pics and pdf's "all about splining" for you...

Good luck...welcome to the forum...
 

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Is the work 4/4 (1??") thick and 3" long?

Or, 4/4 thick and 3" wide?

Or what??

If 3" long, stock that small is/can be difficult to safely work. Looking on the Freud catalogue, the adjustable tongue and groove router bit is 1 3/4" in diameter. With stock 3" long, there is not much material left to ride against the fence and support the work while it is being cut.

The 1/3 design criteria is "spot-on"
 

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I also suggest splines versus tongue and groove...

If you decide on splines, remember that the grain needs to run perpendicular to the boards or the spline will break easily.

When @Stick486 shows up he'll post some pics and pdf's "all about splining" for you...

Good luck...welcome to the forum...
here...
 

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Ross
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Welcome to the forum Kurt.
 
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