need help with tongue and groove

Hey Magnus
Welcome to LJs . Most people don’t use t&g to join there bench tops the just joint and glue all the pieces
together. If you feel it’s nessasary to use T&G you could use router bits if you have a router table. You could use a table saw to make the t&G. with out a dado blade.

-- Jim from Heirloom Woodshop Southern Oregon

Hey Jim.. thx for the response. I know it is not necessary to use T&G, but originally i planned to make my bench out of Hardwood, but it’s too expensive.. I want to add as much strength as I can to my top, so I insist on using one. Sadly, as I already mentioned, I don’t own a router, so it is out of the question. I also figured I could get by without a Dado, but I would like some guidance on how exactly to go about cutting the tongue and groove. how many cuts i’d have to make on 2 inch thick spruce to make the tongue, measurements, etc. I am using a Ryobi 10” 15 amp table saw with a standard combination blade.

magnus,

You might consider a spline and groove which could be a little easier to make. To make the grooves run one edge of your boards through the table saw with the blade cutting just off center. Flip the board to place the other side against the fence and run it again. This should give you a groove ~1/4” wide. Do the same for the board it joins to. Now you can rip a narrow spline that will fit into the grooves which will serve to align and strengthen the joint.

Magnus, if you want to use a T&G joint on your top then, for a 2” thickness, you should plan on making the width and depth of your tongues and grooves about 1/3 of the final thickness or in this case a little less than 3/4” (I probably would opt for 1/2” just for convenience). You can do the tongue in 2 passes on your table saw ripping 1/3 of the width from both sides of the board in each pass and repeating the same cuts with the board on edge. But I would set the blade depth a little under this height so that you can “sneak” up on the final tongue width to fit the groove that should be cut first. The groove would have to be cut in several passes through your saw blade, which will remove, at best, 1/8” with each pass. After each cut rotate the board end for end and repeat the cut with the fence in the same position to ensure that groove is centered. Move the fence less than 1/8” and repeat this process until you get the groove width that you want.

With this process you most likely will have to clean up the groove with some hand work since the combination blade will not leave a flat bottom but that should not be too difficult.

-- With God's help all things are possible- even woodworking. Woodworking is not just a hobby, it is an (expletive deleted) expensive hobby.

So far, I agree with everyone—-Take your pick. All will work, although I’m with Jim—You really don’t need to go to that much trouble. (Funny coming from me, huh Jim?)

-- Kent Shepherd * The goal is-----More Tools!

I see a problem with your being able to make accurate tongue and grooves in boards 5 1/2 feet long because they will probably have at least a small amount of bow and warp. The unintended consequence will be a major struggle in trying to get the boards to line up, and even after you do the edges will not be flush from end to end.

Therefore, I’d consider using dowels. They would enable you to “force” the warp out of the boards insuring that the edges are flush from end to end.

Regarding strength – It is well documented that good glue joints are stronger than the surrounding wood, so the added strength of a tongue and glue joint doesn’t bring a lot to the party.

-- Joe

I would second the idea that you do not need to use the tongue and groove to make the top. Just run them over the jointer. The pieces are going to need to be jointed to fit together nicely with a tongue and groove. The only purpose I can see is for alignment.

If you are dead set on something like that and you don’t have a biscuit joiner consider my favorite alternative to T&G…..... T&S: Tongue and Spline.

Pic from my “blog”http://lumberjocks.com/gizmodyne/blog/1969 on making these.

I have used a slot cutter to cut the groove, but you can use the tablesaw with a feather board to run the grooves or a straight bit in your router table. Then you rip splines to fit. I plane them to fit perfectly but you could finesse it on the table saw if you have too.

Good luck.

-- -John "Do I have to keep typing a smiley? Just assume it's a joke." www.flickr.com/photos/gizmodyne

A T&G joint will not add any strength, compared to long grain to long grain glue up. Make sure the edges are straight (preferably run thru a jointer) and glue them up. The joint will be as strong, if not stronger that the wood itself. You will be wasting a lot of time and effort by adding a T&G joint. Yes, a T&G adds more long grain to long grain surface, but the other adds more than enough. Good luck.

-- SeeWhatISaw

Thx guys for the help. Outstanding responses.. I am not use to recieving such in depth help from other forums. Cheers.. I will let you know how it ended up!

I meant Groove and Spline. Doh!

-- -John "Do I have to keep typing a smiley? Just assume it's a joke." www.flickr.com/photos/gizmodyne