# Strength of locking rabbet joint



## Stilts (Dec 2, 2010)

Am making a stand for my planer so I decided I might as well put drawers in it. I also thought I would use it this as an opportunity to practice. So I would like to use a locking rabbet joint on the drawers. I am using birch ply. My question is will the ply be strong enough for this type of joint?
I made up a test piece and it feels fairly strong. I was sure it would be though with how thin some of the parts are.


----------



## sawdustfactory (Jan 30, 2011)

I'd change the dimensions of that joint a bit if I were you.


----------



## Dominick (May 2, 2011)

Nice joint. But I have to agree with dusty on this


----------



## Stilts (Dec 2, 2010)

What should be changed?


----------



## sawdustfactory (Jan 30, 2011)

I'd make the "gap" narrower, making the "fingers" wider. Sorry don't really know what those parts are called.


----------



## woodnthings (Jan 24, 2009)

*It should look like this*

A locking drawer joint:


----------



## Stilts (Dec 2, 2010)

Makes sense. Where does the strength come from in this joint? I figured that the middle gap is where the glue would go as there is the most significant area to glue.


----------



## woodnthings (Jan 24, 2009)

*strength*

The strength come from the amount of surface area exposed to glue and the actual wood fingers that interlock. In the case of a plywood joint there is a lot of end grain to end grain which is not good for strength, so the tongues or fingers make up for it.  bill


----------



## Stilts (Dec 2, 2010)

So do you think it would be good if each of the sections were 1/4" (the 2 finger and the space).


----------



## cabinetman (Jul 5, 2007)

I use just a plain rabbet with glue and fasteners and they hold just fine. I rabbet the sides, and the fasteners go in from the front at a slight angle. No fasteners show from the sides. I never kept count, but it's in the thousands, and not one ever came apart.








 







.


----------



## johnnie52 (Feb 16, 2009)

I just finished a simple box to hold all my pill bottles from Oak ply using the same joint. It held so strong at dry fit that when I tried to take it apart for glue up, one of the fingers broke.... :furious: Ply is not a good choice for a locking rabbit ....


----------



## woodnthings (Jan 24, 2009)

*The inverse is true*



johnnie52 said:


> I just finished a simple box to hold all my pill bottles from Oak ply using the same joint. It held so strong at dry fit that when I tried to take it apart for glue up, one of the fingers broke.... :furious: Ply is not a good choice for a locking rabbit ....


A locking joint is best for plywood...a simple rabbet next and a butt joint is the least preferred. The locking joint prevents racking or shifting also. A stopped tenon/end rabbet in a dado would also work pretty well, but the end grain will show from one direction.
The locking joint minimizes that a bit.  bill


----------



## Tony B (Jul 30, 2008)

*Locking Rabit*

I usually make the 'locking' part of the rabit about 1/3 the thickness of the plywood so it is less prone to breaking out. 
I also make a separate drawer face, however, your design should work just fine. 
I also use Baltic Birch for drawer boxes. There are no voids and it looks great with a small roundover from a router, not to mention way stronger than standard plywood.


----------



## Stilts (Dec 2, 2010)

When attaching the joint, will glue be enough or should I add some brads? If so, can I shoot them through the side or should they be driven through the fronts?


----------



## cabinetman (Jul 5, 2007)

Stilts said:


> When attaching the joint, will glue be enough or should I add some brads? If so, can I shoot them through the side or should they be driven through the fronts?



Post #10.









 







.


----------



## jschaben (Apr 1, 2010)

Stilts said:


> When attaching the joint, will glue be enough or should I add some brads? If so, can I shoot them through the side or should they be driven through the fronts?


Clamp and glue works just fine. I've used lock rabbets on all my drawers for several years now. Most of the time you can skip the clamps and just put a couple of brads in to hold it together till the glue sits up. Good fitting joints will pretty well self square, especially with a good fitting bottom too. With plywood, I usually glue the bottom in too.


----------



## Stilts (Dec 2, 2010)

Will 1/4 inch hardboard be strong enough for a drawer bottom? The drawers are approx 15 x 25. And range from 3" tall to 8"


----------



## woodnthings (Jan 24, 2009)

*Sure.... if you're gonna put pop corn in them*

If not,.....:no: that 25" width filled with heavy stuff like tools will sag. Don't cheap out on the bottoms use 1/2" and be done with it. You'll never regret it. :smile: bill


----------



## cabinetman (Jul 5, 2007)

Stilts said:


> Will 1/4 inch hardboard be strong enough for a drawer bottom? The drawers are approx 15 x 25. And range from 3" tall to 8"


I've got some tool drawers some larger than that size with 1/4" tempered Masonite (hardboard) bottoms, with 60-75 lbs (tools) without a sag. Bottom should be installed in a groove. All the weight isn't centered with drawers, its dispersed. You could use 1/2" for extreme weight. 








 







.


----------



## Stilts (Dec 2, 2010)

I won't be keeping very many heavy things in it because I have to store most tools in my basement because things rust so much in my garage/workshop. So the drawers will keep mostly odds and ends (sandpaper, tapes, etc.) the heaviest things I'll probably put in there is the hand sanders. 
Next question would be, should I glue the bottoms in the grooves?


----------



## cabinetman (Jul 5, 2007)

Stilts said:


> I won't be keeping very many heavy things in it because I have to store most tools in my basement because things rust so much in my garage/workshop. So the drawers will keep mostly odds and ends (sandpaper, tapes, etc.) the heaviest things I'll probably put in there is the hand sanders.
> Next question would be, should I glue the bottoms in the grooves?


I groove the sides and the front. The back is cut short, and the bottom slides in and gets fastened to the underside of the back. The bottom should be a snug slip fit, so it will square the drawer when slid in. I check the drawer for square with a square before fastening the rear. 

I don't glue in the bottoms, so it can be removed and replaced if ever damaged.











 







.


----------



## Stilts (Dec 2, 2010)

Do you mean that the back piece of the drawer is cut shorter so that it lines up with where the Dado would be for the sides and front?


----------



## cabinetman (Jul 5, 2007)

Stilts said:


> Do you mean that the back piece of the drawer is cut shorter so that it lines up with where the Dado would be for the sides and front?


Yes. The back of the drawer lines up to the top edge of the groove.








 







.


----------



## Stilts (Dec 2, 2010)

Ok. Thanks C-Man.


----------

