We all end up building something out of 4x4, 4x6, or 6x6 lumber at one point or another, so you should now a quick way of reinforcing the corners without cutting lap joints.
Now, a lap joint is going to be a superior joint if glued and screwed; But we want to approach that strength without the time consuming work of cutting the joint. How do we do that?
A doweled joint. But not a wooden dowel. A piece of 3/4 inch rebar that is hammered into a 5/8 inch hole with a heavy construction adhesive. That ought to do it. Interested? Let's get started.
Step 1: I Wrote This Instructable, So As Always: You Need Stuff!!
I'm going to assume your frame is already made and you just want to reinforce it to simplify these instructions.
1: Glue. Liquid Nails works great for this application.
2: Rebar. I used 3/4 inch which is close to 5/8 under the ribs.
3: Heavy hammer or maul
5: Drill bit that is the same size as the rebar under the ribs. You want the ribs to dig into the wood for this to be as strong as it can be.,.
6: HEavy duty drill. 18v or bigger!
7:Speed square for knowing where you need to drill. (if applicable. This piece will not be seen so you can "eyeball" it in my case. )
Step 2: Mark and Drill Hole
this is fairly straight forward on 4x4 material. center the hole on the joint, drill at least the twice the thickness of the wood. (Approximately 8 inches for 4x4 lumber)
On 4x6 and 6x6 material, I'd advise 2 dowels spaced equally.
Once the hole is drilled into both pieces, clean the shavings out of each hole to help the glue bond well!
Step 3: Plenty of Glue.
Insert the glue nozzle all the way into the hole and give one good squeeze to the trigger, forcing glue deep into the hole. Now, squeeze again while withdrawing the nozzle to spread glue along the top side of the hole for a better bond.
There should be glue all the way to the top.
Step 4: Insert the Dowel!
Insert the dowel into the hole, it should resist.
Drive the dowel soundly into the hole with your hammer/maul.
it should be difficult to drive.
After a few good hits (About halfway in), there should be some glue coming out from between the joint. Good. Now, if you want some insurance here, You can spread glue along the top half of the dowel. (I Didn't.)
Continue driving the rebar dowel flush with the wood face.
Wipe off the squeeze out, and set the joint to cure.
Step 5: You're Finished.
This is an easy reinforcement for edging, swing set frames, or even framing for a pole barn. When the glue sets, it will be at least as strong as the half lap joint. Though it won't be as pretty done like this.
If you want a nicer, more unique, look to the joint, You can substitute Carriage bolts for the rebar, and it will look like a large rivet. There is a big benefit to this on painted joinery.
This joint will provide years of service, and if done on wet wood, the wood will shrink around it and never move! I've used this on mailboxes, foundation framing for sheds, sandboxes, and more. It's simple, fast, and strong.
Hope this helps you build more, better!