Cross lap joints, often known as “overlapping” joints, are utilised in wooden constructions and furniture to produce elegant, continuous lines. This article will teach you how to cut clean cross lap joints, particularly in heavier woods where standard woodworking equipment would fall short.
For the purpose of this article, we are going to describe working with cedar posts. For these types of posts, a 7-1/4′′ circular saw is best. In heavier wood, the circular saw blade has adequate room to produce deep cross laps.
Electric routers are frequently used by woodworkers to create comparable cross laps in thinner timber. Keep in mind that routers aren’t always capable of reaching timber this thick. They do, however, clear material with smooth accuracy when suitable. Before starting on a carpentry job or project make sure you have carpenters insurance to cover yourself and your work.
MEASURE AND MARK THE CROSS LAPS
The first stage in cutting cross lap joints is to map out their position extremely precisely. To begin, mark straight lines 6 inches out from the beam ends using a square.
The opposing side can then be marked with a spare piece of 44 material. Rather than depending on measurements, using the real material as a reference will frequently result in more easily created tight joints.
Simply place a cut-off piece of 44 material on the object you want to mark. Line up one side of the chunk with the pencil mark you just made, looking down from above. The other side can then be used as a guide to make a fresh pencil mark.
You may double-check these lines later to ensure they are correct. When looking down the edge of the cut-off piece from straight above, you want to be able to just see them. For more precise markings, use an extremely sharp pencil.
CHOOSE YOUR SAW DEPTH
Cross laps must be exactly half the depth of the material you’re working with in order to perform effectively. They will snuggle together on a parallel line if you pair them this way.
Simply unplug the saw, flip it on its side, and swivel the sole plate to its full depth to set the depth (after unlocking it). Tape your tape measure to the bottom of the sole plate, then draw it out to the furthest reach of the blade teeth in the tool’s centre.
Swivel the sole plate down until it is 1-3/4′′ away from the middle blade tooth’s tip. By locking the sole plate in this position, you can then adjust the depth.
CUT CROSS LAP PERIMETERS
The outermost incisions in this process–the “perimeters”–are the most critical. These cuts will define the cross lap’s bounds, so make sure they’re tight and precise.
You can use a speed square to act as a straight edge to help guide your saw and assure squareness.
Set the saw on the timber and align the blade’s outer edge with the cut’s inner edge. At this point, butt your speed square up to the sole plate.
The speed square will keep the saw absolutely perpendicular to the material as you start cutting. Simply hold the speed square firmly in place with your free hand and push the saw gently and smoothly.
Ideally, your cut should be half the thickness of the pencil line you drew earlier.
Repeat the procedure on the other side of the perimeter. This time, you have the option of sighting along the inner edge of the saw blade or moving around to the far side of the piece and cutting the same way you did the previous time.
CUT THE FILLETS
You’ll want to make a lot of identical cuts through the material to deal with the surplus wood between the perimeter cuts. Standing “fillets”–thin pieces of wood that are significantly simpler to remove than a huge block–will result from these cuts.
To achieve this, you don’t even need to utilise the speed square as a reference. Simply cut the waste wood with the saw every 1/8′′ or so. The blade’s linear shape will keep it going straight for the most part on its own.
Just remember to observe all saw safety precautions when cutting the fillets. Stand marginally to the left or right of the cut, not behind it, with both hands on the tool. Between each pass, let the blade guard fall back into place.
Also, make sure you don’t make any mistakes with your perimeter cuts! A wandering blade can easily nick the edge.
BREAK THE FILLETS
This section is usually a lot of fun.
Standing fillets are extremely weak, especially because they are made by cutting across the grain of the wood. With your fingertips, you can break one open. However, breaking them all at once is faster (and more fun).
Simply tap all of the fillets in one direction from the side with a 16 oz. hammer. Strike as near to the cut’s perimeter as you can. The fillets will collapse on top of each other in a domino effect, resulting in a loud snap.
Simply pick up the waste wood! (Use a flathead screwdriver to break out any remaining parts.)
CLEAN THE CROSS LAP
The cut’s edges will remain jagged, with some fillet bases rising higher than others. This is nearly always the case in locations where the wood grain is slightly harder and denser or where a knot is present.
Start by knocking out any bigger pieces of the cut’s floor using a hammer and chisel. Short, controlled taps with the chisel bevel pointing down can be used to cut towards the base of the fillet from the side.
After the biggest parts have been removed, raze the floor to a smooth, even depth by turning the chisel bevel up and moving it back and forth through the cut field.
To avoid gouging, keep the chisel flat on its back while doing this. If you have a sharp chisel, it will cut clear through the elevated wood fibres at the bottom of the cross lap, leaving an increasingly flat surface.
When the cut’s floor is smooth, use your block to check the fit of the cross lap. If the joint is still too tight, you can broaden the cross lap by making one more pass with a circular saw.
Just remember to use your square as a guide once more–and only take a half-width at a time! It’s quite simple to go overboard and make the cross lap too broad, which is an unforgivable error.
REPEAT STEPS 1-7 FOR SECTION OVERLAPPING
If the fit on the first piece is satisfactory, you can proceed to the overlapping piece.
Remember to keep track of which side of the new beam the cross lap is on.