Box joints are strong and attractive And they dont require any special tools just a table saw a miter gauge and a simple shopbuilt jig

here are a lot of reasons for using JL box joints. They're strong. They don't require any special tools or expensive jigs. And they look good. They can be used to "dress up" a project, like the stacking boxes or the planter. And for other projects, like the magazine boxes, they can give a stately, old-fashioned feel.

interlocking fingers. Box joints are made up of alternating pins and slots, see drawing below. The pins on mating pieces interlock like tiny fingers. This creates a lot of good glue surface and makes for a strong joint But in order for it to be strong, you'll need a snug, accurate fit.

To trick to getting a good fit on a box joint is to get the width of the pins to match the width of the slots. And this is just about as easy as it sounds. All you need is a jig that uses a small key. Ibis key determines the width of both the pins and the slots.

But first, you have to decide whether to use the table saw or the router table. The jig for each is essentially the same. But most of the time, I like to use my table saw. It works much quicker than a router, especially when cutting large box joints.

BOX JOINT JIG

To cut box joints with a table saw, you need three things: a dado set, a miter gauge, and a jig. The jig can be very basic. All you need is a pair of auxil iary fences and a hardwood key.

fences. The fences are joined with carriage bolts and wing nuts, see Fig. 1. The fixed fence is screwed to the miter gauge. If s slotted so the fence in front can be adjusted side-to-side.

key. There's also a small, hardwood key that's glued into a notch cut in

Table Saw Box Joint Jig

BOX JOINT ANATOMY

CROSS SECTION

carriage bolt

Wing nut and washer the front fence, see Figs. 2 and 3. The nice thing about using a key is that once the jig is set up, cutting the box joints is just about automatic. But it also means that the size and position of this key must be perfect

Since the key fits into a notch, its width and height are determined by the dado blade that cuts the notch. The width of the dado determines the spacing of the box joints. And the height of the dado determines the length of the pins.

Note: For my box joints, I set the dado blade a hair above the thickness of the workpiece, see Fig. 2. Then after the key is glued in place, I sand it down, so the workpiece won't bottom out on the key, see Fig. 3.

The position of the key is also crucial. It determines whether the pins will fit or not To get the key close to where it should be, I use an identical sized spacer to position it, see Fig. 4.

tuning the jig. At this point, the jig just needs to be fine tuned. This simply involves cutting a test corner. And for an accurate test I use scrap pieces

TROUBLESHOOTING

that are roughly the same width as the finished pieces.

To cut a test corner, butt one piece up against the key and cut a slot Now, reposition the piece so the slot straddles the key and make another pass.

Repeat this process until you get to the end of the board. Now this piece

SECOND:

Sand height slightly less than thickness of stock

Cut joints'"-^, on test pieces

will help start the same process on the mating piece, see Fig. 5.

Test the fit of the two pieces and make any adjustments necessary, see the drawings below. The goal is to get a snug fit—nothing too tight But the pieces should require a few taps with a mallet to go together.

Loose fit. If there's a gap between each pin, simply slide the key away from the blade, see drawing at right.

Tight fit. If the pins won't fit into the slots at all, then slide the key towards the blade, see drawing at right.

Loose fit. If there's a gap between each pin, simply slide the key away from the blade, see drawing at right.

Tight fit. If the pins won't fit into the slots at all, then slide the key towards the blade, see drawing at right.

To adjust width of box joints, slide adjustable fence . slightly

Short pins. If the dado blade is set too low, you'll end up with pins that are too short. So raise the blade slightly.

Long pins. If the pins extend too far beyond the sides, the dado blade is set too high and needs to be lowered.

k For a perfect box joint, the two pieces will fit snug, and the pins will be flush after a little sanding.

Short pins. If the dado blade is set too low, you'll end up with pins that are too short. So raise the blade slightly.

Long pins. If the pins extend too far beyond the sides, the dado blade is set too high and needs to be lowered.

k For a perfect box joint, the two pieces will fit snug, and the pins will be flush after a little sanding.

Adjustable fence

Adjustable fence

Raise blade slightly above thickness of stock and cut notch

FIRST:

Glue key into notch

SECOND:

Sand height slightly less than thickness of stock

FIRST:

Glue key into notch

Raise blade slightly above thickness of stock and cut notch

Use spacer to set adjustable fence

Use spacer to set adjustable fence

To adjust width of box joints, slide adjustable fence . slightly

BACK

With the box joint jig complete, you're ready to get down to business. But just because the jig is set up accurately doesn't mean the process is completely automatic. There are still a few things that can give you trouble.

ACCURATE BOX JOINTS

When building with box joints, I typically shoot for visual accuracy rather than dimensional accuracy. For instance, the planter on page 20 is supposed to be 63Ae" tall. But whether it ends up exactly this height or not, the important thing is that there's a full pin (or slot) at the top and bottom of a piece.

extra-wide pieces. To do this, I typically start with workpieces that are extra wide and then trim them after the box joints are cut, see Step 6.

Of course, there are times when a workpiece has to be a specific dimension, like when building a drawer. But I still start with an oversize piece. I simply trim the same amount from

BACK

NOTE:

Remove waste from same edge of each piece

NOTE:

Cut oversize blanks to width after cutting box joints

Waste

NOTE:

Cut oversize blanks to width after cutting box joints

Waste

NOTE:

Remove waste from same edge of each piece

FRONT

... ^ NOTE: Waste For best results number corners and cut them in sequence

FRONT

... ^ NOTE: Waste For best results number corners and cut them in sequence both the top and bottom.

label pieces. Another thing I like to do is label the front, back, and side pieces and number the joints so I can cut the joints in sequence, see drawing above and Step 4 below.

consistent pressure. When cutting the box joints (see the steps below), ifs important to be consistent. Even shifting the pressure slightly can affect the fit of the box joints. So I hold the jig with both hands and perform each pass exactly the same.

CLEAN BOX JOINTS

Unfortunately, even if your box joints fit perfectly, you may run into other problems: chipout and uneven slots.

chipout. Chipout is inevitable — sooner or later it's bound to happen.

17o begin, set the top of the first workpiece against the key and hold it tightly against the fence and the table saw. Then cut the first slot.

2 Now, move the piece so the first slot straddles the key and cut a second notch. Repeat this process until all the slots on this end are cut.

3 After all the slots are cut on one end, flip the piece end-for-end, keeping the waste edge on the same side. Then cut the slots on this side.

4 Now, rotate the first piece so the waste is outside and the first slot fits over the key. Butt the mating piece against the first and cut the first slot.

5 Now, slide the just<ut slot in the mating piece up tight to the key. Continue this procedure until the box joints are cut on all pieces.

6 Before assembling the box, rip the waste edge off each piece, so there's a full pin and slot on the top and bottom of the piece.

But there are a few things you can do to minimize it. First, make sure your blade is sharp. And don't push the piece through the blade too quickly. And if you're getting a lot of chipout, slip a scrap piece of hardboard behind the workpiece so the cut can always be backed up completely.

cleaning the slots. Another problem, common with dado blade cuts, is uneven slots, see Fig. 6a. What you want is to get them flat without affecting the accuracy of the fit

To do this, I make a simple sanding jig. Start with a piece of scrap and cut a tongue on one edge, see Figs. 6 and 6a. The tongue should slide smoothly in the slot and match its depth. Next, attach a piece of adhesive-backed sandpaper to the bottom of the tongue and sand the slots flat

SMOOTH ASSEMBLY

At this point you're ready to assemble the box. Here's where things can get a little frantic. But I take a few precautions to avoid this.

First, I try to avoid a lot of mess. After all, there are a lot of opportunities to slop glue around. So I tape the inside edges of the pieces, see Fig. 7. This way, any glue squeeze out can be carefully peeled away later.

time savers. To buy myself more time, I use white instead of yellow glue. White glue sets up slower, which helps when there are a lot of box joints, like on the magazine boxes.

Also, to get the glue on quickly, I use Q-Tips and dab glue onto the sides of the pins, see Fig. 8. You don't want much glue, though. Even a little bit creates a strong hold.

clamping. When it comes to clamping up box joints, I take a couple precautions so there are no surprises.

After dry assembling a project I often make a squaring form out of

scrap wood, see Fig. 9.1 also make sure I have the right clamping blocks, see Fig. 10. The important thing here, is that they don't cover the box joints. Otherwise, they might prevent the joint from pulling tight.

All thats left now is to sand the pins flush with the sides of the box. IS

Mut lesive-uduieu sandpaper

Dado slots uneven

Dab glue on with Q-Tip
corners of form

k A full-length groove for a bottom panel will have a small, square hole. But you can fill the hole with an end grain plug and make it virtually disappear.

HIDING THE GROOVE

k A full-length groove for a bottom panel will have a small, square hole. But you can fill the hole with an end grain plug and make it virtually disappear.

Plug the hole. Start by cutting an extra-long plug to fit the hole. Taper the sides slightly to get a snug fit and glue the plug in place.

Trim the plug. Next use a chisel to pare off the excess by working around the plug towards the center. Then sand it smooth.

Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

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Responses

  • adelfo
    Is a box stronger with routered joints?
    4 months ago

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