Dovetail box bottom

[Claus]

Working my way through the scrap pile, might as well knock out some small boxes and get some dovetail practice.

What’s your favorite way to fit bottoms on dovetailed boxes? Dado? Rabbet? Not sure I’m ready to fiddle with blind dovetails for these.

 

[Charles Lent]

I use small diameter box slotting bits from Lee Valley. You dry assemble the 4 sides of the box and add clamps, if necessary, install the desired slotting bit for the thickness of the intended bottom in your router table and set it's height. You then place the dry assembled box over the bit and slide it around to cut the slot in all 4 sides. The small diameter of these bits lets you cut the slot all the way into the corners, making it only necessary to slightly round the corners of the intended box bottom for it to fit and leave no gap at the box corners. Regular slotting bits are larger in diameter, so if you try to use them they will result in the slot ending before the corners, and a corner gap between the box sides and bottom at the corners.

It's the best and easiest way to install box bottoms that will never pull out. I always set the bit high enough leave about an equal amount of the box side panel to the slot thickness, so if the box bottom is thick, the gap between the slotting cutter and the router table is set a bit higher. You can rabbet the box bottom on all 4 edges if the bottom is thicker than the slot being cut.

Charley

 

[Mike Davis]

Depends on how small and what materials.

I have made some boxes with all sides and bottom dovetailed except the sliding top.
I made some with all sides and top/bottom mitered.
I like a rabbeted plywood bottom for simple butt joint boxes.
I have just glued on the bottom then planed it flush.

In my mind blind dovetails are only for drawer fronts.

 

[Rwe2156]

Groove (dados go cross grain), but I have done rabbets.

If you like hand tools work, a neat way to fit drawer bottoms is with a hand planed raised panel.

There are blind and half blind dovetails. Not quite the same thing. Blind DT's are usually mitered.

 

[Claus]

Good advice from everyone, thank you. What I’m looking for is a way to hide the groove on the sides to hold the bottom. I hadn’t considered a router. I guess I meant mitered dovetails, not blind.

DrBob I get the raised panel idea for the actual bottom but don’t understand how that impacts the grooves in the sides.

 

[ChemE75]

Always liked the look of through DTs on most boxes. Bottoms varied. Most - a groove with thin plywood bottom. Similar to Mike’s solid bottom glued on, I did some with solid bottom with a routed edge profile then glued it on. Also with a mitered frame shirting the bottom with a deep enough recess for a thin bottom panel. Lots of options.

 

[mkepke]

The way I've always done them is stopped rabbets in the sides. Cut them on the router table with a straight bit. You need to set up accurate stops so you can start (plunge) and stop (lift off) cutting at the right spots.

Charles described a different way to do the same thing.

-Mark

 

[Hmerkle]

If you run a strong (wider) half pin on the bottom or bottm and top, it will cover a through groove on the tail board as Dave has drawn it.
Probabl not as asthetically pleasing, but all-around easier to make with hand tools...

 

[Charles Lent]

I have made boxes many ways, but the easiest, fastest, and with less chance of an error is the small diameter bit method that I described when cutting slots in the sides and ends for the tops and bottoms. Stopped DADOs are difficult to cut and so easy to go too far and break out through the corners of the boxes. Cutting them with a table saw results in manual chisel and hammer methods to clean out the last parts of the DADO. Larger diameter router slotting bits don't cut far enough into the corner joints, so you end up chiseling out the ends of the DADO, again time consuming. Using a router and straight bit works pretty good, but you risk breaking through the ends if you don't set stops to limit the router travel, and the need to make small pieces to plug fill the break throughs. They never seem to look very professional when glued in either.

Dovetail corners on boxes are pretty, but very time consuming, even if using a good dovetail jig. I have a Leigh D4R, but it hasn't seen much use since I bought the Incra I-Box jig. Most all of my boxes now get box joint corners, and yet again small diameter slotting bits to make the slots for the bottoms, and sometimes the tops too if using solid wood. Gluing a top or bottom directly onto solid wood sides runs a high risk of the bottom and top splitting as the humidity changes and the box shrinks. I use a Freud SBOX8 blade set most of the time to cut 1/4 or 3/8" box joints in the box corners, then a small diameter slotting bit to make the bottom and tops fit into the grooves made by the slotting bit. When using solid wood, I never have problems when the humidity changes, and the top and bottom panels change size. They have to float in the slots or they will split or pop the corner joints.

I've started making most of my general purpose boxes using Baltic Birch or similar plywood, again because it's faster and easier to get good results with. I've also recently made some pet urns from solid Mahogany with mitered and slotted corners, inserting cross grained splines into the slots to hold the corners tightly together with the glue. Over the last 50 or more years I think I've made boxes just about every way possible, and this method has proven to be the fastest and most reliable.

Attached are a few boxes that I've made using my Incra I-Box jig, my Delta Unisaw, and the Freud SBOX8 blade set. If I want 1/8" box joints I found a Freud Ripping Blade with flat 1/8" kerf teeth that works well. For box joints larger than 3/8" I have a Freud Dial-A-Width DADO blade set and when making box joints larger than 3/8" I've found that the tiny bat wings created by the DADO blade teeth are not that visible or objectionable. I use my table saw with one of these blades and not a router and bit, because a saw blade cuts the slots in only one direction and the backer in the I-Box jig works well to minimize chip out from a saw blade. There is no provision in the design to incorporate a second backer for the router bit rotation problem, so no good way ti minimize chip out. A straight router bit can be used in a router table with an Incra I-Box jig, but the bit rotation makes it cut in both directions as you pass it through the wood, resulting in chip out regardless whether or not you use a sacrificial backer. The I-Box jig has an MDF backer in it's design that works well with a table saw, and it can be moved to a fresh position when setting it up to cut a different size box joint. The box joint in photo 1 shows the quality of fit that can be achieved using the I-Box jig, a good table saw, and one of these or similar blades. In photos 2 and 3 this box was made for keeping the parts of my Incra I-Box jig together, In photos 4 and 5 this box was made to hold a 9 mm pistol, The box in photos 6 and 7 was made to keep all of the pieces of my M-Power router jig together. I think these boxes are all about 10 years old and all but the pistol box are kept in my unheated or air conditioned shop. No joint failure at all yet.

An advantage to using Baltic Birch or similar wood is that it is very stable and not susceptible to humidity expansion and contraction, so the tops and bottoms of these boxes were all glued directly onto the sides of the box and the slotting bit wasn't necessary. I would have used the slotting bit if the tops and bottoms had been made from solid wood and not this very stable Baltic Birch plywood. These were all made from 12 mm sheets, mostly because the hardware screws required this minimum thickness.

Sorry, no plans are available for any of these. I made them piece by piece to fit the contents. The M-Power jig came with the pieces to use 5 different ways. Immediately after building the box, M-Power came up with a sixth way to use the jig and some additional parts that were needed for this sixth feature. I spent most of a day figuring out how to modify the box so it would hold these additional parts, and was finally successful. The box would have been slightly larger if I had built the box after receiving these additional parts, but it all fits, just not quite how it would have been made if I had these parts before starting.


Charley

 

[Canuck]

I have made boxes many ways, but the easiest, fastest, and with less chance of an error is the small diameter bit method that I described when cutting slots in the sides and ends for the tops and bottoms. Stopped DADOs are difficult to cut and so easy to go too far and break out through the corners of the boxes. Cutting them with a table saw results in manual chisel and hammer methods to clean out the last parts of the DADO. Larger diameter router slotting bits don't cut far enough into the corner joints, so you end up chiseling out the ends of the DADO, again time consuming. Using a router and straight bit works pretty good, but you risk breaking through the ends if you don't set stops to limit the router travel, and the need to make small pieces to plug fill the break throughs. They never seem to look very professional when glued in either.

Dovetail corners on boxes are pretty, but very time consuming, even if using a good dovetail jig. I have a Leigh D4R, but it hasn't seen much use since I bought the Incra I-Box jig. Most all of my boxes now get box joint corners, and yet again small diameter slotting bits to make the slots for the bottoms, and sometimes the tops too if using solid wood. Gluing a top or bottom directly onto solid wood sides runs a high risk of the bottom and top splitting as the humidity changes and the box shrinks. I use a Freud SBOX8 blade set most of the time to cut 1/4 or 3/8" box joints in the box corners, then a small diameter slotting bit to make the bottom and tops fit into the grooves made by the slotting bit. When using solid wood, I never have problems when the humidity changes, and the top and bottom panels change size. They have to float in the slots or they will split or pop the corner joints.

I've started making most of my general purpose boxes using Baltic Birch or similar plywood, again because it's faster and easier to get good results with. I've also recently made some pet urns from solid Mahogany with mitered and slotted corners, inserting cross grained splines into the slots to hold the corners tightly together with the glue. Over the last 50 or more years I think I've made boxes just about every way possible, and this method has proven to be the fastest and most reliable.

Attached are a few boxes that I've made using my Incra I-Box jig, my Delta Unisaw, and the Freud SBOX8 blade set. If I want 1/8" box joints I found a Freud Ripping Blade with flat 1/8" kerf teeth that works well. For box joints larger than 3/8" I have a Freud Dial-A-Width DADO blade set and when making box joints larger than 3/8" I've found that the tiny bat wings created by the DADO blade teeth are not that visible or objectionable. I use my table saw with one of these blades and not a router and bit, because a saw blade cuts the slots in only one direction and the backer in the I-Box jig works well to minimize chip out from a saw blade. There is no provision in the design to incorporate a second backer for the router bit rotation problem, so no good way ti minimize chip out. A straight router bit can be used in a router table with an Incra I-Box jig, but the bit rotation makes it cut in both directions as you pass it through the wood, resulting in chip out regardless whether or not you use a sacrificial backer. The I-Box jig has an MDF backer in it's design that works well with a table saw, and it can be moved to a fresh position when setting it up to cut a different size box joint. The box joint in photo 1 shows the quality of fit that can be achieved using the I-Box jig, a good table saw, and one of these or similar blades. In photos 2 and 3 this box was made for keeping the parts of my Incra I-Box jig together, In photos 4 and 5 this box was made to hold a 9 mm pistol, The box in photos 6 and 7 was made to keep all of the pieces of my M-Power router jig together. I think these boxes are all about 10 years old and all but the pistol box are kept in my unheated or air conditioned shop. No joint failure at all yet.

An advantage to using Baltic Birch or similar wood is that it is very stable and not susceptible to humidity expansion and contraction, so the tops and bottoms of these boxes were all glued directly onto the sides of the box and the slotting bit wasn't necessary. I would have used the slotting bit if the tops and bottoms had been made from solid wood and not this very stable Baltic Birch plywood. These were all made from 12 mm sheets, mostly because the hardware screws required this minimum thickness.

Sorry, no plans are available for any of these. I made them piece by piece to fit the contents. The M-Power jig came with the pieces to use 5 different ways. Immediately after building the box, M-Power came up with a sixth way to use the jig and some additional parts that were needed for this sixth feature. I spent most of a day figuring out how to modify the box so it would hold these additional parts, and was finally successful. The box would have been slightly larger if I had built the box after receiving these additional parts, but it all fits, just not quite how it would have been made if I had these parts before starting.


Charley

Excellent writeup , Charley!