Machine Cut Through Dovetail Tutorial
The lads I’m writing these for have been at it over a year now rehabilitating and using basic hand tools, and it’s time to develop mastery of the basic machines to increase efficiency. I can’t think of a better place to begin than some basic through dovetails. The dovetail is a utility joint for joining wood at right angles, one that will remain functional long after its glue has gone to dust, and remains the best joint out there for resisting tension stress like pulling on a heavy drawer. It is often a better joint for carcass corners than the mortise and tenon, especially in thin, Victorian frame and panel construction found in many old yachts…
…and is also one of the easier and faster joints to cut accurately once you master visualizing the joinery principles involved. Shucks, I even use them to join heavy gate frames like the two 7-foot gate leaves below:
Drawers are their most common use, and I’ll begin a run of shallow utility drawers that will also double as tool trays for the shop on this fine rainy day.
I prefer solid, crossgrain cedar bottoms on drawers, especially in damp boat interiors…and also prefer thicker rough sawn stock as my starting point, as it makes for faster panel construction than planed stock. Crossgrain heartwood bottoms are sound, beautiful, classic joinery, can be done almost as fast as using plywood, and more importantly, are a great way to use up all that rip waste that normally goes into the stove. I lay them up above after jointing them so they lay edge grain up for minimum seasonal movement. So long as the bottom face remains flat against the bar clamps, the thickness planer will deal with any and all thickness variations easily. This cross grain bottom is 16 inches wide and 22 inches long. If you only own a 12†planer, simply omit glue in that center joint, plane them after curing, then lay the two halves up again, using a little more care in alignment. No dowels or biscuits are required, merely squarely jointed edges…the planer takes care of most of the alignment and the glue alone is more than sufficient strength. Trying to lay up the whole shebang at once and plane it across rather than with the grain remains a bad idea.
I prepare the stock for the drawer front, back and sides sized to fit the carcass opening, and mark which faces I want to display based on any defects present in the wood. This stock is spalted holly from a small log that was unsuitable for cabin soles in boats, and there is a bit of grain runout and checking. I’ll wait until I glue the drawer up before gluing any checks and splits to save time, and also mark where I’ll have to move a dovetail a bit so any defects don’t fall on a tail or pin.
Next I’ll groove all 4 pieces for the drawer bottom, cutting quarter-inch grooves, three-sixteenth’s deep using multiple passes on the table saw. Notice my blade insert is clearly marked on both sides at exact center of the saw’s arbor, and I’m careful to position a tooth on that mark before attempting to set the blade height to dado the grooves. As this drawer will also function as a tray, I’ve chosen to make all 4 pieces the same, 3/8†thickness.
I set the marking gage to the thickness of the stock…
…and deeply scribe all eight ends on both sides of the stock.
I grooved the stock as a first step to provide a myself a strong visual reference for joint layout and to insure I don’t goof and cut too close to the grooves by mistake. As the drawer front must resist the tension forces of pulling it open, that’s where the pins have to go, and I clamp the front and back pieces together for faster layout.
A common bevel and trysquare are the usual tools for laying out dovetails, but I find these shop-made dovetail squares much faster. They are simple to make from scrap sheet brass by drawing the conventional slopes…1:8 for hardwoods and 1:6 for softwoods…on graph paper. Then that graph paper can be contact cemented to the sheet brass and the blade cut out using a hack saw and files to the lines.
If you make the blades a tight fit in one of your machine’s miter gage slots, that machine table can be used as the perfect gluing jig to epoxy the brass blades into their hardwood dado’s, followed by reinforcement with a couple brass box brads.
I finish the layout by drawing out the entire joint and marking the waste to be removed. Were I cutting these by hand, I’d use the scratch awl for marking. But as today it will be the machine that does the work keeping the cuts square, the pencil alone is adequate. If I do enough of these joints in sequence, I can get to the point where once the grooves are cut as a reference, I don’t need to lay out the pins at all but can go straight to the machine for even more speed. But it’s been a while since I’ve cut one of these, and I’d just be setting myself up for a fall trying to be a showoff.
As my drawer front today is exceptionally thin, I’ll also use 1:6 as my dovetail slope instead of the usual 1:8 for hardwoods.
I clamp a temporary face to the miter gage of sufficient height to keep my fingers a safe distance from the blade, and determine the miter gage angle equivalent to the 1:6 slope I’ll use. Turns out to be 9 degrees…
…and I set my blade height just like I did making the grooves.
Then indexing the face of the board vertically against the temporary face, I can use the miter gage to make the 9-degree cuts using multiple passes on one side of the pins.
I do all four pin ends using one 9-degree miter gage setting…
…then simply change the miter gage over to 9 degrees on the other side of zero to finish the pins.
Simple, fast and accurate. Moreover, you quickly can get to the point where these are so routine; you can lay them out with final saw cuts as opposed to layout tools. As the tail layout is taken directly from the finished pin sockets, the pencil lines are merely a guide. There are two additional techniques I use to avoid mistakes:
1) I always index the grooved side of the piece to the miter gage, insuring I’m always cutting with the widest side of the pin sockets facing forward.
2) Just to make sure I’m not cutting the wrong angle, my first cut is always taken at or near the center of the socket so I can lift the work piece and gander at it to make sure I haven’t lost track of where my brain is. Cut the wrong angle at the edge of the socket as opposed to the middle, and you get to make a new work piece.
Laying out the tails is simply a matter of indexing each corner together and scribing the inside edge of the pin sockets onto the drawer sides to mark the tails. Again, a pencil can be used, although an awl will do a cleaner job and might make accurate sawing of the tails easier for you than the sloppier pencil. Again, the grooves are very useful to insure I don’t get my ends mixed up, as the sockets all vary slightly, requiring each joint to be numbered before proceeding.
The tails are freehanded on the bandsaw, with the center waste hogged out using multiple passes to line scribed by the marking gage. I cut to the outside edge of the pencil lines, using care not to touch them so I’ll have a tight, drive fit.
Finally, the bandsaw miter gage is used to finish. With the tail cuts already made and the lines scribed by the marking gage on both faces, flipping the workpiece to cut the opposite edge is fast and easy.
The drawer is glued and assembled on a dead-flat surface in preparation for getting out the bottom, and the glue is allowed to cure. The speed square is a useful staring point, but square is always taken from the diagonals. If you’ve cut the dovetails sufficiently tight, clamping isn’t required. Many folks use too much glue here…remember that end grain is never a gluing surface and using glue there is waste unless you have some minor gaps you’d like to close. Then if you use a glue with a long open time like urea resin, you can sand the joints into the wet glue prior to indexing the drawer to cure for an effective, one-step filler.
As the solid, crossgrain bottom needs room to move with the seasons; after the glue has cured I rip the drawer back to the top of the groove. I could have done that before assembling the drawer, but having four uniform surfaces to index on the flat saw table during glueup is useful, and ripping the entire drawer as opposed to just the unassembled drawer back is just as fast.
Now I saw out the planed, crossgrain bottom into a perfect rectangle sized to fit the grooves in an easy push fit. Here’s where beginners get into trouble squaring up large panels by relying on the accuracy of their machines and their squares instead of using diagonals. Even the best aftermarket fences and sliding tables require a perfect index surface to achieve their potential for square; one small irregularity or gob of sawdust can throw them off…and wood is never perfect. Large framing squares and T-squares simply aren’t cabinet tools for the same reason. Make a habit of using diagonals to square up large surfaces and spaces, and your unpleasant surprises will be elsewhere.
Getting the two long sides dead parallel is done easily enough on the jointer and table saw rip fence. End grain like in this example is jointed without splitting by nipping one end on the cutterhead, then reversing the work piece to complete the joint. Then I use the speed square and straight edge to mark square at the front edge of the drawer bottom, paring any irregularities close to the line with a block plane followed by a final pass through the jointer to the edge of the line. The rear edge is squared using diagonals to mark the ends, a line drawn, and the cuts made to the edge of the line using the bandsaw followed again by the jointer. Get those diagonals to within a 32nd of each other, and you are as square as can be done in wood.
To finish the panel drawer bottom, I bevel the sides to 10 degrees…
…and rabbet the sides and front edge to fit the groove with a snug, sliding fit.
I install the drawer bottom. Usually, the bottom is held in by one slotted screw through the bottom of the drawer back that allows for seasonal expansion, but as my drawer back is only 3/8†thick in this application, I elect to glue the front of the drawer bottom to the drawer face groove. This isn’t as easily repaired as a screw-mounted bottom, but is still repairable when the time comes.
The drawer bottom was made slightly over long to accommodate shrinkage and a future repair…
…and the dovetailing job is will serve for a long time without repair.
The flat, square drawer is finished by easing a few edges using the block plane followed by a coat of hot boat soup (60-40 linseed-turps with drier and pine tar) applied hot.
“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think…that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ –John Ruskin.
Replies
Bob...you better put the guard on that saw.
Gabe.......call Taunton!
blue
Warning! Be cautious when taking any framing advice from me. Although I have a lifetime of framing experience, all of it is considered bottom of the barrel by Gabe. I am not to be counted amongst the worst of the worst. If you want real framing information...don't listen to me..just ask Gabe!
Taunton?
Call OSHA and send them my love and kisses. (insert wink here)
“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think...that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ --John Ruskin.
Edited 11/19/2004 12:51 am ET by Bob Smalser
That is kool . I like the "hand cut " machine made dovetails.
Never knew that I was supposed to use a different angle for hard wood and soft wood.
wow, thanks bob!
Thank you for an intelligent, well thought out article. Not owning a bandsaw precludes me from the latter half of your process but you have inspired me to take down that dusty dovetail router jig from the wall.
Dovetailing the gate ends is a brilliant idea and would solve every problem I've ever encountered repairing gates. I wonder if I could pull off the cleanouts with a skill saw?
I was suprised blue-eyed devil had nothing at all to say about your preference for speed squares... :~)
Thanks again
Gord
I've done several of those large cedar automatic gates over the years and use a barrel-handled Bosch saber saw to cut the dovetails. It'd cut your drawer side tails in a pinch, too.
Speed squares? Accurate enough...they stand up by themselves...and when you drop them on the concrete floor, you don't knock them out of tune like many others. But my whole point about squares to newcomers was to avoid using them, eh?
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“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think...that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ --John Ruskin.
Edited 11/19/2004 1:43 am ET by Bob Smalser
Yeah, I've got the Bosch jig saw with the grip handle, probably a little more on the steady than a free hand skillsaw cut. I've mounted the jigsaw under a table and used it once as a scroll saw with disasterous results. Much better up on top and in hand where it belongs.
I admire your beautiful work and am feeling jealous of the shop you must have. I have dedicated myself to being portable over the years with all of my work done on site. If I was to set one up a bandsaw would be one of the first things on my list.
Jealous of the shop I must have?
Thanks....but frankly, I haven't built it yet and am operating out of tents like most boatbuilders.
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It ain't the shop.
“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think...that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ --John Ruskin.
Great pics. and descriptions. I saw in FWW awhile back, some guy had done the same with blades ground to match the DT angles..saves a bit of chisel work i guess.I useually do half blinds (the majority, I should say) and at a furniture shop I worked in, they asked me to set up thier router jig for the Mexican help. I proceeded to show the Mexicans how to hand cut and chisel a drawer box in half the time it took to set up the jig.Never used any type of jig except for one a long time ago, that routed the pins out..it was a homemade deal I saw in FWW..just plywood fingers to guide a router collar. It burned in my shop fire, and I just never replaced it..still chopping by hand.Love your posts..we need a DVD next of all your forays.
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Repairs, Remodeling, Restorations.
My experience is similar:
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Any cedar or other scraps I happen to have on hand. I also alternate cedar and other woods if I don’t have enuf of any one species…..makes interesting color contrasts. The cedar you are looking at had just come in from out in the rain….the construction allows for shrinkage sufficiently that wet wood isn’t a big problem.
Some fellas grind the set off of their blades for a dead flat surface….if I’m gonna be that fussy on a particular project, I’ll either cut them by hand or cut short and pare the sawmarks with a chisel. Changing blades is something I generally avoid unless I have to…..when I get into a larger shop, I’ll simply use two TS’s….one with a permanent stack dado mounted.
Those with router jigs should cut a couple drawer sets over long by an inch or more so you don’t waste stock tuning the jig. Tune the jig using the actual stock then trim the stock to length when you are satisfied with the joint.Personally, I find the better ones excellent for large runs of blind-dovetail cabinet drawers of identical thickness….for through dovetails or small runs of mixed size and thickness blind-dovetail drawers I find them fussy, tedious and often slower.An interesting contest would be a couple sets of roll top desk drawers. 3 or 4 pedestal drawers in two thicknesses of drawer front and two drawer depths…a wide center drawer…. and 4 top drawers of a third thickness with two separate depths….all blind dovetails.With a standard of zero stock waste, forcing you to mill separate scrap stock to set up the jig….I wonder how far I’d get cutting them by hand in a race with the jig? If we used through dovetails instead of blind dovetails and I could use the machines above…I might even spot you a drawer.I’m not picking on you, your comment is valid; I’m just pointing out that all methods have their plusses and minuses.
Stiffer bottom and less planing required. Quarter-inch cedar is a bit springy.Half-inch cedar weighs no more to speak of than quarter-inch hardwood ply, either.Wonderful way to use up all that narrow rip waste...nuthin wrong with mixing species for variety, either. So unlike quarter-inch plywood….these drawer bottoms are free.
Expensive ball bearing steel slides?The biggest of all the needless gizmos for most applications, IMHO. Given their considerable expense, I don’t understand their popularity, as they require the same construction tolerances as traditional joinery.Make the drawer and carcass traditionally, and neither weight nor full extension require anything but oak-on-oak and paraffin wax. Even for big file drawers full of books or tools.You don't have to stop watching Norm on TV....just remember his main purpose is to sell you on all the expensive and needless gizmos he's using.
I've repaired them on old furniture. A fancy touch that can reinforce a thin side, but still generally a factory shortcut to avoid using a raised panel and one more glue joint to fail and require repair.
My descendants. These are book chapters I post for y’all to review, provide feedback for clarity revisions, and in return, use as you see fit. Most have been on hand tools, as I believe that’s the best way to start and there is a big gap there among today’s most popular woodworking teachers.I worked for the tradesmen in my family extensively but reluctantly as a kid, as it didn't help my baseball or hunting/fishing careers. I didn't really get interested in what they did for a living until I was older and they were dead.I held up the ends of their planks and sharpened their slicks and Disstons long before "The Great Craft Revival" and its "rediscovery" of hand tools and figured I ought to start writing this stuff down, as there's a lot of really poor hand tool information out there by well-meaning folks who fiddle with them as hobbyists but never actually met anybody who derived the bulk of their living from hand tools.
“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think...that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ --John Ruskin.
It ain't the shop.
Wow, but hey, a couple of walls, some central heating....lol
Thanks again for your insight and techniques. I will certainly use them on my own projects but on a professional level there is a delicate balance between speed and quality, too much emphasis of late has fallen on the former, and its getting worse. Its a shame that a majority of the personnel in Companies I've worked for only see the work on paper.
Keep up the good work Bob, its becoming a lost art.