Machine-CutDovetailsThe look of hand-cut jointsfrom the tablesaw andbandsaw

by Mark Duginske

Duginske's method produces machine-cut through dovetailswith hand-cut accuracy. Both tails and pins are sawn using ashopmade jig on the tablesaw and trimmed with a narrow bladeon the bandsaw. An ingenious system of spacer blocks and shimsdetermines the layout of the joint and maintains a precision fit.

T he dovetail is a classic joint that many craftsmen consider tobe the hallmark of quality joinery. But the traditionalmethod of cutting dovetails by hand requires skill and pa-tience, and unless you're in practice and up to speed, all that saw-ing and chiseling is slow work. Making dovetails with a router andjig is one alternative, but the monotonous look of most router-cutdovetails leaves something to be desired.

I have always felt that there was a missing link between the te-dium of hand-cutting and the limitations of router jigs. After yearsof experimentation, I developed a method for cutting throughdovetails, which combines hand-tool flexibility with machine-toolspeed and accuracy. It's a great system for the small-shop becauseit is fast, simple to use, costs next to nothing and allows you to de-sign the size and layout of dovetails to suit most applications.

How the system worksIn a nutshell, the system employs two machine tools: the tablesawand the bandsaw. A simple shopmade jig shown in figure 1 on thefacing page mounted to the tablesaw's miter gauge supports theworkpiece on edge for cutting both pins and tails with a standardsawblade. The blade is tilted for cutting the tails; for the pins,the miter gauge and jig are angled. While the jig maintains theangle of cut, a set of spacer blocks mounted to the jig spaces

the sawcuts to producea perfectly fitting jointwithout the need tomark the boards indi-vidually. After the table-saw cuts are made, thewaste is removed witha -in.-wide blade onthe bandsaw using thesaw's regular rip fenceas a guide. The narrowbandsaw blade slidesinto the kerfs left bythe tablesaw blade andcleans up the sharp cor-ners between tails and

The dovetail joints' precision fitcan be fine-tuned by adding, or sub-tracting paper shims when the pinsare cut with the tablesaw jig.

pins almost perfectly. Shims, used along with the blocks, allowfine-tuning the joint's fit. Depending on the width of the spacerblocks and the setup of the jig, you can vary the angle, width andspacing of the pins and tails for practically any aesthetic effect.

Although my system is straightforward, it involves quite a fewsteps that must be performed in order. The procedure is better il-lustrated with photographs and sketches than with a written de-scription alone; therefore, I've included a step-by-step account inthe sidebar on p. 68 of how to cut a typical through dovetail joint.Before you begin cutting, there are a few preparatory tasks in-cluding making the tablesaw jig, designing the layout of the de-sired dovetail joint and cutting out the spacer blocks.

Designing the joint and cutting the spacer blocksThe hinge pin of my entire dovetail system is the spacer block:Mounted to the tablesaw jig, the blocks provide a way to cut allpins and tails without having to mark out each board. Before cut-ting the blocks, you must design your dovetail layout including thenumber, size and spacing of the pins and tails. This will determineboth die number of spacer blocks you'll need and their widths.

Following figure 2 on the facing page, you'll see that the numberof spacer blocks needed equals the number of tails in the joint. Inexample 1, four blocks produce a joint with four tails, three fullpins and two half pins. Once you've chosen the number of dove-tails, you'll need to decide on their size and spacing. It's possibleto make the pins and tails the same size, but I find this is too me-chanical looking, not consistent with high-quality work. One of theadvantages of my system is you can easily vary the sizes of pins andtails to make joints look more like they were hand-cut. Traditional-ly, the tails should be larger than the pins, but avoid making thepins too narrow. (Unless you use a special thin-kerf tablesawblade, you won't be able to cut pins less than about in. wide attheir narrowest point and, in my opinion, really skinny pins aretoo weak for most applications.) For the dovetail angle, I'd rec-ommend 10, but avoid an angle outside the range of 8 to 12. Ifthe angle is less, the pins can slide between the tails, defeating thelocking quality of the joint. If the angle is greater, the sharp comersof the tails and pins are fragile and can break easily under stress.

My system allows you to alter the width of individual tails and

the spacing of pins along a single joint. In example 2 in figure 2,the center tail is wider than the tails on either side of it. You couldjust as easily make the outer tails wider or make two wide tails,two narrow tails, two wide and so forthas long as the resultinglayout is symmetrical relative to the center of the joint. This lastpoint is required for this cutting system to work correctly.

Once you've finalized the dovetail layout, you're ready to cut thespacer blocks. As you can see in figure 2, one block is equal to thewidth of one tail at its widest plus the width of one pin at its nar-rowest. In example 1, each block equals one -in. tail plus one

-in. pin (notice that all pins, including half pins, are the samesize). Depending on your design, your spacer blocks may all bethe same width or varying widths, but in either case, the totalwidth of the spacer blocks should equal the width of the stock mi-nus the width of one pin. Both of the examples in the drawing em-ploy spacer blocks that add up to 4 in. wide, yet the number oftails and the layout of each design is completely different.

The spacer blocks are made from scraps of -in. plywood. I cuttwo sets: One set is drilled for the bolts that mount the blocks tothe jig board (an extra block is cut and drilled as the end block).The second set is left undrilled and used to mark the first tailboard, which is necessary for setting the jig before cutting. If yourjoint has tails of varying sizes, number your spacer blocks, so theycan be kept in the correct order (see the top photo on p. 68).

Making the tablesaw jigI made the tablesaw jig shown in figure 1 from -in. plywood. Thejig, which mounts to the tablesaw's regular miter gauge, consistsof two parts: a 4-in.-high baseboard that bolts through the gauge'shead and a jig board that attaches to the baseboard. To allow thejig to be adjusted back and forth for setting different dovetailarrangements, the jig board is bolted through a -in.-wide slot. Apair of toilet bolts, or closet bolts (available in the plumbingdepartment of your local hardware store), connect the two parts ofthe jig. The slot is stepped (routed in two passes) to fit the toiletbolts' heads (see the detail in figure 1), allowing them to slide, yetnot turn when the wing nuts, which lock the jig board to the base-board, are tightened. Another slot routed through the jig boardallows the spacer blocks to be positioned and bolted in place.

You will need a 2-in.-long,-in. carriage bolt, with wash-

ers and a wing nut, for eachblock that you use.

System limitationsAll woodworking methodshave some advantages anddisadvantages, and mine isno exception. First, the jig Ibuilt will only handle work-pieces up to about 12 in.wide, so it won't cut dove-tails on wide carcase sides.Another limitation is thelength of the workpiece. Ifind it's not practical to han-dle stock longer than 2 ft.standing straight up on yourtablesaw top. If you mustmake dovetails on boardswider than 12 in. or longerman 2 ft., I suggest you eitheruse a commercial router dovetail template system (Leigh andKeller both make good ones). Or, if you only need a few dovetails,cut them by hand. Finally, my system doesn't allow pins that varyin width in a single joint or a non-symmetrical arrangement. Inother words, you can't make a drawer side with pins and tails thatare progressively wider from top to bottom. But I can think of veryfew instances where you'd want to do this anyway.

It'll probably take some study and experimentation for you tomaster the process, so don't plan to make drawers from your pre-cious stash of bird's-eye maple the first couple of times that youtry the system. I am a real believer in practice makes perfect. Themore you use this system, the better you will get at it.

Mark Duginske is a woodworker, teacher and author who livesin Wausau, Wis. His book and video Mastering WoodworkingMachines is available from The Taunton Press.

Step-by-stepdovetails

Here are the steps you will need to fol-low for cutting out a set of throughdovetails. The demonstration jointshown in these photos illustrates a typi-cal joint, such as you might use forbuilding drawers. Layout and dovetailsize variations, as well as the construc-tion of the tablesaw jig and spacerblocks needed to cut the joint are dis-cussed in the main article.

Prepare stock: Dress all stock to finaldimensions with tail boards and pinboards of equal thickness; make sureends are square and trimmed to finallength. Set marking gauge to thicknessof stock, which will equal the depth ofthe dovetails, and scribe both faces ateach end of tail boards and pin boards.Stack dovetail spacer blocks and markposition of first tail's edge on one tailboard (see left drawing below).

The tailsCutting on the tablesaw: Set bevel ofsawblade to desired dovetail angle (10)and square miter gauge to blade. Attachthree spacer blocks and end block to thejig, squaring them to the saw table be-fore bolting them on (see top photo).Lower sawblade slightly below depth ofdovetail cuts. Now butt the edge ofmarked tail board up to third spacerblock and slide the jig board untilmark aligns with sawblade, as shown intop photo. Tighten bolts that lock jigboard to baseboard.

Place a tail board against jig, and takea trial cut on one side of the first tail. Setdepth of cut by raising blade and recut-ting until cut reaches scribe mark onstock. Now flip the board end for endand take second cut. For third cut, ro-tate board edge for edge, then end forend for fourth cut. Remove spacerblock one and repeat four cuts, flippingas before. Remove spacer two and re-peat same sequence of cuts to completetails (see bottom left photo). Now per-form entire cutting sequence on each ofthe tail boards.

Bandsawing tail waste: Fit bandsawwith a -in. blade and adjust the ripfence so cutting depth to outside ofblade equals depth of dovetails. Trimwaste from between tails by sliding thestock into the blade via the sawkerfs cuton the tablesaw earlier, as shown inbottom right photo. Flip stock over

and bandsaw again to clean up cornersbetween tails. Do this on all tail boards

The pinsSawing first side: Square tablesawblade to table and lower blade heightslightly. Set miter gauge to dovetail an-gle (10) with right side of jig boardsloping away from blade and replace allspacer blocks. Transfer tail position toone pin board (see right drawingfacing page) and then hold pin board(inside face toward jig) against firstspacer block and adjust the jig board sothe end mark lines up with the saw-blade, as shown in top left photo. Takea trial cut and adjust blade height as be-fore. For second cut, flip board end forend, keeping same face against jig. Nowrepeat first two cuts on all pin boards.Remove spacer block one, take twocuts (flipping board end for end as be-fore), and repeat on all pin boards (seetop right photo). Remove spacerblock two, and repeat cutting sequenceon all pin boards.

Sawing second side: Reset the mitergauge so that it angles (10) in the otherdirection. Reattach spacer block two,but before bolting, slip a stack of adozen or more paper shims betweenend block and spacer three. Align markto blade and set jig board, as shown inphoto at right. Cut only the markedpin board (keeping its inside face againstthe jig), and follow the sequence of tak-ing two cuts, flipping board betweencuts, removing a spacer block and cut-ting again until you've removed all threespacer blocks (see bottom left photo).

Bandsawing pin waste: With thesame bandsaw rip-fence setting as be-fore, carefully tilt pin board at necessaryangle and slip blade into a sawkerf; thenlower board flat onto table and cut awaywaste (see bottom right photo). Holdthe board securely as the blade willwant to grab and pull the board down asyou begin each cut. After sawing eachpin waste, move the small waste blocksaway from the blade with the eraser endof a pencil, for safety sake. Repeat tosaw away waste on first pin board. Nowtrial fit a pin board with a tail board. Ifthe fit is too tight, remove as many pa-per shims as necessary, replace spacerblocks two and three, and recut trial pinboard. Recheck joint fit and removemore shims if needed until dovetail jointslides snugly together. Retaining thisshim arrangement, cut and trim allremaining pin boards as you did withthe trial board. M.D.

SAVEPRINT