The picture shows some dovetails made using the "Perfect Dovetails" method. This is actually the joint at the front of a drawer from a chest of drawers. All ten drawers in a chest of drawers were made using the technique, which proved to both more accurate and quicker than traditional handcut methods (at least in my hands).
The instructions provided here take you through the entire process of creating your perfect dovetails. It is recommended that you read these through completely before starting so that you have a good idea how it all works. After that, you can dip in and out as you need to. There is also a simplified instructions sheet to keep handy in the workshop. The general approach is illustrated by the picture of the bandsaw cutting the pins with the bandsaw table tilted to the left. Note the labelling of the board.
Tools & materials needed:-
Accuracy is the secret to great dovetails, whatever method you use. The "perfect dovetails" method relies on two important things before you start:
As regards the bandsaw, any decent quality bandsaw should be up to the task so long as it
As regards the boards to be joined, the edges should all be square and straight. In particular, one edge (which we will call edge "A") will be used as the reference edge and must be square to the end of the board to be joined. Unlike with the spacer method, the boards do not need to be exactly the same width but bear in mind that edge A will need to line up in the finished joint. Don't forget to make the boards fractionally longer than the finished length to allow for trimming the joint after it is complete (a typical trim allowance might be 0.5mm in which case allow an extra 1mm length if the board is jointed at both ends).
Having got the basics right, you now need to know exactly the dimensions of your boards. I advise working in millimeters throughout as they are a useful scale for most dovetail joints and the spreadsheet takes decimal inputs, not fractions, but if you want to work in cubits, feel free. You also need to know the kerf of your bandsaw blade. This is quite critical, so it is worth measuring it accurately as follows:
Finally, before you start the design tool, label the edges of your boards "A " and "B " so that they all match. For drawers, I normally label the top edge "A ". (see picture above). Important: for the jig method you must label the inside of the tail boards and the outside of the pin boards.
After using my jig for a while, I devised two additions which improved the accuracy while maintaining efficiency:
The moveable clamp (see picture) is a simple s-shaped block (reinforced across the grain with screws). It has a slotted hole which then can be bolted to the stop fence in a number of locations so that it can be clamped in any position. The face which holds the workpiece has a small strip of grip strip applied. This clamp ensures that the workpiece is held firmly against the moveable fence.
The hold-down (see the right-hand side of the second picture) is just a board the same thickness as the pegboard. It locates on the opposite (unused) pivot hole and is held down by the respective toggle clamp. A small strip under the back edge provides a bit of leverage so that the clamp hold the stop fence down securely. The addition of a (front-to-back) piece of grip strip prevents lateral movement of the fence. The purpose of this is to ensure that the whole moveable fence assembly is held down flat on the jig base and cannot twist or move.
It is a good idea to check that your jig works and that the measurements are accurate. The best way to do this is design a one-tailed joint. In the design tool use a kerf of ZERO (in fact you may need to set it to a very small positive number to avoid error messages). Make the pegboard as described below and make an 'anti-clockwise' pin and tail cut into the SAME WORKPIECE. The saw cuts should be in exactly the same place on the top face of the workpiece (you can also check with the 'clockwise' cuts). If they do not coincide then it is most likely that you have an incorrect measurement for the thickness of the jig base or for the distance from the lead hole, in the moveable fence, to the small stop. It is also possible that the bandsaw table may not rotate exactly around the blade (see notes above) or that you made a mistake with the cutting process.
To double check the jig thickness / bandsaw rotation, set your bandsaw tilt to anti-clockwise 14 degrees. With your moveable fence square to the jig in a convenient position, make a cut in a piece of scrap. Without changing anything eslse, rotate the table to clockwise 14 degrees and cut again. Measure the distance between the cuts on the underside of the scrap board (measure from, say, the lhs of one cut to the lhs of the other). Double this measurement: that is the "effective depth" of your jig base.
Now it's time to plan your perfect dovetails and see what they will look like. Put all your measurements into the "design tool" calculator form, namely:
You need to decide how many tails you want, but you can always change this if you want to. You also need to decide the dovetail angle to use. I recommend using a whole number of degrees (which makes it easier to see on your bandsaw table tilt gauge). 8 degrees is about 1:7 which is a good all-purpose angle. Put these details into the design tool calculator. By the way, it is perfectly possible to use a dovetail angle of zero to make a finger joint, but please note the comments in the "Tweaks" section.
Now design and enter the pin widths. The dimensions in each case are the widths at the base of the pins (the widest part). It makes life easier if you set this to be just a fraction more than the width of one of your chisels, so that chopping out the waste between the tails is simpler (i.e. the width of a chisel plus a saw kerf is good). One nice thing about the "perfect dovetails " method is that you can make narrow pins in the traditional style, without being constrained by router shanks. Make them as wide or narrow as you like, you can always change it in the design stage. Of course, they will need to be wide enough to allow the tails to be cut (i.e so that the narrow end of the pins is a bit more than the saw kerf), but the calculator will let you know if you go too narrow.
You also have to specify the widths of the half-pins at each edge of the board. These will normally be a bit wider than the main pins as you don't want them to break off when fitting (they have nothing the other side to support them). You may also need one of the half-pins to accommodate a groove for a drawer bottom. Talking of drawers, you may want to have the back of the drawer a different width from the sides (to accommodate the bottom of the drawer running underneath the back, say, and/or to reduce the top of the back to allow for easy insertion of the drawer). You can do this by specifying a cut-away for the pin board on either or both edges. If you use my convention of the top being side "A" and the bottom being side "B", then you will, for example, set the "Cut-away on Edge 'B'" to be the distance from the bottom of the drawer sides to the top of the groove in them which takes the bottom piece. If you are using different sized boards, then this may not be necessary, but note that the tool will only draw the joint from the point of view of the narrowest board and it is assumed that the reference sides (A) will line up. (Note that either the pin board or the tail board could be cut down after making the joint, but it is usually the pin board that is affected).
Finally enter the "trim allowances ".
Now click "submit & save" and the calculator will draw your joint for you as well as designing the pegboard that you will need. You may get a number of warning messages if the calculator doesn't quite like your specification. Hopefully these are self explanatory. If it can draw the joint then it will do so and this might help you to understand any error messages and how to fix them.
If you are logged in then all the details will be saved. Otherwise they will not be saved and you will need to print them before navigating away from the page.
If you are happy with the result, click the button to view a large scale version of the pegboard. If you have a CAD or similar application which can read .dxf files then download the .dxf file and import it to your CAD application. Set the scale to full size and print it (you may find it won't all fit on your printer paper, but hopefully you can arrange it such that at least all the holes to be drilled are on the same page). If you cannot read a .dxf file, then the next best thing is to print the large scale drawing to a pdf file, open in Adobe, select 'Take a snapshot' from the menu and select an area including the pegboard of known size. You can then paste this in a drawing application and print a full sized image from there - double check the size of the printed image.
Having printed your pegboard, you are ready to make it.
Making the pegboard is really simple - you just paste the printed image on a board, cut it out and drill the holes. However, there are a few points to be careful about and these are described below. Note that, if you are unable to print the template, the design tool gives you all the dimensions you need. However, I would still recommend drawing these on paper and then pasting the template on the board.
Use a reasonably thick board so that the pins will be held firmly and vertically. I have found that 18mm ply works pretty well.
Paste the pegboard image on the board. I find that repositionable spray glue is very useful for this. If the full pegboard image did not all fit on the paper, then you may need to line up and paste more than one sheet, which is when the repositionable glue comes in handy. If all the holes fitted on one sheet, but not the full image, then you maye be able to add the outer edges by hand drawing or pasting separate sheets (see picture - I find that with my bandsaw and the largest jig it will take, the holes will all fit on one page of A4, but not the complete template). Then cut out the board. Note that the 'horns' on the left hand side may need trimming in order to pass the bandsaw pillar when cutting with the table tilted to the left.
Use good quality 'lip & spur' drills and a pillar drill in order to drill accurate and vertical holes (see picture). If you used the .dxf file than the holes will be marked to the exact size. Try and drill the centres spot on: side-to-side inaccuracies will not necessarily affect the fit of the joint but will alter the appearance slightly, front-to-back inaccuracies will make it difficult to fit the pins into the moveable fence. Test fit the pins in the holes to make sure that they slide in and out but are not loose (a bit of vaseline may help).
If you have printed the template, it should provide sufficient instructions on the sheet. Importantly, you will see that one edge is labelled "anticlockwise" and the other "clockwise". This means, for example, that with the anticlockwise edge forwards, the table should be tilted to the left, with the fence at right angles to the rear edge of the jig base, to cut one side of the pins; to cut one side of the tails, the table is placed flat and the the fence rotated anticlockwise by the required angle.
When the pegboard is face up, the boards to be joined will be on the left hand side of the table. If you are making a drawer and 'A' is the top edge and is the reference edge, then this will make the back left or front right corner. To cut the mirror image joint (for the other side of a drawer, for example) the boards will be on the right hand side of the table and the pegboard will need to be turned over. You will now need to label the pegboard "clockwise" on the underside of the anticlockwise edge and vice-versa (it is still rotating the same way, but obviously it is being viewed from the other side - similarly to looking at a screw thread from the other end).
If you haven't already done so, label the boards clearly. The pin board should be labelled on the face side (outside of the box or drawer) and the tails board must be labelled on the inside. The labelled side will then be uppermost throughout the bandsaw work. Also make sure that the edges are labelled "A" and "B" to match all the way round the drawer or box. I find it best to put labels on masking tape as it is clearer and does not mark the wood (see picture). Edge A will be the reference edge and will be placed against the fence.
Double check that the reference edges and ends to be joined are square and straight.
Mark the shoulders on each board, using a cutting or wheel gauge. For the tail boards, the width of the shoulder must be exactly the thickness of the pin board plus the trim allowance as specified in the calculator. For the pin boards, the trim allowance is up to you. Mark the pin board on both sides and mark the tail board all the way round. If you put coloured masking tape on before marking the line, then peel it away, you will have a clear edge to cut to (see second picture).
Now, particularly if this is the first time you have used the "Perfect Dovetails" method, I advise that you make a test joint. Read the sections on cutting the pins and tails before doing this. Use two short pieces of wood the same thickness and width as your real boards and work through the whole joint-making process. (Label the board edges in the same way as the real boards).
Note that on the test pieces in the picture I have done two joints - one for the front and one for the back of a drawer. The joint can be test fitted as shown without fully removing the waste on the tail board edges. This means that if you have made an error, you can reposition the tail board against the fence to see what might have gone wrong (maybe the board was not against the stop when you cut it).
Now at last you get to make the joint. For the purposes of this guide, I will describe how to cut the pins first. However, the typical sequence is pins-tails-tails-pins - see the section on "Process efficiency".
We will assume that the diagram of the joint in the design tool matches the joint you want to make, with edge A on the left hand side (i.e. you are not trying to make the mirror image). Tilt the bandsaw table the required number of degrees to the left. Place your pegboard onto the left hand pivot hole with the 'anticlockwise' edge to the front. Secure the moveable fence in the pegboard using the pins. Assuming you have made the leading holes smaller than the trailing holes then you will use the small pin at the front and the large one at the back. Start with the pair of holes on the left hand side. Use your toggle clamp to hold the pegboard so that the fence is square to the back edge of the jig base. Particularly if you are going to use a stop fence, I would advise clamping the fence to the rear of the board as well, as in the accompanying picture or, better, using a hold-down on the stop fence (see jig add-ons).
Place the pin board, face side uppermost, with the correct side (edge A) nearest the fence, against the small stop. Make sure that the edge of the pin board is flat against the fence (this is only possible if it is straight!). Ideally use a clamp fixed to the stop fence to hold the board in place (see jig add-ons). Slide the whole jig forward (see picture), cutting down to just meet the shoulder line. If you are using a stop fence, you can now position your stop before removing the board from the blade. See the picture for details of the stop: note that it comes to a point in line with the back of the blade.
Note: I prefer not to use a stop as I find it to be quicker, easier and more accurate by eye. If you place some coloured tape on the board before marking your shoulder line, then peel it away when the line has been cut, you have a very visible indication of where to stop.
Gently pull the jig to clear the blade without banging the crosspiece against it. Remove the clamp or loosen the hold-down, but leave the toggle clamp holding the pegboard. Move the fence across to the next pair of holes and re-clamp it to the jig base. Check that it is square and make the next cut. Repeat for all the pairs of 'anticlockwise' holes.
The other side of the pins will be cut with the table tilted to the right and the pegboard rotated 180 degrees such that the 'clockwise' pairs of holes are used.
To cut the tails, place the table level and leave the fence on the left. With the 'anticlockwise' edge forward, rotate the pegboard anticlockwise (surprise!) and secure it. Check that the angle is correct using a bevel gauge or a square and an angled piece of wood. Cut as for the pins, but do be careful to keep the board fully up against the small stop - do not allow it to be pushed back. If you are using a stop fence then with luck it should be in the right position, but do not rely on it - go carefully.
To cut the other side of the tails, rotate the pegboard through 180 degrees, place on the pivot and secure with a clockwise rotation of the required angle (see picture - note that the hold-down has been left off to show the action).
This section describes how to streamline the process particularly when making, for example, a set of drawers. This makes the production of set of drawers a relatively quick process - and all with "Perfect Dovetails". It is assumed that you know how to cut the pins and tails as described in the earlier sections.
The fastest way to make a single joint is to use the following sequence: pins->tails->tails->pins. Cut the 'anticlockwise' pins first. Leave the fence fixed in the pegboard in the last position then set the table for the 'anticlockwise' tails. Cut these then rotate the pegboard and cut the 'clockwise' tails. Once more leaving the fence in the same position on the pegboard, tilt the table and cut the 'clockwise' pins.
Now let's assume you are making a set of drawers. You will probably have two types of joints - one for the fronts and one for the backs, so you will need to do two pegboards. You will also have a mirror joint for the opposing side of the drawer.
Cut the first joint as described above. Now turn the pegboard over and use it on the right hand side of the table to cut the 'mirror' joint, Do not forget that you should always be placing edge A against the fence.
Next cut the mirror image of your other joint using the other pegboard (inverted) and the fence still on the right of the table.
Finally, turn the second pegboard face up and use it on the left hand side to cut the last joint.
Do make sure you have labelled the undersides of the pegboards correctly ('clockwise' underneath the 'anticlockwise' edge and vice-versa).
Mark all the waste before cutting. The space between pins can be mostly cut out with a bandsaw, if you wish, but do cut with the face side down so that you do not inadvertently cut the pins themselves. Remove the remaining waste with a coping saw or fretsaw, then with a chisel, as for hand-cut dovetails. See here for an excellent guide on removing waste. Do make sure that all the waste is removed cleanly and that, if anything, there is a valley rather than a hill at the base of the cut-outs.
Test fit the joint. It will might be a little too tight in places, but usually you should find that it will fit straight from the saw (afer a little cleaning up). A good dovetail should always be a bit tight and it is not advisable to bang it all the way home before gluing it. If it is too tight, carefully trim with a sharp chisel or a file as needed. Again, there are plenty of guides available on how best to do this - for example this one. That blogger says (of hand-made dovetails) 'It is highly unlikely that everything fits hunky dory at this point. Actually, it’s more like never'. Of course, with 'Perfect Dovetails' they will almost always be hunky dory first time! I generally find that with a "fitting allowance" of 0.25mm, all that is needed is a little cleaning up of each joint with a file.
Typically drawer backs will be narrower than the sides, so that the bottom, running in grooves in the sides, can go underneath the back. Also the top of the back may be lower than the sides by a few mm, with the back end of the sides feathered to match. This section describes how to produce these, including cutting out the waste correctly.
The discussion below assumes that you start with the boards the same size.
If the boards are of unequal width then remember that the reference edges 'A' must line up in the proposed joint. Enter the larger board width in the design tool and an amount (positive if the tails board is the larger or negative if smaller) for the cut-away on edge B to account for the difference. If you want the reference edge to not line up in the finished joint, and cutting down afterwards is not practicable, make up the narrower board to the correct width using a strip of wood attached with glue or double-sided tape and remove it after making the joint.
The method described above is only designed to produce through dovetails that are, to all intents and purposes like the hand-cut ones, just quicker and more consistent. If you are making drawers then you may not want the dovetails to show on the face (on the other hand you may be very happy to display your "Perfect Dovetails" in true "Arts and Crafts" style). In this case there are three alternative options:
If you are determined to use lapped dovetails then:
If using method (b), do not cut deeper than the trim tolerance you have allowed for the pins. Remember, this can be any amount you want - it does not need to be the same as the tails trim tolerance, which in this case is negative. So you could plan to trim 1mm from each end of a pin board, giving ample to make a clear guiding cut. Also use a dovetail saw (in step 4 below) with a kerf as close as possible to, but no wider than, the bandsaw kerf.
Once you are comfortable with using the "Perfect Dovetails" method and the "Design Tool", you will realise that you can start to tweak the results to get some interesting and useful results. Before discussing this, it is worth mentioning what happens if you change the dovetail angle. You can do this quite easily by altering the value in the calculator. It is easy to see how the new angle looks, so that you can choose an angle which is aesthetically pleasing (but bear in mind the performance of the wood). You can also put in an angle of zero to make a finger joint. However, note that if you do this, there is an important change to the method of use: when cutting the "Anti-clockwise pins" and "Clockwise tails", you need to add a thin shim next to the fence (thickness equal to the saw kerf plus the fitting allowance). Note that the terms "pins", "tails", "anticlockwise" and "clockwise are still used although the original meaning is lost - this is to differentiate between the elements in a consistent way. Thus the 'pins' board is the one with fingers on the outside and the 'anticlockwise' cut is the one which cuts the half-pin on edge B. Note that you may have to use tail tweaks to get the fingers to the exact size you want, since using the shim offsets one side of the pins slightly. This offset is not shown in the design tool, but to fix it, add the shim amount to the right hand side of each tail.
Tweaking involves changing the sizes of individual tails (and therefore the corresponding pins). This allows you to make a huge variety of decorative joints. If you are doing lapped dovetails, you can make the base of the tails just a fraction wider than a forstner bit - to make removing the waste between the pins easier.
Tweaks are applied interactively in the calculator and you can see how the joint will look:
Click on "Tweak tail sizes" at the top of the table of pin and tail dimensions. Here you enter the amount by which to increase or decrease each side of each tail. Click "Apply" to see the results. Note that pegboard spacing will be changed to enable the joint to be made. To clear all tweaks, click "Clear" then "Apply". Note that the tail tweaks are relative to the main inputs - these will remain the same, regardless of how much you have tweaked them. If you are logged in then all your tail tweaks will be saved and will be loaded next time you load that project - just click the 'tail tweaks' button to see them.
If you come up with any interesting designs and tweaks, why not post them in the "comments" section?
Ordinarily the width of boards you can join with this method is limited by the gap between your moveable fence and the blade. A little extra may be gained by having a large pin on side B. Also the spacer method may cope with a slightly bigger board. However, with a little ingenuity, it is possible to use the jig method to join boards that are twice as wide as usual. This creates the opportunity to use "Perfect Dovetails" to join cabinet panels, for example.
The method does have limitations however - the main one being that your boards to be joined must be exactly the same width as each other. Also you can only use the fence on the left of the blade, to avoid the pier, so cutting "mirror image" joints with the same pegboard (upside down) is not possible. The method proceeds as follows:
Note that the method described above will make a symmetrical joint. If you want to make an asymmetrical joint then you will need to design two pegboards - one for each half of the joint - and just add your "offset" holes to the "right-hand" board.