Thread: FWW article on cutting half-blind dovetails - the hardcore Dark-Side way

Hi Rocker,

I look forward to reading your suggestions for making darkside dovetails easier. If you needed any encouragement, please feel encouraged.

Me too. Consider yourself heartily encouraged. It would be great to have someone reconcile all of the information in one place. I would love to have the time to hand-cut everything, but shed time is so precious that efficiency is more important than 100% darkside. I don't like the idea of DT jigs though, and the next project will have dt's somewhere, I promise!

'Tis why I like the incra fence that I am just starting to use. It isn't a jig persay - it is a highly accurate fence, and as such, makes dovetailing very easy (1/2 and full), as well as box joints, dados etc.

I just use the magnetic LV Dovetail guides with a Jap saw but if I had some more cash I would probably get a leigh jig. While I would like to have the time to practice marking out DT with a thumbnail dipped in tar and cutting them with an old diston, I don't really have time. To each their oen I guess.

As I mentioned in my first post in this thread, it is quick and easy to make the saw cuts for the tails on the table saw, using a high fence attached to a mitre gauge (see Photo). Doing this ensures that the cuts for the tails are precisely perpendicular to the workpiece's face and that they are at a constant angle (7&#176 to its edge. Moreover, it is not necessary to be unduly finicky about ensuring that the saw cuts coincide precisely with the layout lines when cutting the tails. The fit of the joint will depend on how accurately the saw cuts for the pins are made.

The photo also shows the simple jigs and accessories that make the process of marking out and cutting dovetails by hand relatively painless, compared at least to relying on the skill and lengthy experience required to achieve the same results without such aids. Shown in the photo are the LV Marking gauge, dovetail marker, marking knife, dovetail guide and dovetail saw, together with a hammer chisel and clamping jig for holding the workpiece whilst chopping away waste.

When cutting the tails on the table saw I make two contiguous cuts on one side of the tail to give access for a 1/4" bandsaw blade to cut away the bulk of the waste. If you are cutting a large number of tails, it would probably be worthwhile to set up a dado set to cut away the bulk of the waste between the tails, instead of doing it on the bandsaw. Cutting away the bulk of the waste with the bandsaw or dado set eliminates the first stage of the waste removal that the FWW article advises should be done with a chisel.

To chop away the remainder of the waste, I use the clamping jig shown in the photo. The workpiece is clamped so that the gauged line coincides with the vertical edge of the clamping bar. The chisel is placed into the gauged line and its back is held firmly against the vertical face of the clamping bar, and it is then hammered down to remove the small thickness of remaining waste. This can easily and accurately be achieved with three or four fairly light hammer taps. The use of the clamping jig makes it a simple matter to chop away the waste accurately to the marked line. If you try to do this without using a clamping jig, as recommended by the FWW article, you need to exercise a considerable amount of skill to ensure that you make a vertical cut.

Making the saw cuts freehand for the pins of half-blind dovetails is likewise a highly skilled operation unless you use a dovetail guide like the Veritas one, which incorporates rare-earth magnets to ensure that the dovetail saw is held at the correct angle. Removing the waste between the pin cuts by the traditional method, with hammer and chisel only, is also very difficult to do accurately, particularly if the wood has curly or interlocking grain. For this reason, I like to remove the bulk of the waste between the pins either with the router on the Rocker morticing jig, or with a forstner bit in a drill press. Either of these methods will ensure that the waste is removed to a consistent depth, and it is then relatively easy to clean up the rest of the waste using a chisel with the workpiece held in the clamping jig, as for the tails.

Using these techniques, I have found it relatively easy to cut accurate dovetails without a router-based dovetail jig. But doing so without the jigs and accessories described above, as advocated by the FWW article, would be intimidating indeed.

Rocker

If you try to do this without using a clamping jig, as recommended by the FWW article, you need to exercise a considerable amount of skill to ensure that you make a vertical cut.

Just on this point, I always deliberately undercut slightly. The end grain in between the tails and in the sockets of the pin board don't contribute anything to strength and sometimes prevent the joint from closing up properly. For through tails, I chop halfway through from one side of the board and then flip and chop from the other. This way the lines are always clean and straight and the adjacent board sits nice and flush along it.

I don't use any jigs but for through dovetails I often use the table saw to cut the pins and the bandsaw to cut the tails, with a chisel to remove the waste. For half blinds in the past I have used a chisel and a saw only but I might give the forstner bit a go next time.

Originally Posted by silentC

Just on this point, I always deliberately undercut slightly. The end grain in between the tails and in the sockets of the pin board don't contribute anything to strength and sometimes prevent the joint from closing up properly.

I don't agree that the end-grain contributes nothing to the strength of the joint. If it is pressed firmly against the inner face of the corresponding pin or tail, it tightens the joint up nicely. Otherwise the joint is relying primarily on the strength of the glue, rather than the geometry of the dovetail. For this reason, it is essential to achieve as near as possible a perpendicular face on the end grain. This is very easy to do with the clamping jig. I had not previously thought it worthwhile to make the jig, but, when I did so for my current project, I was amazed at how much quicker and easier it made it to chop away the residual waste accurately.

Rocker

Nice one Rocker.

I like the idea of using the clamping jig for guiding the chisel during the process of removing the last of the waste. I think I'll give that one a try.

In the chapter of his book "The Complete Illustrated Guide to Joinery" concerning handcutting dovetails, Gary Rogowski says "Slightly undercutting the waste toward the centre helps the joint seat properly. High spots prevent the joint from going together, and since this is end grain, there's no advantage in terms of gluing surface." As long as the edges of the shoulder are flat and in plane, the face of the adjacent member will sit squarely and firmly.

In any case, I've found that it improves the results I get from dovetails and also improves the shoulders of M&T joints.

Slavo,

Unless you intend to cut a really large number of dovetails, I think it is hard to justify buying a Leigh jig. I mentioned in another thread that I sold mine about six months ago, because I didn't envisage cutting many more dovetails. The setup time and the learning curve for the Leigh jig are not insignificant, and it can be subject to some inaccuracy, unless you carefully ensure that the template guide that you are using with it is precisely concentric with the axis of your router bit, that all the fingers of the jig are clamped very securely in position, and that all the stops are correctly adjusted.

If you are making a chest of drawers in which the drawers have a graduated depth, you will need to change the jig setup for each sucessive drawer, so the time advantage of the jig over hand cutting is not great for a short run.

Rocker

Originally Posted by silentC

As long as the edges of the shoulder are flat and in plane, the face of the adjacent member will sit squarely and firmly.

In any case, I've found that it improves the results I get from dovetails and also improves the shoulders of M&T joints.

SilentC,

Now I agree with you. I had not appreciated that you were talking about undercutting towards the centre, but keeping the edges of the shoulder flat and in plane.

Rocker

One of the many things which is easier to do than say

Rocker,
stupid question from me. Do you tilt the blade 7 deg or do you tilt the wood at 7 deg ???
Regards
Les

Originally Posted by Rocker

The setup time and the learning curve for the Leigh jig are not insignificant, and it can be subject to some inaccuracy, unless you carefully ensure that the template guide that you are using with it is precisely concentric with the axis of your router bit.........

I find a router centring mandrel useful for ensuring that any template guide I use with my router is concentric with the router bit I'm using. The one pictured is from Festool and can be used in either a 1/4-inch or 8-mm collet. All you do is compress the plunge mechanism on your router, loosely install the template guide, clamp the centring mandrel in the collet of the router and then release the router plunge mechanism. The flanged section of the centring mandrel then automatically centres the template guide. Once this is done, all you have to do is tighten up the screws that hold the template guide in place. It works well.

The template guides on my router are held in place with two screws and before the screws are tightened up the template guide is free to move a small amount.

I'm not all that familiar with the mechanisms used to attach template guides to other routers, but if your's attach via a couple of screws then I can't see why this wouldn't work. You don't need to buy one from Festool, you could turn one yourself if you have access to a metal lathe or you could probably even turn one out of wood that would work OK if you only have access to a wood lathe. If like me you don't have access to either type of lathe then you might have to buy one from Festool.