- 4 Dec 2005
- Reaction score
I recently psted a review of Cosman's planing DVD's, but whgen I was at the wood show, he had a packag eoffer, so in addition, I also bought his dovetail DVD's which I cover here. (I have one more still to review on "Drawer-Making, the Professional Approach".)
In North America, the name Rob Cosman is synonymous with hand-cut dovetails, and he continues to reinforce the association by touring the North American woodworking shows to demonstrate his techniques. Cosman does not try to make his magic seem difficult. On the contrary. Just as in his demos, throughout the videos he stresses the point that successful dovetailing consists primarily of accurate marking, and the ability to saw to a straight line. He also asserts that anyone can do it.
Easy to say…
A month ago, after seeing his latest demo at the local woodshow, I was inspired to come home and make my first ever attempt to cut some dovetails by hand. As is painfully evident, the result was not an aesthetic success.
I did follow at least some of his instructions, but clearly, the combination of no marking gauge and a bigger hammer wasn’t the most efficacious. So, I went back and bought the DVD’s.
Did they help? You be the judge. The joint accompanying the cover photos above is my second ever attempt, done this morning after watching them carefully several times, Here’s a larger view. No test fit per Cosman, and I made no repairs. This is exactly how it came out except for a few strokes with a hand plane. (Another pass or two would have eliminated the ink line on the top of the left-side tail.)
I made a DT gauge much like Cosman’s and did the marking out exactly as he instructs. Very ingenious procedure. I used an inexpensive Lee Valley small rip Dozuki saw (Part no. 60T06.10). (Much cheaper than the Lie Nielsen Cosman swears by.)
that has zero set, follows the line better than I can, and cuts on the pull – which I prefer. I also used a cheap coping saw to remove most of the waste since I don’t (yet) have Cosman’s recommended fret saw. (FWIW, I found waste removal to be the operation fraught with greatest potential for disaster.) As the large image above clearly attests, my second attempt barely begins to approach minimum quality, but I’m nonetheless encouraged to continue trying.
With so many router-based jigs available why cut dovetails by hand?
People who have mastered hand-cut dovetails often argue that they can cut them faster than it would take them to set up a router jig. Whether true or not, router bits cannot be made small enough at the base to emulate traditional dovetails, and in any event, no one would argue that machined dovetails can equal the visual impact and beauty of the traditionally made joint. Aesthetics, and the sheer pleasure of craftsmanship. That’s why dovetails are still cut by hand.
At show demonstrations, Cosman interacts constantly with the audience. Since that’s not possible on a DVD, Hand-Cut Dovetails opens in Rob’s shop with his trusty sidekick Bruce Dennis introducing Cosman. Dennis remains to ask questions and make comments. The interplay ensures that the audio is not just a monologue.
Since accurate sawing is the primary key to success, Cosman first discusses the essential qualities of dovetail saws and promotes one from Lie Nielsen saw, because, he says, it’s properly, purpose-made, and ready to go out of the box. Given the recent discussion of wheeled marking gauges on this Forum, and Alf's comprehensive review , you might find it interesting that In this DVD Cosman uses a Veritas, and in the next one, enthusiastically recommends the Glen-Drake Tools version.
Back to dovetail saws, he notes that most manufacturers produce them with a cross-cut tooth configuration when what’s really required is rip teeth. He also presents arguments in favour of minimal “set” i.e. the smallest possible kerf, and demonstrates with two saws why he espouses that view. (The demo certainly shows the difference in aggressive performance between rip and cross-cut saws.)
He then moves onto stock preparation for the sides and front, and offers several very useful tips to ensure precision. Similarly, he shows the techniques to set and use a marking gauge to mark the depth of cut perfectly. (He also discusses the advantages of the newer circular knife models over traditional pin marking gauges.)
In the great and raging debate about “pins or tails first”, Cosman comes down emphatically in favour of tails. He argues that this approach requires that the craftsman master only the ability to make a perpendicular saw cut.
He stresses the need to clamp the workpieces plumb, a basic first step to long term success. Two dividers are used in a very simple method to establish the number and size of pins. A shop-made jig sets the angles of the tails, while Rob explains that softwoods require more “rake’ (wedging angle) than hardwoods. (Curiously, however, he then states that he uses the 1:7 for hardwoods as well, because he prefers their appearance.) Cleverly, the indentations left by the dividers become the registration marks for his pen when he draws the lines for his stock removal.
Given its overwhelming importance, Cosman spends a significant amount of time explaining and demonstrating his sawing technique. Actually making the cuts is very efficient and takes almost no time at all.
One of his well-known “tricks” is to remove most of the waste with a fret saw – not, he emphasizes, a coping saw. As well as eliminating a lot of chisel work, it allows for narrower tails than would be possible with a chisel. (Just how narrow is demonstrated in the second DVD.) He offers a tip on how to “adjust” the fretsaw’s blade for workpieces that are longer than the saw’s throat capacity.
He cleans the joint up with a chisel, and draws a sketch to argue against the oft-proffered advice to undercut the interior of the joint. He sneaks up on his lines with a sharp tool and gentle taps with his mallet. Another tip is given on how to avoid accidentally scarring the outside of the joint.
With the tails cleaned up he provides another tip to make the transfer of marks for the pins easier and more certain. Then, whereas he uses a pen to mark the tails out, he uses a knife to transfer the outlines for the pins. Once again, a tip: don’t use a sharp knife such as an Exacto. He describes how he alters a knife to deliver accurate marks that are readily visible. He makes his marks in a particular order, again contributing to accuracy. With that done, his next step is absolutely counter-intuitive, but he explains the rationale very well. (I’ll leave this one for purchasers of the DVD.)
After extending his lines with his jig and a pen, he once again sets up for vertical saw cuts, and basically repeats the waste removal process.
With the pieces cleaned up, he announces, “We’re ready to glue the joint together,” and starts discussing the use of a small palette knife as an applicator for common white or yellow (aliphatic) glue. However, as yet he’s made no trial fit, nor even eye-balled the 2 pieces close together. Nevertheless, he then grabs a small block of wood and a steel hammer – he explains why steel is more appropriate than a rubber mallet – and sets them ready to hand. As he begins to put glue on the palette knife, Bruce finally asks if he’s going to test fit. His answer is “No, because it will never fit as well the second time as the first time.” He then shows Bruce that “all the scribe lines are still visible on both pieces, so the joint must fit. Trust me…”
Of course, the joint does go together and the fit is perfect.
While waiting for it to dry, Cosman describes half-blind dovetails, and acknowledges that cutting the sockets is a lot of work. Thus, when he recently had to complete a project with 62 drawers, he describes an approach he developed that considerably reduces the work involved.
With the glue now sufficiently set, he demonstrates how to plane the joint to a smooth finish. Although as noted above his fit is perfect even under a magnifying glass, he concludes this video with several very useful tips on how mere mortals can fix small errors and make them virtually invisible.
Advanced Hand-Cut Dovetails opens with Cosman describing what’s to come: first, the traditional approach to making half-blind dovetails, then the mitred-edge dovetail, and last the hounds-tooth dovetail (little dovetails cut into larger dovetails).
He starts the half-blind dovetail demo by carefully preparing the stock - both pieces have to be flat, parallel, and square - and then uses the wheel marking gauge to scribe them in the manner peculiar to half-blinds. Next, a quick review of the use of dividers for marking out the pins. The marking and cutting out of the tails is exactly the same as for through dovetails. At this point, the dialog takes us through a very precise and careful examination of the factors that are crucial for a tight fitting joint. In the case of the half-blind, for example, the shoulders of the tail board have to be cut “right on”.
Transferring the markings to the pin board and cutting the pins – or, if you will, the sockets for the tails - is not the same as for through dovetails. The thin set-back that will cover the ends of the tails is in the way. However, the procedure is explained clearly as he proceeds to cut the pins with a little bit of sawing and a lot of very careful chiseling. This section is replete with helpful hints on technique, including his shop-ground dovetail chisel.
Once again, no dry fit. Just a little glue from his palette knife buttered onto the long grain sides, and assembly with a small steel hammer and block. Perfect, of course.
The mitred-edge dovetail instruction begins with a description of its application (carcase construction), and the rationale for taking the extra trouble to make it – the much more attractive appearance of a mitred joint versus a butt joint. With the front and side prepared as before, it’s back to the marking gauge plus a protractor. A slight variation in approach takes the peculiarities of this joint into account.
Because he wants to have pins that narrow to nothing other than the width of the saw kerf, the use of the dividers is also slightly different. Once the tails are marked out, and the mitre waste area clearly indicated, the sawing of the tails begins. Again, the procedure differs somewhat from the norm, but it’s shown and explained clearly and comprehensively. The tricky bit is to clear out the mitre waste very precisely to ensure that when assembled it’s closed. With that done, the tail outlines are transferred to the pin board as for a through dovetail, but because the pins are so narrow, a very fine knife is required as is extra care in ensuring that the knife stays tight to the sides of the tails.
With the tails and pins cut out, the second half of the mitre remains to be marked and cut with the saw, followed by a little bit of paring with a really sharp chisel. Very, very carefully.
Once again, he goes directly to glue-up, and once again the result is a set of perfect dovetails PLUS a perfect mitre.
With that joint set aside to dry, he shows Bruce an example of the Hounds Tooth dovetail, basically a series of alternating large and small pins.(A triple Hounds Tooh can be seen on the left side of the cover in the opening photo above.) To Bruce’s comment that “This one looks really complicated to me,” Rob replies, “Actually, Bruce, this is the least difficult of the ones we’ve done today.” But, Bruce is right. It does look complicated
With the stock prepared, the marking of the tails and pins begins. Contrary to the half-blind dovetail, this one is marked from the face side. Again, the dividers are used to lay out not one but two sets of dovetails – and Rob remarked that a third set could be inserted to really show off. Scribe lines mark the different depths.
Cutting the tails out is, by now, straightforward except, of course, that there are two stop lines involved, one for the large and one for the small tails. The transfer of the tail markings to the pin board is much more complicated, and Rob stresses the importance of carefully marking the waste areas. The layout, though actually simple, can be very confusing visually. The pins are first cut out as if they were all the same size, and then the small ones are cut back from the wide end to the scribed line at the short end.
With that done, it’s the palette knife, glue, and then, “the moment of truth”.
Did it come out well?
Need you ask?
In summary, both DVD’s are packed full of content, yet the material is presented logically and comprehensibly. The quality of both audio and video are professional. They are a matched set, and clearly show why Rob Cosman is known in my part of the world as Mr. Hand-Cut Dovetail.
Per ardua astra,