Rob Cosman Video on cutting perfect dovetails first attempt

[Rob Luter]

I was lucky to take a few classes from Mr. Cosman when he used to go around teaching and was in my area. I learned his techniques and practiced (a lot). He has thought through every little step and does a great job explaining it.

I do have his saw, but any good saw will work. In fact I have recently made my own dovetail saw and have been using it without issue, although his saw is very nice.

His method of marking out dovetails (which I believe he learned from Alan Peters) is excellent. A few years ago, he solved what I believe is the hardest part of handcut dovetails - cutting the pins. The technique of moving the thickness of the kerf into the waste area has really helped me and now you just follow the steps he has laid out and my dovetails come out great.

Michael

Grasping that has made the biggest difference for me. When I'm sawing I literally remind myself over and over: "Cut to the waste side. Leave the line".

[steven c newman]

Working on it..
Tues. Evening, dry fit .JPG


And done...
Wednesday, right glued in.JPG

And a glue-up..
Wednesday, 2 done .JPG

[Jack Dover]

My dovetail saw was 30$ and I think I was ripped off. Yet it produces dovetails undistinguishable from LN dovetail saw that costs x5 as much. Pretty sure I can give a Cosman's saw a run for its money too. Same applies to coping\fret saws - 20$ says you won't tell which one cut out this particular socket.

[Mike Henderson]

My dovetail saw was 30$ and I think I was ripped off. Yet it produces dovetails undistinguishable from LN dovetail saw that costs x5 as much. Pretty sure I can give a Cosman's saw a run for its money too. Same applies to coping\fret saws - 20$ says you won't tell which one cut out this particular socket.

That's very true. It's much more the hand holding the saw, than the saw itself.

Mike

[Jack Dover]

Now one does not saw to a line (e.g. pin board), but score lines with a mini saw, having created an offset with an aid.

Same applies to Paul Sellers as well: he used to chop mortises freehand, now it's a second or third iteration of jigs that are so conveniently listed for sale (or about to be listed?). Pretty sure a dovetail guide is not too far away, in his tool chest video he kinda explores this idea.

For those starting out, I recommend the 14 tpi Veritas dovetail saw.

A solid advice.

[Michael Bulatowicz]

That's very true. It's much more the hand holding the saw, than the saw itself.

Mike

I agree with Mike; my experience says that while nice tools can be a joy to use, skill in use, setup, tuning, and sharpening is the limiting factor in my own work (mostly skill in use). With very few exceptions, I have yet to be truly limited by the tools themselves.

[Jack Dover]

Two unique ideas that Mr. Cossman has, and actually no one has repeated,

Yes, quite a terrifying idea indeed if you think about it: how the humanity managed to saw dovetails for thousands of years without these unique and obviously innovative ideas? Truth is, though, that these ideas were listed not in just one, but in several woodworking textbooks dated late 19th/early 20th century. Rob might have re-invented this independently, it happens, however none of these ideas were spotted in a wild. He's not alone in this too, the aforementioned Paul Sellers claims he has invented a method of straightening a tenon with a router - also something that can be found in old books. However, if you look the old videos that were posted on this forum (Hawley foundation, that old French video, etc.) you'll notice that craftspeople of the time didn't use these tricks - look at the late Phil Lowe's introduction videos where he does a mortise and tenon and dovetails, it takes him less time than it takes Paul to set up a router.

Any jig in my opinion is actually robbing you of skills and overcomplicates a fairly straightforward thing. It's not too hard to learn to saw plumb or to a line, it's not too hard to learn chopping plumb in between lines. And a workshop is not a circus, so no tricks required either.

[Thomas McCurnin]

Very funny and presumably tongue in cheek, and partially true, Jack.

I never said Cossman invented these two ideas, only that he is the only YouTube instructor that emphasizes them. If you know of another instructor for these two concepts, please elaborate.

Cossman actually has three unique ideas, only one of which was in the text that you mentioned and typically not taught by public instructors:

(1) Using a saw blade to mark the pins. You are correct that this idea is old. It was mentioned in the textbook Modern Practical Joinery by George Ellis circa 1908 on page 66. Cossman actually took this idea and made a small marking knife with a serrated edge the same width as a dovetail saw to facilitate the marking of the pins to the exact width. Yes, he sells the little marking knife/saw.

And (2) Using an offset gauge to move the tail board over to the width of the saw kerf which places the mark (or saw kerf if one is using his knife/saw) exactly at the right place. This idea is not in any book or YouTube program that I have ever seen. I think it is a little fussy and I don't need that kind of accuracy, but I have used the little brass block and it works to offset one side of the pins, and one places the offset on the other side of the tailboard for the other side of the pins. Yes, he sells that marking gauge, which was fabricated by one of his wounded veterans. He is a big supporter of combat wounded veterans, and being one, I really love that guy.

And (3) Using a saw which has coarser teeth for the first few inches to enable the user to start a kerf without the saw bouncing out off the board. I've used the saw and like it at it has a larger handle grip than most, perfect for my big hands, but honestly don't fully appreciate the lower TPI on the first few inches. It works.

Cossman is a good instructor and has an excellent method which is a series of things which is second nature to him and to his students, but some find it a bit too technical and elaborate.

And to your point, yes the dovetail was used since ancient Egypt, and while it seems many instructors are re-inventing the wheel, the methods currently taught are sound, and the student needs to pick one that suits him/her and go with that. I'm more in the Paul Sellers camp and a disciple of that method, but Cossman is great and I have bought his products.

[Warren Mickley]

All these things are designed for beginners. They are like training wheels that you will soon outgrow. A lot of these guys are trying to come up with alternative techniques so guys can avoid gaining skills which would serve them in the long run.

Here is an example: In 2017 Cosman made a video about his KerfX10 tool ($120). He claims he learned this from Tage Frid and that the thing save a lot of time. Does it?

Well, in 2010 when Cosman wanted to show off how he could make half blind dovetails in 6 1/2 minutes, he didn't use a kerf extender at all. And if he really learned this from Frid, he knew about the technique for years (Frid died in 2004) before making the speed video.

Frid did mention this technique in a 1977 FWW article on scrapers. I read it . I tried it. I thought it a waste of time. It is a way for beginners to avoid gaining chisel skills while putting money in someone's pocket.

[Jack Dover]

There's a catch 22 kind of a situation for a beginner, where a badly fettled tool one's ability to do a good job indeed. Some people quit out of frustration of battling several factors at once. This is especially hard for someone who doesn't have friends that could relieve some of these factors. I think paying a bit extra for a better tool that comes set up and works out of the box is justified. However, it doesn't have to be that much extra. LV gents saws were 60$ a pop and they're as good as a handsaw can get, anything over is just bells and whistles or just a brand tax. I think that persuading beginners that they can succeed with premium tools only is predatory.

I once went to a dovetailing class organized by a local guild, just because I wanted to meet people (I think I can dovetail). The instructor provided those 20$ Big Horn gent saws to students, set and sharpened. Out of 8 people present 7 had 100% success (the last person just didn't pay attention and basically just messed around). They all were newcomers, I was helping sharpening their chisels while they were sawing. Again, to make them saw to a line an instructor drew 10 plumb lines and 10 skewed lines on a block of 2x. That was all what was needed, nobody had any issues sawing their first quite serviceable dovetails.

[Assaf Oppenheimer]

progressive pitch on sawteeth is nothing new, I have a Disston D8 rip saw filed that way that was made in the 1920's

[Jim Koepke]

Very funny and presumably tongue in cheek, and partially true, Jack.

I never said Cossman invented these two ideas, only that he is the only YouTube instructor that emphasizes them. If you know of another instructor for these two concepts, please elaborate.

Cossman actually has three unique ideas, only one of which was in the text that you mentioned and typically not taught by public instructors:
…
And (2) Using an offset gauge to move the tail board over to the width of the saw kerf which places the mark (or saw kerf if one is using his knife/saw) exactly at the right place. This idea is not in any book or YouTube program that I have ever seen.
…
And (3) Using a saw which has coarser teeth for the first few inches to enable the user to start a kerf without the saw bouncing out off the board. I've used the saw and like it at it has a larger handle grip than most, perfect for my big hands, but honestly don't fully appreciate the lower TPI on the first few inches. It works.

I have not watched many YouTube instructor videos for a few years.

There are other sources > https://www.popularwoodworking.com/w...-Technique.pdf < shows the Glen Drake offset method and a kerf starter in use.

There is also a discussion about the Glen Drake Kerf Starter here > https://sawmillcreek.org/showthread.php?56293 < In this thread from about sixteen years ago, someone mentions Cossman's using a saw to mark out dovetails.

Coarser was highlighted, in the text, "the lower TPI on the first few inches," following makes your meaning clear.

For me, just learning the mechanics of this method at a LN Tool Event back 2006 or 2007 improved my dovetail cutting with out the expense of purchasing any new tools.

jtk

[Mike Henderson]

There's a catch 22 kind of a situation for a beginner, where a badly fettled tool one's ability to do a good job indeed. Some people quit out of frustration of battling several factors at once. This is especially hard for someone who doesn't have friends that could relieve some of these factors. I think paying a bit extra for a better tool that comes set up and works out of the box is justified. However, it doesn't have to be that much extra. LV gents saws were 60$ a pop and they're as good as a handsaw can get, anything over is just bells and whistles or just a brand tax. I think that persuading beginners that they can succeed with premium tools only is predatory.

I once went to a dovetailing class organized by a local guild, just because I wanted to meet people (I think I can dovetail). The instructor provided those 20$ Big Horn gent saws to students, set and sharpened. Out of 8 people present 7 had 100% success (the last person just didn't pay attention and basically just messed around). They all were newcomers, I was helping sharpening their chisels while they were sawing. Again, to make them saw to a line an instructor drew 10 plumb lines and 10 skewed lines on a block of 2x. That was all what was needed, nobody had any issues sawing their first quite serviceable dovetails.

What I have against Gent's saws (at least the ones I've used) is that they have very fine teeth. They work, but they're slow.

I used a dozuki for years and it's kind of the same thing - very fine teeth. But the dozuki was cheap and it was what I could afford at the time.

When I have some time, I'm going to try making a practice set of dovetails with a panel saw, just to see what effect the saw has.

Mike

[Jack Dover]

Sorry if that came out abrasive. I was just trying to say that if not one, but several people re-invent the same idea independently and over about 150 years timespan - this isn't exactly a unique idea, it's rather a quite obvious one. The second point was that even these ideas seems to be working, we don't see them used by people doing this kind of stuff days in and out. I.e. cutting dovetails on a CNC is also a workable idea, but not really that pragmatic for most folks, right? Or in simple words not every workable idea should be put into one's production work (as in "getting to the final result", not as in "mass manufacturing" sense).

The points you have listed are solutions in search of a problem. If someone can't saw to a line, then that someone most probably can't saw on a line either, so it doesn't matter whether it's a pencil line, a scratch from a saw, or from a saw converted to the marking knife. That offset thing is basically following the previous: an attempt to address people that can't saw, as if putting a saw in a perfectly right position is their only problem (of course it's not even close to be their problem). Same for the graduated teeth: how many attempts did it take you to learn how to start any saw with just a single stroke? A bread knife has lower TPI than a dovetail saw, yet we don't see them with graduated teeth, do we? Nobody seems to have any issues starting a cut with a bread knife either. At any rate for a person without special needs learns how to start sawing in an hour tops: just go to the workshop and try a few times, I promise it will work by the lunch time.

And also let's ask this question: with all these tricks, jigs, guides and other products, how much benefit one gets? I'm asking this in the contest of the hand tools and work by hand forum. For result oriented diehards there are routers and jigs, absolutely no skills required, just a good health insurance maybe. But if one is after working by hands methods "like they did then" - then let's do it by hand like they did then, goddamit, there's no need to replicate the latest Circue de Soleil show, nobody's watching anyway. I don't know, maybe someone finds an idea being reduced to a protein based motor for 100% jigged setups really attractive, but I thought hand methods aren't about this, not nowadays at least.

Obviously you're totally free to buy Rob's products if you enjoy them. I'm pretty sure they're good quality and definitely bring joy to whoever desires them. They're not the key to being good at dovetails or joinery though, practice is - and this is my main gripe, because I think that quite an aggressive marketing misleads people into thinking that some arbitrary physical object can enhance someone's abilities and skills. This is magical thinking on one side and quite an exploitive technique on the other, that's all.

P.S:

This idea is not in any book or YouTube program that I have ever seen

There's a couple of texts that were published around the time the Ellis' book was and they even have it explained with pictures, let me dig my bookmarks, I might find it. Vaguely remember that the text mentioned it is aimed at pupils that struggle with dovetailing no matter what and going as far as stating that "it's not a workmanlike manner" (although I don't know whether I agree with this). Other textbooks show how to use saw for marking, I think it was in Bernard's "Complete woodworker", but I have to double check. I've even seen an offset jig picture in texts - two blocks of wood offset to a width of a kerf, kinda like shop made chamfer marking gages. Since I have never seen anything like that in any auctions or antique stores or anywhere else I have concluded that nobody has used them, pretty much like Moxon vises. If you have seen anything like that in the wild - please let me know.

[Thomas McCurnin]

Nah, you weren't abrasive. I thought the point was well taken, that people have been making dovetails for thousands of years, and really what is there to improve the technique?

Answer--none if you have a technique that works for you. I bought Rob's stuff just to see what it was and try it out. Like mechanical dovetails jigs for routers, I must have a complete box of tools I bought and have not used more than a few times. His saw is comfortable I will say that. The offset block is too fussy for me. The serrated knife/saw really makes a nice layout cut and I do use that, although half the time a sharp .5mm mechanical pencil is what I reach for, which is the Paul Sellers technique that learned at his Waco school and leave the line!

I will say this that the clear plastic Katz Moses dovetail guide, with the magnets was a complete waste of money for me. I tried using it a half dozen times and it was just plain stupid and awkward to hold the darn thing in place while I am trying to concentrate on my sawing technique. Its in the "stupid tools that I don't use" box. Call me a sucker, but I buy these things, and probably have more money than sense.