Friday, September 9, 2016

Dovetails are for the birds, part II

In the last post I explained why I put away all the videos and articles on dovetailing, didn't practice any techniques, went out into my shop, thought about how I could improve at dovetailing and experimented.  I make no claim whatsoever to originality, much of what I write is obvious now that I understand it and this is just a few highlights of what I discovered, not at all comprehensive.  In everything I tried, the goal was to make things as simple and easy as I possibly could, stripping the process down to the bare essentials.  In writing this, I have tried to be somewhat humorous as well and I hope you enjoy it.

Pins or tails first?  Tails.  Why?  The first board only has to be accurate in one dimension while the second board has to be accurate in two in order to fit the first board.  Pins involve an angled cut horizontally and a perpendicular cut vertically while tails involve a perpendicular cut horizontally and an angled cut vertically.  I think pins are easier to saw very accurately, so I'll cut them second.

The tails board.  The tails really need to be sawed perpendicular to the face of the board and you can't saw beyond the baseline, but that's it.  For a tight joint, the spacing doesn't matter and the angles on the sides of the tails don't matter.  Every one of the angles on the sides of the tails can be different and it won't matter, so they don't even need to be marked.  I did draw them in as a reference so the tails would look roughly symmetrical and similar, but there was no need to and I resolved to pay little attention to them.  No problem if I saw off the line.  As an aside, this is why you often see videos of experts cutting tails with nothing but the baseline marked.  As long as they can make cuts perpendicular to the face of the board by eye, nothing else matters.  The angles on the sides of the tails can vary some and it won't be visible, much less affect the fit.  I think this is something most of us could learn to do, in part by using the reflection in the saw plate.  In a relative sense anyway, sawing the tails out first is easy peasy.

For this go round, I didn't want to saw the tails purely by eye, so I knifed in lines for the tails across the end grain with a small square.  This is when I made a discovery that turned out to be the secret to improving:

I can't saw to a line I can't see.

I told you most of this would be obvious.  So, to make the line distinct enough to see, I just dropped a chisel into the knife line and gave it a sharp tap.  Did it move the knife line a little?  Yep.  Does it matter?  Nope.

  This is magnified 15x and you can see how crisp it is.  I lined up my saw to it, preparing to make the first cut and, kerplunk, it dropped in!  This is when I learned of an exception to my discovery:

You can saw to a line you can't see if the saw can find it and you don't interfere.

This is, of course, what we always do with knife lines but it was the first time I had done it successfully on end grain.  Using almost no grip on the saw, I angled it down the line on the side of the tail, gave a push and, what to my wondering eyes should appear, but a cut right where it was supposed to be!  A fluke?  After four cuts, it didn't seem like it.  On reflection, I think I had been like a teenager learning to drive, gripping the wheel and constantly correcting.  By giving up on following the angled line down the edge of the tail, I had followed the line.  By not trying to see the line in the end grain, I had cut on the line, granted as deepened with a chisel.  I could hardly believe it.

Sawing the shoulders and chopping out the waste has never been a problem for me, I do it the usual way, so I'll skip a description.

The pins board.  Crunch time.  Now the cuts across and down the board both matter and they must be exactly in the right place.  I couldn't knife in the lines on the end grain and use a chisel to make them visible like I had done with the tails because I would move the line.  I tried something I had read somewhere:  masking tape.

The idea is that you cut away pieces of the masking tape to reveal the pins.  Yes, this is an extra step but it takes 30 seconds.  Another issue I have had is moving the tail board slightly while I am marking the pins, especially if I use a plane on its side as a support, like you often see the pros do.  The plane is slippery.  I actually clamped mine down.  The result was crisp, high contrast lines I could definitely see.

Could I saw right to them though?  The chisel-deepened knife line for the tails were training wheels that I wouldn't have for the most important cuts.  I lined them up very carefully and, to my surprise, the result was great, at least by my standards:

Why?  The distinct line was essential but I think there was something else as well.  I had never held my dovetail saw so loosely as I had when I sawed out the tails, just the heel of my hand and the lightest touch of my fingers.  From this experience I have learned a new rule:

Never, never try to steer a dovetail saw.  It's all over when the saw first moves.

There may be an advantage to sawing dovetails with a gent's saw or a Japanese saw because the handles and the way you hold them aren't as amenable to steering as standard western dovetail saws like my Lie-Nielsen.  In any case, I now hold my saw just firmly enough to keep it from falling out of my hand.  It's a little nerve wracking because you know if you have lined up the saw to cut into the line, you're toast, but that's the way it goes I guess.  Really makes you pay attention to how you line the saw up.

The result is as good as it gets for me:

So, am I proficient?  No, but I can see it from here.  Now, practice would matter.  The time it takes me is ridiculous, but it would improve.  I'm pretty sure I could learn to saw out the tails very fast, possibly just by eye with only a baseline like some pros do.  Adding the masking tape doesn't take very long.

Will I ever cut a dovetail again?  Yes.  My poor results did affect my thinking about them.  But, it probably won't be very often, only on those occasions where maximum strength is required or the look is what I am after.  


  1. Congrats. I am a new woodworker myself. Last year I was at a Lie-Nielsen event. There was a gentleman by the name of Glen Drake there. He had knife like tool (might have been technically a scraper) that you could use across the top of the wood that would leave a mark like your chisel but the line was the same width as the kerf of his (and many standard) saws. Might be worth looking into.

  2. I use that tool that he wrote about in the comment above. Making that square line across the end grain allows me to concentrate on sawing the angle rather then trying to do both.
    Your dovetails look awfully good for oak. I don't have a a lot of hardwood dovetailing under my belt.