Manual dovetail journey

[Andrew Pitonyak]

I am having trouble scribing the pins from the tails. I don't think I'm using my marking knife properly. I've tried a utility knife as well as some shop made knives and an exacto knife. The thin blades seem to dig into the sides of the tail board or wander from the line. The utility knife works well, but is too thick for deeper/narrower scribing. Also, those lines are tricky to see even in lighter woods.

My heart wants to use a pencil. It just seems like the hard scribing of a knife requires too much force that'll compromise the accuracy.

Before I give up on the marking knife, I'll ask some dumb questions:

1) The straight edge (not the beveled edge) goes against the scribing edge, right?
2) What's an appropriate primary/secondary bevel for marking knives? Too steep, and they wander. To shallow, and they don't cut well.


Does anyone out there use a pencil to mark?

I have been using the Veritas Workshop Striking Knife and/or my Blue Spruce marking knife.

1. The last set of drawers I made, I first worked really really hard to make sure that my tails, which I cut first, were straight and perpendicular. I found that I do a better job of this when clamp my two drawer sides together and clamp them, then I can cut two boards at once. What this really does is give me a longer distance over which I can gage if I am cutting a straight line I suppose. The important thing is that it is straight and perpendicular to the face.
2. After removing the waste, I clamp a board that will contain the tails so that it is horizontal in my Moxon vice.
3. I lay the tail board on top. The tail board is supported so that it lays flat (according to my level).
4. I need to make sure that the tail board stays perfectly on top of the tail board. If the board shifts left or right, then the markings will be off. I have even taken other boards that I placed on each side of the pin board so that the tail board cannot shift (clamped them in place).
5. The next detail (for me) is keeping the tail board so that it does not rotate. I know that some people actually route (or cut) a rabbit in the tail board so that it will sit nicely the correct depth and stay not twisted.
6. Now, we finally get to your question, how do I mark the tails. I set my marking knife with the flat edge against the tail and make a line. I might even do this two or three times so that I can be gentle. It is important that it stays firmly against the tail.

I find that it helps me to drop a perpendicular line along the front face to my scribe line so that I can cut a straight line down (it gives me something to follow).

Another trick that works for me is that when I look at my line scribed in the end grain of the pin board, I will take a chisel and place it in the scribed line and tap it. I can then notch out a groove and set the saw in the groove. This helps me start the cut exactly where it should be.

I have marked with a pencil, but I don't find that I am likely to stick that fine pencil point in at an angle so I cut too narrow. I cannot set the pencil against the the entire tail and mark right at the edge. I remember cutting OK dovetails with them. When I cut using both methods I felt that my knife edges did a better job.

[Chris Hachet]

I pretty much am in the habit of using a knife for most of my cuts...it keeps my knife skills up for when I need them for something precise...

[Jim Matthews]

FWIW - I think your first dovetails shown would glue up without noticeable gaps.
The glue will induce some swelling at the moment of assembly. I recommend hide glue for dovetails as this allows more time to get things together.

I mark all crosscuts with a knife. I take a very light pass the first time, and score deeper on two following passes.
If you're using a marking gauge, mark only the joint your about to cut - as you've seen, small variance in board thickness can result in alignment errors.

Watch this video for a MUCH easier marking out method.

When marking out the pins, I find it helpful to mark with a knife and attempt to "reach under" the tail to cut a slightly heavy pin.
(See 2:18 of the video above for an illustration of the hand position.)

That gives me something to pare, which I find preferable to shimming a loose joint.

I would caution against repeated fitting dovetail joints together, as it bruises adjoining pieces and can make the final product loose.
I concentrate my efforts on the bottom corners, where loose fibers from sawing always seem to gather. I love my LN floats for this step.

I check the cut of each pin and tenon for perpendicular orientation to the "show face" with a small ruler.
Laid in the joint, a small ruler will magnify misalignments and show where paring should take place (thanks to Phil Lowe who casually tossed off that little nugget).

I find that if all the faces are perpendicular to the show face, things will go together. It's tedious, but it beats widdling every intersection.

If you're cutting with a bandsaw, check the first tail and first pin for this critical alignment - then you should be off to the races.

Lastly, I find that using the "140 trick" to establish a small rabbet on the tail board to get both solid registry against the pin board
and to help make for a tighter joint on assembly. If you don't have a fenced block plane to cut the rabbet, it's an additional few steps
with either a saw and small router or a finely adjusted table saw.

[jamie shard]

I'm replying to remind myself more than anything...

It's not a bad idea to chop out the baseline starting a little into the waste area, remove some depth, then slowly pare back to the actual knifecut on the baseline. I've even seen people mark a knifeline 1/64th into the waste, do everything pretending that's the real baseline, and then take one final cut to the real baseline. Even slight taps on the knifeline can push back the baseline.

[Floyd Mah]

Here is my technique for cutting the baseline. It works very well and gives you a nice even cut at the baseline and then provides a shelf to remove the remainder of the waste. Also I guarantee the dovetails will look much better for a reason I give below.

The pitfall in chiseling technique is that the chisel actually travels in the direction of the mid-plane of the wedge, not along one edge as you might think. You will crush the fibers along the non-beveled edge, despite how much you try to control the chisel by holding it rigidly. Also, as you sight along the flat face, you would find it hard to always hold it parallel to your baseline, leading to a jagged baseline cut.

What you want to do first is to score the actual baseline, in between the tails or pins, with a very sharp razor. Since there is a slight bevel to the razor's cutting edge, be sure to tilt the plane of the razor blade slightly towards the waste end. Cut about 1/32 to 1/16" depth. This will sever the fibers on the waste side. (If you examine any of the rabbet planes which cut across the grain, there is a cutter which precedes the blade which scores the line of the final cut. This is the same principle). Cut with one placement of the guide straight-edge. This will assure that the baseline cuts will be lined up all across. If you were to try this with chisels, in my experience, the baseline will be jagged.

Now that the fibers are cut, you want to remove the bit of waste so that you have a shelf for chopping the remainder. If you plant the end of the chisel into the scored line, you will crush the fibers on the good side. The reason for this is that the end of the chisel is a wedge. When you drive the chisel, it will try to head in the direction of the mid-plane of the wedge, damaging both the good side and the waste. This is not what you want.

What you actually do is place the tip of the chisel about 1/16 to 3/32" from the scored line, bevelled side towards the waste. When you strike the chisel, two things will happen. The wedge of the chisel will drive the chisel (which was held vertically at 90 degrees) into the wood, but also slightly towards the keeper end. This will cause the small chip of wood to rise at the scored end, while the chisel end is depressed into the wood. What you will get is a chip removed from the workpiece. One side will be perfectly even (the scored end) and the other side will be crushed by the chisel. On the workpiece, you will have a small groove: the keeper side will be perfectly even (the scored side) and the other edge will be crushed.

Do this for both sides of the board. I usually remove the waste with a coping saw and then pare the waste between the shelved areas with the board held vertically in a vise.

Give this a try. You'll be surprised at how clean your dovetail will look. In addition, having created a shelf for chopping the waste, it become a lot easier to finish the chopping.

[Prashun Patel]

Wow, guys. This is generous and valuable information. Thanks SO much. I'm going to try these techniques.

[jamie shard]

Agreed! (Floyd, thank you for that description, I could "see" it as I read it!)

[Floyd Mah]

Despite your best efforts, when you first start trying to cut dovetails, you end up having to pare the pins and tails to get a good fit. When I first attempted this, I found that I had unsightly gaps where I had cut incorrectly, so when the pieces are fitted together, there were holes where I didn't want them. So, how do you avoid this?

If you want to do this without making cutting jigs, which work well to directing your cuts, what you need to do is examine your joints carefully. It turns out that if you study the mismatched joint, there are sides of each interface that can be pared, even undercut, without it being visible on the final work. I don't mean the visible wood on the surface, but the wood just below the surface where the resistance to a perfect match is.

Imagine this: Suppose that only the surface of the joint existed, that is, it was paper-thin. In your final work, that is the part that is easy to cut, after all, it is paper-thin. You could cut it with a light touch of the paring chisel. You could get a perfect result every time! That's not the part of the joint that is giving you trouble.

So, next move on to the part of the joint that is giving you trouble. That's the stuff that is below the surface. You can tell where it is because that's where the wood is burnished when you push the parts together. Use a pencil and mark that area. Now pare that area away. Also note that not all of the joint is visible from the external examination. Those parts of the joint you have more liberty with, since an error cutting that part isn't going to show in the final work. Of course, these areas are responsible for the final rigidness of the joint, but cosmetically, they are less important. Stay away from the surface unless there is a gross mismatch because you cut the joint incorrectly (bad saw cuts).

I want to re-emphasize the part about staying away from the material on the surface as much as possible. Also, remember that since there are two sides to each interface, try to trim only one side at a time. Mark that side with the pencil.

It's important to use a pencil to mark the tight areas. I tend to forget where I wanted to trim after the first few shavings. After you have trimmed the pencil-shaded areas, try the fit and repeat.

Again, I guarantee your joint will look much better with this process. The most important thing to remember is which areas are cosmetically less important and which areas are visible in the final result.

[Floyd Mah]

My last suggestion is that if you have a choice between making the workpiece slightly long or slightly short, make it slightly long. The reason is that if your goal is to fit a drawer into a predetermined space, it's easier to trim the box with a small, sharp plane than it is to make it grow bigger. Also, pertaining to my previous post, beware of vigorous paring to make the joints fit, since previously hidden gaps can be uncovered as you plane the joint down.

I'll try to be more clear. When you are done fitting the joint and before trimming, the sides of the joint will be slightly proud, not the pins or tails. If you are trimming the ends of the pins or tails, you are shortening the lengths. When you trim the sides, you are converging on the desired lengths of the box.

I remember reading about cutting dovetail joints when I first started. Someone recommended getting two 4 foot lengths of board and cutting joints. When you are done, cut the joint off and start over. When you finally run out of wood, you are an expert.

[Prashun Patel]

Here is my latest attempt. 2" thick glued up ash. I'm amazed how much easier it is to saw straight in thicker stock. Even though you have a longer distance to cut, the saw just keeps the line better; I guess the thick stock acts like a good guide.

I think I'm getting the hang of the base lines of the pins. Honestly, I haven't found the magic; it just seems to get easier with practice. When placing my chisel on the base of even before I strike I can now predict a little better whether it's going to compromise the fit.

What I'm still having trouble with is the base lines of the tails. In a way, this is the most visible part of the joint on drawers. I'm going to practice undercutting the meat in between the three shoulders. I do rabbet my tail insides, which is great for pin alignment. However, it puts demands on proper gauge setting for the depth of the tails. I wonder if there are very slight misalignments between the inside baseline and the outside ones. I wonder if cutting the outside shoulders a hair shallower than the inside will fix this...

[Robert Hazelwood]

Those outside shoulders of the tails (half-pin socket) are tough. Assuming you're marking the baseline all around with a knife, you should be able to see the track of the knife line in the finished shoulder. I usually end up paring these down. If I try to take big bites with the chisel I will find that the knife track disappears (i.e. my chisel got pushed down past the knife line). That ends up being a gap. I found best results by using a chisel that is narrower than the shoulder width and paring in from all 3 sides. I chisel at a slightly upward angle that leaves the inner area proud. Then I come back and level or slightly hollow the inner area. Don't place the chisel directly into the knife line until there is just a tiny sliver of wood left above it.

That's a tedious but effective way to do it.