Chopping out Dovetail waste

[Dennis McDonaugh]

How do you keep the back of the dovetail from blowing out when you are chopping out the waste. I've finally gotten to the point where the dovetails fit fairly well, but I'm getting chip out on the back side.

One other thing, there was an article in Fine Woodworking about clamping several drawer sides down at once, kinda like a stair step, and chopping out the dovetails on all of them without having to move and reclamp them. How do you keep from marking up the drawer slides with chisel marks?

[Jason Roehl]

Simple enough---don't chop all the way through. Only chop in approximately 1/2-way, then flip it over and finish from the back side.

[Donnie Raines]

Also, when you are close to the score line, do not place the chisel directly on the score line. Place it aprx 1/16th in front of and plunge it downward. The chisle will drift back toward the score line and make for an even tighter joint line.

DonnieR

[Richard Gillespie]

I chop half way through on one side and then flip the work piece. Also, I was taught not to worry about any chip out that occurs. The strength of the glue joint is along the sides of the pins and tails. The end grain at the chip out doesn't give that much additional strength to the joint.

You do want a tight appearance to the joint and Mr. Raines suggestion to walk the chisel back to the line is what I was taught to do.

[Donnie Raines]

One more thing...work from the outside in. Meaning, make all the through cuts on the portion that will face outward....that way if you do get some chip out, it will be on the inside(drawer, case construction.....) so and so forth.

DonnieR

[Alan Turner]

This is a recurrent problem when cutting dovetails, and there are several ways to handle it. When the bevel of the chisel is pounded into wood, it forces the chisel off of vertical, towars the back, and actually moves the chisel into and through the scribe line, which leave a joint which has a gap.
1. Use a coping or fret saw, and cut the bulk of the waste out, to about 1/16", then pare the balance.
2. Make a number of vertical cuts into the waste, stopping about 1/16" shy of the scribe line. The wate will come out quite efficiently, and you can, again, pare the last 1/16" to the line. I find that #2 is quicker since you already have the rip saw in your hand. I always try to pare the last bit, and the cut is quite clean, with no blow out.
Alan

[Martin Shupe]

How do you keep the back of the dovetail from blowing out when you are chopping out the waste. I've finally gotten to the point where the dovetails fit fairly well, but I'm getting chip out on the back side.

One other thing, there was an article in Fine Woodworking about clamping several drawer sides down at once, kinda like a stair step, and chopping out the dovetails on all of them without having to move and reclamp them. How do you keep from marking up the drawer slides with chisel marks?

Maybe I am confused, but are you chopping all the way through from just one side? If so, then you need to chop halfway through, then turn the board over, and chop halfway through to the other side.

Also, you want to end up with the "large" side of the waste face down when you finish it up, so the waste will not be forced against the sides of your pins when it finally breaks loose.

When you first start to chop, put your chisel right on your scribe line and make a very, very small chip. Then, the deeper you go, the bigger the chip can be.

I am not an expert, but took Kelly Mehler's class, and these are techniques he teaches.

[Marc Hills]

Martin Shupe said:

"Maybe I am confused, but are you chopping all the way through from just one side? If so, then you need to chop halfway through, then turn the board over, and chop halfway through to the other side."

Hey, I'll be the first to admit that I did exactly what Dennis did when I first tried dovetails.

What seems so obvious now is often mysterious to the uninitiated. Does anyone remember when it wasn't clear which direction the chisel bevel should even face?

Everyone is giving great advice; the simplified answer is of course, don't chisel all the way through from one side. But don't assume anything. People are talking about walking the chisel up to the score line. That assumes the beginner is even using a score line. I remember when I didn't understand the importance of scoring the dovetail marks rather than using a pencil. It didn't occur to me that in addition to being more accurate, severing that first 1/64" of the wood fibers would itself reduce chipping and tearout.

But the really great thing about these basic questions is that even on things I think I understand cold, a little nugget comes along that I can add to my mental tool kit. Martin's reference to a small, small initial chip directly on the score line made me think of an illustration I saw once on exactly that aspect of dovetail technique. It didn't really click at the time, but it's suddenly clearer now, especially in the context of Dennis' initial question. So thank you Dennis and Martin.

[Dennis McDonaugh]

Yup I am chopping all the way through. I think I'm going to try to cut out most of the waste with a coping saw and finish by paring. Thanks for the help.

[Alan Turner]

I haven't read him for quite some time, but I think it is Ian Kirby who makes this recommendation.
Alan

[Eric Sanford]

Yup I am chopping all the way through. I think I'm going to try to cut out most of the waste with a coping saw and finish by paring. Thanks for the help.


I originally started by chopping all the waste, then switched to the coping saw method. I think you will like the results. As mentioned above, this process puts less pressure on the chisel blade so it doesn't get forced back into your shoulder line, making for cleaner joints......and I find it faster, too :)

Eric

[Derek Cohen]

Dennis

Here is a jig I made that can help you pare the shoulders of your dovetails. It makes it very easy to flip over the board and accurately pare/chop to the line from either side.

Keep in mind that you must:
(1) chop halfway from each side
(2) begin this cut a few mm in front of the shoulder line

Link to jig:

http://www.woodworkforums.ubeaut.com.au/showthread.php?s=&threadid=7221

Regards from Perth

Derek

[Tom Scott]

Dennis

Here is a jig I made that can help you pare the shoulders of your dovetails. It makes it very easy to flip over the board and accurately pare/chop to the line from either side.

Keep in mind that you must:
(1) chop halfway from each side
(2) begin this cut a few mm in front of the shoulder line

Link to jig:

http://www.woodworkforums.ubeaut.com.au/showthread.php?s=&threadid=7221

Regards from Perth

Derek

Derek,
I like your jig and will probably try to build one when I get the time.

A question on how it's used, though...
In the last picture where you say you are using it to measure and mark the pin board, are you using it to only mark the depth of the pins, thus forgoing the use of a marking gauge? If so, I assume you use the same technique when marking the base line of the tail board...clamp the board down with an overhang equal to the thickness of the board you are joining, and then score with a marking knife. You don't actually mark the pins with it in this configuration do you?

Thanks,
Tom

[Jim Becker]

One other thing, there was an article in Fine Woodworking about clamping several drawer sides down at once, kinda like a stair step, and chopping out the dovetails on all of them without having to move and reclamp them. How do you keep from marking up the drawer slides with chisel marks?

Frank Klausz shows this technique in his video about hand-cutting dovetails. Although I have something from Time/Life that has him doing this, the more comprehensive video from Taunton looks like it has a lot more meat on this subject.

[Dennis McDonaugh]

Thats a nice looking jig Derek. I'll have to build something like it until I get the hang of it. Thanks.

[Derek Cohen]

[QUOTE=Tom Scott]

"...are you using it to only mark the depth of the pins, thus forgoing the use of a marking gauge? If so, I assume you use the same technique when marking the base line of the tail board...clamp the board down with an overhang equal to the thickness of the board you are joining, and then score with a marking knife. You don't actually mark the pins with it in this configuration do you?"


Tom

There are two ways you can go:

(1) Think back to the Frank Klausz video (I wet my pants the first time I saw it!). He cuts the pins by eye, then marks the tails from the cut pins.

My jig (I use this term loosely since ideas came from several others) allows you to do much the same thing, just with the security of (a) ensuring that the shoulders of the pins can be cut in line and pared square, and (b) making it easier to hold the pins over the mated board so that you can draw/scribe the angles more securely and, therefore, more accurately (do this freehand or with the pin end clamped against the fence).

It is then possible to then cut these scribed lines and form the tails.

(2) I prefer to plot and draw the lines for my pins more purposefully, then cut to these lines. As before, when I measure up for the tails, the jig helps me hold the board securely, but I am just ensuring that the ends line up. I will draw the tails from these points. (I am sure this is all as clear as mud). The jig can also help with the depth of cut by transfering directly from the cut pins to the tail board.

I hope this answers your question.

Regards from Perth

Derek

[Greg Wandless]

Dennis,

One thing I do is to clamp a thick piece of maple (~1-1/2) along the bottom the tails or pins and use it to keep the chisel from wondering off the line. If the edge is square and you take small chips the inside of your tail or pin will be also. And, as others have said, go half way and turn it over for the other side.

Greg