I am still working on perfecting my hand cut dovetails. I am improving bit by bit.
One concept or more correctly technique that I cannot really figure out is “splitting the scribe line ” when cutting pins with my saw. I typically cut the tails first then lay that on my tail board and I use a small swiss army knife to scribe the lines for cutting the tails.
I always try to cut on the waste side but how in the devil can one really “cut the scribe line in half” with a saw. I use a Lie Nielsen dove tail saw and though the kerf small it doers “take away’ the tentrie scribe line.
So I end uop still cutting a bit to the outside of the scribe line to make sure my tails are not cut too small. If I cut “right on the lione” a ttimes my pins are small and I have tiny gabs.
Any suggestions?
Replies
If you are using a knife to mark the pins, you don't want to "split" the line, but instead saw right to the line from the waste side. A knife line is of no practical width. Hence there is no need to "split" it. Also, it can be very helpful to add knife lines not just ont he end grain, but also down the face of the board on both sides. Then, you should endeavor to have the edge of the saw kerf perfectly meet of just barely consume the knife lines on all sides as you saw.
Thanks you comments make sense to me. Do you, too, recall hearing or reading about the notion of splitting the line. I even think in Kirby's book he mentions it. You are right, on the line has no really width, it delinetaes where not to cut in my view.
As I understand it, splitting the line makes sense when you mark with a pencil as the pencil line is somewhat thick (at least relative to a knife mark) and all in the waste. So if you think of the pencil line as similar in size to the saw's kerf, by splitting the line, you erase it - and since it's all in the waste, you arrive at a perfect fit.
The concept of splitting the knifed scribe line still makes sense. Of course it is only the very edge of the saw kerf that is to split the line--the balance is all on the waste side. The phrase just emphasizes that ideally you want to cut so exactly on the line, not inside, that the joint fits together both with no gap, and without messy paring with the chisel. I can't accomplish this, but it is the goal at least, and there certainly are those who can.
I agree. As I said in my earlier message:
"you should endeavor to have the edge of the saw kerf perfectly meet or just barely consume the knife lines "
Oh, and I should add, I too cannot accomplish this consistently enough to risk it on DTs that will be prominent on a piece. For those, I pare.
Edited 3/6/2007 2:14 pm ET by Samson
Samson
In all my layouts, be it construction, millwork or cabinetry, I always split the visible line and encourage others working on my projects to do the same. It matters not to me if the line is a pencil line or a knife scribe; I try to treat it in the same way. Like you and Steve, I do not always succeed, but I agree with Steve that it is the standard to aim for. JL
JL,
The OP's question was directed specifically to dovetails. Are you talking about splitting a knifeline when dovetailing, or more generally? If I sawed my DT's right down the knife lines, all my DTs would be half a kerf to loose everywhere.
But perhaps I'm not doing it right.
OOPS
I am not paying enough attention. I still think that the principle of splitting the line applies to all layout as it is translated into finished product, but I will be leaving now, and allow you all to get back to dovetails. Sorry. JL
Splitting the knife line, taken literally' means to leave the "good" side of the cut, and remove the waste side of the cut, not to center the kerf on the knife line. So, if the knife lines are correct, the joint slides together with no gaps.
I think Kirby is also a pins first and no dry fit guy. I needed one 8"x 19 7/8" x 16"drawer for my current project which I decided to dovetail. My buddy bought a Leigh and offered it's use, but he hasn't got it out of the box yet and I didn't feel one drawer was worth the learning curve. I hadn't done any hand cut details for a couple of years. I did tails first and tried to saw right to the knife line with my "Z" saw Dozuki. I test fit the 1st joint and it was OK, but far from perfect, so for the rest of the joints I sawed clear of the line and pared to the line - much better fit that way. So I had a drawer with 3 really tight joints and one a little sloppy, which kind of bugged me, but I decided to live with it - so I glued up the drawer. I figured I'd cure the gaposis with the saw and some shim stock later. Well when I went to test fit the drawer to it's opening I realized it was exactly 1" too wide so I got a second chance for more practice :)John O'Connell - JKO Handcrafted Woodworking
The more things change ...
We trained hard, but it seemed that every time we were beginning to form up into teams, we would be reorganized. I was to learn later in life that we tend to meet any new situation by reorganizing; and a wonderful method it can be for creating the illusion of progress while producing confusion, inefficiency, and demoralization.
Petronious Arbiter, 210 BC
spitfire,
I split the line with a router bit :)
Paul
Spitfire
Here's what I do. I mark the line with a sharp awl (same as a marking knife). That line is exactly where you want that cut to go. One side is waste, and the other side is the pin, right.
Next, take a pencil, and run it on your knife line, as if to highlight it. What you will get is TWO lines, because the pencil lead is too small to fit in the knife mark. Now, practice cutting one of those lines, while leaving the other. This will split your knife mark, in theory, in half. What actually happens is that once you get proficient at cutting to one of the lines, your dovetails will be snug, and fit darn well.
Practice, practice, practice, and you will find that after not very long, your dovetails, and all other joinery, will fit a whole lot better.
Jeff
PS Another nice trick for filling the "ocasional" gap (ha..) is to wet the area with some blonde shellac, and sand it in wet. The sawdust mixes with the shellac, dries quickly, and fills the holes very nicely. Also, it'll accept finish very well, while many glues don't.
Spit, any body who tells you he can split a scribe line in half across its width is jerking the hind #### in a big way. A true scribe line is around 1/10 the mm thick (about 4 thou) in wood that is-in metal it is even thinner.
If he means a pencil line then he is probably a carpenter and those pencils they keep in their ears make lines about 1/8th inch thick or more-not too hard to split, and not accurate either.
A knifed line of any use will also be too thin to "split" with a saw or even a line from a cutting gauge....
If you have made a line that is an unequal vee shaped in cross section you could leave half of it behind if you have cut close to it then placed a chisel in it for reference when chopping.
For dovetails I prefer to do something that I can easily see without the use of extra glasses- for all but the smallest doves I use either the inner of a Parker ball point or a draughting propellor pencil-if the line is intact, with no wood visible on the waste side, all is well.The sides of the tails will marked like that while the base lines will be scribed(incised) with a gauge. People should do whatever gives good results....
It is really quite straightforward.
As Philip and others have stated, a knifed line has no width to split.
A pencil line is thick, however since it is marked against a pin or tail wall, the edge of the line marks where the waste begins. Since pencil line vary in width, you are cutting to the edge of the line not splitting the line.
Both a pencil line and a knifed line are simply marks that deliniate where the waste begins.
In theory, one would cut to the edge of the line, so removing the waste. In practice, this depends on the wood one is using. If both boards are hardwoods, then you want to have no waste since there will be little compression (and danger of fracturing). If you have one hard wood and one soft wood (always my first choice), then leave a tad more of the waste as the softer wood will compress and fill any gaps.
The bottom line is that one aims to cut waste only, which is the wood that falls on the waste side of the line.
Regards from Perth
Derek
Derek,I am with you. I have thought about this one for years, and it really is simpler than I used to make it out to be.When you layout the pins after having cut the tails, the knife line is scribed by following the outline of the tails. It is actually scribed in a place NEXT to the waste. When you cut, you want to remove the waste, but leave the line (since the line is next to, but not in the waste).A thin knife line has no real dimension, as was pointed out earlier. Even my LN DT saw or a Japanese rip dozuki has a finite kerf that is wider than the scribed line. Thus if I were to "split" the line, I would obliterate it, and not know what is waste, and what is not. I often use a 0.3 mm mechanical pencil to highlight the line, so I can see it better (particularly through saw dust). By leaving the scribed line, I know where the waste is. When I am finished sawing and chopping out the waste, I look at the pins closely. If a bit extra waste is visible next to the intact scribed line, it is very easy to clean up with a sharp chisel. Since the pins run straight up and down in the endgrain (not sloped like the tails), placing a sharp chisel on the end and paring off a thin shaving or two will take you down to the scribed line, where you will know to stop. I find this the easiest way to do DTs, saw carefully (practice, practice, practice) leaving the scribed line, and then easily clean up any remaining waste with a sharp chisel. The better I get at sawing, the less clean up I need to do.Glaucon
If you don't think too good, then don't think too much...
When I say "split the line", I just mean that you center the saw kerf on the line you have.
I cut tails first then scratch in a line with an awl in the end grain of the pin board. Theorhetically, I shoule leave that line and I'd have a perfect fit. But if I do that, I can't get joint together. So I tend to saw out the line,
My advice to you is to remember that the way you chop out the DT waste, effects this. I leave the baseline and undercut through the thickness. That's why I have to saw out the line.
So these discussions, which comee up quite frequently, need to always include mention of the chisel work. If you put your chisel in the gauged line, you WILL undercut that line. That means you will have to leave or leave more of the line on the pin board. Does this make sense.
Adam
Spitfire,
Here's a thought I picked up recently from a marketing brochure that came with my 'Tite-Mark'marking gauge by Glen-Drake Toolworks:
"Why is hand-cut joinery so inviting? We think it's because hand-cut joinery softens what is physically a very rigid structure. There are ways to soften edges, but once a joint goes together, there's not much you can do to soften it. It has to be soft to start with, and machines leave rigid angles and rigid edges, not soft ones."
They go on to say using their tools you can select the fit you want; snug, press, loose fit.
I have never heard this distinction between soft and hard ...I've mastered loose fit...press is where I usually stop...not sure about snug .
Anyhow, was interested if anyone else recognizes these concepts....or is it just a left coast thing..lol
WOW...that make perfect sense!
Well, if you can make a cut at all then you can make it go where you want it to go. Don't let the line freak you out.
So, you can just make a knifed line crumble if you want (crumbling represents the saw teeth barely kissing the line - not quite leaving the line and not quite splitting it; this is the absolute ideal). If you are using soft materials for the drawer sides, say White Pine, you can probably get away with a crush fit by just barely leaving the whole knifed line. If you use this method, do not test fit the joint. It won't fit the second time down; a cut that crumbles or barely splits the knifed line will tolerate one test fitting but no more. One would think the opposite to be true, but it is not.
Strive not to test fit at all. If the marking out and sawing are good then the joint has to fit so need need to test it. This is a very attainable level of competence. However, there is no decent woodworker/woodworker~writer who does not include gap repair in his or her presentation on cutting dovetails. It happens to the best and you know exactly the moment it does - the saw got a little greedy and went into the marked line too much.
I enjoy blaming the tool at a moment like this. All my tools have names specifically for such an event and I unleash a stream of expletives blaming them for the whole sorry matter. Some famous golfers over the years have punished their putters when they've missed clutch putts - putters left out in the rain, tied to the back of a car and dragged, you name it. One has to keep one's ego intact. I highly recommend it.
Edited 3/7/2007 1:37 pm ET by VeriestTyro
saw to a pencil line...chisel to a knife line...
a saw will tend to "track" in a knife line, making it difficult to keep the kerf entirely on the waste side...
you can saw close to the knife line, and with practice very close to the knife line, but you will probably still need to clean up to the line with a chisel.
If you intend on cutting to the line with no chisel work you might want to use a pencil with the tip sanded to a chisel point. It leaves a very crisp sharp line, but does not separate the wood fibers. A saw blade is not going to "track" in a pencil line...
there are as many ways to do this as there are woodworkers doing it...this is my opinion and it is no more or less valid than anyone else's opinion....
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