Cutting the waste on dovetails (long & pedantic! )

Note

Dan Donaldson

>The semicolon at the end of the codes is necessary.

Re: Another Note

William R. Duffield on the Cohansey

>Another note: If you use the Preview Message button, the Forum software will convert the codes in the Message box, beginning with the ampersand and ending with the semicolon, into the characters you want displayed. If you need to preview your code, use your "back" button to restore the unconverted text in the Message box, make any needed edits there, and then post the message. Do NOT immediately follow the Preview Message button with the Post Message button, or you will lose the visible characters, and your browser will attempt to interpret them as HTML. I know this explanation is not intuitively obvious. If you need to understand it better, it is best that you experiment with previewing a test message.

Good point

Dan Donaldson

>That has bitten me a couple of times ;-)

Saw Notes #1

Don Thompson, Cutler Ridge, South of Miami FL

>I believe that this is from one or more postings by Dave Barnett:

USING JEWELERS SAWS FOR CUTTING DOVETAIL WASTE

"We had a discussion a while back, and it looks like the black handled one from Woodcraft came out the winner, based on easy blade change, and two ways to tension it. "

That's a fair price for the jeweler's saw and three dozen skip tooth blades; perfect for dovetailing (Woodcraft). However, Contenti (see below) offers the same saw in a 6" throat if you want a bit more clearance or maybe for smallish marquetry (you'd probably want 2/0 blades for that, and not skip tooth).

If you don't need more throat depth and an adjustable frame (I use mostly fixed frames for goldsmithing - more rigid and precise), try either the Swiss "Lightweight" #400-383 or the French "Best Quality" #400-363. (Notice the top of the blade holding mechanism on both adjustable and fixed French saw frames if you wonder why they're more expensive.)

http://www.contenti.com/products/saws/sawframes.html

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Well, Contenti doesn't carry skip tooth, and for dovetails, that's what I'd use (NOT the reverse skip tooth, though). As far as brands go, Olson is good and ubiquitous. Best deal I've heard about lately is a closeout sale on the older style of Olson skip tooth blades. $15.00 dollars a gross in assorted sizes. That's $1.25/dozen, but the regular price from this vendor for the newer blades is only $2.15/dozen, which is about half what some retailers get for them.

I've never purchased from these guys, but here's the URL:

http://www.advmachinery.com/default.asp?pg=products&grp=62

I've used Olson and they're okay for woodworking. Good blades are important, as are good saw frames that can take advantage of them. Bad ones will wander, snap, drive you nuts. Not worth it. Worst blades I've ever used came in a sampler pack from Lee Valley. Love just about everything else I've ever bought from LV -- but not those blades. I think they do carry some skip tooth blades that are acceptable, though, but I'd ask if they're from a different manufacturer.

Most of my sawing is with metal blades (Swiss-made LaserGold from Rio Grande), from 4/0 down to 8/0. A 2/0 is about as big as I use for metal and as small as I use on veneer (what Silas Kopf used in his marquetry class). So I'd kinda like to know what others with more experience sawing out DTs have to say, as I'm down to my last two #7s.

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You asked: "I have a couple of questions about the French non-adjustable saw. First, where does it tension? Do you turn the handle, like a coping saw?"

Jeweler's saws are properly tensioned by compressing the entire frame as a spring, inserting the blade, tightening it in place, then releasing. The usual way of doing this, after the frame has been set somewhat larger than the length of the blade (I'll go into this later), is to place the top bar (away from the handle) into a notch in the bench pin (a small protruding platform for sawing, sort of like a "bird's mouth") or the bench itself, then pushing forward with one's torso/belly against the handle to compress the frame to accept the blade, which is fastened with the two thumbscrews before releasing. This gives significant tension.

The screw at the top of the frame (if there is one) is then adjusted until the blade sounds right to the ear when plucked, or just "feels right". Usually, this means letting it off a tad. But then, I weigh more than a Unisaw. So the screw is more for fine tuning -- tweaking. But the frame bar adjuster is (properly) never used to tension the blade once it's set into the nuts.

Clamp the blade in the nut at the handle, (or the other end if you must), then:

Initially, for an adjustable model, set the saw frame to 1/4" longer than the blade. Then add 1/8" (test it again), then 1/16ths until the blade "almost" touches the limit it can be inserted into the top nut (if it's the type that has a stop), or until it's about 1/16" of an inch into the frame (if it doesn't have a stop). Try it until it seems "right". If you feel like it's going to spring the frame, back it off by all means and let it out a bit.

Pluck the blade. It should have a nice pure "ping". If it's too loose, you'll know it. If the blade seems unduly "hard" to the touch and the sound is "strained" and lacks volume, or is downright "dead", back it off. Too tight.

For a fixed model, insert the blade under tension, clamp, try it. Tighter and slacker are pretty intuitive here.

The proof's in the sawing, though. Not the sound.

You will find a nonadjustable ("fixed") frame compresses much more easily (and comfortably), holds the blade quite rigidly, and saws very smoothly with less blade breakage. At least it seems so to me. While the difference between fixed and adjustable frames may matter more to someone using 8/0 blades on gummy 22k gold, understanding the proper tensioning technique should still save blades, extend the life of the frame, and make sawing out DT waste pleasanter.

"Second, will the lug mechanism turn 90 degrees in its holder, so that the blade is held at right angles to the plane of the frame?"

Mine won't. I've seen a few of these but they're less common, I think. It would seem to be an advantage, but the way I do it, it wouldn't matter whatsoever. (This is where I wish I could draw a picture.)

Imagine you've kerfed the tails. Instead of insinuating the blade down the kerf to the corner, then sawing across, I start at the top, then make a sweeping, curving cut from the upper right to the lower left corner, kind of like the downward slashing stroke in the the number "2". Next, I make a flatter curving stroke to the other corner, kind of like the lower stroke on a freely drawn letter "Z" (how high to start this depends more on your saw frame throat depth). Then I sort of clean out the corners with blade. I don't know that this really helps, but it's a habit. Finally, I pare out the floor with a Japanese 1/8" DT chisel (triangular section) when I can find it, or use a couple copies made from old triangular or barrette needle files that work just as well.

Rob's right. You can easily twist the blades. Wax carvers are known to twist them into a spirals to cuts in any direction, sometimes drawing the temper with a match or torch before twisting.

"The fret saws that only have one tensioning mechanism are not as good - you can't get the tension you want on the blade."

While that may be generally true with some jeweler's saws, especially the cheaper ones, it's certainly not so with well-made saw frames, such as Gesswein's #187-1097 (link, below), but that's fifty-seven dollars, too.

http://www.gesswein.com/catalog/catalog.cfm?cat=2&sub=9&subsub=12&catalog=1&CFID=120354&CFTOKEN=39801709

Even the least costly frame I own, my ten dollar Grobet fixed frame (#187-1120), holds both standard metalworking blades and skip tooth blades (which I use mostly for cutting hard waxes) at sufficient tension, and looks like it'll last longer than I will. On the other hand, some of those Indian imports, no matter how you tension them, will soon weaken and misalign. Nothing will help a weak frame.

If you look at the way an adjustable frame is constructed, you'll see why fixed frames are better: the fixed frame springs continually throughout its length and chordal segments. The adjustable frames WERE more useful for different blade lengths (more common before the 5" standard), esp. when blades were scarcer and far more expensive to buy or make for oneself -- its real advantage to mount partial blade sections. But they never seem to tension as well as continuously springing saw frames. At least not in my experience.

So, with the quality and affordability of modern blades, I'll opt for fixed saw frames.

Lastly, I guess I should repeat that the Woodcraft saw with three dozen skip tooth blades is a good deal for dovetailing any way you look at it.

Saw Notes #2

Don Thompson, Cutler Ridge, South of Miami FL

>More stuff:

For my [dovetails cut with] dozukis, it takes about a No. 2 fretsaw blade (thickness 0.012", 20 tpi) to snake down the kerf. You might try a No. 3 at 0.013" (18 tpi) or No. 5 at 0.015" (16tpi), because they would be faster blades and cooler running. Which one will fit depends on how much set your dozuki has.

If you're going fretsaw, or jewelers saw, the frame matters, because it affects how much tension you can put on the blade--more is better--and also whether you have enough throat depth to reach in and make the cut. The highest tension frame I have is sold by Garrett Wade (#14I01.01--Extra Rigid Fret Saw, 10" deep, $32.50). This frame has a deep enough throat to handle about any dovetail drawer or side width. However, I find the blade change drill to be a big PITA, involving an allen wrench and removable lugs, and for that reason ordinarily use a jewelers saw, where the pieces will not fall in the sawdust and get lost. YMMV, and this is a great saw otherwise.

I kinda like jewelers' saws, even though you can't get as much blade tension as you'd like for 4/4 stock. I use the one sold by Woodcraft with the black handle and about 2-3" of throat depth. I like it for two reasons: I can put the blade in at 90 degrees to the plane of the frame, and saw with the frame vertically oriented over the board I'm sawing. Secondly, it has a tensioner at the end of the frame, in addition to the tensioner up above the handle, so I can get max. tension on the blade (although it is still lacking). The comparable Lee Valley saw only has the one adjuster up top, and you would need to ask LV if the blade can be mounted sideways, cause otherwise there wouldn't be enough throat depth to make the sawcuts on most drawers. I believe the blade probably can be mounted sideways on that saw.

Using a fretsaw in 4/4 material or thereabouts, I find you go through a lot of blades. So once you figure out the setup you like, order a bunch of blades. I found a place in Tennessee that sold me a gross of No. 2 skip tooth Olson's for $17.

Now there's a whole nother way to go. Which is to forget about going down the kerf. Instead, use a heavier saw and make two cuts per socket: each cut is from the middle into the corners. This leaves you more chisel work, but it's pretty fast. For this, you can use a coping saw.

So really I don't find any one method that is clearly superior. And in talking with others, I find they are split between jewelers saws, the two-cut method, and the high-tension GW fretsaw. I suspect you'll end up doing your own experimenting to make your choice. Hope this helps.

Absolute best price I could find on Olson blades (and good service, too) was Sloan's Woodshop, Lebanon, TN, www.sloanswoodshop.com

1(888)615-9663