Friday, March 11, 2011

It's Always Sunny in Brooklyn. (Part 2)


Back to the lab with a pen and a pad.

Disclaimer: This was the first time making a saw handle and for the most part I was winging it. As a result some of the steps may be mildly-to-fully ass-backward. Also, I once said I wasn’t going to blog how-to's, I sort of lied, deal with it. For what it’s worth, this a more of a how-did anyway.

When our story left off, I had a plan and a sketch of a handle that looked halfway decent. In the scanned image above, you’ll see how that sketch has developed and, although you can’t necessarily tell, the drawing has been spray-mounted to the wood . Two things to point out at this… point is that I have already drilled 1/8 pilot holes in drawing block and that there is addition of a sharpie line that corresponds exactly to the position of the saw plate aligned with those 1/8” pilot holes.  The new profile of the handle adjusted to account for the actual position of the saw plate to ensure that I maintained the strongest lamb’s tongue and wasn't in danger of cutting through it. Also worth noting are the position critical radiused sections which will later be drilled out with forstner bits saving lot of finicky shaping (don’t worry there will be plenty of finicky shaping later).
So here's where things get interesting. This is where my little  handle how-did starts differing from every other how-did/do that I’ve seen. As you can tell from the shape of my sharpie layout line, the saw plate of the D8 is not straight- it’s circular, actually its DOUBLE-CIRCULAR! Before you start flipping out and asking yourself “What does it mean?!?” I’ll say that this is the feature that allows for a “let in handle”, which as far as I can tell was most likely almost purely a cosmetic marketing ploy, perhaps to enable the saw handle’s increased hang (the angle of the handle relative to the toothline) and to differentiate the D8's from the no.7’s, 9’s, 12’s, etc. I’ll tell you one practical difference with this style of handle is it increases the ass-pains to cut this slot by several orders of magnitude. Or does it? *dun dun duhhhh!*
Well, yes, yes it does.

Clearly this slot was cut at the factory with some thin circular cutter following a pattern. Alternative techniques that have previously been put forward on the internets for the cutting of this sneaky-slot include:

1. Cutting a slot with a thin circular saw blade on the table saw using some kind of jig and raising the blade into the handle and then filling the oversized gap with a thin strip of filler wood.
Sheen-Analysis: Scary-tablesaw action, overly complex set up, and a difficult glue up which will still be visable. Loosing, duh, next!

2. Cutting a straight slot per usual techniques and fill the top slot with a piece of filler.
Sheen-Analysis: Simpler, but more visible patch right where you stare at everytime you use the saw. Not so fast trolls, losing, bye-bye, duh, next!

3. Buying a very expensive carbide or HSS cutting wheel and make some kind of jig to cut the slit, maybe using a milling machine or a drill press
Sheen-Analysis: Most direct/accurate method, but requires most $$$ and still scares me. Nice try trolls! You should be chugging “tiger’s blood” instead of sipping on V8, thought-torpedo deployed, BOOM! losing, DUH!

Ok, so the method I devised for the task is simple, winning and required no extra tooling or filler material. First step, put down your chalice of tiger’s blood (last Sheen reference, I swear) and pick up a marking gauge to mark out a center-line on your handle blank. Next head to the bandsaw set up with a tall resaw fence. Offset the blade from the centerline the thickness of the blade (only 1/32” not that it really makes a difference). Saw the blank in half. Now stop, and admire out the spectacular grain figure in this chunk of walnut! This wood came off an offcut that contained a nasty knot in it, I aligned the grain with the profile of the saw handle to maximize the long grain traveling through the critical areas for strength. The wild pattern, while gorgeous, also flows ideally through the handle minimizing short grained areas giving it the strength of a team of unicorns driven by Zeus himself. It’s scientifical.

Ok, now that you have two slices of lignum-love, take the thicker of the two pieces and using your pilot holes as a guide mark out the profile of the blade onto the sawn surface.
I then used a large gouge to stake in this profile. Next, take your handy-dandy marking gauge and set it to the thickness of your saw plate. Transfer this measurement to the blank. I then took 3-4 pieces of blue tape and created two bearing surfaces for my router plane. This is to allow the plane to move smooth-ishly and not to damage the texture of the saw-marks (which will be important later for the glue up). Also, I should add that on my blank, I left about an inch of extra material at the toe end. I will remove this later, but it gives me a place to support the router plane and will keep the plane from tilting as I work the far end of the slot. Now all I had to do was gradually remove material until I reached the scribe line left by the gauge cutter. BAM, circular-slotular-perfection! (That cooking guy, not Sheen)

The next step was to coat each sawn face with a thin layer of Titebond II for dark woods and carefully realign the two pieces. To aid in the process I cut several reference keys in the sides of the blank and check by finger-feel that they are all flush under light clamping pressure. It is important not to go nuts with the glue here because excessive squeeze out with interfere with checking that the pieces are aligned and glue will fill the precious shapely saw slot you have just carefully created. I used a thinned down damp popsicle stick scrape the slot and spread around any glue in the slot (although, I did this as an afterthought and was running around like a crazy person). Ultimately when the clamps came off and I slipped the blade in it bottomed out prematurely on some glue residues, so I rolled a little hook burr on the end of a card scraper and excavated the void a bit until I could line up the bolt holes. I contemplated over-sizing the slot to avoid this step, but I think I made the right decision. This way the sawplate is firmly butted up against the rear of the slot and will be supported during a cut and wont have anywhere to shift to. Will wood movement cause the plate to split the wood in the future?
I don’t know, but we’ll find out wont we. The best part about this technique is that it's safe, very precise, required no jigs, and relatively quick.

Below is a picture of the glued up piece, with the edges dressed up a little. As you can see the seam is almost invisible. I have used this techniques many many times without physical keys (like pins) and it works very well.If the need arises in the future to make another handle in this manner, I think might try to use pins in the pilot holes to align the pieces. The holes are already there and might as well make use of them. Like most things this only occurred to me in hindsight. Whatever, looks good as winged, no?

Alright, that completes round 2. As I ramble on into part 3, we’ll be maxing our burn and continuing to get a handle on this situation, sculpting this blocky-bastard into shape for bikini-season.

Over and Out.


zeke said...

Fucking nice work, Mr. Man.

nielscosman said...

Thanks Prof. Zeke!
Game recognize game.