Sunday, September 26, 2010

Jumbo Joinery: Half-blind Ostrich Tails?

The focus these days is less on the benchtop--thank goodness, it's getting old--and more on the interesting components. My original thinking on the skirt was to use 3" wide 4/4 maple to wrap the top. I've since decided to go with 6.5" wide 8/4 maple instead. The reason for this shift to the massive lumber is that I've decided on employing a method whereby the skirt helps to flatten the top. Let me try to explain...

The above photo shows the benchtop upside down and if you look closer you can see that I have routed a slot around its perimeter. That slot is a uniform distance from the top of the benchtop all the way around. The skirt components will have a corresponding slot routed the same distance from their respective tops all along their insides. I plan on cutting what I call "floating tongues" that will be inserted into the matching slots where the super-rigid, super-straight skirt pieces will pull any deviations in the benchtop into alignment. If this doesn't make sense, hopefully the pictures I take when I attempt it will do a better job. I'm looking forward to seeing if this will work. 

Now on to the skirt. Skirts aren't necessary on benches and in fact some people prefer not to have them because it makes it easy to clamp anything anywhere to the benchtop. This skirt will be so thick that I don't think that will be a problem. I got another one of those massive 8/4 beams from Carlton's the other day. Carlton's is over by Georgia Tech but it isn't often that I have a car over there. I had a job interview on that side of town on Thursday so I drove my car to school, went by the wood store to pickup the beast and then went to the interview. I wonder how many people show up for a job interview with 14' 2"x7" strapped to their roof rack. Not enough is my answer. 

I planed, jointed, ripped, and crosscut to spec and then approached the joinery. As I've written about previously I'm a fan of the half-blind dovetail these days. I think it makes sense here because the skirt will also be the inner jaws of the two vises. The half-blind allows me to keep that inner jaw area as purely face-grain instead of a face-grain/end-grain combo. So I whipped out my new marking gauge and got to it. Expect a forthcoming post on this style gauge versus my previous one.

First cut:
Not great, a little ragged, at least it's square.

Finished my tail cuts:
 Two good ones, two mediocre ones.

Then I cut the shoulders for the tails:
(Notice trashcan o' shaving No. 2 in background. Yep, just about full)
A couple comments: This will probably be my last project using Japanese saws so I thought that the dozuki should get a glamor shot. It's been a good saw that has served me well and I'll explain my transition to Western saws in a future post. Also, I'm really looking forward to having proper traditional woodworking vises on this new bench but this situation demonstrates how handy it is to always have a little vise floating around that you can clamp anywhere. This Groz was one of the first woodworking purchases I ever made. 

Chopping the waste:
I've never done dovetails this big before. Typically when you are chopping the waste from between the tails you can just use a coping saw for the majority and then pop the bottom of it out with a couple of hard, well-aimed chisel blows to either side. Not the case here: I approached this as I would the sockets of the pin board. I clearly establish the bottom of the waste with a big chisel and then take aggressive paring cuts into the grain. This removes the waste in a pretty controlled manor. 

Halfway through:
Time to flip it over and work from the other side. 

All finished.
 I didn't screw anything up too badly. Phwew!

Then I align the tails on the pin board and transfer the tail profiles with a marking knife
You can see my marking knife in the top left corner. It is beveled on one side only which is pretty dumb: subject for a future post? Maybe. 

Alright, now for the tedious part: wasting the sockets for the pins.
After some nervous moments on the first one, I tried a new approach for the second one. I drilled relief holes down into the sockets ala "burn holes" from the tunnel blasting industry. Previously when I would pry that waste out of the tapering socket, it risked damaging the pins by scraping and compressing them on the way out. The relief holes A) divide the waste into smaller pieces and B) give the waste substantial lateral leeway so it doesn't damage the pin walls on the way out. A real dovetail chisel would also be nice for getting into those deep corners. *sigh* Lie-Nielsen, why you gotta be so expensive? Oh, that's right...actually made in America.

Tap it in...
I hope nothing splits! 


I'm going to take a second to brag here. This fit "right off the saw." In other words, no trimming and adjusting was needed. A lot of people are taught to cut almost to the line and then use chisels to trim it to fit. I like Konrad Sauer's philosophy. Essentially he says that if you practice cutting almost to the line, you are never going to get to the point where you can fit pieces right off the saw. And that's the goal, isn't it? You need to practice cutting to the line from the very get-go. This is the only way to get really good. Now I'm not saying I'm really good, but this joint is not too shabby (that gash in the left-most pin was the result of slopping chisel-work...not sawing.) 

In retrospect, that would've been a good name for this blog: "Right Off the Saw." On the other hand, the acronym ROTS isn't so great for a woodworking blog now is it?

Personal Stuff:
They say that there is nothing more exhilarating than being shot at and missed. I'd say that a close second to that is having serious car trouble and then finding out that the problem is covered by a manufacturer's recall. I've never felt so alive!!!

Also, if you are enjoying these posts may I suggest that you become a Follower by clicking the button at the top of the page? Does that make me a Leader? I wish I had something special to give my followers...I'll tell you what: the first follower to come by my house can have a full trashcan's worth of saw dust and wood shavings. It's great for fire-starter, rabbit hutches, mulch, chemical absorbent, prank itchy name it, it does it. But no, you can't have the trashcan. 

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