Sunday, March 17, 2013

More Efficient Dovetails

Last week I scanned the walls of my crammed little shop, wishfully looking for space for a new shelf. Hmmm.....if I move the fire extinguisher......and shift that clock over.......maybe I can find space for a shelf almost 4' high by 2' wide. Yup, that'll work.

I decided to make it from Douglas Fir, as it's the cheapest best wood in these parts. I looked for poplar, but it cost twice as much. I like to do dovetails on the shop furniture, to hone the skills (and I use the term "skills" loosely).

The other issue was time. I didn't have much. So I wanted this to go quickly. And to complicate things, bad weather had delayed picking up the wood. It's in a big lumber yard, under a tarp. I pick through the piles, get what I want, cut it to fit in the 4Runner, and I'm on my way. 

I ended up picking up the wood on Friday, letting it acclimate in my garage for Saturday (while I was otherwise occupied with family stuff; i.e. what my wife makes me do), and building the carcass on Sunday. Even tho it is kiln dried, the 2 x 10s are not what you would call dry when I get them. So I knew as soon as I started milling it, it would start moving. Another reason to get the dovetails cut and the carcass glued up today. And I have my fingers crossed that it won't go wonky on me after it's been on the wall for a while.

Milling consisted of rough cutting to approximate lengths with a hand saw, then trimming up the edges with a bandsaw followed by jointing with a number 6. Then I resawed it to about an inch thick on the bandsaw, and ran it through the planer to just a hair over 7/8". Ran it through the shooting board using the BU Jack to square up the ends.

Then it was dovetail time. I wanted it to go quickly, and I wanted the joints to fit off the saw. If there were minor gaps, I didn't care. It's a shop shelf. Here are the steps I followed, with some pics for illustration. This was tails first. By the way, one of the best tips I found was in Chris Schwarz' blog, and had to do with gang-cutting the tails. 

0) (I had to make this step zero because I forgot to put it in) Use a Moxon vise or other vise that elevates your work.

1) Use one set of dividers. Don't measure, don't use two sets of dividers, use ONE set of dividers. First mark out how big you want the half pins to be - eyeball it. Then adjust the dividers to fit between these marks for however many tails you want. Fewer is better, I should have done one or two less than I did.

2) Gang-mark and gang-cut the tails. This is what I borrowed from Chris S. Here's a pic after marking and cutting.





3) I used the LV dovetail guide to start the tail cuts. This helped me tremendously as I used to fuss over this step, taking way to much time. My excuse for using a guide is "Why not? We mark the darn things with guides, why not cut them with a guide?" And I only did a partial cut with the guide. Also, if you are off even just a hair, the mistake is magnified because you are going through twice the thickness. Seemed like a smart thing to do when you are in a hurry. Plus it was a Christmas gift that I hadn't used yet.




4) After getting the cut started, I switched to the LV dovetail saw. It cut faster than the pullsaw - going through almost 2" of Doug Fir was a challenge for the pullsaw.




5) Gang-cutting the waste. Another two-for-one. And I worked a little harder to get closer to the lines, so there would be less chopping.




6) You can't gang-cut the pins or waste between the pins (or if you can, let us in on your secret), but you can mount two boards in your moxon at once, saving a few steps.




6) Size your pins and tails to match your chisel sizes.




So did it work? I'm happy to report it did. Every joint went together right off the saw, without any extra paring. They probably weren't my best dovetails, but they were my best fast dovetails. This is a dry fit, and they'll look better after clamping and glueing.





 


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