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Corner Post Dovetail Pen Box Build Thread (Lots of Pics)

56K views 28 replies 14 participants last post by  Aparelo  
#1 ·
So now that I “kinda” know what I’m doing I wanted to tackle a project with some nicer woods. After learning many lessons with this project:

http://www.routerforums.com/show-n-tell/6653-dovetail-attempt-2-1st-completed-box.html

I figured it was time to give this design a try with wood not bought at Lowes.

One thing to note before getting started. You won’t find the specific instructions for a corner post dovetail in the large glossy Incra master guide. Instead find it here in the Rocker jig version’s PDF manual:

http://www.rockler.com/tech/RTD10000168AA.pdf

Back to the wood. 1st up is some Spalted Maple provided by a fellow WoodNet. I saw a sample of his stash in this post:

http://www.forums.woodnet.net/ubbthreads/showflat.php?Cat=&Number=3433365&page=&view=&sb=5&o=&vc=1

He was generous enough to sell me a few boards and even thickness plained them perfectly for me at .5”. Next up was a quick order from Heritage Wood (www.heritagewood.com) for some contrasting walnut. This too was dimensioned perfectly at .5”. Good thing since I don’t own a plainer.

Here are a few shots of the raw materials:

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Since I have penalty of wood on hand I’m going to make two boxes. Because there is a ton of set up with this project it makes sense to construct two at once. Also this allows me to keep one for myself and to have one ready for a gift.

The 1st step was to “rip” all the planks to the same width. For this I use my router table as a “Jointer”. This does a great job of squaring up the edges and allows me to finely adjust the width of the boards.

After making some dust (ok, lots of dust) I have two maple boards, one walnut board and one poplar set up board ready to go:

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As far as accuracy… I was going for 4.25”:

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Close enough!

Now the intention of this design is to end up with a cube. Since the corner posts will be .5” and the dovetails will be about .375” this means cross cutting the box sides at 4” (lots of sketching and double checking of math came into play here). Here are the pieces cut up for the two boxes:

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It is important now to decide and mark the outside surface of the box (the nicer side). Also to number the pieces in order so the wood grain will flow from side to side.

I’m lucky enough to be using an Incra Ultra for this project. If anyone in on the “fence” about getting one of these, just do it! You will not be sorry. For this project I’ll be using a 1/2” 14 deg dovetail bit. The Incra master guide shows that my tails and pins should work well with the width of my boards (whew):

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The 1st part of setting up the jig is to center the bit to stock. This can be done a few different ways but I wanted to try a new toy. Incra sells this contraption for just this purpose:

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Using my poplar set up plank I use the fine adjustment knob of the fence to dial in the center. Cool toy:

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Next its time to install the bit and set the approximate height. I’m using a Whiteside 1/2” 14 deg dovetail bit:

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I use another Incra gizmo to set the initial height at the recommended 3/8”:

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#2 ·
Next it’s time to check the accuracy of the centering jig. For this you make a small cut in a sample board then flip it around. If the cut is perfectly centered the bit will fit into the cut precisely when flipped. From this shot it’s hard to tell but the bit is about 5 thousandths off center:

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Not Bad!!! A quick dial to adjust the fence and the next test cut comes out perfect!

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With the bit perfectly centered in the board I slide the jig rule to the recommended center mark of “10A”:

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From here I’ll use the jig rule marks for positioning the fence. If a cut falls on an A line the fitting piece will be cut to the corresponding B line (and vise versa). Then by either leaving out or making extra cuts I can make the pins and tails different sizes. This whole process takes some getting used to. But that’s what cheap Lowes wood is for!

Next comes the process of fine tuning the bit height. For this I make some test cuts in two poplar boards at once:

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The initial fitment shows things are too loose:

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So now it’s “Heighten to Tighten” as opposed to “Lower to Loosen”. The cool thing is the gap between the pins and tails shows you how much you need to heighten the bit by.

After another attempt I’m close:

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Another tweak and I’m where I want to be:

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The fit should go together snugly with hand pressure (no hammer needed) and stay together under gravity. This is another process that takes some getting used to. Keep in mind that a joint will get tighter when it’s covered in glue and the wood swells slightly. This was another lesson learned the hard way.

With the set up done it’s time to clamp in the real thing and start cutting:

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A few things to note here. When using the 90 deg jig with this system be sure to adjust the nylon screws carefully. You want them as tight as possible with the jig still being able to slide. If not you will get play in your cuts and things will not fit so great (another hard learned lesson).

Be sure to use a scrap backer to reduce tear out (in this case poplar).

When making cuts, pass the wood through the bit then turn off the router before backing out the jig. I’m convinced this makes the cut more accurate by not allowing the bit to cut twice just in case things tweak a little while backing out the jig. JUST BE SURE THE BIT STOPS SPINNING BEFORE YOU BACK OUT THE JIG. Don’t ask how I know about this warning…

The next tip is to take light passes on a cut when you can (in this example when a cut is on an outside edge):

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Take the last cut with the smallest increment possible (1/32”). This will result in a clean cut and reduce the chance of chip out. Of course sometimes this is not possible (like the cut in the center of this board).

After making some noise and dust here are the four box sides cut up:

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#3 ·
Next its time to work on the walnut corner posts. For this I’ll use a 6” long board and cut with the piece flat on the router table. To keep things safe and accurate I use feather boards and push blocks:

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Here’s the 1st corresponding cut:

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After making light passes here is the corner post board cut up and ready to go:

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An initial dry fit shows things are looking good:

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Now this is where you would cut perfect 1/2” strips on your table saw for the corner posts. But since tear out and accuracy are an issue for my table saw (that ‘s a long story) I’ve come up with a more laborious method (but with great end results).

The 1st step is to isolate two opposing box sides to fit the corner post material to (this is where that initial sequential marking comes in handy).

Now glue the corner post material to the box side with a little intentional overhang. I use a piece of 1/64” plywood to set the overhang:

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Why the intentional overhang? Because later it is MUCH easier to sand the corner post down flush rather the meatier box side (another hard lesson learned).

Some tips for this process. Be generous with the glue. Also regardless of how tight you think your joints are clamp them securely and evenly. This glue joint is important later when the comer posts get routed. If the joint is not secure the router bit will tear our the small amount of material that is left over in the process. This makes for some creative swearing opportunities. Again, a hard learned lesson from previous projects.

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Squeeze out is not a concern since things will get sanded later. After clamping overnight (just to be sure) here’s the piece :

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The next step is to cut the excess off, again leaving some overhang:

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Using this method means more forgiveness for accuracy and tear out.

Now the process can be repeated with the left over corner post material on the other side.

Next comes the pain of this process. Sanding. The good thing is the box sides will act as a guide. You’ll be able to tell when your overhang is gone and everything is flush.

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#4 ·
Once this process is done I give the box side a quick mineral spirits wipe to check out the contrast:

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So far so good.

Here is what we got so far:

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Two opposing sides of the box have the “through dovetail” material glued and sanded flush:

Now the rest of the steps are the same as a typical “half blind” dovetail joint.

Back to the router…

Using the Incra stop I set the slide about 1/16” away from the bit:

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This sets the depth of cut for the pins I’m about to cut.

A quick test with a scrap board shows the cut is not deeper than the thickness of the boards:

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This is important to double check. If your cut is too deep it will be visible from the inside of your finished box. That would NOT be cool…

Next it’s time to cut the real thing. Again taking light passes (an 1/8” at a time) and cutting the final cuts at the smallest 1/32” increment. Doing this puts less stress on corner post material and reduces the chance it will chip away:

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After cutting up one side this is how it looks:

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If you tried to put the box together at this point the tails would not fit flush:

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#5 ·
There is still one step left to do. Cut rabbets in the tails to allow for clearance. This is done with box side held up against the fence and VERY light 1/32” passes:

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The Incra master guide recommends a rabbet of 7/32”. After making 7 light passes this is how the tails look:

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This provides more than enough clearance allowing the tails to fit flush with the box sides. Now I dry fit everything together and get the 1st glimpse of a cool corner post dovetail joint:

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Next it’s time to contemplate the box bottom. For contrast and to tie the posts together I’ll be making it from walnut. Since I don’t own a plainer I use a straight bit in my router table to whittle away enough material to end up with a thickness of about .15”:

Why .15”? I want a bottom that is slightly thicker than 1/8”. More on this later…

Here I’m taking the 1st passes with a ¼” spiral up cut bit:

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The final passes remove a small amount of material to leave a material thickness of .15”:

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Here’s the piece after the router plaining:

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Now I cut the “feet” off with my table saw and I have a perfectly thickness plained plank for my box floors:

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Next its time to finish sand in side surfaces of the box before cutting a stopped dado for the box bottom and glue up.

First I hit the inside surfaces with my new Bosh RO sander:

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I start with 80 then switch to 120.

Because of the nature of this wood there are some defects and tear out from the plaining process:

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#6 ·
So it’s time to contemplate a filler before the final sanding with 220. 1st I collect some dust from my sander:

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Then I mix it with some gloss poly until I have something the consistency of wood filler:

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Now I use the mix the same way I would store bought stuff:

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After 24 hours I give the insides a final sanding with 220 and a quick mineral spirits wipe to check for any rough spots. Here’s that pit all filled:

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The filler looks a little dark but with the sporadic nature of this wood it works.

Now that the insides are prepped its time to cut the dados for the floor bottom. For this I’ll be using a stopped dado for a clean look from both the top and bottom of the box. Be sure to finish sand the floor bottom before starting to cut and test the dados. Or it might fit too lose after sanding!!!!

Back to the router table. I throw in my 1/8” spiral up cut bit and adjust it to a height of about ¼” I then adjust the fence to the 1st cut will leave about 3/16” of meat under the floor. I might have been able to make this measurement smaller, say 1/8”, but I’d rather have some more material below the floor with figured wood like this.

The sides without the posts glued get run straight through the bit:

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Next I set up stops (one Incra, one block of wood) so that the dado on the sides with the corner posts will stop about an 1/8” from the edges:

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Hence the stopped dado. This hides the dado from the ends of the box.

Now this means dropping the wood onto a spinning router bit. This is safe and accurate with a few tips (and some practice).

First make sure you hold the material firmly against the fence at all times. Start with the piece about ¼” away from the right stop. Rock the piece back and forth slightly as you drop it on the bit. Then “up cut” to the right stop that ¼” (this makes the end of the dado cleaner and more precise):

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Then continue the cut to the left stop:

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Shut the router and wait for the bit to stop spinning before lifting the wood off the table. The best tip of all… Practice on cheap wood!!!!

After the 1st cut is done it’s time to fine tune the fence position for the 2nd pass. This is why I made the floor bottom slightly thicker than 1/8”. Now I use the Incra’s fine tune dial to open up the dado on a second pass for the perfect snug fit:

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Each line on the dial represents a thousandth of an inch. This is where the Incra system shines. And why I think it is an injustice to call this thing a “jig”. It is much more versatile than an average joinery jig.

After the 2nd pass here is the stopped dado:

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#7 ·
And the side which can be cut through:

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Yes I cut into the tail slightly. It’s the back of the tail and will not be visible.

A quick test fit with the floor stock shows things look good:

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With all the router work done it’s time to break out the glue, in this case Tirebond III. I mask the insides to prevent any squeeze out from making a mess on the inside of the box. After all the insides are sanded and ready for finishing.

1st I glue one corner. A clamped square assures I’ll end up with a square box and not a parallelogram:

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Next the bottom gets finagled into the dado and another side gets glued:

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Finally the 4th side gets glued, and we have a box:

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After some initial sanding with coarse and medium paper the joints blend together nicely:

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Of course with wood that is figured you run the risk of some tear out. And here is the worse of it:

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After a few rounds of filling with the dust/poly mixture and sanding with fine paper the tear out issues are at bay. A quick mineral spirits wipe allows me to check for any rough spots and to check out the repaired tear out:

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And the boxes are ready for finishing. In this case 3 coats of Watco natural Danish Oil per Dough Hick’s schedule from his web seminar. The last coat gets wet sanded with 400 grit paper.

If you want to check out his seminar go here:
http://www.woodworkingonline.com/2007/11/12/podcast-28-oils-and-varnishes/
And I highly recommend the 5 buck seminar guide. Doug breaks down many natural finishes step by step.

Here are some shots of the completed boxes:

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#8 ·
Here’s a dovetail detail:

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Note how the grain flows around the box in these shots:

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The results of numbering the sides at the beginning of the construction are well worth it!

And here are some shots of the bottom fitted into the stopped dado:

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That’s all folks! Fire off any questions or comments. I’d also like suggestions for other contrasting wood combinations that would work well with this style joint.
 
#14 ·
Well Nick., what can I or any one else for that matter say but WOW for the project and WOW for the tutorial, Apart from skill, you must have enormous patience! It seems a pity that most of us for various reasons don't have a fence set-up like the Incra which I think would be essential for such accuracy.