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No clamps required for this assembly

March 24, 2010 By Al Navas

What else can I add? Thank-you Sandy — your help was invaluable!

This was an assembly of a large desk base with four aprons, three stretchers, and four legs; it was assembled with mortise and tenon joinery, prepared as I showed in an earlier blog entry. You can follow the work on the stand-up desk at this link.

After applying glue to the mortises and the tenons, I applied a little glue to the tapered tips of the pegs and drove them home; the liquid hide glue is a wonderful lubricant, too! No clamps were required to assemble the aprons to the legs (and the stretchers to the legs, etc.):

Drawbore pegs after leveling with block plane.

I used liquid hide glue, as it has a long open time; I felt this was the best way to assure myself of a panic-free, clamp-free, and relaxed time during the glue-up of a very large desk base. After the glue dried, I trimmed the pegs with a flush-cutting saw, and leveled all the pegs using a little block plane. Now the drawer fitting begins in earnest, including stops and alignment strips to ensure straight travel during opening and closing. In the meantime I will be touching up the shellac layers, to blend the areas I planed to the surrounding areas. Finally I will apply a durable varnish, Target Coatings’ Emtech 2000wvx.

I had to use a few clamps to hold the dust cover in place, while the glue dried – here is the dust cover in place:

Dust cover in place.

If you want to eliminate much of the anxiety during large glue-ups, I recommend the use of the drawboring technique to pull together all mortise and tenon joints tight. Even the double-tenon/double-mortise joints I used on the stretchers between the legs went together flawlessly; properly tapered, the pegs snaked their way nicely. This was the double mortise and tenon joint at the end of a stretcher, and made with an FMT Pro:

Dual mortise and tenon joint on stretchers.

I admit this was the joint I was most concerned about prior to the glue-up, due to the spacing (“Will the peg find its way through the second tenon…???”). But I am a happy camper now; well, maybe a happier woodworker, as the drawboring technique worked beautifully.

— Al Navas

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Filed Under: Blog, Drawboring, Joinery, Mortise, Tenon Tagged With: drawboring, Joinery, Mortise, stand-up desk, Tenon

The stand-up desk: drawboring the joints, and starting the finish

February 15, 2010 By Al Navas

I finally reach the point at which all the preparation of the joinery leads to careful pre-assembly layout for drawboring the mortise and tenon (M&T) joints on the desk. For example, for the leg stretchers, I drill only one hole using an egg beater drill – the tape marks the depth for other holes, such as on the legs:

I find it important to keep track of which side will eventually be up, and which will be facing the floor:

I always make a spare of everything, including legs. This allows me to test the joinery; in this case I am able to test the offset for drawboring, to ensure truly tight assembly of the joint:

The pre-drilled joint:

And testing for offset of the holes, which will allow pulling together the joint truly tight – - the holes in the tenon are offset from the holes across the mortise by approximately 1/32″, and closer to the shoulder; it is this offset that allows pulling the joint tight:

The pegs I will use to pull together the joints on the legs will be 2-5/8″ long:

The front aprons also will be pulled tightly to the legs by drawboring. In the following photo I am marking the tenons from the already-drilled holes on the leg:

Once the drilling is finished, I turn my attention to sanding, in preparation to applying the finish. To avoid rounding corners unnecessarily, I place the two leg stretchers together on the bench, and sand them in tandem:

The larger pieces, such as the legs, are sanded first with the random orbital sander; then I sand the corners by hand, using one grit higher, and sand lightly to avoid leaving scratches:

In preparation for dark toning the dust cover that will also be the support for the drawers, I apply two coats of a wash coat of dewaxed shellac to the surface that will be under the desk, facing the floor:

I am getting close to being able to do the final assembly, followed by application of the finish.

Finishing tip/preview: Some of you will wonder why I apply the wash layers of dewaxed shellac. I do this to ease the process of applying the finish. I will also be applying a wash coat of dewaxed shellac to all the aprons and the drawer fronts, which are made of white oak. This is crucial, as the shellac will isolate the highly acidic (that is, low-pH)  white oak surfaces from the waterborne topcoat I will be using. Why is this necessary? Waterborne coatings are typically high pH, around 10, or even higher; if used directly on high-tannin woods, pin-holing of the topcoat is very likely to result, with ugly results, and ruining of the finish. Using dewaxed shellac isolates the wood surface, paving the way for a beautiful finish using a waterborne alkyd varnish. This makes it much easier to achieve proper leveling of the four topcoat layers I will apply.

Related posts:
Additional reading about the stand-up desk.

— Al Navas

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Filed Under: Blog, Education, Joinery, Mortise, Tenon Tagged With: drawboring, finish, Joinery, Mortise, Tenon

Preparing a hollow mortise chisel

February 4, 2010 By Al Navas

One question from a reader prompts me to illustrate the process I use to prepare hollow mortise chisels before I even approach the benchtop mortiser.The process is called “tuning a hollow chisel”; it prepares the chisel for efficient cutting of the mortise, and eases penetration into the wood while minimizing burn marks. This results in smoother mortise walls, faster cutting, and better chip ejection while keeping the chisel cooler. So far I have not had to sharpen any of the drilling bits on any of the chisels.

In this photo you see the hollow chisel as received. The grinder marks are plainly visible:

Just like a bench chisel, the sides of the chisel should be lapped using either sandpaper or, as I show here, with sharpening stones. Following preliminary lapping on the 1,000-grit stone, I continue with the 6,000-grit or finer stone:

In this next photo you see how the steel begins to shine, and the tool marks have disappeared near the cutting edges – not quite ready for work, the chisel is getting close to being ready to cut:

Next I use a diamond-covered abrasive cone, to sharpen the inside surfaces of the tip of the chisel. The cone holder is part of a set available from various sources:

Careful inspection is a must, before using the chisel. Look carefully at the inside surfaces, to make sure the cone has left smooth, shiny surfaces:

Yup, that is the BenchCrafted tee shirt. And it is a shameless plug for the company that makes, along with 11 other winners, the Popular Woodworking magazine’s Best New Tools for 2009, the BenchCrafted Tail Vise. I was the lucky recipient of one tee shirt at the Valley Force conference:

To my friend Jameel Abraham, of BenchCrafted.com, and his brother Fr. John, congratulations for winning the award – it is well deserved!

Disclosure: I am a happy owner of one BenchCrafted tee shirt; I have no commercial or any other interests in BenchCrafted.com. And I love the vises they make.

— Al Navas

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Filed Under: Blog, Education, Joinery, Mortise, Sharpening, Tenon, Tutorial Tagged With: chisel, Education, hollow, Joinery, Mortise, Sharpening, Tenon, Tutorial