Several readers asked how to use a laser for drilling compound angles in chairmaking after I posted my love letter to green lasers.
Here it is with some important caveats:
Yes, you can use two lasers like Greg Pennington does. If you have two lasers, go for it. I have only one.
I use lasers as a teaching tool or when I am drilling weirdo angles that are unfamiliar to me. Once you get the feel for drilling routine mortises you might set the laser aside. You might not. Either way is fine by me and the portion of humanity that is kind and decent.
Yes, alternately you can use a mirror. Or a spotter who holds a stick or a bar clamp or straightedge. Or the Force.
So here’s the deal: When you drill an angle – any angle – you can easily see whether you are tilted too far left or right. It’s difficult, however, to see if you are tilted too far forward or backward. The laser acts as a spotter to guide you forward or backward.
The driller can see if the drill needs to be shifted left or right. (Note the laser line passing through both mortises).
To do this, position the laser 90° to where you are standing. Shoot the laser so its line intersects both mortise holes in a chair (or tilt it to the desired angle, such as 81°). Now stand in position to drill the hole. Tilt your drill left or right until you are lined up with both mortises.
The drill bit is in the correct position when the laser shoots up the shaft of the drill bit.
Then tilt the drill forward or back until the laser line shoots up the middle of the drill bit. Drill – and keep the laser line centered on the shaft of the bit. After you drill through the arm, position the lead screw of the bit on the mortise location on the seat. Again, line up the laser. Use your fingers to keep the bit centered in the mortise in the arm. Drill the mortise in the seat.
Move on to the next hole, moving the laser so it is always 90° to your drilling position.
And that’s it.
— Christopher Schwarz
Use your fingers (and the laser) to guide the drilling into the seat.
Bean and Wally are THRILLED about the upcoming gift guide.
We will kick off the Anarchist Gift Guide on Thursday, Oct. 21 (tomorrow!). That’s a little earlier than usual, but the world is off its axis, and we want to give you plenty of time to get your gifts sorted for the holidays. Plus, this will be our biggest gift guide yet.
If you aren’t familiar with the gift guide, it has been a yearly tradition here for about a decade. It’s mostly little things that we find useful in the shop. It’s not sponsored and not affiliated. It doesn’t plug or promote our products. We do it because we love you (even you, John Cashman).
Hey – That Feels… Almost Normal
It was a relief to receive Nancy R. Hiller’s “Shop Tails: The Animals Who Help Us Make Things Work” from the printing plant in Tennessee. It took only 10 weeks to get it printed. That turnaround time is not like the old days when five weeks was the norm. But it’s way better than some other recent titles. (“The Stick Chair Book” is coming up on 17 weeks in gestation.)
So if you are looking for Lost Art Press books as gifts, here are four quick updates.
“The Stick Chair Book” should be shipping the second week of November. Fingers crossed.
“The Handcrafted Life of Dick Proenneke” is also scheduled to ship about that same time.
We are running dangerously low on stock of “The Anarchist’s Tool Chest.” The cotton cloth we need for the cover is in limbo. If you need this book for a gift, don’t hem. And don’t haw.
With publishing mostly on the ropes, Megan and I have been full-time furniture makers and tool designers during the last few months. We’ve been sending a lot of furniture out the door lately, but that doesn’t help you with Christmas (unless you ordered a chair or a tool chest from us).
The good news is that we should have Crucible Planing Stops in stock before Christmas. These ductile iron bench accessories should be less than $50 and will be super easy to install (drill a 5/8” hole in the movable block; drive the stop in; done).
We have also been working on two new tools that are now in the prototype stage. One is a sliding bevel that holds its setting better than any tool I’ve ever used. And the second is a handy waist apron that is great for woodworking (and will feature a cool vintage-y screen print). Both of these new tools will launch in early 2022.
And by then I hope things will get back to normal, and we’ll have some new titles to announce.
This week I am building a Hobbit-y chair for a customer in black cherry instead of white oak. Is cherry strong enough for a stick chair such as this? Of course. How do I know? I added 1/8” in diameter and thickness to some key components. So now I can sleep without worry.
If the above paragraph makes little sense, then you haven’t read my chapter on wood in “The Stick Chair Book.” No, this isn’t an advertisement to twist your arm into buying the book. Instead, I hope to help you think about the strength of wood in a different way.
First, I think we can agree that when we increase the thickness of a tenon, that it will be stronger. Right? So let’s say we have a 1/2”-thick tenon and we decide to double its thickness to 1”. Because we have doubled the thickness, that should double its strength. Right?
Wrong.
When we double the thickness of that 1/2” tenon, it can increase the strength of the component by four-fold or eight-fold. How much additional strength you get depends on the component – whether you are testing its “modulus of rupture” or its “shear strength” (this is covered in detail in the book – this is still not a commercial, I promise!).
The bottom line is this: small increases in the size of components can increase their strength dramatically. This is hugely important when building chairs, stools, benches, workbenches or any object that will see abuse.
Let’s get back to this Hobbit-y chair for a moment. Cherry is weaker than oak. But if I increase the diameter of the leg tenons or the thickness of the seat by a mere 1/8”, I will more than make up for the difference between the two species. And the 1/8” added thickness isn’t really noticeable to the naked eye.
Take a look at these charts for some details.
These formulas are not my doing. They are created using the formulas from the “Wood Handbook” from the U.S. Department of Agriculture (a free download). For me, they help me design furniture that is strong without being bulky. I know that I can increase the thickness of a tenon by 1/8” and get a disproportionate increase in strength. I can do the math to prove it to myself.
Or, as I discussed before, I can prove it with a sledgehammer.
WAIT, FROM THE LUMBERYARD? You can build a stick chair with almost any wood. Yes, you can rive it from green wood. But you can also buy it at the lumberyard and get parts that are plenty strong enough.
Editor’s note: What follows is a short excerpt from “The Stick Chair Book,” which is scheduled to be released in hardcover form in early November. Until that date, you can buy an “Early Adopter Digital Package” of the book for $25. This digital package includes lots of extra goodies. When the hardcover book is released, this package will go away forever.
Most chairmakers are ridiculously worried about the wood they use in their chairs. Is it strong enough? Is it dry/wet enough? Is the grain straight enough? Can I get the parts I need from this chunk on my workbench?
But aside from those narrow concerns, there is a lot of flexibility when it comes to the wood you use to make a chair. The wood can be:
• almost any species • air-dried, kiln-dried or vacuum-dried • a softwood or hardwood • sawn or riven • ring-porous, semi-diffuse-porous or diffuse-porous • from the lumberyard, the log yard or your backyard.
Put another way, almost any wood can be used in a chair as long as it is strong enough, dry enough and the right size. What follows is how to evaluate your stock in terms of its strength, moisture and size – without turning you into an intern at the Forest Products Laboratory.
TWO STICKS, ONE DISASTER The stick at top has grain running its entire length. The one below has short grain and is doomed to snap. Training your eye to see short grain at a glance is a helpful skill.
Strength Every stick of wood is a bundle of wood fibers. If the fibers run continuously from one end of the stick to the other, that stick will take far more abuse compared to a stick where some of the fibers run across the width of the board (sometimes called “short grain”).
You can create one of these super-strong sticks using a few methods. You can rive the wood – like firewood – so it splits along its long fibers. You can saw it out by following the direction of the fibers with your saw blade. Or you can use a combination of these two methods.
Neither method is magic. As long as the fibers run straight through the stick, you have done your job. The other aspect of strength derives from the species of wood. A strong species, such as white oak, can be extraordinarily tough when it is only 1/2″ in diameter and its fibers run continuously from one end to the other. A similar stick of cherry or walnut might have to be 3/4″ in diameter (or larger) to possess equal strength.
While it sounds like I am about to offer a chart, graph or equation to determine the optimal-sized chair part, I’m not. Instead, I’m going to suggest you find a sledgehammer.
SLEDGEHAMMER TEST When I make a chair, I make a few extra sticks and hit them with a sledge. I recommend it. You will learn a lot about how wood breaks and how some species (like ash) seem indestructible. Below are two victims. Short-grain walnut and brash cherry.
You can easily test a sample chair part by propping it up on two blocks of wood, one on either end of the stick. Hold the stick in place with one hand and strike the stick with a small sledgehammer (2 lbs. or 3 lbs. will do). If the stick survives the strike, the part is strong enough. If it snaps, you should increase the bulk of the stick or find one with straighter grain.
Why isn’t there a Holy Chart of Diameters and Species with recommendations for chairmaking? Because wood is so variable. For example: Slow-growth and fast-growth oak can be radically different when it comes to strength. (Slow-growth oak is far more porous and easily snapped.) How the tree grew, how it was dried and how straight you cut it all play a part in how strong a stick is. But one way to resolve all the variables is to hit a sample stick with the sledge.
The idea for this test came from fellow chairmaker Chris Williams, who was looking for a way to test wood for brashness – a defect where the wood is so brittle it can be snapped like a corn chip. It is also a method that the USDA Forest Products Laboratory has used to test brittle woods.
How hard should you hit the stick? Like you are striking a nail. Should you use a surviving stick in the chair after you hit it? It’s your call, but I usually use them.
A reader named Jason Stick (he claims that’s his real name) pointed out an error in ‘The Stick Chair Book’ that I’d like to point out to you.
On page 494 of the chapter on the lowback, the text says the resultant angle for the front legs is 25°, and the resultant for the back legs is 28°. But in the drawings, the resultant is shown at 23° for both.
Here’s the good news: Either will work. Use the 23° resultant if you want to match the cherry lowback shown on the opening page of the chapter. Use 25° and 28° if you want a little more dramatic rake and splay to the legs. I used more drama when I built the first two prototypes of this chair, but then dialed it back for the final chair. I did this mostly so the resultants would match two other chairs in the book (for the sake of simplicity).
Shame on me for not catching this inconsistency, which will appear in the first edition. Bad Zoot!
Printer update: The book is due to ship from the printing plant’s dock on Nov. 5. We are fortunate that it’s Nov. 5 of this year and not next year.
