Difference between revisions of "Folding Stool 2A Prototype"

From Wayne's Dusty Box of Words
(Finishing)
(Making the Arms/Feet)
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===Making the Arms/Feet===
 
===Making the Arms/Feet===
Here's that opportunity to make some firewood you've been waiting for. The arms and legs are basically two sets of mirrored components. The easiest way to lay them out that I have found is to make one leg frame completely and then the matching frame. I'll explain below.
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Here's that opportunity to make some firewood you've been waiting for. The arms and legs are basically two sets of mirrored components. The easiest way to lay them out that I have found is to make one leg frame completely and then the matching frame. I'll explain it below.
  
Start by making 4 identical boards. They must be long enough to accommodate all 8 legs but they can be as much longer as you like. I used  15" long as shown here.
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Start by making 4 identical boards. They must be long enough to accommodate all 8 legs but they can be as much longer as you like. I used  15" long as shown here. The shapes and decorations for these pieces vary quite a bit. We are going to keep it simple for this basic stool and whack off the top corners at 45°. Do this now, while it's a minor thing, it will help you keep the parts straight.
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We will layout the mortise locations now, so take two of those, lay them side by side with the clipped corners on the same side (the right, for instance). The arms have the mortises on the bottoms (sides without the clipped corners), the feet have them in the top (sides with the clipped corners). See? Handy already.
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For the whole layout, you need only two measurements. One is the offset on the "near" side and the other is the center to center distance between legs. Take a look at the photo to the right where I demonstrate this with two pairs of dividers.
  
 
===Making the Seat===
 
===Making the Seat===

Revision as of 06:59, 18 May 2020

This walk-through was made while completing three of these stools for friends. I had hoped that doing them batch fashion would result in some efficiencies. That didn't seem to happen. Part of that might be due to my rather chopped up shop time and lack of excitement for making stools #5, #6 and #7.

That said, it doesn't take that long to make one, I just have a long list of things I'd like make and things that need to be done around the house. These took me 4-5 hours each. Finishing and final assembly was about half of that. It's really hard to put finish on an assembled stool. You really need to do it as you go. I'll cover that in more depth in the finishing section.

That total could be shortened considerably if you are less fussy than I am about your finished product. You could do a "munitions grade/basketman" level of stool in about 2 hours. But that's not how I make things, so follow along if you want a nice stool that will last a couple of hundred years if you're careful.

A note about measurements: pre-industrial furniture didn't follow carefully measured plans. there are parts that are important and those were laid out with care. Everything else was cut to fit. For this chair, the critical part is the layout of the holes for the folding mechanism. Other than that, there's room in almost every other measurement. If your legs turn out 24" instead of the specified 23½", it's fine, really.

Preparing the Stock

Pile of Stool Stock

Your wood of choice is a clear hardwood. I recommend oak, it's cheap and more than strong enough. But feel free to use whatever you have to hand, this doesn't take a lot, about 4 board feet.

Everything is cut from ¾" thick stock and all parts are 1½" wide. You can either mill this down from 4/4 rough stock, or, if you're wealthy, you could buy 2S2 red oak from Home Depot or similar and rip it to width.

You'll need 31 linear feet of ¾" x 1½" stock cut like this:

  • 8 Legs @ 23½"
  • 4 Feet/Arms @ 15"
  • 8 Seat boards @ 14"

My recommendation is to cut all your stock to width first, then cut things to length as you need them. It's important that all seat and leg parts be the same width if you want this to fold. Have a couple of extra pieces so when you mess something up, you have more of the same width already to hand.

The Folding Mechanism

Folding Mechanism

Let's discuss the folding mechanism and how to layout the pivots before we get into making firewood. Math isn't my strong suit, much less geometry, so there are probably better ways to go about this, but this works for me. There are no doubt many different angles that make a sittable chair, but I am going to stick with 45 degrees for the very practical reason that it makes construction simple.

Take a look at the photo to the left (you might need to click into it and look at the full resolution version to see the measurements), the basis of the mechanism is a right triangle formed by the 2 seat pivots and the leg pivot. Bisecting that gives us the information we need to layout the pivot holes on the legs. Yes, I know the measurements are not exactly correct, but they are close enough for woodworking.

This makes a seat that's 14" wide. Fine for a stool, but narrow for long seating, at least for some of us. I scaled this up to ducal size for the Type 2B stool I built. That used 10" & 14" for the spacing, which yields a seat that is 20" wide.

Making the Legs

The legs take the most work, so we'll start there. Cut 8 pieces to 23½". The exact length doesn't matter, but for a good result, they should all be EXACTLY the same length. Or at least the exact same length between the shoulders of the tenons you are about to cut.

But before we do that, it's probably best to drill the pivot holes in the legs. A drill press is useful here, for the best results, you want these holes centered in the material (for strength) and straight (to keep the resulting chair from binding when you try to fold it).

All 3 sets of stock drilled

The rule of thumb for M&T joinery is to make the tenons ⅓ the thickness of the stock. That's generally fine guidance, which would mean ¼" dowels for this ¾" stock. But I find those dowels to be a little flimsy, so I use 5/16" dowels for my pivot pins. And since I typically use oak, I am not worried about making the legs too weak with the larger holes.

YMMV, but check your dowel stock once you pick a size. I have found that dowels from the big box store tend to run a little undersized (or oval which means they weren't all that dry when formed). On the other hand, I have a bundle of dowels from a millwork vendor online and they are all slightly oversize.

If they are oversize, and you have a dowel plate, it's a simple matter to resize them. If they are undersized or, if you don't have a dowel plate, you'll need to pick an appropriate sized drill bit. I have a dowel plate, so I resize my dowels to 5/16" true. You are going to want a hole that's slightly oversize so things pivot easily. I use 11/32" for my 5/16".

Layout the holes as follows:

  1. one hole 2" from one end
  2. one hole 12" from the SAME end

You need to be careful here, it's easy to get confused and drill the second hole from the wrong end. Believe me, I've done it. The functioning of the fold depends on these holes lining up through 8 boards. So you need to either be precise or so sloppy it doesn't matter. I prefer a tidy, precise job personally so I used a drill press, fence, and a stop block to make consistent holes.

OK, with the holes sorted, it's time to move on to cutting the tenons on the ends of the leg boards.

Going back to good practice for M&T joints, we're going to make the tenons ⅜" x ¾" and ¾" long. Again, if you want this to look nice, the distance between the shoulders on all the legs need to be exactly the same. There are tons of articles and videos out there covering this joint so I won't go into here. Just want to say, neatness counts.

Making the Arms/Feet

Here's that opportunity to make some firewood you've been waiting for. The arms and legs are basically two sets of mirrored components. The easiest way to lay them out that I have found is to make one leg frame completely and then the matching frame. I'll explain it below.

Start by making 4 identical boards. They must be long enough to accommodate all 8 legs but they can be as much longer as you like. I used 15" long as shown here. The shapes and decorations for these pieces vary quite a bit. We are going to keep it simple for this basic stool and whack off the top corners at 45°. Do this now, while it's a minor thing, it will help you keep the parts straight.

We will layout the mortise locations now, so take two of those, lay them side by side with the clipped corners on the same side (the right, for instance). The arms have the mortises on the bottoms (sides without the clipped corners), the feet have them in the top (sides with the clipped corners). See? Handy already.

For the whole layout, you need only two measurements. One is the offset on the "near" side and the other is the center to center distance between legs. Take a look at the photo to the right where I demonstrate this with two pairs of dividers.

Making the Seat

Seat Boards

The seat boards are the simplest of the parts. All 8 boards are identical. Start at 15" long, they get trimmed to fit, it's really around 14¾" I think, The seat boards get the other two holes. And, like with the legs, care and precision pay off.

The first hole is ⅞" from one end, the second hole is 7⅞" from the SAME end. It's not quite symmetric, so, again, care pays off. Layout and drill all the holes.

You have to bevel one end to 45° to lay on the legs, but the "back" end, at the pivot, doesn't need to be beveled. I do it anyway because it looks better. In the period illustrations, some were and some were not, so it's up to you.

Assuming you are going to do it right, chop off that pivot end at 45 deg. I cut them just far enough to get a full bevel. You don't want to weaken the pivot area too much.

The other end, I would leave ⅛" to a ¼" long for now. When we assemble the stool, we'll trim it so it's a perfect fit. Don't assume you can nail it, maybe you can, I can't. But then I want the seat real flat. You can be a little off and it's fine, just a little lumpy.

Finishing

Parts laid out for finish

I use a Boiled Linseed Oil blend (see all about that Using BLO). You really want to do most of the finishing before you assemble the stool. Once it's together, it's really hard to get the finish in all the places you want. So, tape off the mortises and tenons to keep the oil from fowling the glue surfaces and go to town.

I go with 3 coats on something like this. On stuff I love, the more the merrier. If it starts to look dry or dusty, recoat. This isn't the type of finish that lasts forever. But it's dead simple to renew. Just wipe more on.

Assembly

Maple 2A Almost Finished

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