I hate making jigs. I am not set up for it. I make almost all of my stock by hand, so getting lots of parts carefully dimensioned and then assembled is a pain. Screws? Glue? I stink with these things.
But I made a jig the other day to hold the turned seat rails for grooving them with the plow plane. I’ve done it free-hand with the plow’s fence before, but it has its moments that way. Most plow fences won’t reach very far down the turned stock’s side for support.
This cradle will hold either turned seat rail; those with turned tenons, or those with rectangular tenons. It’s just over 1 3/4″ inside, so I can hold rails that are either just a tad too thick, or thin. Or even those that are just right. If it can wiggle in there, I shim it with 2 wedges. It’s important to use 2, so I can keep the centerline of the rail centered within the jig. So one on each side of the rail.
The front end of the jig has a small block in it that supports the rectangular tenon at the right height for running the plow plane. There’s a hole bored in this for the turned tenon, then the block is sawn apart so it’s only 1/2 the height.
Here’s the rectangular tenon sitting on top of that front end:
And a turned tenon nesting in the half-hole, You can also see the centerline scribed along the top of the seat rail:
In use, the plow plane’s fence rides along the outside of the box/cradle. I had scribed a centerline down the length of the rail, and set the fence accordingly. The back end of the cradle is held under a holdfast to keep it steady.
A good result – the groove is perpendicular to the rectangular tenon, just as it should be.
A reader asked if I cut the joinery before turning or after, thinking it would be difficult once the stock is round. I do cut it after, I bet you could do it lots of ways, but this is the way I’ve always done it, and with care you can get accurate joints this way. I learned some of these techniques way back with my predecessors at Plimoth Plantation, Joel Pontz and Ted Curtin. As always, it starts with careful layout. This seat rail is sitting in two “joiners’ saddles” – blocks with notches cut in them. I tend to position the stock with the growth rings running horizontally, this is probably over-kill. But it helps later on.
The reason the saddles are boosted up on that scrap board is because I’ve mis-placed my small square that I normally use to scribe the center plumb line across the end grain of this turning. I want the blade of the square right snug against the turning. Then I scribe a vertical line right through the center. Repeat on the other end.
These plumb centerlines become the basis for accurate tenon layout (same for mortises on the posts, actually). I scribe a line along the top of the turning connecting one end to the other. This line is only on the tenon, not along the seat rail itself. Then I can mark out from this centerline the thickness of the tenon – in this case 1/2″. Drop these down the end grain too. I highlighted these lines with a pencil so they show up.
Then it’s just a matter of cutting the shoulders and forming the tenon. I held it in the wooden bench hook, sawed with a backsaw. Careful to check that you’re coming down evenly. No need to hurry here.
Then I split the tenon cheeks. Once they’re both roughed out, check them with winding sticks so you know both tenons are in a plane. Then pare them flat.
Straight-grained ash splits like nobody’s business. Whatever that means…
Mortise layout is just the same. Then bore holes at the top and bottom end of the mortise. I use the square to help align the brace and bit. I have forsaken period accuracy for plain ol’ accuracy and am using auger bits instead of spoon bits. There’s 112 holes to be bored in this chair. One hundred and twelve. That’s a lot.
I have a project underway that relates back to one of my earliest posts on this blog. I’m making a copy of a seventeenth-century turned chair with a board seat captured in grooves in the seat rails, rather than a woven seat around the seat rails. The chair I’m now building has four legs, back in July 2008 I wrote one of my first blog posts about a three-legged version. https://pfollansbee.wordpress.com/2008/07/05/three-footed-chair/
here’s an earlier version I did of this chair:
Its main feature to my eye is the construction of the seat rails. Because the seat is a panel captured in grooves, the seat rails need to all fall at the same height. With woven seating, the seat rails are staggered in height, so the joints don’t interfere. (usually the side rungs are higher than the front and rear rungs, maybe always) But with the board seat, the joints actually intersect. Often, like the chair I’m working on now, it’s a combination of a rectangular tenon pierced by a round tenon. One thing all this means is the parts are very heavy and thick. Here’s the rectangular tenon test-fit into one of the posts.
I’ve used the following photo a lot over the years, it shows the round tenon running right through the rectangular one. This is from a 3-legged version, but the effect is mostly the same for 4-legged ones. Easier geometry.
This chair is ash, (Fraxinus, usually around here Fraxinus americana) riven from a straight-grained log, hewn and prepared (either by planing or shaving with a drawknife) then turned on the lathe. The seat rails are 1 3/4” in diameter, the posts are 2 1/8”-2 1/4” thick. That’s heavy stuff. Good straight ash splits evenly and easily, it’s a real treat to use.
The original chair I’m working from is one of two by the same unknown maker, both at Pilgrim Hall Museum in Plymouth Massachusetts. One belonged to Governor William Bradford,
the other to the church elder William Brewster.
Brewster died in 1644, Bradford in 1657. His inventory included lots if itemized and well-described furniture:
“a Court Cubbard £1-05, winescot bedsteed and settle £1-10,
4 lether Chaires £1-12, 1 great lether Chaire 10s, 2 great wooden Chaires 8s, a winscott Chist & Cubburd £1-05, 2 great Carved Chaires £1-04, a smale carved Chaire 6s, 1 great Chaire and 2 wrought stooles £1, a Carved Chist £1″
Well, we know this chair at Pilgrim Hall is not the “carved” chairs, nor is it leather. So it’s either one of the “great wooden Chaires” or just simply the “great Chaire” that was listed along with the “wrought” stools. Aren’t they all wooden chairs, you ask? Often the adjective describes the seating material – thus these could be referred to in the period as wooden chairs. “Great” is taken to mean either “large” or often, “with arms.” One thing about the Bradford inventory that vexes me is the value assigned to the 2 great wooden chairs – 8 shillings. If the chairs are equals, then 4 shillings isn’t a lot for a chair like this. If the 2 great carved chairs are also equal, they’re worth 12 shillings each. A pretty big difference, I’d guess this chair is as much work as a carved one, maybe more. The great chair listed with the 2 wrought stools is harder to estimate because of the stools. “Wrought” usually means “worked” in some way. In stools and chairs, it’s often considered upholstered.
The Bradford chair is in better condition than the Brewster. It’s missing some height, the bottoms of the posts are right at the stretchers. One thing I like about this wear & tear on this original object is it clearly shows the type of bit used to bore this mortise – a round-bottomed hole like that is the result of using what we now call a spoon-bit.
Here’s a spoon bit, showing the rounded tip that makes a hole like the one above:
The upper rear rail is thought to be a replacement, as is the board seat. Brewster’s is missing several spindles, a couple of stretchers, upper rear rail and has a leather seat wrapped around the rails.
I’ll post construction notes and photos as I go. Lots to see in this chair.
For some details about the chairs’ histories, see the page at Pilgrim Hall’s website about their furniture. If you’re near Plymouth, don’t miss the museum. They have great stuff. http://www.pilgrimhall.org/ce_funiture.htm