Flattening

Flattening

If you follow me on Instagram you’ll know that I’m building a Moravian workbench. I’m not writing about it here because it’s been so well covered by Will Myers in his step-by-step guide on wkfinetools.com and his video with Joshua Farnsworth.

I will be writing about the end vice I’m building which might be useful to those who haven’t yet fitted a vicious toothed planing stop and doe’s foot to their bench.

Checking for flat
Planes come with a built-in reference edge

 

Yesterday I was at Richard Arnold’s open day and listened to Oli Sparks talking about flattening the ways on his milling machine. He does this by hand marking the high spots using machinist’s dye and a very flat reference plate.

I have been struggling to find a way to measure the flatness of my workbench top end to end. Checking for wind and flatness side to side is easy.

 

Winding?

That’s straight enough for a six foot bench!

But other than squinting I have no way to check flat along the length of the bench. On the drive home yesterday inspiration struck. A piece of string, pulled taught will let me see hollow and humps. When I was fishing out a crayon to mark the spots shown by the string I found my chalk line. Even better. Pulled taught and dragged across the bench this showed up the humps very quickly.

 

 

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With the humps nicely coloured in I could flatten them out. I was a bit worried that I was making a rod for my own back. How flat does a workbench need to be? (That’s a rhetorical question – I’m happy with my own answer!) The chalk line quickly revealed that the ends were high. With a bit of planing I started to see the humps in the middle.

 

Planing
Plane until the blue has gone

I often find myself chasing my tail when flattening long wide pieces. I go too far on one section and then have to level the rest to it. With this method I did a lot less planing and a lot more checking (which is considerably less tiring!).

Once the big humps had disappeared and the chalk line was just colouring the whole bench blue I switched from the scrub to the jointer plane and made a couple more passes until the blue had disappeared. You’ve got to be sure that you’ve got the thickness to carry on planing once the humps have gone because that chalk gets everywhere and you’re going to need a final pass to get rid of it. On a 4 inch workbench top that’s not really a problem.

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Caveat: the blue gets stuck in the tearout. But this is workbench, not a piano.

The Workbench

The Workbench

“After a while you can get used to anything.” Albert Camus, The Stranger

I’m thinking of rickety workbenches, not being incarcerated in an Algerian prison for murder, but you take the point: I have a high tolerance for ropey workbenches.
But I’ve finally been jolted into building a better bench. I’d like to extend the Camus analogy by making a parallel between my passive acceptance of the wobblyness of my bench and Meursault’s sleep-walk towards his own execution but that would require me to draw a link between him waking from his ennui by shouting at a priest delivering his last rights and my own renaissance. My shame was far more twenty-first century: flamed on YouTube for a shaky bench. Twice. It’s amazing what people can get cross about.
So before I launch into this timber framing project let’s take a look at what led up to it. It started here:

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Dad likes Workmates so much that he owns two. And modifies them. He had a blue one when we were kids. I wonder what happened to it. We did a lot of work on that bench.

Picnic bench

This isn’t the one we used. It didn’t survive the abuse.

Despite the Workmate a lot of my early woodworking was done on a picnic table. They make surprisingly good workbenches. The seats are at the perfect height for breaking down stock with a hand saw and the table-top has gaps between every slat. On some tables these are big enough for clamp. If you’re careful you can line the gaps up with the circular saw kerf. If you’re not you learn how to repair picnic tables.

Short of a decent vice what’s not to like? Some are a bit wobbly and perhaps that’s where my existential malaise started.
At school, like every child of my generation, I used the standard British joiners’ bench. One vice, a tool well and a brush. Sweeping up was as much a part of woodwork classes as learning to saw straight. It was here that I learnt to love tool wells. And sweeping.

Sawhorse workbench

Camus notwithstanding I never got used to the Japanese saw (it doesn’t help that it doesn’t match the bench hook) and my tolerance for these two terrible squares didn’t last longer than this project.

As an adult with limited storage space I went back to the Workmate but as projects got bigger space remained tight and I built a sawhorse workbench: two strips of plywood bolted to sawhorses with insert nuts in the tops. This was surprisingly robust; it barely moved. I put this down to the number of legs. But it still didn’t have a vice or any decent workholding other than clamps. So I built a ‘lightweight’ folding bench. Originally it had a crochet and no vice. (There are proponents of viceless woodworking out there: people who encourage beginners to take up a craft with one hand tied behind their backs. I have bad words for them.) So after a few years I installed a massive Record 53 on the front of my lightweight bench. This led to the hole in the workshop floor and the floorboard repair I did last year.

 

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Matriphagy is not uncommon with workbenches.

During my last project I spent quite a bit of time thinking about how I used the bench and what I wanted to keep and change.

 

Staying

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Tool tray

I like my tools on the bench, not the floor. Wells and trays fill up with shavings, reduce the usable space on your bench and allow bad habits to form but I don’t care. I like them and I’m sticking with them.

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 Holdfasts and holes

All holes will be round, or more accurately, cylindrical. With astonishing timing Simon James decided to start making 1″ holdfasts at a sensible price when I bought the timber for the bench. I’ve been using the late Richard Tomes’ 3/4″ holdfasts for several years and if Simon James’ version are as good I’ll be delighted. They are absolutely massive and won’t need much of a tap to set them solidly.

 

Tail vice

I use a Veritas inset vice and bench dogs. It’s slow but excellent value and with a clever two position dog. I’m sure a batten and toothed stop work but one can grow used to luxury as well as privation and my next end vice will bigger and better.

Portable

More on this later.

Going

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Never been used

Apron

I only use one of the holes on the apron a lot and it will be in the leg of my next bench. The others are largely redundant. I used them more before I installed the vice.

 

 

 

 

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The old bench is starting to feel a bit emasculated

Lightweight

Colin Chapman said “Simplify, then add lightness.” But he was building things to move – quickly. Two inches of ash aren’t enough to stop a bench roaming around the workshop. The legs will be four times the cross sectional area and the top twice as thick.

Folding

I’ve been procrastinating about this for years. I wanted something very heavy but portable. Hard to achieve.

I do occasional demonstrations but most of my itinerant woodwork has been done at the boatyard. For several years I thought I’d build a massive French bench with wheels and floor locks. Then I realised that although I could get it out of the workshop, across the garden and through the kitchen it would never turn the corner in the hallway of our Victorian terrace (row house).
Then Will Myers published a terrific account of building his Moravian workbench. It’s been on my list for a while and I’ve finally got a gap between projects. It has everything I want: weight, portability, a tool tray and great workholding.
Will built his from white pine. I’m making my life more difficult (and expensive) by using oak. But it adds weight and weight is good.
I have an idea for a pair of wheels that fit on an axle that passes through a dog hole. This should make the four inch laminated top a bit more mobile.

I’ve glued up one set of legs. Eventually it will have two sets: high and low, carving and joinery. Don’t hold your breath; it’s a big project. But waiting is something you can get used to.

 

 

Clamp front chest 5: finishing

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Like many woodworkers, I suspect, I stick to what I know when the time comes to coat the project I’ve sweated, sworn and bled over, with finish. In my case it’s usually three coats of Osmo and one coat of homemade carnauba wax for furniture. Boats get as many coats of Sadolin Ultra as I my patience allows on the bright work.

2018, however, will be the year in which I spread my finishing wings (and get them covered in noxious chemicals which bring me back to Earth). I have a French polishing course booked and am trying something on this chest that is deeply out of character.

Usually I’m with Tony Konovaloff where changing the colour of wood is concerned, “If you want a different colour, choose a different wood.” And I’m certainly not about to start staining beautiful English oak. However I really want to keep this piece light. There seems to be a fashion for adding ‘patina’ to new wood. Black wax is rubbed into the grain to imitate age. Patina is another word for dirt. I grew up in schools with acres of oak panelling and much of it was so darkened by smoke and the paw prints of small boys that it was rather oppressive. My reaction to this is to keep oak as light as possible.

To this end I’m (brace yourself) liming this chest.

Our front hall is not a particularly light place and we want this shoe box to brighten it, not lurk in the corner slowly ‘patinating’. So rather than let the grain fill up with dirt I’m going to charge it with lime wax.

Lime wax has a bad reputation. Beloved of shabby chicists it usually gets smeared onto antique furniture that was hoping for a quiet retirement and instead had to be ‘reinvented’ by someone who finishes every sentence with a question mark. I want a rather more subtle effect than shabby chicistas usually go for. To this end I’m prefinishing all the pieces in an effort to control the intensity of the colour and keep the big blobs of wax that get stuck in the corners off my chest.

Shabby chicartistes recommend ‘opening the grain’ with a brass brush so that it accepts more liming wax. Instead I sanded to 240. Then I smeared on the wax, across the grain, rubbed it in and off and then took some 0000 steel wool to it. I would usually use a grey pad for this but I’m running low and accidentally bought a lifetime’s supply of steel wool several years ago. (Caveat:  never use steel wool directly on unsealed oak. Just don’t.)

The steel wool removes most of the liming wax. You can control it quite carefully. Then I applied carnauba wax. This uses D Limonene as a solvent and that also removes some of the liming wax. If the area you’re working on has a bit too much white in the grain you can knock it back a little by applying and rubbing off more carnauba wax.

One last polish brings up a shine and the job’s done.

 

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‘The possibilities are endless’ stage. Just shellac, rubbed out.

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The ’Oh my God, what have I done?’ stage. Applying the liming wax.

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The ‘I’m a terrible person. This oak tree gave its life for my project and I’ve defiled its memory.’ stage. Rubbing in and off the liming wax.

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The ‘Perhaps this is salvageable.’ stage. Rubbing off the liming wax with steel wool.

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The ‘Actually I rather like this’ stage. Rubbing in carnauba wax.

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The ‘I wonder if anyone will notice the hours of work I put into this’ stage. Buffing the carnauba wax.

Clamp front chest 4: dry fit

Clamp front chest dry fitProgress over the last few months has been slow and sporadic. Today I reached a milestone: the first dry fit. It wasn’t intentional; I don’t like joinery to suffer more abuse than absolutely necessary but I needed to put it together to transfer some lines to between the front, back and the ends.

This is a bit of joinery I’ve been worrying about and looking forward to in equal measure. I drew it out, at one quarter scale, before I started so I knew it should work. But those are famous last words.  The style/leg joins the front and back to the sides. A simple groove in the long grain of the bottom panels on the faces and ends  is easy to cut with a plough plane. But this groove must be carried through the leg. There are two mortices and tenons to navigate as well so it was always going to be interesting.

Fortunately it was less than exciting. Having ploughed the grooves in the front and back panels I put the styles on and marked the housing. Once I chopped them I assembled the whole shooting match in order to make sure everything lined up and to mark the grooves for the end pieces.

This gave the first glimpse of what it will look like. Of course I couldn’t resist the temptation to carry it across the back garden (hardly an epic journey) through the house (again – not a great marathon) and put in the front hall – just to see how it looks.

But that photograph will wait for another day.

Clamp front chest 3: movement

I was really hoping to get to some joinery done this weekend. But the best laid plans…

This design is definitely utilitarian but it won’t tolerate this much movement. So I’ve planed the offending pieces back into line and will give them another week to think about what they’ve done and decide whether they really want to be a part of this project…

Clamp Front Chest 1: A bit of background

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C14th Oak Clamp Front Chest. Image courtesy of Marhamchurch Antiques

It’s time to rediscover the clamp-front chest

Lurking in the furniture record somewhere between the six-board and its heir, the frame and panel, lies the clamp-front chest or hutch. Without the cross-grain problems of its older relative or the need for thicker timber, like its younger sibling, the clamp-front chest offers some opportunities for the modern woodworker.

Six board chests are either constrained by the width of the boards available or require panels glued up from narrower boards. With its grooved and pegged joinery the clamp front chest requires little or no glue, can be scaled up or down with very few problems and needs only a small tool kit with no clamps to complete.

Described by one antiques dealer as a form of ‘proto-joinery’ they are relatively simple to build. Clamp-front chests or arks, as the curved lid variants are sometimes known, appeared in the late medieval or early middle ages. Several period pieces survive today in museums, antique dealerships and private collections; their longevity is a testament to their design. Many surviving examples are from churches and country estates across Europe. Some measure up to six feet wide and use timbers two inches thick but much smaller chests, under 30 inches also survive.

The majority of existing examples date from between the 13th and 17th centuries. Six plank chests from the same period are at least as common but with one key difference. Many of the surviving chests are heavily bound with iron straps. Few such chests exist that were only nailed or pegged together without the metal reinforcement. Yet a surprising number of clamp fronts, that use only pegs or nails as fasteners, are still going strong. This highlights the advantages the design has. Six board chests suffer from cross grain movement. The grain on the end boards runs vertically but the sides, with their grain orientated at 90 degrees, move with the seasons causing splits and loosening fastenings. Often the solution was heavy, iron corner straps. Few large chests have survived without this crutch. Hutches from the period sometimes exhibit splits along their front or back boards but these are rarely terminal and some careful planning with slotted peg holes, as might be done on a clamped (or bread board) table top, will prevent them.

The frame and panel chest superseded the clamp front but it may now be time to revisit this design. It makes conservative use of timber. The rails are often the same thickness as front and back panels which can be made from several boards and need nothing more than a tongue and groove or even a shiplapped edge. The joinery is as simple as it gets. Front and back panels are given a tongue on each end, grooves are cut into the rails and each assembly is pegged together. Different solutions have been tried to keep the front and back together and the ends on. Without the material for pegs other techniques have been used: mortice and tenon stiles, dovetails on either end of a stretcher and occasionally a metal strap.

Clamp front chest drawingThe chest I’m building is designed as a boot box for the front hall but it can be scaled up very easily. The construction would work well for a tool chest or blanket box. With creative use of different thicknesses of timber in the panels you can create runners for tills or shelves as we’ll see later. I wouldn’t use timber less than ¾” thick for the uprights . You’ll be ploughing grooves, pegging through and cutting tenons in it and you’ll need the thickness but 5/8″ will be fine for the panels.

I started with the internal dimensions needed to store six pairs of shoes or boots without creating an obstacle course in our narrow front hall. Change any of the dimensions to suit your own project but think carefully about the width of the four corner posts. These must be wide enough to accommodate the groove that takes the front and back boards and have enough left to accept the wedged mortice and tenons for the side boards. Anything less than three inches will give you some concerns.

The end boards are set in from the outside of the posts so you’ll lose a little internal space. Bear this in mind if your internal dimensions are critical.

The drawing developed from the size of chest needed and the timber I had on hand. I use air dried oak a lot. These boards had been sitting in the timber yard for a couple of years before I bought them and then in my workshop for at least a year after that. I started by choosing the prettiest bits of timber for the lid, then the front, posts, ends and back in that order. The bottom can be built out of old pallets – don’t waste your best stock on the bit no one will see. In my case it will be a rather over-complicated grate to allow air circulation to sweaty shoes and to make cleaning a bit easier.

Next time we’ll have a look at the design and joinery in a bit more detail and then start planing some oak.

A few examples of clamp-front chests

Hutch chests in Kloster Isenhagen

15th Century Oak Chest Sold by Period Oak Antiques

Early medieval chest sold by Marhamchurch Antiques

14th Century Oak Chest sold by Marhamchurch Antiques

13th Century Safe Deposit Chest at Merton College, Oxford

Medieval woodworking part 4: plank chest 2

Medieval woodworking part 4: plank chest 2

My nearest and dearest tell me that I have a lot of tools (they’re too polite to say “too many”). Each one, I say in my defence, has a purpose. No two are identical.

However there’s no doubt that there is some redundancy in the ranks. ‘Efficiency savings’ could be made. Some are more flexible than others. Chisels, for example can do a host of different tasks but require more skill to do some of those tasks well. Other tools perform only one task but they’re easier to use. Let’s take cutting a housing (dado if you’re American) as an example:

  1. Knife two parallel lines, chisel a wall to guide a saw, saw to depth, chisel out the waste (using a mallet), use a router plane to level the bottom. Six tools, one of which probably didn’t exist in medieval times.
  2. Clamp or nail a batten across the board. Use a dedicated dado plane to depth. Only two tools (if you don’t count the batten) but the clamps and dado plane are relatively recent inventions. The dado plane is about as dedicated a tool as you’ll find. It just cuts housings. At a specific width. Not adjustable.
  3. Clamp or nail a batten across the board. Spend half an hour setting up an electric router. Spend ten minutes finding and putting on protective clothing (mask, goggles, ear defenders, chainsaw trousers). Spend 30 seconds in abject, gibbering terror cutting the housing. Have a cup of weak tea while you recover.
  4. Get good with a chisel. ‘Knife’ the lines with the chisel, chop out the waste with the chisel. Level the bottom with the chisel.

IMG_3081I had two housings to cut. If this were not a masochistic act of reenactment and I were using a milder wood than oak I would have taken option 2. In the spirit of the thing I tried to only use tools I have evidence for having existed at the time. Option 4 it is.

Oddly I didn’t take a photograph of the result. It works but it’s not pretty.

Here’s the start of the second housing using option 1. I convinced myself that a plane, as they say, is just a chisel in a jig. Any idiot can find a video of Paul Sellers making a router plane with a block of wood, a chisel and a wedge on YouTube. What’s that you say? They didn’t have YouTube in the thirteenth century? Arrant pedantry.

With four rebates to cut I tried the chisel method again. This is easier than the housings. It’s a lot like cutting half blind dovetails but without the worry about nice crisp tails. I did even it up with a shoulder plane. And then used a moving fillister for the other three.

IMG_3101I marked the semi-circles for the feet with a pair of compasses. All period-correct so far. I’ve seen evidence of bow saws from the period but not a turning saw as such so I decided to see if I could form them with a saw, chisels and gouge. Kerfing went swiftly. Chiselling the waste out was quick as well. Fortunately I have a very large carving gouge at a fractionally quicker sweep than the chosen curve. Again – very straightforward.IMG_3116 I don’t think that a turning saw would have saved me a great deal of time and I’m much more confident with a gouge than a thin blade in 3/4″ of oak.

I did cheat a little bit and chamfered one curve with a spokeshave. The other I did with a chisel.

The only joinery left was to peg it all together. At this point I gained a lot of respect for the medieval joiner. The rebates on the ends of the front and back panels are there to help when assembling.

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Tight when made but worked a little looser by the time the chest was assembled.

Nevertheless unless the boards are dead flat and the rebates dead square putting this together without clamps would be next to impossible. I spent a lot of time with shoulder planes fettling every joint. A modern woodworker with good glues and a rack of clamps would pull a half millimetre gap closed and drive home a fastening, content in the knowledge that it wouldn’t show its seams before the customer got it home. The medieval craftsman had to get the joints perfect just to be able to drill the holes for the pegs. Some antique dealers use the word “primitive” to describe pre-industrial furniture with little ornamentation. One should earn the right to use that word about someone else’s work.

Sat astride my low workbench, the boards resting against pegs and being held by my knees I managed to drill a couple of holes. With a dowel at each end of the board holding it fast the others went in more easily. With a now-familiar sigh of relief I went back to my joiner’s bench and my clamps for the other three ends.

There’s surprisingly little joinery in a six board chest. With a jointer, thickness planer and a dado stack in a table saw (I wonder if the dado stack will be legalised in the U.K. Post-Bexit?) I imagine it would take less than an afternoon. For the pre-industrial craftsman with a frame saw, chisel, mallet and auger it’s a somewhat greater endeavour.

With the edges chamfered and the rougher grain scraped I put on some finish. The use of linseed oil was widespread in this period but its use on furniture is, as far as I know, undocumented. In the C12th Theophilus1 wrote in his treatise for artists that using linseed oil on wood is ‘tedious’. Boiling linseed oil to speed up polymerisation was known in the Middle Ages, as was adding lead to do the same thing, but Theophilus was apparently using it raw.

1. Theophilus (C12th) On divers arts Republished by Dover Art Instruction (2000)

Medieval Woodworking Part 3: plank chest 1

One down. At least three to go. The list of projects for this demonstration gets longer every time I open a book. With the workbench finished I’ve turned my attention to some ‘flat work’. Staked stools and demonstration tools  can wait. There are at least three chests I’d like to build for this: a Viking piece based on the Mastermyer chest, a clamp-front and this project.

I’m writing this half way through building  it and have I realised that I’m going to have to do it twice. Once to have a complete chest to show and then again to demonstrate the process. Fortunately it’s about as easy as furniture construction gets: a ‘six board’, ‘six plank’, ‘slab-end’ or just ‘boarded’ or ‘plank’ chest. Six bits of wood and some fastenings.

I’ve taken the opportunity to try a variety of techniques. There are several surviving chests that use pegs and at least as many that are nailed from around the period we’re interested in. Copper rivets1 were also in use and since I’ve got plenty kicking around from boatbuilding projects I’m hoping to squeeze some in. Two chests may not be enough.

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A starting point: riven oak late medieval plank chest. Courtesy of Marhamchurch Antiques.

This chest will come from a single rough-sawn board. It is definitely a small chest;  height and depth are dictated by the available timber. The inspiration for this piece is from two different chests (above and below) that have been sold by Marhamchurch Antiques in Devon. They’re a bit later than the period we’re interested in but the only strong sign of this are the trefoil arches on the first chest that form the feet. Other than that either could have been built hundreds of years earlier.

Marhamchurch flat sawn chestSix board chests are built with simple construction rather than longevity in mind. The grain on the sides is perpendicular to the grain on the ends. The movement of the timber will eventually cause the fastenings to loosen and the boards to split. Despite this many survive because there are ways around this:

  • Version 2Keep it small. The narrower the long planks the less movement there will be and so the fastenings are more likely to be able to resist the seasonal changes and the  boards won’t split. I estimate that the front board from the riven oak chest from  Marhamchurch Antiques is about 18′ high and even in riven stock that creates a lot of movement causing a split near the bottom.
  • Build it from cleft (riven) or rift-sawn stock. Movement across the grain in the tangential plain (at a tangent to the growth rings of the tree) is twice that in the radial plain (a straight line going from the middle of the tree to the bark). Radially cleft, or riven, timber was common in Anglo-Scandinavian England2. This means that the pieces will inevitably be narrower than flat-sawn panels and the movement will be significantly reduced. You can see this in the first chest to the right but not in the second which appears to be built of flat sawn boards. In the second chest the sides may have shrunk away from the notches at the bottom leaving a gap. In the first they have not.
  • Marhamchurch flat sawn chest strapsUse metal straps. Many surviving large six board chests have substantial metal reinforcements. However a lot of these are ecclesiastical pieces or come from the estates of powerful and wealthy individuals. They are not the focus of this demonstration. The second chest from Marhamchurch compensates for its flat sawn grain by reinforcing the joints at the top. It’s hard to know whether this was done at the time of manufacture or later as the joints worked loose with the seasons. The position of the strap over the nail and the difference between the two nails suggests the latter.

The design of this chest is dictated by the timber. Though the Egyptians had glue thousands of years before this time period I can find no evidence that the Anglo-Saxond or Anglo-Scandinavians did. Even if they did it was animal glue and would have faired poorly in the damp. That means that wide panels made up from a number of boards were not used. The front of a chest was as long and as high as the planks as the widest board you could get from a tree.

Forklift and boardTime spent picking through boards at the timber yard is well rewarded. (And so is being nice to the man with the huge forklift. I learnt a lot from him that day.) I wanted to select wide stock with vertical grain. Access to large-diameter fresh cut oak is rare so riven stock is out of the question and that left me searching for the widest boards sawn from the middle of the log.

With a newly commissioned low bench sitting in the garden I started by trying to work the boards to their final dimensions in a manner that might be familiar to a medieval joiner. Sawing went well. It’s little more than a giant saw bench and I’m comfortable using it as such. Heavy planing was more of an issue. Bent forward, pushing a plane with just my arms was hard and uncomfortable work. When standing at the traditional joiner’s bench many more of my muscles help out. The much bigger and more resilient muscles of my legs do a lot of the work.

Frustrated and realising that I would wake up the next day aching and with much less work done than I had planned I went back to my familiar friend – the joiner’s bench. There is plenty of time to play with the low bench between now and the  demonstration.

Stickered oak.jpgI planed each piece to just over 3/4′ leaving a little spare to remove once the boards had moved a little more. A couple of weeks in stick and they were ready for joinery.

This gave me a bit of time to decide on fastenings. Chris Schwarz3 asserts that nails are the the secret to surviving chests’ longevity. They “allow you to get away with serious crimes of wood movement… a nail will allow the wood to expand and contract, bending back and forth through the yearly humidity cycles.” This also means that they will loosen over time. But it’s the best of a bad job.

Dowel plate

Not a medieval dowel plate. Its laser cut descendant.

Nails were made by blacksmiths, each one hand forged. So if a joiner wants to join a chest with nails s/he must buy (or trade for) them. But a dowel plate is a one-off purchase and then you’ve got pegs for life.

There aren’t enough extant medieval plank chests to be able to draw a conclusion about what was used more – pegs or nails – but in the interest of self-reliance I’ve used the trunnels for this chest.

Next time: joinery.

 

1. “Radially split offcuts of other species include… an alder fragment with 30-40 copper alloy rivets embedded in it…” Morris, C., Wood and Woodworking in Anglo-Scandinavian and Medieval York p. 2221-2223
2. “Most conversion of wood for artefacts was done by radial splitting…” Morris, C., Wood and Woodworking in Anglo-Scandinavian and Medieval York p. 2104
3.

Even professionals get it wrong

imageBefore I had the time and space (and skill and confidence?) to build such a thing my wife and I bought an oak sideboard. It purported to be made in England from domestic oak and I have no reason to doubt that. It’s got big, chunky, machine cut dovetails and the drawer fronts are applied. We still like it a lot. It’s a simple design with little decoration, nice proportions and is solidly constructed. The flat panels and simple, turned wooden pulls might be described as ‘Shaker’ by those who need to put a label on simple vernacular furniture.

At the same time we bought a ‘matching’ blanket box. It has an issue that I should have spotted even then. We were clearly carried away with the sideboard and didn’t pay enough attention. Those furniture salesmen eh? Wiley Devils. Here are the tops of both. Can you see the problem?

On the left is one panel of the top of the sideboard. The panel is fitted into an open backed frame and is rebated so that the surfaces of the panel and frame are flush. As the seasons change the panel expands and contracts and sometimes (as now at the end of a warm, damp summer) protrudes beyond the back of the frame. Because the grain is orientated so that it runs lengthways it will never expand along the length of the piece and so will never distort the frame. Good thinking sideboard-maker.

For whatever reason (lack of longer lengths of timber? ignorance? malice? who knows) the blanket box maker has orientated the boards so that they run front to back putting all of the expansion and contraction along the length of the box. Here is the result:

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By the end of winter that reveal is even. This tells us two things: the box was built in winter when the timber was at its least moist. And it was built by someone who didn’t know about (or care about?) seasonal movement.

Hoadley’s calculation for wood movement tells us that the change in dimension across the grain is equal to the initial dimension of the timber multiplied by the total shrinkage percentage of that species of wood multiplied by the product of the change in moisture content divided by the fibre saturation. There are going to be some estimates in this!

ΔDi=DS(ΔMC/fsp)

ΔDi=(31.5)(0.105)((0.28-0.22)/0.28)

ΔDi=0.95

This would be bad enough if I was working in centimetres but I’m using imperial! Almost an inch of potential movement. I’ve been fairly conservative in my estimates and we still end up with horribly large number. Some cabinet makers use a rule of thumb that wood will move up to 4% during the seasons. That’s 1 1/4 inches.

Note to self: Use narrow panels. Work out where the extra wood is going to go.

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When I made this panel at the start of the summer I broke the rules in the same as the way as the maker of our blanket box. The timber is flat sawn and so has more movement than vertical grain planks and the long grain runs in the shortest dimension.

Aware that I was breaking these rules I cut the groove in the frame deep and let the panel in half way into the groove.

It moves around a lot if you make it but it’s never going to show a gap or prise its frame apart.