Oak Refectory Table
Friday 22 August 2008
Mark Ripley makes a refectory table fit for a feast
If there is one kind of furniture that gets my creative juices running it is big oak pieces for a well-proportioned and well-lit space. Such is this table which is constructed from over 60m3 (20ft3) of prime and character oak. It will eventually be accompanied by 12 chairs and twin sideboards.
I designed the tops of the table to separate into three sections to create visual interest, bringing the base frame construction up into the top. A considered benefit of this design is that the piece breaks down into components of a manageable size for transportation. Weight notwithstanding, the table would have been too big to manoeuvre into the house fully assembled.
Manageable piecesThe rough-sawn boards are too heavy for one person to lift until laboriously reduced to smaller sections with a heavy-duty portable circular saw. Further conversion into planed components is a process as much of careful thought as it is of heavy machining. By the time an accurately prepared cutting list is neatly stacked I feel as though half the work of a piece is done! Most of the difficult decisions regarding design, costings and timber selection have been taken by this point and I can look forward to the enjoyable task of actually doing some serious furniture-making.
Start at the topI was working to a Christmas deadline - something my next door neighbour reminded me I'd promised myself I would not do again after the last time! I could not forsee any particular problems, though, and felt comfortable about the timing. All the same I needed to start building up the finish on the top as soon as possible and so made this part of the table first.
Having spent some time laying out the boards on the floor - to decide on the best balance of colour - prepare the butt joints. My planer beds are only 1200mm long, which is adequate for most things, but not a 3000mm joint. However, using a couple of support rollers it does a surprisingly good job, which I finish off by hand with a No.7 bench plane.
The joints are fitted with loose tenons into routed mortices and pegged with 6mm (1/4in) turned oak dowels. The joints are clamped up dry before gluing to check the joints. I use PVA adhesive. The better quality exterior grade products are excellent. Wetting both surfaces with glue using a brush ensures a good bond. The pegs are fitted after assembly and so serve to retain the joint rather than pulling the parts together, as with a draw peg joint.
Largely to save time, I had the top speed-sanded at a large joiner's shop and chamfered ready for finishing.
Make the frameThe frame construction consists of end assemblies that do have proper draw peg mortice and tenons. The lower stretcher rails are through-wedge mortice and tenons, while the top rails are bridle jointed over the legs. To allow for expansion and contraction across the top, the bridle joints are cut over-size on the leg assembly.
On the stretcher rail itself the joint is close-fitting. There is no fixing between the stretcher rails and leg assemblies. Instead, I suggest that you fix the tops to the stretcher rails and to the top frames of the leg assemblies. Do this using screw blocks and slotted
End assembliesNow we come to making the end assemblies. Marking out the mortice and tenon joints is straightforward enough, though their size makes cutting the mortices difficult.
Although I can just get the rails under the mortice cutter, I am not satisfied with the depth of joint cut by the standard 12.5mm chisel - the largest I can fit in my bench-top morticer. To make the joints stronger bore and chop out another 25mm (1in) of depth by hand. Cut the tenons on the bandsaw.
Having cut the tenon cheeks on the bandsaw, cut the shoulders using the sliding table on the bench saw. They could equally well be cut using a router run against a trammel. Holes are bored into the horizontal members for the pegs with a lip and spur bit. The assemblies are clamped up dry and the positions of the holes marked by pushing the drill bit into the holes. The holes in the tenons are drilled 1.5mm closer to the tenon shoulders than the marked centre. This is so that the peg, when driven through, pulls the joint up tight. To aid this, the pegs themselves are made 130mm (5 1/8in) long with the first 25mm (1in) tapered.
Making the legsThe through-mortices in the legs can be cut from both sides and the tenons are prepared in the same way as the leg tenons. The cheeks of the through-tenons are planed clean. Small through-mortices are also cut in the stretcher tenons to take the wedges.
With the end frames and lower stretcher rails assembled dry, you can mark out the top rail bridle joints. As mentioned before, the joint cut in the end frame is wider than the rail joining it. These are routed out and the notches sawn and chiselled out by hand.
A corresponding notch in the top stretcher rail completes the joint. These are cut by hand - under the circumstances, it's the quickest way to do the job. The components are simply too big to offer up to a machine safely or effectively. The scalloped shaping on the top stretcher rails and top and bottom members of the end frames are bandsawn and sanded. At this stage a full dry assembly is set up to check all the joint-making and to trim the top stretcher rails to match the length of the top.
Sensitive touchIf ever there was a candidate for some sensitive hand-tooled chamfering and planing then this table is it. Good machine-made joinery looks very sharp and clean and produces accurate joints quickly. For some types of work a high degree of precision is a desirable visual attribute. For others - like this table - a more artistic human touch is required and the piece needs 'easing off' a bit.
All the chamfers are cut with a router cutter to remove the waste but are finished with a block plane. The 45 degree chamfer stops are marked out and cut to a pencil line with a sharp chisel. If you have the luxury of time, you could hand-plane the whole table - though this one is sanded.
End framesThe end frames are glued up next. Hammering in the pegs is great fun - you really need to whack them in! Hand planing the glued-up leg assemblies is very satisfying as the big joints and the end grain of the pegs form a very pleasing combination. During the process of finishing, make the blocks for fitting the tops. Make them in strips, which greatly simplifies routing the slots and boring the holes. Each block is cut off and individually chamfered on the face edges.
My usual practice when finishing dining tables is to build up a surface with three coats of thinned Polyurethane, lightly denibbed between coats. This is a basis for three further coats of Danish oil. The oil is applied with a rubber and left wet to dry off overnight in a heated workshop. However, it must be applied thinly or it won't dry at all! Fewer coats are needed for the base frame. Finally the piece is burnished and given three coats of clear Liberon Black Bison wax.
Carol concerts came and went, the children broke up from school and the row of Christmas cards on my work bench got longer. My workshop neighbours watched my progress with gentle amusement as the days marched past. However the piece was safely delivered at 2pm on Christmas Eve!