Wood-fired!

Just finished!

Finally my chair for the ‘Chairs of the Alumni’ exhibition is finished. You will have noticed the lack of the promised progress reports. Just too much on I’m afraid but I have the photos and will publish some ‘making’ posts in weeks to come.

The exhibition which runs in parallel with the George Ingham Retrospective opens this Friday. Details are here. I’ve put up a skeleton website about George, the book about his work which has just been published and the two exhibitions here. I will be adding lots of material from the book and exhibitions over the next month or two.

Stay tuned.

7 comments September 29th, 2009

Alumni chair - shaping the stretcher joints

My design for a chair for the Chairs of the Alumni exhibition has ’sculpted’ joints where the stretchers intersect the legs and where the middle cross stretcher intersects the two side stretchers.

I’ve just completed the two joints where the stretchers meet. This progress post shows how these were made. However, as always seems to be the case, the most interesting stages are when you forget to pick up the camera - so you might have to join the dots yourselves.

1. Mortices are cut in the middle of the two side stretchers to receive the tenons from the cross stretcher.

2. The elements are rounded in a modified router lathe leaving ample blocks of material for making the joints. (I will describe the router lathe and the process in a later post.)

This pic shows the two side stretchers in the middle and the cross stretcher that joins them at the front of the picture.

3. The tenons cannot be cut before this stage because the router lather requires mounting holes to be centred at each end. The tenons are cut to fit the mortices and then tested and tuned.

The joints can then be fitted and glued. I have no pic of the gluing setup I’m afraid but effort was made to ensure the whole structure was flat and the elements were square.

Cramping pressure was applied across the whole structure using custom-made clamping blocks that fitted the curve of the elements. Additional clamps were used to ensure the flange on each side of the joint was firmly pressed against the side stretcher.

4. The excess material is carved, filed and sanded away leaving a smooth transition between the elements.

In the next installment I will show how the legs are shaped and then glued to this stretcher assembly.

2 comments August 16th, 2009

Sixty by six

Sorry about the long break between posts. A retinal detachment and its subsequent repair had me lying on one side for 5 days straight. Glad to be back upright! The detachment became apparent just as I finished my latest project - 2 hours before it was due to be presented. Nice timing in one way!

I’ve been keeping this project quiet because it is the basis of a collaborative present for my dear friend Jeremy who turned 60 in June. (We presented it to him on July 13th since he was in Panama and the US in June.)

I made a slim wall cabinet with 60 pigeon-holes designed to accomodate 60 cubes of memorabilia created by his family and friends.

The cabinet was made from Tasmanian blackwood. I will post some workshop notes on the construction techniques in the near future. This is a rare view with none of its contents loaded.

As I had hoped, the cubes that people made were diverse in theme and material. We had cubes made from metal, wood, ceramic, acrylic, wool and of course paper. They featured original painting, cross-stitch, knitting, pastels, a jigsaw, appliqué, a tartan bow and even a chocolate. Themes included many photos from Jeremy’s long past, his favourite things and interests, various bones of contention, his exploits, the passions of the people making the cubes, and foremost the special relationship all the contributors have with Jeremy including rememberances of many past events.

We wrapped the cabinet with a dozen of the cubes pre-loaded to give some feel for the intent and wrapped the remaining four dozen separately so he could examine each one and choose a spot for it in the cabinet. Six of the loaded cubes displayed letters that spelt out his name.

We presented the gift to him at our traditional ‘Xmas in July’ dinner so there was some element of surprise involved though I think he harboured a few suspicions.

He was very pleased and touched I think by the efforts that everyone had put in and seemed to relish the process of recognising the origin of each cube (some more quickly than others) and adding it to the array.

One cube contained a jigsaw depicting a group photo from one of our Xmas holidays at Merimbula. Jeremy completes it with the aid of his assistants.

The collection nears completion. Once it is hung in his home he will have plenty of time to explore, rotate and relocate each cube. I saw it hanging in his living area last Tuesday and will post an in situ picture soon.

All 60 cubes in place. The metal cube in the bottom row (which contains the jigsaw) has one of its two eyes detached. Rather appropriate to my circumstances at the time!

Thanks to everyone who contributed to this present for Jeremy. I think it was very successful and Jeremy certainly appreciated it.

6 comments July 18th, 2008

Base and Lid - Part 4 of the Wedding Present

This continues the tips and techniques for the document box known here as the Wedding Present. This post deals with the bottom panel and the lid.

The base

Before the carcass was glued-up a slot was cut on the lower inside of each side piece (taking care to stop at the tails).

Slots: The lower slot is the groove to take the ‘tongue’ of the base panel. (The other slot is for a narrow rail that will support the gondola.)

The base is a floating panel. This allows the base to expand and contract across its width with changes in humidity. The panel was prepared by edge-joining two pieces and thicknessing to 6mm. A rebate was cut on each edge to match the slot cut in the sides of the box. A very slight bevel was put on the edge that will be visible from the bottom.

Base panel: A rebate is cut to leave a tongue that is a firm fit in the thickness of the slot. The depth of tongue leaves 1mm each side for expansion across the grain. (The panel is shown upside down - the tongue is flush with the top surface.)

This diagram shows the arrangement. The orientation is chosen to give a continuous closed surface inside the box. The underneath will show the narrow gap between the base and the sides of the box that allows for expansion of the base. The small bevel relieves the sharp edge that would be visible.

The base panel was sanded and fully finished (with nitrocellulose lacquer) and fitted before the final glue-up of the carcass.

The lid

The lid is a floating panel in a narrow frame. The frame is mitred at the corners and strengthened by floating tenons. The same tongue and groove method was employed to hold the panel as for the bottom.

The mortice for the floating tenon is made with a slot cutter mounted in a router table. Marks on the fence tell me where to start and stop the cuts.

The frame was made before the bevels were put on the outside edges so that the maximum cramping area was available. The chevron-shaped floating tenons are visible in the following photo.

Clamping a frame

The setup used to glue the corners of the lid frame. Note two of the chevron-shaped floating tenons in the middle.

I use this method for nearly all frame and box construction where the corners are mitred. A scrap of wood (usually MDF) is glued to the outside faces of the members so that good cramping pressure can be securely applied.

The brief account of the process is:

1. cut 45° triangular blocks of the same thickness as the elements
2. glue the long side (hypotenuse) of the blocks to the frame element - mark or estimate the centre of the joint and place the blocks so that the clamping pressure can be applied directly across that centre
3. glue up and cramp the joint
4. saw away most of each cramping block when the joint is dry - taking care not to touch the frame
5. plane the outside of the joint to remove the remaining waste material

Plane the remains of the cramping block from the lid.

Now this seems like a lot of effort. However weighed against the risk of not getting a good joint in a frame or box I believe it is well justified. (Anyone who has tried to fudge the cramping only to have it fall apart in the middle of glue-up knows that this is a good bet.) I have used this technique on dozens of projects. It is the best way to guarantee a minimal glue-line and joint longevity.

I usually use yellow glue for this. Some people apply only a dab and don’t rub the components together in the hope that the block will snap off afterwards but this carries its own risks. I have also tried using double-sided tape, but the risk is still there and has certainly bitten me. My advice is to glue it on strongly so you’re not afraid to use plenty of cramping pressure and just plane it off afterwards!

I always use tape to mask the faces in the inside corner of the joint to aid in cleaning up the excess glue (as described here).

After two corners have been glued and cleaned, the finished panel is inserted and the last two corners are glued at the same time.

Gluing the last two corners of the lid with the finished panel in place

The completed box lid.

The lid after bevelling and finishing.

Part 1 The present
Part 2 The wood
Part 3 The dovetails

Add comment April 17th, 2008

Dovetails - Part 3 of Wedding Present

The dovetails

This is part 3 of a series of articles based on the construction of The Wedding Present. If you’re only interested in my dovetail methods, just read this. If you are interested in the context of the dovetails, start here.


As it’s a while since I hand-cut dovetails I did a little practice work. (I’m a traditionalist and cut the pins first and mark the tails from the pins.)

Pins: Pins cut in test piece	Tails: Cut from the pins

Tools

This lead to a re-examination of my tools. My dovetail marking guide is homemade from a piece of 1½” brass angle. While it has served me well for many years it has some drawbacks including not being as symmetical as I’d like. While searching for a replacement I came across the tools of Chris Vesper.

Old: Old dovetail guide made from brass angle.	New: Chris Vesper’s dovetail guide.

I bought his dovetail guide and found it handles very well. The extension of the reference bar on each side of the guide makes the marking of pins near to the edge of the piece much easier than with my angle guide. (The red ‘X’ on the 1:6 guide is just to remind me that I should be using 1:8 in case I accidentally turn the guide around.)

Another acquistion: Chris Vesper’s ‘double square’

While I was at Chris’ site I picked up his marking knife (I’d also been just managing with a sharpened length of 1″ hacksaw blade for 15 years - still useful for some applications) and his ‘double square’. The latter is a small square that has a movable blade like a traditional large combination square. As well as being a beautifully finished tool that is a pleasure to use, the adjustable blade has proved its worth many times in the short while I’ve used it. Woodworkers will know the annoyance of putting a narrow board into their vise for edge-planing and then reaching for their 2″ square only to find that the edge of the board is just less that 2″ above the jaws. Rather than reposition the board in the vise so that the square fits, you can just shorten the blade of Chris’ double square to check your edge. The narrow blade shown in the photo interchanges with the larger blade. It is extremely useful for checking squareness in tight confines. This is exactly what you need when checking the squareness of your tails if you cut very narrow pins as I do.

New saw: Adria’s dovetail saw

I’ve never been quite happy with my Pax dovetail saw - mostly from its lack of balance in the hand. I was happy to discover on Chris Vesper’s site a maker of dovetail saws in Canada - Adria Saws.

Having received all my new tools I could no longer put off cutting into these beautiful pieces of wood.

Over or under?

The first decision in cutting dovetails is whether you mark up so that the pins and tails protrude slightly beyond the outside face of the joining piece or stop slightly short of the face. By far the most common practice is to allow the pins/tails to protrude by 1/3 to 1/2 of a millimeter. This makes planing the outsides flush very easy because you only need to remove the excess from the pins/tails rather than planing down the entire side. However it does mean that cramp-up is more complex because you cannot just cramp against the face but have to make a cramping block that will allow the protruding pins/tails to . well .. protrude.

My teacher, George Ingham of the respect for tradition school, always insisted on leaving the pins/tails just short of the face. After all if you can’t competently plane the face of your wood, what are you doing cutting dovetails! I’ve always been somewhat agnostic about this and tend to use the method that suits the project. I have also had a bet each way and let the pins protrude (because the cramping block for this side has plenty of leeway and lots of area to push against, and cut the tails just shy of the face because when you use narrow pins there is very little surface to cramp against. I also make the difference very small (like about 1/6mm) so that it is easy to clean up either way. The difficult grain in the pieces I was using meant that I didn’t really relish planing too much off the faces.

In this case I have chosen to cut the pins on the shorter side pieces so that the front elevation of the box shows only the narrow ends of the pins. The blockier tails show on the sides. When you use dovetail joints on drawers, the orientation is all important and the tails must go on the sides so that the inherent strength of the joint is used to resist the force of the drawer being pulled from the front. As there is no directional bias of forces on a box the choice can be based on asthetics alone. In this case I wanted the front to be uncluttered.

Cutting the pins

I mark the width of the joining pieces (+ or - 1/6mm) on the inside face of the pin pieces with a knife. The mark is transferred to the outside across the bottom of the piece (the small knife mark will be planed out when the base of the box is flattened. I use a fine pencil line on the outside as a guide until the pins are marked.

I lay out the pins on the end of the pieces using a dovetail guide and then extend the marks square to the end until they meet the knife mark on the inside and the pencil line on the outside. Once the narrow edge of the pins are marked on the outside face, the pencil line is replaced by a knife mark in the waste areas only.

Dovetails: Pins are cut and pared

The faces of the pins are then sawn and the waste removed with a coping saw. The base of the waste area is pared flat and square to the faces. I don’t believe in undercutting these surfaces in order to obtain a better final appearance (at least not deliberately!). If I learned anything from George Ingham it was to respect the integrity of the joint. This relates not only to the structural strength of the joint but also to the very reason we choose to hand-cut dovetails in the first place.

Marking the tails

The traditional rationale for cutting the pins first and then marking the tails from the pins is that the tails are marked onto the face of the tail piece. If you do it the other way around you have to mark the pins onto the end-grain of the pin piece. End grain is generally less able to sustain a clear marking line than face grain. This argument applies more to the softer woods used in traditional European furniture than it does to the hard Australian woods which can usually carry a fine line in their end-grain. Nevertheless I have always had better results cutting the pins first so I tend to stick with this approach.

Dovetails: Setup for marking the tails from the pins. The tail piece is held steady by a bench clamp (out of shot). The block to the left aligns the reference edges of the two pieces.
When marking the tails from the pins, it is always worthwhile spending a little extra time creating a stable and well lit arrangement. Trying to steady two pieces of wood and mark at the same time when shadows are working against you is a recipe for error. My setup for this job is shown in the picture above. The block on the left-hand side aligns the two pieces on their reference edges. A waste piece (with a very square end) is positioned on top of the tail piece so that its end aligns with the knife mark on the inside. Both pieces are held in place with a bench cramp.

Dovetails: The tails have been marked from the pins

Three possible marking tools are shown - a pencil, a scribe and a knife (No. 11 scalpel blade in this case). I favour (and used in this case) the scalpel blade as it can make very clean marks, has good access to the tight spaces and doesn’t restrict vision too much. As it is double-beveled you need to be careful to maintain a angle that makes sure the cutting edge is hard against the pin while still making an essentially vertical cut into the piece. A fine single-bevel, pointed marking knife would be ideal here but I’ve not yet found one. The resultant marks are shown in the photo.

Cutting the tails

Dovetails: The tails are cut from the marks on the inside face

The tail markings are squared across the end of the tail pieces. The marked lines are then sawn down to the width of the pin piece. It is inherent in the geometry of constructing a dovetail joint that the transfer of the shape of the pins is to the inside face of the tail piece. This means that the tails must be sawn absolutely square to the face because it is the fit of the pins to the outside of the tail piece that we actually see.

Paring the tails

Dovetails: Paring the tails
The waste between the tails is removed (in this case with a jeweller’s saw because of the small space). The base of waste area is then pared. Placing a light source directly behind the cutouts can help with paring a flat base to the narrow space. The following picture shows a pared shoulder. You can see the knife cuts around the edges extending about 1/3mm into the wood. These marks are used to pare the rest of the shoulder flat.

Dovetails: Paring the shoulders

Fitting

Each joint is then tested for fit and tuned if required. These are some shots of the cut joints assembled dry.

Dry assembly: The slight protrusion of pins and tails can be seen

Dry assembly: Special attention is paid to the fit of the top of the joint as this the most visible part of the joint in the finished work.

Dry assembly: A completed joint ready for glue-up

Pre Glue-up

There are a few things to be done before glueup - like fitting the bottom panel, the runners and the magic catch. These are described in the following posts. However there are also some tasks specific to the dovetails that I will describe here.

The inside surfaces of the four sides must be fully sanded as it is impossible to sand these surfaces well after the box is assembled.

And you need to choose a method for cleaning up the excess glue on the inside of the joint. There are several ways to do this including washing the excess glue away with water and a toothbrush after cramp-up but before the glue goes off. I usually have too much to do in the short time available during glueup so I prefer to use the following method.

Find a thin sticky tape that you are sure will peel off the wood without leaving any gum residue. It needs to be thin so you can get the edges right into the inside corners of the glueup. I used to use a brown packing tape that was ideal because it was very thin and very waterproof. The latter means that the excess glue will not even stick to the tape and is very easy to remove. Unfortunately all the packing tape I have bought in recent years leaves lots of residue when you peel it off. This is as hard to remove as the glue. I now use a blue masking tape made for painters. It is slightly thinner than ordinary masking tape and is easy to remove.

Pre-glueup: Inside of joint taped to handle excess glue

The plan is that you apply the tape to the inside faces (the ones that are hard to clean up after glueup), making sure you place the edge of the tape exactly on the intersection of the joint. The excess glue will flow out on top of the tape and harden there. After the glue is dry, you can just peel off the tape and remove most of the glue. Any remaining glue is usually a fine sliver which can be removed with a marking knife. The intention of all this is to prevent the excess glue soaking into the wood and marring the appearance of the piece after the finish is applied. (I don’t have an image of the box sides with tape applied but the accompanying image shows the same technique used on the box lid.)

Glue-up

I use a yellow PVA glue for glueups like this where high strength, longevity and minimal glueline are the main criteria. In this project I used Titebond’s PVA for the first time.

Glueup: The dry run for gluing the front-left corner
The first two joints are glued in separate sessions so that I have the maximum time to attend to each joint. (The time from starting to apply the glue to having the joint in the cramps under pressure should be less than two minutes - then you have a few minutes to check and adjust squareness.)

Glueup: The last two joints (the two at the front of the bench) are glued at the same time.
The remaining two joints have to be glued in the same session (dictated by the geometry of dovetails and most other joints).
It is essential to do a dry run for each glueup session to make sure everything fits and that all the cramps and cramping blocks are adjusted and ready to go.

Part 1 The present
Part 2 The wood
Part 4 The lid

Add comment July 13th, 2007