Moving Forward
We left off last time with a dry fit and thoughts about fitting the drawer blades. I shall describe the strategy I developed in due course. First it was necessary to complete the rebates at the rear for frame-and-panel that will be fitted at the end.
A warning about the rebates – they are stopped rebates, which is risky to do and not generally recommended for this type of construction. The rebates terminate short of dovetails that lock the two sides via the top rail. It is easy to weaken and damage them. The only reason I am going down this route is to maintain a clean exterior – I want to finish the back of the chest at the same level as the front. The joint will be strong once the parts are glued up.
This is where the rebate will go …
The plan is to use a rebate plane. Those who have tried this are aware that planing from one end to the other will create a curve, with the depth deepest in the centre of the side, and tapering off to the ends. Eventually the plane will stop cutting ..
To plane this successfully, first remove enough waste from each end to enable the rebate plane to continue planing to depth ..
Do the same at the other side …
Now you can plane with confidence as the rebate can be taken to full depth along the whole length.
Those familiar with the Veritas Skew Rabbet Plane will notice that the front knob has been removed (as well as fitting a deeper sub-fence). The knob seems superfluous to me since I cannot find a reason to use it. There is far more control pushing the plane into the rebate, that is from the side.
What I have discovered is that the place where the knob went makes a handy position for the thumb – better than the fence alongside the edge of the blade … where inevitably I cut myself!
This is the completed rebate. The rear panel will sit in a frame that fits in the rebate. The sizing of this rebate enables the rear sliding dovetails to be sawn inside it and then hidden behind the frame.
Planning the sliding dovetails for the drawer blades
With a parallel-sided carcase, all one needs is a story stick to mark off the dados for the drawer runners. You can rout them, or whatever way you wish to form the grooves, sides completed separately - no problem as the grooves are vertical/square on both sides. As long as they are done accurately, the dados will face each other, that is, will be coplanar.
But what happens when you have a curved side that is no longer parallel? If you rout straight down into the side, it will be at the same angle as the curve. There are multiple curves, one for each drawer runner.
I scoured the Internet for bombe builds, just to see how the blades were installed. David Boeff's website was one I looked at. He does good work.
One of his images is useful in explaining the situation for those who are not clear about what I am trying to do. The typical cabinet (and bombe) has solid sides ....
This means that the sockets must be fitted from each end. There is no choice.
However a frame-and-panel construction breaks this rule - the frame opens the door for the socket to be formed on the inside of the frame … which will create that clean face I am after.
The only problem is that I have not found anyone doing this, and therefore no example or descriptions of methods for doing so.
I worked out a simple method for obtaining accurate sliding dovetails for the drawer blades.
I had originally planned to cut shallow housings first, with just enough flat area to register the dovetailed drawer blade on from the inside, and then mark out and cut the dovetails. This just appeared to be too complicated.
I also realised, if I continued down the existing path, that I would run out of room for an adequately sized sliding dovetail.
The drawer is similar to this (but coped to the curved angle of the inside). The underside butts against the drawer blade, acting as a stop. The drawer face is 22mm thick, which leaves 22mm in the frame for the sliding dovetail. Too short for sufficient support.
Consequently I decided to add on a 25mm wide fillet behind the front leg/stile to extend this width to close to the original frame.
It then occurred to me that one could clamp the fillet inside the rear leg/stile, and then mark and saw the dovetails from the rear (sawing the frame and fillet together). Moving the fillet to the front would ensure that the dovetails rear and front would be identical. (Note that it is planned that the fillets will be glued to the frame but not to the panel, which must be allowed to move).
Both sides are done at the same time.
The drawer blade is made to fit beforehand, and dovetailed at the ends. This is made 45mm wide (includes waste), and then ripped into two pieces – 15mm to add to the rear (to compensate for the loss of width in shaping the rebate) and 25mm for the front (to compensate for the width of the drawer front).
So, in effect, the front sliding dovetails are fitted from the outside of the rear of the carcase. A shallow housing for the dovetail is also now unnecessary. Altogether a simpler construction that will be easier to make and do so with accuracy.
I drew up a simple sketch to illustrate this, partly to share with others my convoluted thinking, and partly to help guide me along this route:
(Note that since this drawing was completed I have made the decision not to use a Tip On mechanism. The drawers will instead use a pull for opening).
Marking out the fillet
Here is a fillet held in plane against the rear of the panel …
The (lower most) positions of the drawers are transferred from the frame to the fillet ..
This is done for both sides, and the positions are checked against one another to ensure they are the exact same height.
Once this is done we are finally in a position to (hide) glue up the carcase - since all the dovetailing must be done from inside the carcase to ensure that later there is no movement to throw out these measurements.
The base is perfect – same angles for each corner, front and rear.
Above is the panel for the secret drawer. This also serves to ensure that the opposite sides are square. It is let into a groove at each end. The panel is free to move in the same manner as a drawer bottom, with screws in slots under the frame. The position of the screws on one side can be seen above.
The top sections are now fitted. They are pulled into equal angles by angling the clamp. Everything is nicely square. I cannot ask for more.
Below: the glue has now dried and the basic carcase is complete. The fillets are clamped on each side at the rear ready for dovetailing.
The next step will be to size and dovetail the drawer blades. These are below, double width, so that they may be ripped into two, one for the front and one for the rear of the carcase. They are 18mm (3/4”) thick. They are going to add significant mass to the construction.
And that is for next time.
Regards from Perth
Derek
July 2015