The Chair – Slotting the Stretchers (Part 2)

There were a great many responses to the question I posed, “How would you do this?”. These were divided into the groups: those that would saw the slot, those that would drill-and-chisel the waste, and those that would plane it out.

Of the sawyers, Rob was the first to mention sawing against a fence. Then Wiley suggested using an azebiki, a Japanese panel saw to do this. This was echoed by a few others.

This is likely the correct way to achieve the goal, however I lack the confidence to try it. The difficulty I have is not just that the slot is 3mm (1/8”) wide, which leaves little space for parallel kerfs, but that the front and rear stretchers are complex curves, that is, they bend in two directions at the same time. I could not imagine a saw following a “complex” fence along this complex course.

There was a group that suggested planing or scraping the waste away with a coach maker’s router ….

… or a quirk router …

There was also the suggestion of making a scratch stock to scrape a groove.

In this group the problem lies with the Jarrah – it is too hard, too brittle and too thick for any of these tools to work. The likely scenario would be a shallow groove with chipped edges.

Onto the third suggestion, drill and chisel the waste. Essentially, this is what I planned to do, along with one addition. This would be to first create a shallow groove, one with clean edges, and then work from below the surface of the stretcher, thereby preserving it.

As I noted in my previous post, the Veritas router plane with inlay cutters appeared to be the best tool I had to create a clean, parallel set of lines at a 30mm distance from the lower edge of the curved stretcher.

Below I shall demonstrate how the slot was created in the rear stretcher. There were three tasks involved. The first was to mark out the slot, the second to remove the waste from within the slot, and the third to round off all the edges on the stretcher.

Marking out the slot

The Veritas router plus inlay cutter was used to mark the parallel lines, 3mm apart and up to 30mm from the ends. The latter distance is taken from the slot being 30mm from each edge.

The fence for the Veritas router plane is reversible, either able to run along a flat or a round edge. I have a slight modification, this being the addition of a slot to the knob to aid in tightening it. There is nothing worse that a fence that loosens itself and causes the blade to wander across the surface of the wood.

The lines may be deepened by repeating the back-and-forth run, progressively deepening the cutters. Or you could use a thin-bladed knife in the lines. The lines will be deepened until the groove is 3mm below the surface.

Once deep enough to start removing waste, chisel across the grain ..

First one side of the groove, and then the other. Now the remaining “pyramid” of waste can be removed with a small router plane.

I have a router plane I built that takes the Veritas router blades, in this situation a 1/8”. Also, for fun, I purchased the Veritas miniature router plane, which comes with a 1/8” blade. It may look like a toy, but it works like a real tool.

Excellent, easy shaving from both small router planes …

One of the reasons is that the blades are sharp. Very sharp.

To get them this way, my system is to first hollow grind the bevels, which then makes it much easier to hone. This was done with both router planes.

There is a tutorial here.

The attention given earlier on to ensuring everything was square is going to pay off now. The plan is to drill from each side and meet in the middle.

A vertical guide for the eggbeater drill was made from a wooden vise and steel rule …

The drill bit is limited by a depth stop.

Here is the result.

Once the one side was done, the stretcher was flipped over and the process repeated.

One addition needed was support to ensure that the surface to be drilled was horizontal. The stretcher was secured with a holdfast …

Here is the second side on completion …

The end of one side was chopped through …

… just enough to thread a coping saw. The purpose was to saw through the centre of the groove, which would make it easier to chisel out the waste.

The waste was then removed by a little paring and a little chopping …

The sides of the slot with cleaned up with a chisel, and then smoothed off further with a fine file.

At this point the stretcher is slotted but the edges are sharp. They need to be rounded off as the Danish Cord will be pulled across the corners.

The tool of choice to round off the inside edges is a scratch stock. One was made up for this task …

The steel comes from a used ¾” bandsaw blade. The first task it to smooth it off. I used a diamond- and water stones. In the second picture the blade has been shaped with files …

The blade holder is a re-treaded marking gauge …

Here is the result …

Lastly, the outer edges were rounded off with a small Japanese moulding plane …

Here is the final result …

Now to do the other three stretchers.

Regards from Perth

Derek

January 2014