The Modified Gottshall Joinery Exercise:
Charles Mak teaches a class on chisel skills, using the Gottshall exercise.
Charles Mak teaches a class on chisel skills, using the Gottshall exercise
Never heard of the ‘Gottshall Block Test’? It is an exercise for beginning woodworkers included in Making Antique Furniture Reproductions by Franklin H. Gottshall, a period furniture writer. The key value of this exercise lies in understanding that grain directions play a critical role in how you use a chisel. Your goal is to keep the chisel edge from digging in and splitting the wood. After teaching classes modelled after Gottshall’s exercise to woodworkers who are not beginners, I can safely say that the Gottshall exercise is a worthy pursuit for the average traditional woodworkers as well.
The modified exercise and the tools
When I teach, I follow a slightly different approach from Gottshall’s as our focus is on the chisel. First, I replace the round and mitre corners with a tail (see diagram). Second, the only cutting tools we use are the handsaw and chisels, no drill or coping saw. Lastly, the handsaw is used only on the tail and the curved cut-out. We scribe all lines across the grain with a square and marking knife, and all lines along the grain with a marking gauge. You can use a bevel gauge to mark out the tail, or simply do it by eye while a compass is
used to draw the arc. Find yourself a small square that will allow you to check squareness even in tight places. The only other thing you will need is a free morning or afternoon in the shop.
Check every joint for flatness and squareness
A keen edge gives you superior control and hence better results
The rebate (or fillister)
We lay out one joint at a time, or, if you followed Gottshall, you would lay out all the joints in one go. Let’s start with the rebate. The challenge in this joint is to chisel a flat cheek that is square to the shoulder, a task that is usually finished with the aid of a router plane or shoulder plane. Here, you will do all that with a single chisel! First, scribe the rebate to width and depth across the block. Unlike Gottshall, we do not use a saw for this joint. Start with vertical chopping about 1.5mm from the scribed line and then angle the chisel to chop away the waste. Repeat the vertical and slanted cuts to remove about half the waste from the baseline. Then, only if the grain allows, chisel in from the end grain to remove the bulk waste.
When you get closer to the baseline, switch gear and pare cross grain from both edges to level the cheek. Finish the job by paring down on the shoulder line perpendicularly.
Throughout this whole exercise, we chop vertically with the chisel’s bevel facing down and towards the waste, while we pare horizontally with the bevel up, also towards the waste.
Using a trick attributed to woodworker Chris Schwarz, I set the marking gauge by placing its cutter into the engraved line on a ruler
You may also scribe a second line on the waste side from the shoulder line to guide your initial chopping
Watch the grain when paring at the end to avoid removing wood beyond the baseline
Trim the depth of a rebate freehand, or use a block that matches the rebate lip as a guide
The gain (or stopped housing)
The gain involves both cross-grain and along-the-grain cuts. Chiselling down along the grain runs the risk of splitting the wood. The trick is, therefore, to make cross-gain cuts first, so they act as a stop to prevent
any splitting along the grain. Lay out the gain and define its perimeter with what British teacher Paul Sellers calls the knife walls. The edge of the knife wall is where to start the cross-grain chopping, away from the scribed line. Work from both sides towards the middle with vertical and slanted chopping until a hill is formed. Then pare away the middle waste and level the bottom, taking care not to go below the baseline.
Lastly, chop or pare on the scribed lines, first across and then with the grain to complete the stopped housing.
To prevent lifting up the fibre, cut the knife walls across the grain first
Remove the waste from both sides towards the centre with alternating vertical and angled cuts
Pare down on the scribed line to remove the last bit of waste
The dado (edge-grain notch)
Gottshall called a notch on the edge a dado. The challenge here lies in cutting it perfectly aligned on both faces. You must mark out the joint perfectly identical on both faces and work in from both faces, eliminating any chance of blow-out.
Unlike Gottshall, we do not use the saw here. After cutting the knife walls on both faces, use vertical and angled cross-grain cuts to remove about half of the waste down on one face. Then flip the block and repeat the same kind of cut to break through the waste. Finally, working from both faces, pare the cross-grain side walls clean and then the end wall.
Work on the two cross-grain walls first, chopping from both faces
The end-grain notch
While a dado has side walls going across the grain, the end-grain notch’s side walls go with the grain. This means after chiselling the knife walls, we make our vertical and slanted cuts on the end wall first, from both faces. As with the rebate, we also chisel in from the end grain to remove some of the waste. In the last steps, flip the block and remove the other half of the waste, followed by the final paring of the end wall and then the two side walls.
Always be watchful of the grain direction when working from the end
The tail
The challenges of a dovetail joint are well documented. My primary advice to a beginner has always been to start a saw cut with the workpiece held plumb. My second bit of advice – one that should prevent many unnecessary spoiled cuts – is to check that the initial kerf on the end grain is square to the face before charging ahead. After sawing the tail, clean up the shoulders with a sharp chisel from both faces.
Hold a workpiece level in the vice before starting the saw cuts
It is never too late to correct a faulty start if you check the first saw kerf for squareness
The mortise
By now, you will have already tried the various techniques that will be needed to cut a mortise. A mortise has four walls, two (end walls) going across the grain and two (side walls) with the grain. Again, you’ll work from both faces and cut the mortise walls going across the grain first. Gottshall drilled out the waste before he started. If your plan is to use a mortise chisel and not a bench chisel, avoid boring, because a square chisel in a round hole doesn’t work well. After incising the knife walls, cut out the end walls from both faces and then pare the side walls clean.
Eliminate the risk of splitting by doing the cuts across the grain first
The concave cut-out
In the last operation, you use a chisel as a shaping tool. Lay out the arc on both faces with a compass. While Gottshall removed the bulk waste with a coping saw, we use a handsaw and chisel. Lastly, with steady pressure and movement, trim along the concave curve – from both directions with the grain.
Make a series of saw cuts about 3mm apart, down close to the pencil line
Orient your body so you can see that the chisel is perpendicular to the wood
For a concave surface, use the bevelled face of a slightly wider chisel to shape with the grain
Voilà! You’ve just expanded your woodworking repertoire with a set of time-honoured techniques that will serve you well in your next joinery challenge.
