Stack Marking – More:
Robert Paul Gurney continues his series on marking and measuring techniques.
If you could take your marking and measuring method directly to your hand and machine tools, you could reduce marking in all but a notional way. There is a way of doing this that is also exceptionally accurate and it involves using the stack marking method discussed in F&C 254. Stack marking can work directly with the setting of your tools just as it works with your marking knife and gauges. With finely tuned tools, you can produce exceptionally accurate cuts.
The mitre saw’s main operation is cutting boards to length, which means setting stops. Setting accurate stops makes this machine a precise cutting tool. The ‘stack’ helps make this possible.
The ‘stack’ could be used to set stops between the blade tooth and stop but you risk indexing the ‘stack’ to the wrong part of the tooth or, worse, chipping a tooth. The better way is to make a test cut. The test is done with the stop set further away from the blade than your intended cut. The workpiece should lie face down with its face edge against the fence. Make sure the ‘face end’ sits against the stop.
Once you make your test cut you can set a temporary stop against the freshly cut end. This stop becomes a reference point against which you will place the ‘stack’ and then reset the original stop. With this stop set you can remove the temporary stop and the ‘stack’ and make your cut.
If you start by cutting your longest pieces first you can place a partial ‘stack’ against the stop for the next shortest piece and repeat this for ensuing shorter cuts. If your first board was cut to 350mm and you want to cut a board to 280mm, you would place a 70mm ‘stack’ against the stop and make your next cut.
Clamp your work in as many ways as you can, for safety and to avoid any movement during cuts. The actions you take for precise cuts lead to better safety.
In the same way that the ‘stack’ is used with the mitre saw, it can also be used for crosscuts on the tablesaw – with one difference. Since a crosscut sledge should, for safety’s sake, not span the blade, it isn’t possible to set a temporary stop as you did with the mitre saw.
The solution is to place a machinist’s block against the freshly cut end and slide the fence against this block. You now have a reference surface against which you can set your ‘stack’ and reset your original stop. As with the mitre saw, you can add a partial ‘stack’ to cut shorter pieces.
Rip cuts on the tablesaw can be a hit-or-miss process: measurements using a tape measure or the scale on the fence rails are questionable. To use the ‘stack’ to make accurate rip cuts
with the tablesaw you will need another tool: a mitre slot calliper holder. These aren’t very expensive, in fact you could even make your own. To do this, start by ripping a board wider than you want. Place the end of the dial calliper (in the holder) against the freshly cut edge and lock it. This is the reference against which you will place the ‘stack’ and thereby set your fence. In this case, you can rip your boards to width in any order.
Drilling holes at precise locations is not easy – even with a pillar drill – and drilling holes at multiple locations is far more difficult. When you also have to drill, countersink and tap at each location, the difficulty is manifold. A simple, inexpensive addition to your tool kit – plus the ‘stack’ – can solve all these problems.
That item is a precision drill rod. A precision drill rod (unlike a plain rod) is ground to a precise diameter. That diameter should be 10mm, as you’ll find out soon. It should be around 150mm long.
When you are drilling at multiple locations, the sequence of setting up your pillar drill becomes very important. It starts by setting the table at the approximate location. Having to change the table for every operation is a large part of the reason for drilling inaccuracy but that won’t be a problem, as you’ll see.
After setting the table approximately, set your fence position and your stop. Once you have the fence and stops set it is time to set the final depth of the hole. To set the fence and stop in the correct position, place the drill rod in the chuck so it’s just above the table. Locate the fence and the stop by placing the ‘stack’ between them and the drill rod. This is the distance from the edge of your workpiece and the centre of the drilled hole.
The reason for the drill rod being 10mm is because it’s easier to subtract 5mm – half the drill rod diameter – from your intended dimension. If your hole position is closer than 5mm from the edge there is a trick you can use. Place a machinist’s block on the opposite side of the drill rod and calculate your ‘stack’ from there. If you wanted to drill a hole 3mm from the edge of a board, then you would place a 7mm ‘stack’ against the machinists block and set your fence against that.
Like the saws you can set your stops and fence to their furthest position and set a partial ‘stack’ for subsequent locations. This works well for the aforementioned multiple hole locations. Plan things so your face edge, side and end are against the table, fence and stop.
If your stops have to be set outside the realm of your drill table, it’s a simple matter of using a longer fence. A piece of wood clamped to the underside of the fence can temporarily support the ‘stack’ and the workpiece.
Setting the final drill bit depth is the final step and the ‘stack’ can help with this. After removing the drill rod, loosely chuck in your drill bit and place your ‘stack’ under it then tighten the chuck. If your workpiece is 20mm thick and you want a 15mm-deep hole then place a 5mm ‘stack’ under the drill bit.
Re-setting your countersink after each operation can be very troublesome. Any minuscule change in its depth setting and the countersink isn’t concentric with the hole. By using the ‘stack’ to take a measurement under the countersink you can accurately repeat this setting each time for subsequent countersinks.
When I want to drill a through-hole, I don’t drill all the way through, it saves the drill table and prevents tearout. This means using a 1/1000in (or metric approximation) brass shim under the drill bit spurs. After you’ve done all your drilling, it’s a simple matter of removing the tissue-thin remainder with the drill bit held in your hand.
Hand tools can be tentative tools. We take a shaving off here and a shaving off there, as we cautiously approach our knifed line. It can be a very satisfying process or it can be a little time-consuming and error-prone. The ‘stack’ can be used to pare these shoulders in a very direct manner. The trick is to use your machinist’s block in the ‘stack’. Make it the last in the line – the one against the shoulder.
You can now pare against the block to get an accurate and perpendicular shoulder. It may not always be possible to clamp this block, but it will help if you can find a way.