Re: Chopping and drilling-long :(
Adam Cherubini, NJ
>My suspicion is that the technique so many of you use or were taught is the carpenters� craft. Best for producing poor quality mortises quickly. Its fundamentally inaccurate (whether chopping or drilling and paring).
Chopping is particularly hard on bench and tools. Ever wonder how old mortising chisels have survived so long? Maintaining perpendicularity is difficult. Nothing about the tool or technique assists you. Only your own craftsmanship allows for plumb mortises. Every new set of chops is another opportunity to introduce twist into your mortise. When working wide mortises in small stock one runs the risk of cracking out a thin cheek.
Using a fine edge tool as a level sounds fishy to me, regardless of who says it. (Both Roy Underhill and Mike Dunbar teach this technique). Most of us realize that after a few chops (I say three) a chisel ceases cutting and becomes a wedge.
That said, there are guys whose hand eye coordination is so good that they can pull this off. The tools they seek are essentially cold chisels. How many they can do in a day and how often they stop to sharpen are questions I�ve never had the guts to ask. (Too argumentative, even for me!)
Drilling and paring is common for timber framing. This technique is best when lots of material must be removed. Drilling perpendicular holes by hand is the first challenge. Making several holes parallel is the next. Timber framers/ traditional carpenters eventually developed the beam boring machine for this reason. Paring is accomplished using a long thin framing chisel. I like a curved edge on mine since, despite their size, they are really performing a paring operation. Driving this tool with a mallet generally causes it to undercut (or submarine). The resulting wedge shaped mortise is generally good for a carpenter, bad for the joiner or cabinetmaker.
Evidence of the use of this technique in fine furniture goes back centuries. Good cabinetmakers employed this technique. Unlike the first technique which is generally merit-less, drilling and paring can work okay, save your hands, tools, bench etc. Its use on fine furniture may point to the labor disputes of the time and the very formation of the Joiners Guild. Joiners claimed their building method and mortising technique was superior and sought protection against Carpenters who applied their techniques to furniture. (In most other cultures, no distinction is made between furniture makers and carpenters). They received that protection in 1632. Just as organized labor disputes are common today, the 1632 ruling didn�t stop all carpenters from �joining� furniture. Here in America, without the Guilds� political power, tradesmen pretty much did whatever they wished. That explains the myriad of different techniques employed here.
The only technique that makes sense to me, is easy on tools, and hands, takes full advantage of the key features of mortise chisel, and is similar to other basic period techniques.
Last first. Throughout period joinery we see the repetition of basic principles. Gauging is one, tool slaving is another. When attempting to saw straight, the goal is to put as much of that long straight saw into the kerf as possible (lowering the angle). That way, the cut you make is indexed off of the cut you already made.
The mortise chisel has a few unique features: A very deep blade (which results in a long bevel/bezel). A precisely ground blade width-wise up the length of the tool. A relief or draft ground through the chisel�s sides (depth-wise). An excessively large handle. BTW- The handles are often larger than framing chisel handles and never are seen with metal rings, so the supposition that the handle is sized to manage heavy blows doesn�t seem to fit.
When examining, for lack of a better name, the direct paring technique I advocate and have written about several times, we see so many of the problems, brought here repeatedly, solved. The tool is pushed with one�s shoulder, saving hands, the delicate cutting edge, and the bench. The fat handle is comfortable in the small of the shoulder. The wide bevel sits directly on the work allowing for instant perpendicularity. The long cuts maintain the straightness of the mortise, regardless of the angle chosen, making angled mortises easy and consistent. The precise width of the chisel, registers inside the mortise further improving quality with little help from the craftsman. The resulting mortise is the width of the chisel all the way through.
Put it all together and you�ve got the technique used by (at least some) CW chairmakers. It�s a technique that makes sense, but also fits within the sensibility of period workers, and explains/utilizes the key design features of the tool. Lastly, it�s a secret worth keeping from the carpenter next door. I believe this is the reason we chop mortises today.
Adam