The Monsoons in North India have thus far been rather unsatisfactory although they seem to have picked up somewhat in the last one week. The weather has remained extremely humid despite the lack of rain and there is damp everywhere, more so in my little workshop which has remained incredibly stuffy and uncomfortable. I have only been able to work in short stretches in there and that too intermittently due to other preoccupations. All I have been able to do since my last post several weeks ago is to prepare six teak planks, each roughly four and a half feet in length. I first ripped the raw planks to five inch wide strips, then glued two together to form ten inch wide planks. The pieces seem to have stabilized and I have tried my best to flatten them with my 18 inch long jointer plane. After flattening them the best I could, I used my smaller smoothing jack plane to further level out the surfaces.
This has proved to be hard work because the planers in the timber market where I sized the wood had left a lot of knife marks on the surface of the wood. I have discovered that there is no way to ensure that the cutters and planers at the lumber yards do not leave any marks at all. I doubt whether the blades of their massive planer-thicknessers are sharpened very often. Each of these machines go through prodigious amounts of hard wood each day and it is unlikely that their blades remain sharp for very long.
The other problem with the glued up planks was the slight but noticeable undulations particularly along the glue lines as the original pieces had not been jointed after being sawn and hence did not align perfectly. I managed to get the planks pretty flat but not perfectly flat. I aspire to perfection but rarely achieve it!
|My hand planes - the bigger one is the jointer|
The other time consuming issue was tuning my hand planes. In India planes are very cheap (cost between Rs 400 and 800 compared to the world famous Rs 15,000 planes made by the Canadian company Veritas) but most need considerable tuning to work well. To begin with, the soles of the planes are rarely perfectly flat as they need to be to function well. To flatten them I glued two long strips of sandpaper (one 80 grit and the other 120) to a pieces of glass and then painstakingly ground the bottoms of the planes. This procedure took several hours and buckets of perspiration even though I worked outdoors.
Then I took apart the planes and adjusted the shoes on which the blades sit and so on. Then came the business of grinding and sharpening the blades. Much has been written about this process and various methods are recommended by different woodworkers. One person who has been very influential in recommending the sharpening and use of hand planes is the celebrated English woodworker David Charlesworth and his methods are worth looking up on the Internet. Blade sharpening can be a long and tedious process especially if it the blade is new. The blades come from the factory with clear grind marks and a rough bevel. Much needs to be done before they can produce clean shavings.
Sharpening consists of producing a fine angled edge – usually between 30 and 25 degrees. This requires the long side of the iron to be ground to a fine degree of flatness. The entire length of the iron need not be flattened as only the last inch or so is relevant. Once this side has been flattened and has acquired a polish, the bevel on the other side needs to be similarly ground and polished so that the intersection of the bevel and the flattened back forms a keen edge.
Charlesworth recommends the creation of a fine secondary bevel at the very tip of the flat side. This is achieved by placing a a thin strip of metal such as a hacksaw blade on one edge of an abrasive stone of high grit (perhaps 1,000 or so) and further grinding the flat edge of the iron. Very little grinding is required to produce this secondary bevel but it seems to work like a charm. While Charlesworth and other master craftsmen prefer to use expensive Japanese water stones for sharpening, I get by with sandpaper and a few cheap diamond stones I had acquired some years ago. I find the results with these cheaper alternatives to be more than effective for my needs. I must confess however that I have no idea what it feels to use one of those expensive Canadian or US hand planes.
Once re-assembled, my cheap, mostly Jalandhar made, planes can produce extremely fine, ribbon-like shavings. Once tuned, the ordinary hand plane becomes something of a precision tool that is a delight to work with. Although the smoothing achieved by a plane can be superb, I still need to have a go with the belt sander and then with a random orbital sander. This is because of the chip outs and serrations caused by the knife blades at the lumber yard.
preparation of wood, especially hard woods like Teak and Sheesham, is
complicated by their inherent imperfections. Knots and complex grain patterns can
cause many problems. I find that the less than perfectly sharp blades of a thicknesser
can cause random chip out in the areas where the grain pattern changes or the
wood hardens. Planing works well when the grain direction is uniform in one
direction. In such wood, like Mahogany, planes rarely tear our pieces of wood
or produce unseemly gouges. The problem occurs when the grain direction changes
dramatically as in the case of knots and swirls. The hardness of the wood also
varies in these spots. Machine planers, especially if their knives are not
perfectly sharp, tend to gouge out little pieces of wood leading to much
imperfections on the wood surface.
|Fine Shavings from my Jalandhar made hand plane|
|Knots and Swirl Patterns|
Rectifying such imperfections is almost impossible with a hand plane not only because the dents can be deep (as much as an 1/8th of an inch) but also because the hand plane too tends to create gouges when it hits the cross grains of the knots. These parts can only be planed with a smaller plane worked along the grain pattern.
|Wood dust and cyanoacrylate glue|
Deeper gouges, dents, depressions and loose knots have to be filled and fixed. There are various methods of doing this; I prefer to use wood dust (generated by my random orbital sander) and cyanoacrylate adhesive. The wood dust should be packed into the dents, holes and so on and then covered by a few drops of CA glue. The glue hardens in about an hour and the glue-saw dust patch can be sanded down pretty well. Be aware that the wood treated with CA glue tends to darken significantly but stain and a good finish is all that is required to disguise it completely.
|Knots in the wood have been plugged but serrations remain|
26 August 2012
26 August 2012