A couple of weeks ago I picked up a cheap block plane from Delhi’s Chawri Bazar. The plane was no great shakes; it looked roughly made and had deep mill marks on its sides, sole and on the iron. But still I decided to give it a try and see if I could tune it up. If it did not work I could always throw it away – it cost only Rs 120.
|Block Plane: Note the Deep Mill Marks. Even the plane iron was deeply marked.|
|The plane disassembled: the cast iron body, the red iron cap and the steel plane iron or blade|
The first thing that I found was that the sole was deeply etched with milling marks and the sole was not flat. Even the critical part of the sole, the part between the throat and the front edge, was a little convex. It took more than an hour of hard grinding on 80 and 120 grit sandpaper to flatten it. I did not feel like following up with higher grits to give the sole a polish.
I next began to prepare the plane iron or blade. As in preparing all plane irons, one side of the blade, the long side which ends at the bevel edge, needs to be flattened and polished. There are various ways to grind and polish a plane iron; most people in India use a two part Silicon Carbide stone but I use different grits of sandpaper. Abroad, woodworkers use oil stones, Arkansas stones, Japanese water stones or diamond stones for sharpening but these are expensive options as the stones cost hundreds of dollars.
|Edges of the plane Iron Marked to Check for Flatness|
The easiest way to test the flatness of any edge or steel surface is by marking it with permanent ink and then rubbing it against a flat abrasive surface. If all the marks are uniformly rubbed off then the surface is flat; else it is not and the parts where the marks have not rubbed off are the low spots. In this blade, I found low spots on the front edge of the iron’s corners and edges, which took a lot of elbow grease to flatten.
|See the uneven pattern of the marks after they have been rubbed on sandpaper|
Flattening and polishing the back (or the front, depending how one sees it) of an iron for the first time is a slow and time consuming affair. I started off with 80 grit sandpaper and gradually moved up to 400 grit, using 120, 180 and 240 grits in between. For providing the final polish, I used 600, 1200 and 2000 grit papers. This gave me a mirror finish.
|Now one side has been flattened and polished to a mirror finish|
The next job is to grind and polish the bevel. This can be done using a honing guide but I find that I am able to do it by hand. I can sense when the bevel is not moving at the right angle – the feel will be different if an edge is being abraded as opposed to the entire bevel. At any rate, I went through the entire process, going from a lower grit to a higher progressively and ending up with 2000 grit. Some people will go higher, perhaps to 5000 or 8000 grit but I haven’t been able to lay my hands on such high grits here in the Delhi or NCR. The edge is sharp enough when it is able to pare the hair on one’s arm.
|A sharp edge will pare the hair on one’s arm.|
With this, the plane is pretty much ready. The block plane’s iron attaches at a much lower angle than regular bench planes and the plane iron has to be inserted with the bevel side is on top. This is the exact opposite to a bench planes which has its bevel facing down and its top edge capped with a chip breaker. In the block plane there is no chip breaker and the iron is held in place with the iron cap.
|The block plane reassembled|
The block plane is not designed to plane or smooth wood: it is primarily designed to cut end grain. It can also be used to soften edges or chamfer them and take thin shavings of tenons and similar parts of some joints. I often use it for roughing out ends of a work piece prior to sanding it square and also find it useful to pare down the sides of doors to make them fit.
I did not succeed in getting fine, paper like shavings with this plane; probably the iron or its geometry was not right or perhaps my sharpening wasn’t up to the mark. Still, I won’t complain: for a 120 rupees plane it does a good job.
23 March 2013
23 March 2013