Combine the flours and salt in a food processor or bowl; process or mix to blend well. Sprinkle 7 tablespoons (2/3 cup for large recipe) water over the dough and process or blend until it looks like cornmeal. Pick up a portion of dough in your hands and see if it will form a cohesive mass. If not, sprinkle on a little more water, blend it in, and try again. Process the dough 1 1/2 minutes, changing the position of the dough every half minute, or knead it 12 minutes by hand. The dough will not quite form a ball in the machine, so turn the dough out onto an unfloured work surface and knead it 2 minutes. Let the dough rest covered with plastic wrap, 1 to 3 hours. Cut the dough in half for the small recipe and into thirds for the large and keep the remaining pieces covered. Pat one piece into a rectangle about 1/4-inch thick. Lightly flour the dough and roll it through the pasta machine at the thickest setting. Fold the dough in thirds and feed the unfolded end through the rollers again. Repeat the procedure twice more. Lightly flour the dough again and pass it through the next finest setting twice. Pass the dough through the third and fourth settings, flouring the dough if necessary. Place a lightly floured plate under the thinnest cutting blades. Roll the dough through the blades, allowing the noodles to fall onto the plate. Lightly sprinkle more flour over the noodles and gently toss to coat them with flour. The noodles are very delicate so be careful not to break them. Roll and cut the remaining dough pieces, allowing each to dry on its own plate. Allow the noodles to dry about 20 minutes. Cook the soba in rapidly boiling water 45 seconds to 1 minute, or until they lose their floury taste. These soba may be used in any recipe calling for soba or udon or may be wrapped well in foil and frozen. The smaller recipe makes about 1 pound soba; the larger recipe makes 1 1/2 pounds. Note: This is a traditional recipe that is converted for use with a food processor and a pasta machine. Though you can make these noodles by hand, it is not easy to cut them into the thin, 1/6-inch strands without a machine, and this recipe works beautifully. Source: Linda Burum; Asian Pasta, A cooks guide to the noodles, wrappers and pasta creations of the East. Typos by Brenda Adams ; MC formatted by MC_Buster; mc posted 9/22/97 Recipe by: Linda Burum, Asian Pasta Posted to MC-Recipe Digest V1 #796 by Badams on Sep 22, 1997