![\"plane](\"https:\/\/www.rpwoodwork.com\/blog\/wp-content\/uploads\/2017\/05\/IMG_4520_edited-2.jpg\")
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To master handplanes, a woodworker must master the matter of blade camber. To introduce the bevel-up\/bevel-down\/frog angle issue, please refer to my 2009 post<\/a><\/strong>. Here I want to present a more intuitive approach to guide you at the sharpening bench.<\/p>\n The issue<\/strong><\/p>\n When checking the blade after grinding, you naturally hold it up and observe<\/strong> the camber, sighting at 90\u00b0 to the face of the blade, like this<\/a>. But when the blade sits on the frog at an angle, the effective<\/strong> amount of camber is reduced. Think of it this way: if the cambered blade were laid flat, there would be effectively no camber at all.<\/p>\n So, you have to create what looks like more camber than you need, and just how much<\/em> more depends on the bed angle<\/strong>.<\/p>\n Please note that I am not suggesting that you take out a leaf gauge and measure the camber! I took measurements for these posts and other writing but that is not my method in the shop. I suggest use the guidelines set out in part one<\/a> of this series, work intuitively, using a bit of trial and error, and get a sense of how the camber that you see performs on the wood.<\/p>\n As an example,<\/strong> in the photo at the top,<\/strong>\u00a0with the blades standing vertically, the blade on the left shows about .004″ camber, and the one on the right about .14″. In the photo below<\/strong>, the blade on the left is set at 45\u00b0 and the blade on the right is set at 12\u00b0. This results in an effective<\/strong> camber of about .003″ for both of them.<\/p>\n So, to get the same effective camber<\/strong>, we had to grind an additional approximately 1\/3 more (observed) camber for the blade bedded at 45\u00b0, but for the blade bedded at 12\u00b0, we had to grind almost five times more (observed) camber.<\/p>\n Here is a handy table<\/strong> to help absorb a general sense of the differences.<\/p>\n Bed angle<\/u>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Grind this multiple more<\/em> camber than what the plane needs<\/u><\/p>\n 12\u00b0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 4.81 [whoa, must grind lots more to get what you want]<\/p>\n 20\u00b0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 2.92<\/p>\n 22\u00b0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 2.66<\/p>\n 45\u00b0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 1.41 [grind just a little more than what you want]<\/p>\n 50\u00b0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 1.31<\/p>\n 55\u00b0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 1.22<\/p>\n 60\u00b0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 1.15 [what you see is just about what you get]<\/p>\n And another thing<\/strong><\/p>\n Camber is somewhat of a nuisance to grind into the blade edge. It slows down grinding and, especially, honing. Unfortunately, and, I contend, for little or no good reason, almost all bevel-up planes<\/strong> made today have a 12\u00b0 bed. That requires you grind a lot more camber than in a bevel-down plane. If the bevel-up plane had a 22\u00b0 bed, this problem would be greatly reduced.<\/p>\n This is yet another reason why I continue to advocate that bevel-up planes should be made at about 22\u00b0. I explored the matter several years ago in this post<\/a> and elsewhere.<\/p>\n Skip this part if you want<\/strong><\/p>\n For those who like this sort of thing (as I do), here is the derivation of the chart above. The key point is that it is a non-linear function because of the sine curve. So, there is a big difference between 12\u00b0 and 22\u00b0, and much less difference between 50\u00b0 and 60\u00b0.<\/p>\n![\"plane](\"https:\/\/www.rpwoodwork.com\/blog\/wp-content\/uploads\/2017\/05\/IMG_4527_edited-2.jpg\")
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