{"id":4947,"date":"2017-08-13T01:29:14","date_gmt":"2017-08-13T05:29:14","guid":{"rendered":"http:\/\/www.rpwoodwork.com\/blog\/?p=4947"},"modified":"2017-08-13T14:18:27","modified_gmt":"2017-08-13T18:18:27","slug":"a2-steel-plane-blades-are-not-all-the-same","status":"publish","type":"post","link":"https:\/\/www.rpwoodwork.com\/blog\/2017\/08\/13\/a2-steel-plane-blades-are-not-all-the-same\/","title":{"rendered":"A2 steel plane blades are not all the same"},"content":{"rendered":"<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-4948\" src=\"https:\/\/www.rpwoodwork.com\/blog\/wp-content\/uploads\/2017\/08\/IMG_4635_edited-2.jpg\" alt=\"A2 steel chipping\" width=\"570\" height=\"444\" srcset=\"https:\/\/www.rpwoodwork.com\/blog\/wp-content\/uploads\/2017\/08\/IMG_4635_edited-2.jpg 570w, https:\/\/www.rpwoodwork.com\/blog\/wp-content\/uploads\/2017\/08\/IMG_4635_edited-2-150x117.jpg 150w\" sizes=\"auto, (max-width: 570px) 100vw, 570px\" \/><\/p>\n<p>Before making my point, here is a synopsis of the differences between <strong>A2 and O1<\/strong>\u00a0blades, as I understand them, and have experienced in using them. Better however, you should also <a href=\"http:\/\/hocktools.com\/products\/perfectedge.html\" target=\"_blank\" rel=\"noopener\">read<\/a> a much more learned discussion by the Man of Steel himself, Ron Hock.<\/p>\n<p>In general, for comparable quality blades:<\/p>\n<ul>\n<li>O1 is finer <strong>grain<\/strong> steel and can be brought to a <strong>sharper<\/strong> edge than can A2. It is not a big difference but may be important depending on the application.\u00a0Some dispute this; perhaps O1 only seems to get sharper because it is easier to sharpen, and because of this next point.<\/li>\n<li>Due to the difference in grain size, the honing <strong>angle<\/strong> for A2 should be a few degrees higher than for O1.<\/li>\n<li>A2 is more <strong>difficult<\/strong> to sharpen than O1, both in speed and in feel on the stone. However, both are well within the range of a basically skilled sharpener.<\/li>\n<li>Owing primarily to its tough chromium carbide particles, an edge in A2 is more <strong>durable<\/strong> than in O1.\u00a0However, that is not the whole story because . . .<\/li>\n<li>They may <strong>dull differently<\/strong>. The O1 edge is likely to slowly and simply round over, while A2 may chip.\u00a0Ron\u00a0<a href=\"http:\/\/hocktools.com\/tech-info\/o1-vs-a2.html\" target=\"_blank\" rel=\"noopener\">explains<\/a> that chipping occurs when oversized chromium carbide particles in A2 steel pop out of the edge.<\/li>\n<\/ul>\n<p>This last point is the one I would like to explore, specifically with regard to <strong>differences among A2 blades<\/strong>. We would expect some differences among manufacturers because they vary in their formulas and processes.\u00a0However, I suspect there can also be significant variations in edge behavior \u2013 the tendency to chip \u2013 among blades of a given brand, and even within a single blade.<\/p>\n<p><strong>I want slow and steady dulling<\/strong> wherein the edge simply rounds over increasingly. I do not want precipitous edge break down \u2013 chipping. It is unwelcome, though I suppose tolerable, in a jack plane, but downright infuriating in a smoothing plane. Everything is going fine until, ugh, those little ridges suddenly appear on the wood surface that I am trying to finish plane to otherworldly exquisiteness. And so, a certain Bad A2 Blade <strong>(pictured above)<\/strong> has been banished from my shop. It got those hideous chips as I planed not teak, but affable poplar, and only for several minutes.<\/p>\n<p>I have sharpened this blade exactly the same (same <a href=\"https:\/\/www.rpwoodwork.com\/blog\/2015\/09\/26\/diamond-stones-in-a-sharpening-system\/\" target=\"_blank\" rel=\"noopener\">stones<\/a>, 33\u00b0 secondary bevel)\u00a0as other A2 blades which hardly ever chip in typical use. Even more annoyingly, the bad blade has behaved worse after some sharpenings than after others. I would think 33\u00b0 is high enough for the grain structure of A2, and anyway, going a bit higher gave little or no better results.<\/p>\n<p>Perhaps chipping is not a problem with any blades of one or more brands, and thus the problem could be avoided simply by choosing a good brand. <strong>Interestingly,<\/strong> I have two other A2 blades of the same brand as the Bad Blade that do not have this tendency to chip. I also have two Hock A2 blades that give me no such problems, and I had another blade of another brand that exhibited a milder but still troublesome tendency to chip.<\/p>\n<p><strong>This is not a tool test,<\/strong> so I cannot fairly generalize from this sample size as to which brand, if any, is best in this respect. I can only relate my experience. There is some <a href=\"http:\/\/www3.telus.net\/BrentBeach\/Sharpen\/Hock%20A2%20test.html\" target=\"_blank\" rel=\"noopener\">test evidence<\/a> that Hock A2 blades are indeed better in avoiding chipping, but this is based on testing a single blade. I wonder if one of the magazines might explore the issue using adequate sample sizes to account for potential variability within, as well as among, brands.<\/p>\n<p><strong>Which brings me to my main point:<\/strong> There seems to be considerable inconsistency among A2 plane blades \u2013 among brands, within at least some brands, and perhaps even within individual blades. To me, this uncertainty is a disadvantage of the A2 genre as a whole. That is not to dismiss A2 altogether, but simply to recognize this among its disadvantages<\/p>\n<p>So, for my bevel-down smoothing plane, it&#8217;s <strong>O1<\/strong>. A2 is just not worth it in that role; the uncertainty plus its inherent disadvantages outweigh its advantages. By the way, PMV-11 is another matter for another day, but I do currently use it in my bevel-up planes. And the Hock A2 in my good old bevel-down jack is going to stay there because the edge is wonderfully durable and it does not chip.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Before making my point, here is a synopsis of the differences between A2 and O1\u00a0blades, as I understand them, and have experienced in using them. Better however, you should also read a much more learned discussion by the Man of Steel himself, Ron Hock. In general, for comparable quality blades: O1 is finer grain steel [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"class_list":["post-4947","post","type-post","status-publish","format-standard","hentry","category-tools-and-shop"],"_links":{"self":[{"href":"https:\/\/www.rpwoodwork.com\/blog\/wp-json\/wp\/v2\/posts\/4947","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.rpwoodwork.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.rpwoodwork.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.rpwoodwork.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.rpwoodwork.com\/blog\/wp-json\/wp\/v2\/comments?post=4947"}],"version-history":[{"count":23,"href":"https:\/\/www.rpwoodwork.com\/blog\/wp-json\/wp\/v2\/posts\/4947\/revisions"}],"predecessor-version":[{"id":4971,"href":"https:\/\/www.rpwoodwork.com\/blog\/wp-json\/wp\/v2\/posts\/4947\/revisions\/4971"}],"wp:attachment":[{"href":"https:\/\/www.rpwoodwork.com\/blog\/wp-json\/wp\/v2\/media?parent=4947"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.rpwoodwork.com\/blog\/wp-json\/wp\/v2\/categories?post=4947"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.rpwoodwork.com\/blog\/wp-json\/wp\/v2\/tags?post=4947"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}