{"id":1685,"date":"2024-08-21T13:45:05","date_gmt":"2024-08-21T13:45:05","guid":{"rendered":"https:\/\/artchery.org\/wordpress\/?page_id=1685"},"modified":"2024-09-28T20:36:02","modified_gmt":"2024-09-28T20:36:02","slug":"yumi-making-re-examined","status":"publish","type":"page","link":"https:\/\/artchery.org\/wordpress\/index.php\/yumi-making-re-examined\/","title":{"rendered":"Yumi Making Re-Examined"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-page\" data-elementor-id=\"1685\" class=\"elementor elementor-1685\">\n\t\t\t\t\t\t\t<div class=\"elementor-element elementor-element-a01ad3c e-flex e-con-boxed e-con e-parent\" data-id=\"a01ad3c\" data-element_type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;,&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-19dd9b8 elementor-widget elementor-widget-heading\" data-id=\"19dd9b8\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<style>\/*! elementor - v3.18.0 - 08-12-2023 *\/\n.elementor-heading-title{padding:0;margin:0;line-height:1}.elementor-widget-heading .elementor-heading-title[class*=elementor-size-]>a{color:inherit;font-size:inherit;line-height:inherit}.elementor-widget-heading .elementor-heading-title.elementor-size-small{font-size:15px}.elementor-widget-heading .elementor-heading-title.elementor-size-medium{font-size:19px}.elementor-widget-heading .elementor-heading-title.elementor-size-large{font-size:29px}.elementor-widget-heading .elementor-heading-title.elementor-size-xl{font-size:39px}.elementor-widget-heading .elementor-heading-title.elementor-size-xxl{font-size:59px}<\/style><h2 class=\"elementor-heading-title elementor-size-default\">Yumi Making Re-Examined<\/h2>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-47bd97e e-flex e-con-boxed e-con e-parent\" data-id=\"47bd97e\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-cdf7ac3 elementor-widget elementor-widget-text-editor\" data-id=\"cdf7ac3\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<style>\/*! elementor - v3.18.0 - 08-12-2023 *\/\n.elementor-widget-text-editor.elementor-drop-cap-view-stacked .elementor-drop-cap{background-color:#69727d;color:#fff}.elementor-widget-text-editor.elementor-drop-cap-view-framed .elementor-drop-cap{color:#69727d;border:3px solid;background-color:transparent}.elementor-widget-text-editor:not(.elementor-drop-cap-view-default) .elementor-drop-cap{margin-top:8px}.elementor-widget-text-editor:not(.elementor-drop-cap-view-default) .elementor-drop-cap-letter{width:1em;height:1em}.elementor-widget-text-editor .elementor-drop-cap{float:left;text-align:center;line-height:1;font-size:50px}.elementor-widget-text-editor .elementor-drop-cap-letter{display:inline-block}<\/style>\t\t\t\t<p><strong>The photographs of Fig. 1 document an outcome of the yumi making process we describe here.\u00a0 The materials and design are mostly traditional.\u00a0 The main departure from tradition is the presence of 14 mill = 0.014&#8243; carbon laminations beneath the back and belly bamboo skins.\u00a0 They appear as the black lines in the third panel.\u00a0 They are an essential reason for re-examining the yumi making process.\u00a0 In the traditional process, the Urazori height right after lamination is typically much greater than the final 15-20 cm.\u00a0 The final Urazori shape is gradually approached by many sessions of heat aided bending.\u00a0 The initial lamination with carbon strips under the bamboo skins has very little malleability.\u00a0\u00a0 Hence, the\u00a0 lamination process must produce\u00a0 the correct Urazori shape at the outset.\u00a0 <br \/><\/strong><\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-caf2768 e-flex e-con-boxed e-con e-parent\" data-id=\"caf2768\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-2524da7 elementor-widget elementor-widget-image\" data-id=\"2524da7\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<style>\/*! elementor - v3.18.0 - 08-12-2023 *\/\n.elementor-widget-image{text-align:center}.elementor-widget-image a{display:inline-block}.elementor-widget-image a img[src$=\".svg\"]{width:48px}.elementor-widget-image img{vertical-align:middle;display:inline-block}<\/style>\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img fetchpriority=\"high\" decoding=\"async\" width=\"664\" height=\"633\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/Rokusun.jpg\" class=\"attachment-large size-large wp-image-1692\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/Rokusun.jpg 664w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/Rokusun-300x286.jpg 300w\" sizes=\"(max-width: 664px) 100vw, 664px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 1:  First panel:   overall shape with \"broken mirror symmetry\" proportions.  Second panel: upper strike plate.  Third panel:  side view in vicinity of the grip.  The thin black lines are the carbon laminations.   Fourth panel:  bottom strike plate and signature.<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e3d21b4 elementor-widget elementor-widget-text-editor\" data-id=\"e3d21b4\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-b544981 e-flex e-con-boxed e-con e-parent\" data-id=\"b544981\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-2299cfb elementor-widget elementor-widget-text-editor\" data-id=\"2299cfb\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>Not surprisingly, it is the layup that radically departs from tradition.\u00a0 Instead of the ropes and splints pictured in Fig. 3 of the article <a href=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2023\/12\/Aesthetics_geometry_and_the_yumi.pdf\">&#8220;Aesthetics, Geometry and the Yumi,&#8221;<\/a> the layup happens on the spline table depicted in Fig. 2.\u00a0 Clamping is achieved by an assembly of half cylinders and plumber&#8217;s band clamps, also evident in Fig. 2.\u00a0\u00a0 We return to details in due course.\u00a0\u00a0<\/p><p>For completeness, we describe the whole process, both in its debt to and departure from tradition.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-d367e56 e-flex e-con-boxed e-con e-parent\" data-id=\"d367e56\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-57af2e3 elementor-widget elementor-widget-image\" data-id=\"57af2e3\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" width=\"992\" height=\"676\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/clamp.jpg\" class=\"attachment-large size-large wp-image-1693\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/clamp.jpg 992w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/clamp-300x204.jpg 300w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/clamp-768x523.jpg 768w\" sizes=\"(max-width: 992px) 100vw, 992px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 2:  Band clamping of the laminations:  Top of yumi, bottom of yumi, and full length.<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-0340bab e-flex e-con-boxed e-con e-parent\" data-id=\"0340bab\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-121f6af elementor-widget elementor-widget-heading\" data-id=\"121f6af\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h4 class=\"elementor-heading-title elementor-size-default\">The bamboo grove<\/h4>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-8cc364a e-flex e-con-boxed e-con e-parent\" data-id=\"8cc364a\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-fe182c6 elementor-widget elementor-widget-text-editor\" data-id=\"fe182c6\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>Figure 3 shows an &#8220;entrance&#8221; into a bamboo grove in Durham NC\u00a0 where my\u00a0 culms are harvested.\u00a0 It is as thorny and brambly as it looks.\u00a0 Traditionally, harvesting happens in winter.\u00a0 I&#8217;ve harvested in late fall or early spring as well.\u00a0 Summer is hot, humid and buggy.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-438092b elementor-widget elementor-widget-image\" data-id=\"438092b\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" width=\"768\" height=\"1365\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/grove2-1-768x1365.jpg\" class=\"attachment-medium_large size-medium_large wp-image-1710\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/grove2-1-768x1365.jpg 768w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/grove2-1-169x300.jpg 169w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/grove2-1-576x1024.jpg 576w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/grove2-1-864x1536.jpg 864w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/grove2-1-1152x2048.jpg 1152w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/grove2-1-scaled.jpg 1440w\" sizes=\"(max-width: 768px) 100vw, 768px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 3:  Entering the bamboo grove.  Yes, it is as awful as it looks.<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-3a2a613 elementor-widget elementor-widget-text-editor\" data-id=\"3a2a613\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>In Fig. 4,\u00a0 the bright green culm to the right is young growth.\u00a0 Through attractive looking and unblemished, it is not what we are looking for.\u00a0\u00a0 The culm to the left is old growth.\u00a0 Old growth culms have a faded grey-green surface, often with blemishes.\u00a0\u00a0 They are harder and denser and more elastic than young growth.\u00a0 In addition, they have much better dimensional integrity under air drying and tempering.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9d28d49 elementor-widget elementor-widget-image\" data-id=\"9d28d49\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"270\" height=\"465\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/young_old.jpg\" class=\"attachment-large size-large wp-image-1711\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/young_old.jpg 270w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/young_old-174x300.jpg 174w\" sizes=\"(max-width: 270px) 100vw, 270px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 4:  Young and old growth culms.<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-f2cc309 e-flex e-con-boxed e-con e-parent\" data-id=\"f2cc309\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-0a36bfa elementor-widget elementor-widget-text-editor\" data-id=\"0a36bfa\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>The most exacting requirement of initial culm selection is related to nodal spacing.\u00a0 I have thin furring strips marked with white dots indicating nodal spacings for Namisun, Nissun, Yonson and Rokusun yumi.\u00a0 Figure 5 shows a culm which nicely matches the spacing of dots on the &#8220;Nissun&#8221; strip.\u00a0 The fussier you are about nodal spacings, the longer time you will spend in the bamboo grove.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-773002d e-flex e-con-boxed e-con e-parent\" data-id=\"773002d\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-26fcbd3 elementor-widget elementor-widget-image\" data-id=\"26fcbd3\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"624\" height=\"97\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/nodes.jpg\" class=\"attachment-large size-large wp-image-1716\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/nodes.jpg 624w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/nodes-300x47.jpg 300w\" sizes=\"(max-width: 624px) 100vw, 624px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 5:  The nodes of a this culm closely align with the white marks on the \"Nissun\"strip below it.<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-11da51c e-flex e-con-boxed e-con e-parent\" data-id=\"11da51c\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-bd9b259 elementor-widget elementor-widget-text-editor\" data-id=\"bd9b259\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>Once a culm is selected, the first job is to cut a roughly 300 cm length near its base free of branches and leaf nodes.\u00a0 The extra length gives flexibility in mating back and belly laminations with the nodes correctly positioned relative to each other.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-4fff0ce e-flex e-con-boxed e-con e-parent\" data-id=\"4fff0ce\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-aeae9d4 elementor-widget elementor-widget-heading\" data-id=\"aeae9d4\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h4 class=\"elementor-heading-title elementor-size-default\">Splitting, drying and heating of bamboo laminations<\/h4>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-27305ed elementor-widget elementor-widget-text-editor\" data-id=\"27305ed\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>The culms are split into strips somewhat wider than yumi immediately after harvesting.\u00a0 A traditional splitter consists of two wedges that cross at right angles.\u00a0 Culms typically have some bend, so the splitter has to be oriented so as to obtain two sections which can be laid out flat.\u00a0 The other two, which cannot, are cut into narrower strips for\u00a0 the yumi core.<\/p><p>My process begins by securing the ends of the culm with blocks and clamps so its center axis traces an arch in a vertical plane.\u00a0 A 1 1\/2&#8243; wide strip of masking tape straddles the ridge of the culm, marking one strip for a yumi lamination.\u00a0 Lengthwise cuts following the edges of the masking tape are executed with a Japanese pull saw.\u00a0 The cuts accurately trace the intended lines with pull strokes of minimal force. After the cuts are done, the strip marked by masking tape remains lightly secured to the culm by internal walls which span cross sections of the culm at nodes. Leave it in place. Now flip the \u201darch\u201d upside down, so what was formerly its \u201dunderside\u201d is exposed. The ends of the culm are elevated and its center touches down onto the work table. A second strip of masking tape straddling the ridge of this underside marks the second strip for a yumi lamination. Two more Japanese pull saw cuts follow the edges of the masking tape as before. After the second pair of cuts is done, the culm is easily deconstructed into the two yumi lamination strips, and two \u201dcurvy\u201d leftovers. These leftovers are easily band sawed into narrower strips about 1 cm wide for the yumi core.<\/p><p>The green, wet strips are passed through a spindle sander jig to produce a uniform width slightly greater than the width of the yumi limb at the grip.\u00a0 The inside surface is sanded flat to obtain a rougth approximation to a yumi lamination.\u00a0 The immediate processing of green culms into rough yumi laminations has these advantages: (i) It prevents splitting:\u00a0 As an intact culm dries, circumferential stresses which induce lengthwise splitting arise. Due to their much smaller cross section dimensions, the initial rough yumi laminations have much smaller internal stresses. They dry without splitting. (ii) Air drying is much faster:\u00a0 Due to all the cutting and sanding, the pithy, moisture-laden layers beneath the hard outer surface of the culm are much more exposed. Moisture content reaches a dry equilibrium in a few weeks.<\/p><div class=\"page\" title=\"Page 5\"><div class=\"layoutArea\"><div class=\"column\"><p>The cross sections of laminations cut from old growth are stable during\u00a0 rapid drying. Laminations cut from young growth, not so much. As the soft and moist inner layer contracts relative to the hard outer layer during drying, the cross section buckles as depicted in Fig. 6.<\/p><\/div><\/div><\/div>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-9549c5f e-flex e-con-boxed e-con e-parent\" data-id=\"9549c5f\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-2be469e elementor-widget elementor-widget-image\" data-id=\"2be469e\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"161\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/young-300x161.jpg\" class=\"attachment-medium size-medium wp-image-1725\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/young-300x161.jpg 300w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/young-768x413.jpg 768w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/young.jpg 1024w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 6:  The cross section of a young growth lamination buckles as it air dries.  (a)  Initial cross section.  (b)  Cross section after drying.<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-1ba15e1 elementor-widget elementor-widget-text-editor\" data-id=\"1ba15e1\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"page\" title=\"Page 5\"><div class=\"layoutArea\"><div class=\"column\"><p>The air dried rough laminations undergo a final heat treatment before refined sanding. Figure 7 shows the \u201doven.\u201d Two sections of 6\u201d diameter sheet metal stove pipe are joined to achieve a total length of 9\u2032. Inner 3\u201d diameter pipes are fastened inside the walls of the outer pipes. When the two outer pipes are joined, there is a gap between the two inner pipes. Heat guns placed at both ends drive streams of heated air towards this gap and they come out through the inner pipes. This design is adaptation of an oven developed for tempering bamboo fly fishing rods. A 250<sup>o<\/sup> to 300<sup>o<\/sup> temperature is established and maintained for a half hour. This is a bit below the requirements for real tempering. Nevertheless it drives out waxes and oils through the hard outer layers of the strips. The heat treatment alters the cross section of a strip as depicted in Fig. 8.<\/p><\/div><\/div><\/div>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-af07c15 e-flex e-con-boxed e-con e-parent\" data-id=\"af07c15\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-6a05c56 elementor-widget elementor-widget-image\" data-id=\"6a05c56\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"240\" height=\"604\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/oven.jpg\" class=\"attachment-large size-large wp-image-1732\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/oven.jpg 240w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/oven-119x300.jpg 119w\" sizes=\"(max-width: 240px) 100vw, 240px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 7:  Oven for heat treating bamboo laminations<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-60d22cf e-flex e-con-boxed e-con e-parent\" data-id=\"60d22cf\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-1ceb975 elementor-widget elementor-widget-image\" data-id=\"1ceb975\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"50\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/heat-300x50.jpg\" class=\"attachment-medium size-medium wp-image-1733\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/heat-300x50.jpg 300w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/heat-768x127.jpg 768w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/heat.jpg 1020w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 8:  Change in cross section induced by the treatment.  Dashed lines show the cross section before heating.  The solid lines show the cross section after heating.  The inside surface bulges into convexity.  It is flattened by later fine sanding.<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-88b4237 e-flex e-con-boxed e-con e-parent\" data-id=\"88b4237\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-7a4628b elementor-widget elementor-widget-heading\" data-id=\"7a4628b\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h4 class=\"elementor-heading-title elementor-size-default\">Fine shaping and pairing of bamboo laminations<\/h4>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2ef6cec elementor-widget elementor-widget-text-editor\" data-id=\"2ef6cec\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>Fine sanding begins by refining the uniform width of the bamboo laminations.\u00a0 The uniform width of\u00a0 all laminations, including the core, facilitates\u00a0 the potentially tricky layup with glue.\u00a0\u00a0 Next, the glaze of oils and waxes on the outer surfaces is cleaned away with fine steel wool doused in acetone.\u00a0\u00a0\u00a0 The outer bamboo surfaces are covered with blue masking tape which remains in place until the laminated yumi is cured.\u00a0 The inside surfaces of the laminations which became convex after heat treatment are sanded flat by a pass through the spindle sander.\u00a0\u00a0 Due to the irregular geometry of the convex outer surface with its nodal bumps, there is no fence for this pass through the spindle sander. It is done by hand, eye and feel.<\/p><div class=\"page\" title=\"Page 8\"><div class=\"layoutArea\"><div class=\"column\"><p>After the first pass, the maximum thickness of the cross section is measured with a digital caliper at a sequence of positions along the length, half way between adjacent nodes. The measurements are written down on the blue masking tape with a white out pen at the locations where they are taken. Corrective sanding follows, until all measured thicknesses are within 10% of a uniform value. For Don Symanski yumi I\u2019ve examined, 0.150\u201d is a typical thickness. A belly lamination pried off an old Japanese take-yumi is 0.200\u201d thick. My laminations tend to be thinner, between 0.100\u201d and 0.125\u201d thick. The dense, hard outer layer of the bamboo which provides most of the strength is about 2 mm \u2248 0.080\u201d thick. Material near the inner surface of a culm is much spongier and weaker than this hard outer layer.<\/p><\/div><p>Mating of back and belly pairs is straightforward if we use the two laminations that come from a single culm.\u00a0\u00a0 Any node of a belly lamination should be nearly half way between adjacent back nodes. Hence one lamination is displaced by half of a nodal spacing relative to the other. The laminations are oriented so that as we ascend the yumi from bottom to top, we ascend the culm in the direction it grew. The nodal spacing increases significantly as we ascend a bamboo culm, so the staggering of belly and back nodes relative to each other is approximate.<\/p><\/div><\/div>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-ff92030 elementor-widget elementor-widget-heading\" data-id=\"ff92030\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h5 class=\"elementor-heading-title elementor-size-default\">Belly laminations under the strike plates<\/h5>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-97e7955 elementor-widget elementor-widget-text-editor\" data-id=\"97e7955\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>Looking closely at the second panel of Fig. 1, you can see that the belly lamination continues under the strike plates.\u00a0\u00a0 This innovation was introduced by Don Symanski.\u00a0 In this construction, there is no vertical joint where the belly lamination ends and the strike plate begins, as you will see in older, more traditional constructions.\u00a0 Such a vertical joint is an obvious place of weakness.\u00a0<\/p><p>One question:\u00a0 How do you join the strike plate with the convex surface of the bamboo?\u00a0 You don&#8217;t.\u00a0 Figure 9 depicts an end segment of the belly bamboo sanded flat, and feathering to zero depth where the end of the strike plate will be.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-1cd2038 elementor-widget elementor-widget-image\" data-id=\"1cd2038\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"489\" height=\"134\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/belly_tip.jpg\" class=\"attachment-large size-large wp-image-1745\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/belly_tip.jpg 489w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/belly_tip-300x82.jpg 300w\" sizes=\"(max-width: 489px) 100vw, 489px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 9:  Outer surface of belly bamboo sanded flat to receive a strike plate.<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-8d6dd0b e-flex e-con-boxed e-con e-parent\" data-id=\"8d6dd0b\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-a8995d6 elementor-widget elementor-widget-heading\" data-id=\"a8995d6\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h4 class=\"elementor-heading-title elementor-size-default\">The yumi cross section and tapering<\/h4>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e02d6e7 elementor-widget elementor-widget-text-editor\" data-id=\"e02d6e7\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>Figure 10a depicts the cross section of a traditional take-yumi based on an illustration from the book &#8220;Kyudo: The Essense and Practice of Japanese Archery,&#8221;\u00a0 by Hideharu Onuma, with Dan and Jackie De Prospero.\u00a0 The side and middle strips of the core are hardwood. There are four bamboo strips, two on either side of the middle hardwood strip.\u00a0<\/p><div class=\"page\" title=\"Page 10\"><div class=\"layoutArea\"><div class=\"column\"><p>Figure 10b is a schematic cross section typical of my work. Some details: The hardwood strips are Hickory, whose strength and elasticity metrics are conspicuously greater than most domestic hardwoods. The growth rings are aligned close to vertical. The bamboo strips are thinner than traditional, so they consist mainly of the strong, dense fibers from the outer 2 mm layer of a culm. A thin Hickory lamination is included in addition to the traditional core. Its thickness is easily modified so that the overall limb thickness meets a design value, which in turn is related to the yumi strength. As mentioned before, the biggest departure from tradition is the inclusion of 10 mill = 0.010\u201d or 14 mill = 0.014\u201d unidirectional carbon laminations between back and belly bamboo and the core.\u00a0\u00a0 These are indicated by the thick black horizontal line segments in Fig. 10b.\u00a0 Another departure from tradition is the overall shape of cross section. A traditional cross section is trapezoidal, with the back lamination wider than the belly. My cross sections are closer to rectangular. They are also thinner, relative to the cross section of a Take-yumi of similar strength.<\/p><\/div><\/div><\/div>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-59c6c01 e-flex e-con-boxed e-con e-parent\" data-id=\"59c6c01\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-ea0788e elementor-widget elementor-widget-image\" data-id=\"ea0788e\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"250\" height=\"300\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/cross_sections-250x300.jpg\" class=\"attachment-medium size-medium wp-image-1754\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/cross_sections-250x300.jpg 250w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/cross_sections.jpg 429w\" sizes=\"(max-width: 250px) 100vw, 250px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 10:  (a)  Typical cross section of a traditional take-yumi.  The back lamiation is above the  belly lamination.  (b)  Yumi cross section typical of my work, with carbon laminations between bamboo skins and the core.<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-b7e7cb9 elementor-widget elementor-widget-text-editor\" data-id=\"b7e7cb9\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>The cross section is not uniform along the length of the yumi. \u00a0 The widths of Don Symanski yumi have\u00a0 modest tapering as we proceed from the grip to either tip, on the order of 10%.\u00a0\u00a0 The thickness of a Don Symanski yumi also tapers, so the thickness at either tip is close to 3\/4 the thickness at the grip.\u00a0 The bamboo skins have close to uniform thickness, so the thickness tapering is mainly in the core.<\/p><p>The preparation of\u00a0 hardwood and bamboo strips for the core with their rectangular cross sections is straightforward.\u00a0 The surfaces of the strips that join in glue lines are coated with EA 40 smooth-on epoxy.\u00a0 The proportion of resin to hardener is two to one by weight. \u00a0 The main innovation is the layup, depicted in Fig. 11.\u00a0 The half cylinders come from 1\u201d dowels cut lengthwise in half. Polyethylene is glued to their flat surfaces which contact the core. The half cylinders press the core from above and below when band clamps which wrap around them are tightened. The width of the core should exceed the 1\u201d width of half cylinders and the aluminum strip so the band clamps press the core from the sides as well.\u00a0 After the clamps are secured, the clamped core is inserted into the long oven depicted in Fig. 7. The two heat guns with their lowest fan and heat settings easily maintain a curing temperature of 130 <sup>o<\/sup> for six hours. Finally, the cured cores are passed through a spindle sander jig to create an initially uniform thickness with clean, flat surfaces.<\/p><div class=\"page\" title=\"Page 12\"><div class=\"layoutArea\"><div class=\"column\"><p>Later, when we laminate the Urazori shape of the yumi, the band clamp system really comes into its own. The surfaces of half cylinders which contact the back and belly laminations are cambered to match their convexity. The band clamp system easily accommodates the curves of the Urazori shape.<\/p><div class=\"page\" title=\"Page 15\"><div class=\"layoutArea\"><div class=\"column\"><p>How is core tapering actually carried out in the shop? Since my cores tend to be thin relative to typical take-yumi, large and powerful machines such as thickness planers are risky. The thin tapers used in western bow limbs are shaped by belt sander jigs. The slow but highly controlled sanding process allows you to achieve thicknesses less than half a millimeter. In my shop, I have \u201dreference tapers.\u201d These are strips 4 cm wide and 1.5 m long, with thickness tapering rates of 0.002 mm\/mm or 0.003 mm\/mm. These can be tacked onto cores with rubber cement. The cores backed with tapers are run through a spindle sander jig, with the taper against the fence. Tapering above the grip uses the 0.002 mm\/mm taper, and the tapering below uses 0.003 mm\/mm.<\/p><\/div><\/div><\/div><\/div><\/div><\/div>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-2016f4c e-flex e-con-boxed e-con e-parent\" data-id=\"2016f4c\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-67f1446 elementor-widget elementor-widget-image\" data-id=\"67f1446\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"634\" height=\"225\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/clamp_core.jpg\" class=\"attachment-large size-large wp-image-1759\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/clamp_core.jpg 634w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/clamp_core-300x106.jpg 300w\" sizes=\"(max-width: 634px) 100vw, 634px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 11:  Layup of the core.<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-7290f14 e-flex e-con-boxed e-con e-parent\" data-id=\"7290f14\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-c1be3ce elementor-widget elementor-widget-heading\" data-id=\"c1be3ce\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h4 class=\"elementor-heading-title elementor-size-default\">Spline table lamination of the Urazori shape<\/h4>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2966557 elementor-widget elementor-widget-text-editor\" data-id=\"2966557\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>As mentioned in the beginning, the shapes of yumi with carbon strips between back and belly bamboo laminations cannot be modified by heat aided bending, so the initial layup must achieve the correct Urazori shape at the outset.\u00a0 The &#8220;spline table&#8221; layup shown in Fig. 2 has\u00a0 more precision and control than the traditional ropes and splints process.\u00a0 Here, we explain the details.\u00a0<\/p><div class=\"page\" title=\"Page 16\"><div class=\"layoutArea\"><div class=\"column\"><p>The approximate reconstruction of a curve in the plane from a sampling of points along it is called interpolation.\u00a0 Here is how it was done in the era before digital computers:\u00a0 Heavy brass cylinders are laid on top of the graph, each &#8220;kissing&#8221; one of the sample points.\u00a0 An elastic strip, called a &#8220;spline&#8221; is threaded through the maze of cylinders.\u00a0 After some trial and error adjustment, the spline passes through all of the sample points, so defining a smooth curve that &#8220;interpolates&#8221; the sample points.\u00a0<\/p><p>The &#8220;spline table&#8221; depicted in Fig. 2 has two inch diameter pine cylinders\u00a0 secured to an 8\u2032 1\u2032\u2032 \u00d7 12\u2032\u2032 pine board by 1\/2\u2032\u2032 hex bolts.\u00a0 These are analogous to the brass cylinders placed on the scientist&#8217;s graph paper.\u00a0 The &#8220;spline&#8221; is in fact the uncured yumi threaded through the cylinders.\u00a0 The aforementioned trial and error adjustment is done with the dry stacked laminations (no glue).\u00a0 The cylinder placements are adjusted until the surface of the back bamboo closely follows the prescribed Urazori shape which is penciled on the table beforehand.<\/p><\/div><\/div><\/div><p>Figure 12 depicts the Urazori shape for a Nissun yumi to be traced on the spline table.\u00a0 The hollow dots mark curve endpoints, the solid dots, midpoints.\u00a0 The curve endpoints are labeled by their Cartesian coordinates in cm.\u00a0 The perpendicular displacements of midpoints from the chord lines connecting endpoints are indicated, also in cm.\u00a0 This shape is the embodiment of &#8220;broken mirror symmetry&#8221; as formulated in the article, <a href=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2023\/12\/Aesthetics_geometry_and_the_yumi.pdf\">&#8220;Aesthetics, Geometry and the Yumi.&#8221;<\/a> Similar Urazori curves are constructed for the other yumi sizes, Namisun, Yonsun and Rokusun.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-58546dc e-flex e-con-boxed e-con e-parent\" data-id=\"58546dc\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-6ebc24b elementor-widget elementor-widget-image\" data-id=\"6ebc24b\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"159\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/Urazori_layout-1024x159.jpg\" class=\"attachment-large size-large wp-image-1772\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/Urazori_layout-1024x159.jpg 1024w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/Urazori_layout-300x47.jpg 300w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/Urazori_layout-768x119.jpg 768w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/Urazori_layout.jpg 1257w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 12:  Lay out of Urazori curves for Nissun yumi.    <\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9c2bb17 elementor-widget elementor-widget-text-editor\" data-id=\"9c2bb17\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>Figure 13 depicts the spline table with a yumi core serving as the spline.\u00a0 There are cylinders close to the curve endpoints and midpoints.\u00a0 The arrows give a qualitative sense of the forces upon the spline inposed by the cylinders.\u00a0\u00a0 The dashed circle indicates a &#8220;missing&#8221; cylinder marking the left endpoint of the top curve.\u00a0 It isn&#8217;t needed, since the spline nicely interpolates this endpoint with no force required.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-7376327 e-flex e-con-boxed e-con e-parent\" data-id=\"7376327\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-3cd14a4 elementor-widget elementor-widget-image\" data-id=\"3cd14a4\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"181\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/spl_table-1024x181.jpg\" class=\"attachment-large size-large wp-image-1777\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/spl_table-1024x181.jpg 1024w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/spl_table-300x53.jpg 300w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/spl_table-768x136.jpg 768w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/spl_table.jpg 1160w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 13:  Dry run of the spline table.<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-9291ca8 e-flex e-con-boxed e-con e-parent\" data-id=\"9291ca8\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-a5d11f7 elementor-widget elementor-widget-heading\" data-id=\"a5d11f7\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h4 class=\"elementor-heading-title elementor-size-default\">No-drama layup<\/h4>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d03132a elementor-widget elementor-widget-text-editor\" data-id=\"d03132a\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<p>A visual preview of the layup is shown in Fig. 2.\u00a0 Here, we fill in details.\u00a0 All surfaces of laminations which join in glue lines are coated with the EA 40 Smooth-on epoxy. As mentioned before, the proportion of resin to hardener is two to one by weight. There are simple common sense details. For instance, let\u2019s say we have coated the joining surface of the belly bamboo. We lay it coated face up on the work table and place one of the carbon strips on it. We wet the exposed surface of the carbon strip, peel it off the belly bamboo and lay it back on with the coated face joining the coated bamboo surface. The partially coated carbon surface is now fully coated. Now lay the core on top of the carbon strip and wet the exposed surface. Again peel it off and lay it back on coated side down. As with the carbon strip before it, the partially coated core surface is now fully coated. It is clear how this process continues with subsequent laminations. The strike plates are joined to the assembly. The joining surfaces of the strike plates are not flat, but curve so the top and bottom yumi curves continue over the lengths of the essentially rigid strike plates. The completed stack of laminations is not stable due to \u201dlubrication\u201d by uncured glue. The stack is loosely secured by masking tape wrappings or small zip ties.<\/p><div class=\"page\" title=\"Page 19\"><div class=\"layoutArea\"><div class=\"column\"><p>Now comes the installation of the band clamps and half cylinders in a configuration similar to Fig. 11. The surfaces of the half cylinders are concave so they fit snugly on the convex bamboo surfaces. There is some common sense logistics. The band clamps are already closed, and we \u201dstring\u201d them along the proto-yumi like beads on a necklace. We concentrate them in appropriate bunches so they don\u2019t get in the way when we thread the proto- yumi through the cylinders of the spline table. Now, one by one, we insert the half cylinders and lightly tighten the band clamp screws. In addition to the cylinders with the nominal 2\u201d length, we have short extras, 1\u201d or 1\/2\u201d long, to deal with irregularities like bamboo nodes, or proximity to a spline table cylinder.\u00a0 The panels of Fig. 2 labeled &#8220;top&#8221; and &#8220;bottom&#8221; show how the band clamp process is modified along the sections with the strike plates.<\/p><div class=\"page\" title=\"Page 19\"><div class=\"layoutArea\"><div class=\"column\"><p>Now comes the installation of the band clamps and half cylinders in a configuration similar to Fig. 14. The surfaces of the half cylinders are concave so they fit snugly on the convex bamboo surfaces. There is some common sense logistics. The band clamps are already closed, and we \u201dstring\u201d them along the proto-yumi like beads on a necklace. We concentrate them in appropriate bunches so they don\u2019t get in the way when we thread the proto- yumi through the cylinders of the spline table. Now, one by one, we insert the half cylinders and lightly tighten the band clamp screws. In addition to the cylinders with the nominal 2\u201d length, we have short extras, 1\u201d or 1\/2\u201d long, to deal with irregularities like bamboo nodes, or proximity to a spline table cylinder. We also need to adapt the band clamp process to the sections with the strike plates.<\/p><div class=\"page\" title=\"Page 19\"><div class=\"layoutArea\"><div class=\"column\"><p>The Urazori shape is very close to a plane curve: 1\/8&#8243; spacers seperate the layup from the flat surface of the spline table. The final step of the layup is to tighten all the band clamp screws, sufficient to close all glue lines. For epoxy, the tightness need not be excessive. The layup process is detailed and fiddly. How long does it\u00a0 take?\u00a0\u00a0 From mixing the epoxy to the final tightening of clamps, two hours. Well within the the working time of the EA &#8211; 40 Smooth on epoxy.<\/p><div class=\"page\" title=\"Page 20\"><div class=\"layoutArea\"><div class=\"column\"><p>Figure 14 shows how the spline table is the floor of a \u201dcuring oven.\u201d The two heat guns at either end are set to a 280 <sup>o<\/sup> F temperature, which is low for them, and at the lowest fan setting. In the photograph to the right, the lid of the oven has been installed, along with three digital meat thermometers. The heat transfer is by air convection, and a steady oven temperature of 130 <sup>o<\/sup> F is soon achieved and maintained over a cure time of six hours.<\/p><\/div><\/div><\/div><\/div><\/div><\/div><\/div><\/div><\/div><\/div><\/div><\/div>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-f35299f e-flex e-con-boxed e-con e-parent\" data-id=\"f35299f\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-b0bdb84 elementor-widget elementor-widget-image\" data-id=\"b0bdb84\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t<figure class=\"wp-caption\">\n\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"768\" height=\"389\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/yumi_oven-768x389.jpg\" class=\"attachment-medium_large size-medium_large wp-image-1790\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/yumi_oven-768x389.jpg 768w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/yumi_oven-300x152.jpg 300w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2024\/08\/yumi_oven.jpg 845w\" sizes=\"(max-width: 768px) 100vw, 768px\" \/>\t\t\t\t\t\t\t\t\t\t\t<figcaption class=\"widget-image-caption wp-caption-text\">Fig. 14: Left: Spline table serves as a floor of the curing oven. Right: Curing oven with the lid installed.<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-22355de e-flex e-con-boxed e-con e-parent\" data-id=\"22355de\" data-element_type=\"container\" data-settings=\"{&quot;content_width&quot;:&quot;boxed&quot;}\" data-core-v316-plus=\"true\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-c2325c9 elementor-widget elementor-widget-heading\" data-id=\"c2325c9\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h4 class=\"elementor-heading-title elementor-size-default\">Finish work<\/h4>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-ab46ff4 elementor-widget elementor-widget-text-editor\" data-id=\"ab46ff4\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"page\" title=\"Page 20\"><div class=\"layoutArea\"><div class=\"column\"><p>We pass the cured yumi lamination though a spindle sander jig to clean glue dribble from the sides and impose a uniform width along its entire length. We cut and shape the notches at the tips that hold the tsuru loops. We can brace the proto-yumi for a first look at its shape.<\/p><p>The 10% tapering of the yumi&#8217;s width from the grip to either end is carefully controlled:\u00a0 Paper strips glued to the belly bamboo serve as templates.\u00a0 The nominal 10% tapering may be modified by contingencies. For instance, if the the braced shape indicates too much stiffness in the upper limb, we may taper it a bit more than the nominal 10%. Tricks like this produce very modest shape changes, so the initial un-tapered shape should not be too far off.<\/p><div class=\"page\" title=\"Page 21\"><div class=\"layoutArea\"><div class=\"column\"><p>Next we produce the traditional rounding of the yumi\u2019s sides. Since the yumi lamination includes carbon which is extremely destructive to steel rasps, we use improvised rasps consisting of 50 grit belt sander strips glued to 18\u2032\u2032 by 2\u2032\u2032 wooden slats. The rounding of the sides with the belt sander rasps is somewhat tedious. Nevertheless some attention to detail is recommended. Sections of yumi near bamboo nodes are more resistant to abrasion. Careless rasp work can result in yumi with scalloped sides. I\u2019ve seen it (not in Don Symanski yumi).<\/p><p>Finally, there is the truly tedious business of finish sanding as one eliminates all of the scratches due to the 50 grit sanding belt rasps. In particular, the first coat of lacquer or polyurethane over sanded surfaces tends to reveal hidden scratches and you go back to sanding.<\/p><\/div><\/div><\/div><\/div><\/div><\/div>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-39dac8d elementor-widget elementor-widget-heading\" data-id=\"39dac8d\" data-element_type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t<h5 class=\"elementor-heading-title elementor-size-default\">Grip underlayment<\/h5>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-dea6adf elementor-widget elementor-widget-text-editor\" data-id=\"dea6adf\" data-element_type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"page\" title=\"Page 21\"><div class=\"layoutArea\"><div class=\"column\"><p>Grip underlayment, nigiri, and rattan work are in the realm of routine maintenance, so we don\u2019t dwell on them, save for one innovation: A traditional grip underlayment may be consist of paper layers stuck together with wheat paste or glue, or rubber strips with a rounded upper surface. Alternatively, one can saturate layers of leather in water-based wood glue and stack them to produce a thickness on the order of a quarter inch. The stack is taped to a PVC pipe with a 3\u2032\u2032 radius and allowed to cure. The cured stack fits nicely onto the convex surface of the belly bamboo. The cured stack is trimmed to proper length and width. Finally, it is sculpted with sanding drums of a Dremel tool to produce customized shapes upon request. The finished underlayment is secured to the yumi with contact cement.<\/p><\/div><\/div><\/div>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-0baf052 elementor-widget elementor-widget-image\" data-id=\"0baf052\" data-element_type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"547\" height=\"32\" src=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2023\/12\/watakuri.jpg\" class=\"attachment-large size-large wp-image-80\" alt=\"\" srcset=\"https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2023\/12\/watakuri.jpg 547w, https:\/\/artchery.org\/wordpress\/wp-content\/uploads\/2023\/12\/watakuri-300x18.jpg 300w\" sizes=\"(max-width: 547px) 100vw, 547px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>Yumi Making Re-Examined The photographs of Fig. 1 document an outcome of the yumi making process we describe here.\u00a0 The materials and design are mostly traditional.\u00a0 The main departure from tradition is the presence of 14 mill = 0.014&#8243; carbon laminations beneath the back and belly bamboo skins.\u00a0 They appear as the black lines in &hellip;<\/p>\n<p class=\"read-more\"> <a class=\"\" href=\"https:\/\/artchery.org\/wordpress\/index.php\/yumi-making-re-examined\/\"> <span class=\"screen-reader-text\">Yumi Making Re-Examined<\/span> Read More &raquo;<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"site-sidebar-layout":"no-sidebar","site-content-layout":"","ast-site-content-layout":"full-width-container","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"disabled","ast-breadcrumbs-content":"","ast-featured-img":"disabled","footer-sml-layout":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"footnotes":""},"class_list":["post-1685","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/artchery.org\/wordpress\/index.php\/wp-json\/wp\/v2\/pages\/1685","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/artchery.org\/wordpress\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/artchery.org\/wordpress\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/artchery.org\/wordpress\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/artchery.org\/wordpress\/index.php\/wp-json\/wp\/v2\/comments?post=1685"}],"version-history":[{"count":298,"href":"https:\/\/artchery.org\/wordpress\/index.php\/wp-json\/wp\/v2\/pages\/1685\/revisions"}],"predecessor-version":[{"id":2736,"href":"https:\/\/artchery.org\/wordpress\/index.php\/wp-json\/wp\/v2\/pages\/1685\/revisions\/2736"}],"wp:attachment":[{"href":"https:\/\/artchery.org\/wordpress\/index.php\/wp-json\/wp\/v2\/media?parent=1685"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}