{"id":524,"date":"2020-03-19T22:13:57","date_gmt":"2020-03-20T02:13:57","guid":{"rendered":"http:\/\/www.irrelevant-tech.com\/?p=524"},"modified":"2020-04-08T18:01:23","modified_gmt":"2020-04-08T22:01:23","slug":"knurling-on-a-small-lathe","status":"publish","type":"post","link":"https:\/\/www.irrelevant-tech.com\/index.php\/2020\/03\/19\/knurling-on-a-small-lathe\/","title":{"rendered":"Knurling on a Small Lathe"},"content":{"rendered":"

First a short note on lathe safety.\u00a0 Modern industrial CNC lathes and machining centers have comprehensive safety systems including guards and light curtains.\u00a0 Hobby and bench lathes are a completely different animal.\u00a0 While a table saw or band saw will take off fingers, carelessness with a lathe will kill you.\u00a0 Do not wear long sleeves or jewelry to include rings, bracelets, wristwatches, or necklaces.\u00a0 Do not wear gloves.\u00a0 Do not wear a tie, Bolo, or scarf.\u00a0 Tie your hair back if it’s long.\u00a0 Do not wrap crocus or emery cloth around your fingers to polish a moving part.\u00a0 If you’ve had a drink, put off the lathe work until tomorrow.\u00a0 Operating a lathe requires continuous attention, concentration, and clear judgement.\u00a0 If you are interrupted or distracted, disengage the feed and step away from the lathe before turning to address the issue.<\/p>\n

Knurling on a lathe is usually performed with a push type toothed roller tool as shown in figure 1.\u00a0 The tool is pushed into the rotating part using the cross-slide.\u00a0 This works fairly well on 12 – 14 inch and larger lathes.\u00a0 Scaled down versions are traditionally supplied with smaller 6 and 7 inch lathes.\u00a0 Figure 1 illustrates the tool supplied with the 6 inch Atlas lathe.\u00a0 Using Atlas as an example, the 6 inch lathe looks just like the 12 inch, only scaled down.\u00a0 The problem here is that a 6 inch lathe is not adequate to press regular knurls into harder materials like steel or brass.\u00a0 The lantern tool holder and the cross-slide are simply not strong enough.\u00a0 While it looks like it ought to work,\u00a0 for proportional cross sections, a 12 inch lathe is 8 times stiffer and stronger in bending and 16 times stiffer and stronger in twisting than a 6 inch.\u00a0 On YouTube, mrpete222 (tubalcain) has videos (#333-#336 ) about making a new 6 inch Atlas cross-slide to replace a broken one that obviously had too much force applied to the tool post.\u00a0 I speak as someone who has broken a 6 inch Atlas\/Craftsman lantern, although not while knurling.\u00a0 The one in figure 1 is a slightly beefed up O1 replacement tempered to RC50.<\/p>\n

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Figure 1<\/figcaption><\/figure>\n

Another problem with push type knurlers is that the stock has to be strong enough to resist bending under the knurling force and may need to be supported with a live center or steady rest.<\/p>\n

A solution to both problems is the pinch style knurler shown in figure 2.\u00a0 In this style the part is trapped between an upper and lower roller.\u00a0 Depending upon the model, the diameter is adjustable from 1 or 2 inches down to zero.\u00a0 Since all the knurl force is due to the pinch between rollers there are no unbalanced forces against the work piece or the tool holder.\u00a0 This allows knurls on unsupported long parts without difficulty.\u00a0 The cross-slide simply centers the knurl wheels on the part and the carriage travel is used to make longer knurls. \u00a0 As a result deep knurls on steel are easily produced even on the smallest lathes.\u00a0 The remaining difficulty is that to start the knurl, the work piece needs to be turning while the clamping knob is tightened to the desired depth.\u00a0\u00a0 On short parts to be knurled near the chuck the small clearance between the spinning chuck and the hand adjust knob creates a major safety problem.\u00a0 Figure 2 shows a stock tool.<\/p>\n

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Figure 2<\/figcaption><\/figure>\n

Here is the solution I came up with for my lathe.\u00a0 A 3 inch extension of the clamp knob moves my hand far enough from the chuck for comfort.\u00a0 I am not suggesting that you do this, just reporting on my solution to a perceived hazard.<\/p>\n

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Figure 3<\/figcaption><\/figure>\n

I used a through tapped spacer from McMaster-Carr for the thread as I didn’t have a deep hole M6 tap and didn’t feel like counter boring all the way from the top.<\/p>\n

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This is pretty mundane but now there’s one less thing for me to worry about.\u00a0 By the way, the 0XA quick change tool holder as shown works well on the Atlas 6 inch.\u00a0 Cutoffs are WAY better.\u00a0 You will need to cut rabbets on the plate that comes with the tool holder as can be seen in figure 2.\u00a0 A single piece of steel the thickness of the T-slot is not strong enough for a solid tool holder lock-down.\u00a0 It flexes and doesn’t have enough thread engagement.<\/p>\n

Please leave comments using the post in my comments category.<\/p>\n","protected":false},"excerpt":{"rendered":"

First a short note on lathe safety.\u00a0 Modern industrial CNC lathes and machining centers have comprehensive safety systems including guards and light curtains.\u00a0 Hobby and bench lathes are a completely different animal.\u00a0 While a table saw or band saw will take off fingers, carelessness with a lathe will kill you.\u00a0 Do not wear long sleeves … Continue reading “Knurling on a Small Lathe”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[72],"class_list":["post-524","post","type-post","status-publish","format-standard","hentry","category-engineering","tag-small-lathe"],"_links":{"self":[{"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/posts\/524","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/comments?post=524"}],"version-history":[{"count":19,"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/posts\/524\/revisions"}],"predecessor-version":[{"id":632,"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/posts\/524\/revisions\/632"}],"wp:attachment":[{"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/media?parent=524"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/categories?post=524"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.irrelevant-tech.com\/index.php\/wp-json\/wp\/v2\/tags?post=524"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}