{"id":1104,"date":"2019-04-03T22:29:57","date_gmt":"2019-04-03T22:29:57","guid":{"rendered":"http:\/\/www.gregkuchyt.net\/?page_id=1104"},"modified":"2019-04-03T22:30:49","modified_gmt":"2019-04-03T22:30:49","slug":"lathe-chuck-key","status":"publish","type":"page","link":"https:\/\/www.gregkuchyt.net\/?page_id=1104","title":{"rendered":"Lathe chuck key"},"content":{"rendered":"\n

Nothing crazy exciting here. We needed a new lathe chuck key for our Sharp 1340 lathe. Our spindle nose uses a D-4 camlock system which shares a 3\/8″ square drive with 3-jaw and 4-jaw chucks. Our 5C collet chuck uses a smaller, metric square drive and has its own key.<\/p>\n\n\n\n

One of the biggest things we needed was a shaft height that cleared the headstock as the hold-over chuck key we had would frustrating wrap your knuckles into the head stock. As a frequent 4-jaw user I also wanted enough leverage to be able to crank down a 4-jaw chuck.<\/p>\n\n\n\n

So I set into Fusion360 to design a new chuck (drawing below). I decided on using 1144 (aka stress-proof) for the handle as it’s been partially heat-treated and tempered to create a stable material with some durability. The chuck key we had previously was made of CRS and eventually work-hardened and then rolled over at the edges to the point that it spun in the square drive slot.<\/p>\n\n\n\n

The new skill I shot for here was to work on shrink fits. I had designed this to work as an FN2 fit. Unfortunately that didn’t go as well as I was hoping. Even though I had worked out the thermal expansion numbers I was able to get the parts to slip fit. I need to read more as to whether FN2 implies a press fit assembly. Based on my numbers though by heading the chuck body to 400\u00b0 F and and cooling the handle shaft to about -30\u00b0 F, I should have had a slip fit.<\/p>\n\n\n\n

Lacking any machine tool grinding capabilities, I ended up bumbling around on the lathe with some abrasives to knock down the diameter to get to the point where I was able to get a light interference fit that required hammering with a brass hammer to drive the handle into place. So, FN1?<\/p>\n\n\n\n

Time will tell how this holds up.<\/p>\n\n\n\n

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Finished product<\/figcaption><\/figure>\n\n\n\n
Lathe Chuck Key Drawing v9<\/a>Download<\/a><\/div>\n\n\n\n
Lathe Chuck Key Handle Drawing v1<\/a>Download<\/a><\/div>\n","protected":false},"excerpt":{"rendered":"

Nothing crazy exciting here. We needed a new lathe chuck key for our Sharp 1340 lathe. Our spindle nose uses a D-4 camlock system which shares a 3\/8″ square drive with 3-jaw and 4-jaw chucks. Our 5C collet chuck uses a smaller, metric square drive and has its own key. One of the biggest things […]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":1096,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1104","page","type-page","status-publish","hentry"],"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/P4mwGD-hO","_links":{"self":[{"href":"https:\/\/www.gregkuchyt.net\/index.php?rest_route=\/wp\/v2\/pages\/1104","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.gregkuchyt.net\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.gregkuchyt.net\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.gregkuchyt.net\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gregkuchyt.net\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1104"}],"version-history":[{"count":3,"href":"https:\/\/www.gregkuchyt.net\/index.php?rest_route=\/wp\/v2\/pages\/1104\/revisions"}],"predecessor-version":[{"id":1110,"href":"https:\/\/www.gregkuchyt.net\/index.php?rest_route=\/wp\/v2\/pages\/1104\/revisions\/1110"}],"up":[{"embeddable":true,"href":"https:\/\/www.gregkuchyt.net\/index.php?rest_route=\/wp\/v2\/pages\/1096"}],"wp:attachment":[{"href":"https:\/\/www.gregkuchyt.net\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1104"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}