Thicket data repository for the EEG
anil.recoil.org
1{
2 "id": "https://www.tunbury.org/2021/08/16/ratchet-adapter",
3 "title": "Ratchet Adapter",
4 "link": "https://www.tunbury.org/2021/08/16/ratchet-adapter/",
5 "updated": "2021-08-16T19:41:29",
6 "published": "2021-08-16T19:41:29",
7 "summary": "I want to electrically drive this ratchet mechanism to avoid the manual labour of turning it by hand. I found a motor with a 1600:1 gearbox on eBay (shipping from China of course) which looks perfect, however it has a 10mm diameter keyed output shaft which doesn’t nicely couple to my 3/4” square ratchet shaft.",
8 "content": "<p>I want to electrically drive this ratchet mechanism to avoid the manual labour of turning it by hand. I found a motor with a 1600:1 gearbox on eBay (shipping from China of course) which looks perfect, however it has a 10mm diameter keyed output shaft which doesn’t nicely couple to my 3/4” square ratchet shaft.</p>\n\n<p><img alt=\"Ratchet with pipe\" src=\"https://www.tunbury.org/images/ratchet-with-pipe.png\"></p>\n\n<p>From the photo it is clear that a 1” steel tube fits reasonably well over the shaft. A wooden plug and a little bit of brute force provided a flat surface which was pre-drilled and a flang screwed on.</p>\n\n<p><img alt=\"Wooden block version\" src=\"https://www.tunbury.org/images/wooden-block.png\"></p>\n\n<p>This worked fairly well except that the grub screw on the flang was insufficent to withstand the forces required. Therefore a keyway was cut into the flang to prevent slipping.</p>\n\n<p><img alt=\"Flang with keyway\" src=\"https://www.tunbury.org/images/flang-key-1.png\"></p>\n\n<p>And a key was made to fit.</p>\n\n<p><img alt=\"Flange with key\" src=\"https://www.tunbury.org/images/flang-key-2.png\"></p>\n\n<p>This worked very well, but unfortunately about two years later things took a nasty turn. One of the screws snapped and others were about to pull out.</p>\n\n<p><img alt=\"Wear and tear\" src=\"https://www.tunbury.org/images/wear-and-tear.png\"></p>\n\n<p>Taking the 1” tube and turning it sideways gave a metal surface on to which the flang could be bolted. Cutting a hole in the bottom side of the tube would accomodate the 3/4” ratchet shaft.</p>\n\n<p><img alt=\"Pipe with holes and cutout\" src=\"https://www.tunbury.org/images/ratchet-connector-with-cutout.png\"></p>\n\n<p>And with the flang in place it looks ready for use.</p>\n\n<p><img alt=\"Flang in place\" src=\"https://www.tunbury.org/images/ratchet-connector-flang.png\"></p>\n\n<p>Hopefully this will last a little longer this time.</p>\n\n<p><img alt=\"Ready for operation\" src=\"https://www.tunbury.org/images/in-operation.png\"></p>",
9 "content_type": "html",
10 "author": {
11 "name": "Mark Elvers",
12 "email": "mark.elvers@tunbury.org",
13 "uri": null
14 },
15 "categories": [
16 "raspberrypi",
17 "obs"
18 ],
19 "source": "https://www.tunbury.org/atom.xml"
20}