http://diylilcnc.org/forum/tags/switch Free, open-source plans for a low-cost 3-axis CNC mill by Taylor Hokanson and Chris Reilly. Sponsored by the School of the Art Institute of Chicago. en-US Wed, 22 May 2013 05:28:28 +0000 http://bbpress.org/?v=1.0.2 q http://diylilcnc.org/forum/search.php http://diylilcnc.org/forum/topic/limit-switches#post-247 Mon, 08 Feb 2010 21:53:40 +0000 DIYengineer 247@http://diylilcnc.org/forum/ <p>Ok! 9+1 switches ordered! (One extra just in case i need a backup laying around, just as you suggested, not a bad idea!). Hobby CNC said the pro board will handle all 9 as well with ease. </p> http://diylilcnc.org/forum/topic/limit-switches#post-243 Sun, 07 Feb 2010 17:13:03 +0000 Chris 243@http://diylilcnc.org/forum/ <p>One more point, if you construct the limit switches <a href="http://en.wikipedia.org/wiki/Series_and_parallel_circuits">in series</a> as mentioned above in the HobbyCNC instructions, you'll only end up needing one board input for each axis, leaving you with one to spare. </p> http://diylilcnc.org/forum/topic/limit-switches#post-242 Sun, 07 Feb 2010 11:54:33 +0000 Taylor 242@http://diylilcnc.org/forum/ <p>9 is exactly how many you need (assuming you don't plan on making any mistakes ;)). Check the HobbyCNC documentation to check on whether the board can handle that number of switches. I imagine it can, but I'm not sure. </p> http://diylilcnc.org/forum/topic/limit-switches#post-241 Sat, 06 Feb 2010 17:56:11 +0000 DIYengineer 241@http://diylilcnc.org/forum/ <p>You explained that extremely well, thank you. If I wanted to incorporate home switches how many more switches would I need? 3, one for each axis? So tonight if I order 9 of the above switches I should be set correct? Will the controller accept that many switches? </p> http://diylilcnc.org/forum/topic/limit-switches#post-239 Sat, 06 Feb 2010 15:31:50 +0000 Taylor 239@http://diylilcnc.org/forum/ <p>There are a couple terms at work here. Hard limits are the physical limitations of the rig - hit those and the machine will mechanically lock up and potentially damage itself. Limit switches should be placed where they will arrest machine movement before it can reach hard limits. You can program the machine to instantly stop whenever one of the limit switches is tripped (due to careless jogging/manual movement or a toolpath that accidentally runs the machine to a hard limit). </p> <p>Home switches are used to run the mill back to a default starting location. When you run the same kind of job over and over, you might benefit from an additional set of home switches (if you used 1/2" material exclusively, for example). You can also use the hard limits as home switches, where you effectively tell the computer to run all three axes until the homes are tripped. We usually just jog the device by hand with a careful eye and reset the axes for each job as material thickness and positioning changes.</p> <p>You're right about the number - you need 2 switches to limit each axis. </p> http://diylilcnc.org/forum/topic/limit-switches#post-238 Sat, 06 Feb 2010 13:32:23 +0000 DIYengineer 238@http://diylilcnc.org/forum/ <p>How many would I need? Im guessing 6 right? 2 for each axis? What is a home switch? Are they just speaking of the same thing, or is that another that needs its own switch. I will order them up when I hear back from you, thanks for your help. </p> http://diylilcnc.org/forum/topic/limit-switches#post-234 Fri, 05 Feb 2010 08:58:31 +0000 Chris 234@http://diylilcnc.org/forum/ <p>@DIYengineer, the plans currently do not include limit switches, but they are easy enough to set up. We ran a few tests but left them out of the plans for simplicity's sake. </p> <p>We had good luck with <a href="http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&amp;productId=2076279&amp;catalogId=10001&amp;freeText=2076279&amp;app.products.maxperpage=15&amp;storeId=10001&amp;search_type=jamecoall&amp;ddkey=http:StoreCatalogDrillDownView">these switches from Jameco</a>. In a nutshell, the switch ties in with the 5V line from the driver board, then terminates in the appropriate pin. Here's a blurb from the HobbyCNC instructions about how to set it up:</p> <p><img src="http://diylilcnc.org/wp-content/uploads/2010/02/DIYLILCNC_limit_switch_tip.jpg" /></p> <p>EMC2 can accommodate either <a href="http://en.wikipedia.org/wiki/Switch">normally open (NO)</a> or <a href="http://en.wikipedia.org/wiki/Switch">normally closed (NC)</a> switches, and the instructions above are right that normally closed switches are better since they fail safe. Check <a href="http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Homing_And_Limit_Switch">here</a> for info about how to set up the signal controls once you get the wiring done. </p> http://diylilcnc.org/forum/topic/limit-switches#post-231 Fri, 05 Feb 2010 00:01:43 +0000 DIYengineer 231@http://diylilcnc.org/forum/ <p>I just ordered everything tonight! What i didn't see on the list was any kind of limit switches. Does your cnc have them installed? Where do you advise getting them? </p>