**NOW AVAILABLE** Improved versions of these limit switches, on professionally-made PCBs, are now available for purchase on my Tindie store, with wiring and neodymium magnets optionally included! www.tindie.com/products/kevpa...
I also have professionally-made breakout boards for both sensor and stepper motor wiring, suitable for panel-mounting. Check out these items and more, here: www.tindie.com/search/#q=Creltek
Here's some information about a set of custom limit switches I made for my Shapeoko 2.
The limit switches are built on small PCBs with a hall-effect sensor as the active element. The hall-effect IC senses the proximity of a suitably oriented magnetic field, and closes the switch circuit when the magnet is close by.
I included a small bi-color LED (along with other miscellaneous support components) to give a visual indication of state. "Green" indicates that the limit switch is powered and ready. "Red" indicates that the switch has been triggered.
The switches are activated by small neodymium magnets that are mounted on the moving portions of the machine. The magnets are positioned so that the switches are triggered at a practical extreme axis position (with an appropriate safety margin, of course.)
The switches themselves are attached to the Shapeoko using small machine screws (into holes that I tapped, where needed).
The switches are wired to a TinyG motion controller using standard "flat" 4-conductor telephone cord. I was able to run this easily through various channels in the Shapeoko and keep things looking neat. The cords terminate with standard RJ-11 telephone plugs, which are plugged into a gang of RJ-11 jacks on a custom breakout PCB that I made. At some point in the future the TinyG, along with the power supplies and breakout boards, will be mounted in a suitable enclosure. (Right now they're screwed to a nearby wall stud under my basement stairs.)
28 дек 2014
